Cisco ASA Series Command Reference, I - R Commands
name -- num-packets
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Table of Contents

nac-authentication-server-group through num-packets Commands

nac-authentication-server-group (deprecated)

nac-policy

nac-settings

name

name (dynamic-filter blacklist or whitelist)

nameif

names

name-separator

name-server

nat (global)

nat (object)

nat (vpn load-balancing)

nat-assigned-to-public-ip

nat-rewrite

nbns-server (tunnel-group webvpn attributes mode)

nbns-server (webvpn mode)

neighbor

neighbor (EIGRP)

neighbor activate

neighbor advertisement-interval

neighbor default-originate

neighbor description

neighbor disable-connected-check

neighbor distribute-list

neighbor ebgp-multihop

neighbor filter-list

neighbor local-as

neighbor maximum-prefix

neighbor next-hop-self

neighbor password

neighbor prefix-list

neighbor remote-as

neighbor remove-private-as

neighbor route-map

neighbor send-community

neighbor shutdown

neighbor timers

neighbor transport

neighbor ttl-security

neighbor version

neighbor weight

nem

network

network (EIGRP)

network BGP

network-acl

network area

network-object

nop

nt-auth-domain-controller

ntp authenticate

ntp authentication-key

ntp server

ntp trusted-key

num-packets

nac-authentication-server-group through num-packets Commands

nac-authentication-server-group (deprecated)

To identify the group of authentication servers to be used for Network Admission Control posture validation, use the nac-authentication-server-group command in tunnel-group general-attributes configuration mode. To inherit the authentication server group from the default remote access group, access the alternative group policy from which to inherit it, then use the no form of this command.

nac-authentication-server-group server-group

no nac-authentication-server-group

 
Syntax Description

server-group

Name of the posture validation server group, as configured on the ASA using the aaa-server host command. The name must match the server-tag variable specified in that command.

 
Defaults

This command has no arguments or keywords.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Tunnel-group general-attributes configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.2(1)

This command was introduced.

8.0(1)

This command was deprecated. The authentication-server-group command in nac-policy-nac-framework configuration mode replaced it.

 
Usage Guidelines

Configure at least one Access Control Server to support NAC. Use the aaa-server command to name the ACS group. Then use the nac-authentication-server-group command, using the same name for the server group.

Examples

The following example identifies acs-group1 as the authentication server group to be used for NAC posture validation:

ciscoasa(config-group-policy)# nac-authentication-server-group acs-group1
ciscoasa(config-group-policy)
 

The following example inherits the authentication server group from the default remote access group.

ciscoasa(config-group-policy)# no nac-authentication-server-group
ciscoasa(config-group-policy)
 

 
Related Commands

Command
Description

aaa-server

Creates a record of the AAA server or group and sets the host-specific AAA server attributes.

debug eap

Enables logging of EAP events to debug NAC messaging.

debug eou

Enables logging of EAP over UDP (EAPoUDP) events to debug NAC messaging.

debug nac

Enables logging of NAC events.

nac

Enables Network Admission Control on a group policy.

nac-policy

To create or access a Cisco Network Admission Control (NAC) policy, and specify its type, use the nac-policy command in global configuration mode. To remove the NAC policy from the configuration, use the no form of this command.

nac-policy nac-policy-name nac-framework

[ no ] nac-policy nac-policy-name nac-framework

 
Syntax Description

nac-policy-name

Name of the NAC policy. Enter a string of up to 64 characters to name the NAC policy. The show running-config nac-policy command displays the name and configuration of each NAC policy already present on the security appliance.

nac-framework

Specifies the use of a NAC framework to provide a network access policy for remote hosts. A Cisco Access Control Server must be present on the network to provide NAC Framework services for the ASA.

If you specify this type, the prompt indicates you are in config--nac-policy-nac-framework configuration mode. This mode lets you configure the NAC Framework policy.

 
Defaults

This command has no default settings.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes

  • Yes

 
Command History

Release
Modification

8.0(2)

This command was introduced.

9.1(2)

This command was deprecated.

 
Usage Guidelines

Use this command once for each NAC Appliance to be assigned to a group policy. Then use the nac-settings command to assign the NAC policy to each applicable group policy. Upon the setup of an IPsec or Cisco AnyConnect VPN tunnel, the ASA applies the NAC policy associated with the group policy in use.

You cannot use the no nac-policy name command to remove a NAC policy if it is already assigned to one or more group policies.

Examples

The following command creates and accesses a NAC Framework policy named nac-framework1:

ciscoasa(config)# nac-policy nac-framework1 nac-framework
ciscoasa(config-nac-policy-nac-framework)
 

The following command removes the NAC Framework policy named nac-framework1:

ciscoasa(config)# no nac-policy nac-framework1
ciscoasa(config-nac-policy-nac-framework)
 

 
Related Commands

Command
Description

show running-config nac-policy

Displays the configuration of each NAC policy on the ASA.

show nac-policy

Displays NAC policy usage statistics on the ASA.

clear nac-policy

Resets the NAC policy usage statistics.

nac-settings

Assigns a NAC policy to a group policy.

clear configure nac-policy

Removes all NAC policies from the running configuration except for those that are assigned to group policies.

nac-settings

To assign a NAC policy to a group policy, use the nac-settings command in group-policy configuration mode, as follows:

nac-settings { value nac-policy-name | none }

[ no ] nac-settings { value nac-policy-name | none }

 
Syntax Description

nac-policy-name

NAC policy to be assigned to the group policy. The NAC policy you name must be present in the configuration of the ASA. The show running-config nac-policy command displays the name and configuration of each NAC policy.

none

Removes the nac-policy-name from the group policy and disables the use of a NAC policy for this group policy. The group policy does not inherit the nac-settings value from the default group policy.

value

Assigns the NAC policy to be named to the group policy.

 
Defaults

This command has no arguments or keywords.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Group-policy configuration

  • Yes

  • Yes

 
Command History

Release
Modification

8.0(2)

This command was introduced.

9.1(2)

This command was deprecated.

 
Usage Guidelines

Use the nac-policy command to specify the name and type of the NAC policy, then use this command to assign it to a group policy.

The show running-config nac-policy command displays the name and configuration of each NAC policy.

The ASA automatically enables NAC for a group policy when you assign a NAC policy to it.

Examples

The following command removes the nac-policy-name from the group policy. The group policy inherits the nac-settings value from the default group policy:

ciscoasa(config-group-policy)# no nac-settings
ciscoasa(config-group-policy)
 

The following command removes the nac-policy-name from the group policy and disables the use of a NAC policy for this group policy. The group policy does not inherit the nac-settings value from the default group policy.

ciscoasa(config-group-policy)# nac-settings none
ciscoasa(config-group-policy)
 

 
Related Commands

Command
Description

nac-policy

Creates and accesses a Cisco NAC policy, and specifies its type.

show running-config nac-policy

Displays the configuration of each NAC policy on the ASA.

show nac-policy

Displays NAC policy usage statistics on the ASA.

show vpn-session_summary.db

Displays the number IPsec, WebVPN, and NAC sessions.

show vpn-session.db

Displays information about VPN sessions, including NAC results.

name

To associate a name with an IP address, use the name command in global configuration mode. To disable the use of the text names but not remove them from the configuration, use the no form of this command.

name ip_address name [ description text]]

no name ip_address [ name [ description text ]]

 
Syntax Description

description

(Optional) Specifies a description for the ip address name.

ip_address

Specifies an IP address of the host that is named.

name

Specifies the name assigned to the IP address. Use characters a to z, A to Z, 0 to 9, a dash, and an underscore. The name must be 63 characters or less. Also, the name cannot start with a number.

text

Specifies the text for the description.

 
Defaults

No default behaviors or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

7.0(4)

This command was enhanced to include an optional description.

8.3(1)

You can no longer use a named IP address in a nat command or an access-list command; you must use object network names instead. Although network-object commands in an object group accept object network names, you can still also use a named IP address identified by the name command.

 
Usage Guidelines

To enable the association of a name with an IP address, use the names command. You can associate only one name with an IP address.

You must first use the names command before you use the name command. Use the name command immediately after you use the names command and before you use the write memory command.

The name command lets you identify a host by a text name and map text strings to IP addresses. The no name command allows you to disable the use of the text names but does not remove them from the configuration. Use the clear configure name command to clear the list of names from the configuration.

To disable displaying name values, use the no names command.

Both the name and names commands are saved in the configuration.

The name command does not support assigning a name to a network mask. For example, this command would be rejected:

ciscoasa(config)# name 255.255.255.0 class-C-mask

Note None of the commands in which a mask is required can process a name as an accepted network mask.


Examples

This example shows that the names command allows you to enable use of the name command. The name command substitutes sa_inside for references to 192.168.42.3 and sa_outside for 209.165.201.3. You can use these names with the ip address commands when assigning IP addresses to the network interfaces. The no names command disables the name command values from displaying. Subsequent use of the names command again restores the name command value display.

ciscoasa(config)# names
ciscoasa(config)# name 192.168.42.3 sa_inside
ciscoasa(config)# name 209.165.201.3 sa_outside
 
ciscoasa(config-if)# ip address inside sa_inside 255.255.255.0
ciscoasa(config-if)# ip address outside sa_outside 255.255.255.224
 
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address sa_inside mask 255.255.255.0
outside ip address sa_outside mask 255.255.255.224
 
ciscoasa(config)# no names
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address 192.168.42.3 mask 255.255.255.0
outside ip address 209.165.201.3 mask 255.255.255.224
 
ciscoasa(config)# names
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address sa_inside mask 255.255.255.0
outside ip address sa_outside mask 255.255.255.224

 
Related Commands

Command
Description

clear configure name

Clears the list of names from the configuration.

names

Enables the association of a name with an IP address.

show running-config name

Displays the names associated with an IP address.

name (dynamic-filter blacklist or whitelist)

To add a domain name to the Botnet Traffic Filter blacklist or whitelist, use the name command in dynamic-filter blacklist or whitelist configuration mode. To remove the name, use the no form of this command. The static database lets you augment the dynamic database with domain names or IP addresses that you want to whitelist or blacklist.

name domain_name

no name domain_name

 
Syntax Description

domain_name

Adds a name to the blacklist. You can enter this command multiple times for multiple entries. You can add up to 1000 blacklist entries.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Dynamic-filter blacklist or whitelist configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.2(1)

This command was introduced.

 
Usage Guidelines

After you enter the dynamic-filter whitelist or blacklist configuration mode, you can manually enter domain names or IP addresses (host or subnet) that you want to tag as good names in a whitelist or bad names in a blacklist using the address and name commands.

You can enter this command multiple times for multiple entries. You can add up to 1000 blacklist and 1000 whitelist entries.

When you add a domain name to the static database, the ASA waits 1 minute, and then sends a DNS request for that domain name and adds the domain name/IP address pairing to the DNS host cache . (This action is a background process, and does not affect your ability to continue configuring the ASA).

If you do not have a domain name server configured for the ASA, or it is unavailable, then you can alternatively enable DNS packet inspection with Botnet Traffic Filter snooping (see the inspect dns dynamic-filter-snooping command). With DNS snooping, when an infected host sends a DNS request for a name on the static database, the ASA looks inside the DNS packets for the domain name and associated IP address and adds the name and IP address to the DNS reverse lookup cache. See the inspect dns dynamic-filter-snooping command for information about the DNS reverse lookup cache.

Entries in the DNS host cache have a time to live (TTL) value provided by the DNS server. The largest TTL value allowed is 1 day (24 hours); if the DNS server provides a larger TTL, it is truncated to 1 day maximum.

For the DNS host cache, after an entry times out, the ASA periodically requests a refresh for the entry.

Examples

The following example creates entries for the blacklist and whitelist:

ciscoasa(config)# dynamic-filter blacklist
ciscoasa(config-llist)# name bad1.example.com
ciscoasa(config-llist)# name bad2.example.com
ciscoasa(config-llist)# address 10.1.1.1 255.255.255.0
ciscoasa(config-llist)# dynamic-filter whitelist
ciscoasa(config-llist)# name good.example.com
ciscoasa(config-llist)# name great.example.com
ciscoasa(config-llist)# name awesome.example.com
ciscoasa(config-llist)# address 10.1.1.2 255.255.255.255
 

 
Related Commands

Command
Description

address

Adds an IP address to the blacklist or whitelist.

clear configure dynamic-filter

Clears the running Botnet Traffic Filter configuration.

clear dynamic-filter dns-snoop

Clears Botnet Traffic Filter DNS snooping data.

clear dynamic-filter reports

Clears Botnet Traffic filter report data.

clear dynamic-filter statistics

Clears Botnet Traffic filter statistics.

dns domain-lookup

Enables the ASA to send DNS requests to a DNS server to perform a name lookup for supported commands.

dns server-group

Identifies a DNS server for the ASA.

dynamic-filter blacklist

Edits the Botnet Traffic Filter blacklist.

dynamic-filter database fetch

Manually retrieves the Botnet Traffic Filter dynamic database.

dynamic-filter database find

Searches the dynamic database for a domain name or IP address.

dynamic-filter database purge

Manually deletes the Botnet Traffic Filter dynamic database.

dynamic-filter enable

Enables the Botnet Traffic Filter for a class of traffic or for all traffic if you do not specify an access list.

dynamic-filter updater-client enable

Enables downloading of the dynamic database.

dynamic-filter use-database

Enables use of the dynamic database.

dynamic-filter whitelist

Edits the Botnet Traffic Filter whitelist.

inspect dns dynamic-filter-snoop

Enables DNS inspection with Botnet Traffic Filter snooping.

name

Adds a name to the blacklist or whitelist.

show asp table dynamic-filter

Shows the Botnet Traffic Filter rules that are installed in the accelerated security path.

show dynamic-filter data

Shows information about the dynamic database, including when the dynamic database was last downloaded, the version of the database, how many entries the database contains, and 10 sample entries.

show dynamic-filter dns-snoop

Shows the Botnet Traffic Filter DNS snooping summary, or with the detail keyword, the actual IP addresses and names.

show dynamic-filter reports

Generates reports of the top 10 botnet sites, ports, and infected hosts.

show dynamic-filter statistics

Shows how many connections were monitored with the Botnet Traffic Filter, and how many of those connections match the whitelist, blacklist, and greylist.

show dynamic-filter updater-client

Shows information about the updater server, including the server IP address, the next time the ASA will connect with the server, and the database version last installed.

show running-config dynamic-filter

Shows the Botnet Traffic Filter running configuration.

nameif

To provide a name for an interface, use the nameif command in interface configuration mode. To remove the name, use the no form of this command. The interface name is used in all configuration commands on the ASA instead of the interface type and ID (such as gigabitethernet0/1), and is therefore required before traffic can pass through the interface.

nameif name

no nameif

 
Syntax Description

name

Sets a name up to 48 characters in length. The name is not case-sensitive.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Interface configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.0(1)

This command was changed from a global configuration command to an interface configuration mode command.

 
Usage Guidelines

For subinterfaces, you must assign a VLAN with the vlan command before you enter the nameif command.

You can change the name by reentering this command with a new value. Do not enter the no form, because that command causes all commands that refer to that name to be deleted.

Examples

The following example configures the names for two interfaces to be “inside” and “outside:”

ciscoasa(config)# interface gigabitethernet0/1
ciscoasa(config-if)# nameif inside
ciscoasa(config-if)# security-level 100
ciscoasa(config-if)# ip address 10.1.1.1 255.255.255.0
ciscoasa(config-if)# no shutdown
ciscoasa(config-if)# interface gigabitethernet0/0
ciscoasa(config-if)# nameif outside
ciscoasa(config-if)# security-level 0
ciscoasa(config-if)# ip address 10.1.2.1 255.255.255.0
ciscoasa(config-if)# no shutdown
 

 
Related Commands

Command
Description

clear xlate

Resets all translations for existing connections, causing the connections to be reset.

interface

Configures an interface and enters interface configuration mode.

security-level

Sets the security level for the interface.

vlan

Assigns a VLAN ID to a subinterface.

names

To enable the association of a name with an IP address, use the names command in global configuration mode. You can associate only one name with an IP address. To disable displaying name values, use the no names command.

names

no names

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

No default behaviors or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

To enable the association of a name with an IP address, use the names command. You can associate only one name with an IP address.

You must first use the names command before you use the name command. Use the name command immediately after you use the names command and before you use the write memory command.

To disable displaying name values, use the no names command.

Both the name and names commands are saved in the configuration.

Examples

This example shows that the names command allows you to enable use of the name command. The name command substitutes sa_inside for references to 192.168.42.3 and sa_outside for 209.165.201.3. You can use these names with the ip address commands when assigning IP addresses to the network interfaces. The no names command disables the name command values from displaying. Subsequent use of the names command again restores the name command value display.

ciscoasa(config)# names
ciscoasa(config)# name 192.168.42.3 sa_inside
ciscoasa(config)# name 209.165.201.3 sa_outside
 
ciscoasa(config-if)# ip address inside sa_inside 255.255.255.0
ciscoasa(config-if)# ip address outside sa_outside 255.255.255.224
 
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address sa_inside mask 255.255.255.0
outside ip address sa_outside mask 255.255.255.224
 
ciscoasa(config)# no names
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address 192.168.42.3 mask 255.255.255.0
outside ip address 209.165.201.3 mask 255.255.255.224
 
ciscoasa(config)# names
ciscoasa(config)# show ip address
System IP Addresses:
inside ip address sa_inside mask 255.255.255.0
outside ip address sa_outside mask 255.255.255.224

 
Related Commands

Command
Description

clear configure name

Clears the list of names from the configuration.

name

Associates a name with an IP address.

show running-config name

Displays a list of names associated with IP addresses.

show running-config names

Displays the IP address-to-name conversions.

name-separator

To specify a character as a delimiter between the e-mail and VPN username and password, use the name-separator command in the applicable e-mail proxy mode. To revert to the default, “:”, use the no version of this command.

name-separator [ symbol ]

no name-separator

 
Syntax Description

symbol

(Optional) The character that separates the e-mail and VPN usernames and passwords. Choices are “@,” (at) “|” (pipe), “:”(colon), “#” (hash), “,” (comma), and “;” (semi-colon).

 
Defaults

The default is “:” (colon).

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Pop3s

  • Yes

  • Yes

Imap4s

  • Yes

  • Yes

Smtps

  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

The name separator must be different from the server separator.

Examples

The following example shows how to set a hash (#) as the name separator for POP3S:

ciscoasa(config)# pop3s
ciscoasa(config-pop3s)# name-separator #
 

 
Related Commands

Command
Description

server-separator

Separates the e-mail and server names.

name-server

To identify one or more DNS servers, use the name-server command in dns server-group configuration mode. To remove a server or servers, use the no form of this command. The ASA uses DNS to resolve server names in your SSL VPN configuration or certificate configuration (see “Usage Guidelines” for a list of supported commands). Other features that define server names (such as AAA) do not support DNS resolution. You must enter the IP address or manually resolve the name to an IP address by using the name command.

name-server ip_address [ ip_address2 ] [...] [ ip_address6 ]

no name-server ip_address [ ip_address2 ] [...] [ ip_address6 ]

 
Syntax Description

ip_address

Specifies the DNS server IP address. You can specify up to six addresses as separate commands, or for convenience, up to six addresses in one command separated by spaces. If you enter multiple servers in one command, the ASA saves each server in a separate command in the configuration. The ASA tries each DNS server in order until it receives a response.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

dns server-group configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.1(1)

This command was introduced.

 
Usage Guidelines

To enable DNS lookup, configure the domain-name command in dns server-group configuration mode. If you do not enable DNS lookup, the DNS servers are not used.

SSL VPN commands that support DNS resolution include the following:

  • server (pop3s)
  • server (imap4s)
  • server (smtps)
  • port-forward
  • url-list

Certificate commands that support DNS resolution include the following:

  • enrollment url
  • url

You can manually enter names and IP addresses using the name command.

Examples

The following example adds three DNS servers to the group “dnsgroup1”:

ciscoasa(config)# dns server-group dnsgroup1
ciscoasa(config-dns-server-group)# name-server 10.1.1.1 10.2.3.4 192.168.5.5
 

The ASA saves the configuration as separate commands, as follows:

name-server 10.1.1.1
name-server 10.2.3.4
name-server 192.168.5.5
 

To add two additional servers, you can enter them as one command:

ciscoasa(config)# dns server-group dnsgroup1
ciscoasa(config-dns-server-group)# name-server 10.5.1.1 10.8.3.8
 

To verify the dns server group configuration, enter the show running-config dns command in global configuration mode:

ciscoasa(config)# show running-config dns
name-server 10.1.1.1
name-server 10.2.3.4
name-server 192.168.5.5
name-server 10.5.1.1
name-server 10.8.3.8
...
 

Or you can enter them as two separate commands:

ciscoasa(config)# dns server-group dnsgroup1
ciscoasa(config-dns-server-group)# name-server 10.5.1.1
ciscoasa(config)# name-server 10.8.3.8
 

To delete multiple servers you can enter them as multiple commands or as one command, as follows:

ciscoasa(config)# dns server-group dnsgroup1
ciscoasa(config-dns-server-group)# no name-server 10.5.1.1 10.8.3.8
 

 
Related Commands

Command
Description

domain-name

Sets the default domain name.

retries

Specifies the number of times to retry the list of DNS servers when the ASA does not receive a response.

timeout

Specifies the amount of time to wait before trying the next DNS server.

show running-config dns server-group

Shows one or all the existing dns-server-group configurations.

nat (global)

To configure twice NAT for IPv4, IPv6, or between IPv4 and IPv6 (NAT64), use the nat command in global configuration mode. To remove the twice NAT configuration, use the no form of this command.

For static NAT:

nat [ ( real_ifc , mapped_ifc ) ] [ line | { after-auto [ line ]}]
source static { real_obj | any } { mapped_obj | interface [ ipv6 ] | any }}
[ destination static { mapped_obj | interface [ ipv6 ]} { real_obj | any }]
[ service { real_src_mapped_dest_svc_obj | any } mapped_src_real_dest_svc_obj ] [ net-to-net ] [ dns ] [ unidirectional | [ no-proxy-arp ] [ route-lookup ]] [ inactive ] [ description desc ]

no nat [ ( real_ifc , mapped_ifc ) ] [ line | { after-auto [ line ]}]
source static { real_obj | any } { mapped_obj | interface [ ipv6 ] | any }}
[ destination static { mapped_obj | interface [ ipv6 ]} { real_obj | any }]
[ service { real_src_mapped_dest_svc_obj | any } mapped_src_real_dest_svc_obj ] [ net-to-net ] [ dns ] [ unidirectional | [ no-proxy-arp ] [ route-lookup ]] [ inactive ] [ description desc ]

For dynamic NAT:

nat [ ( real_ifc , mapped_ifc ) ] [ line | { after-auto [ line ]}]
source dynamic { real_obj | any }
{[ mapped_obj ] [ pat-pool mapped_obj [ round-robin ] [ extended ] [ flat [ include-reserve ]]] [ interface [ ipv6 ]]}
[ destination static { mapped_obj | interface [ ipv6 ]} { real_obj | any }]
[ service { mapped_dest_svc_obj real_dest_svc_obj ] [ dns ] [ unidirectional ] [ inactive ] [ description desc ]

no nat [ ( real_ifc , mapped_ifc ) ] [ line | { after-auto [ line ]}]
source dynamic { real_obj | any }
{[ mapped_obj ] [ pat-pool mapped_obj [ round-robin ] [ extended ] [ flat [ include-reserve ]]] [ interface [ ipv6 ]]}
[ destination static { mapped_obj | interface [ ipv6 ]} { real_obj | any }]
[ service { mapped_dest_svc_obj real_dest_svc_obj ] [ dns ] [ unidirectional ] [ inactive ] [ description desc ]

or

no nat { line | after-auto line }

 
Syntax Description

( real_ifc , mapped_ifc )

(Optional) Specifies the real and mapped interfaces. If you do not specify the real and mapped interfaces, all interfaces are used. You can also specify the keyword any for one or both of the interfaces. In transparent mode, you must specify the real and mapped interfaces; you cannot use any .

Because twice NAT can translate both the source and destination addresses, these interfaces are better understood to be the source and destination interfaces.

after-auto

Inserts the rule at the end of section 3 of the NAT table, after the network object NAT rules. By default, twice NAT rules are added to section 1. You can insert a rule anywhere in section 3 using the line argument.

any

(Optional) Specifies a wildcard value. The main uses for any are:

  • Interfaces—You can use any for one or both interfaces ( (any,outside) , for example). If you do not specify the interfaces, then any is the default. any is not available in transparent mode.
  • Static NAT source real and mapped IP addresses—You can specify source static any any to enable identity NAT for all addresses.
  • Dynamic NAT or PAT source real addresses—You can translate all addresses on the source interface by specifying source dynamic any mapped_obj .

For static NAT, although any is also available for the real source port/mapped destination port, or for the source or destination real address (without any as the mapped address), these uses might result in unpredictable behavior.

Note The definition of “any” traffic (IPv4 vs. IPv6) depends on the rule. Before the ASA performs NAT on a packet, the packet must be IPv6-to-IPv6 or IPv4-to-IPv4; with this prerequisite, the ASA can determine the value of any in a NAT rule. For example, if you configure a rule from “any” to an IPv6 server, and that server was mapped from an IPv4 address, then any means “any IPv6 traffic.” If you configure a rule from “any” to “any,” and you map the source to the interface IPv4 address, then any means “any IPv4 traffic” because the mapped interface address implies that the destination is also IPv4.

description desc

(Optional) Provides a description up to 200 characters.

destination

(Optional) Configures translation for the destination address. Although the main feature of twice NAT is the inclusion of the destination IP address, the destination address is optional. If you do specify the destination address, you can configure static translation for that address or just use identity NAT for it. You might want to configure twice NAT without a destination address to take advantage of some of the other qualities of twice NAT, including the use of network object groups for real addresses, or manually ordering of rules. For more information, see the CLI configuration guide.

dns

(Optional) Translates DNS replies. Be sure DNS inspection is enabled ( inspect dns ) (it is enabled by default). You cannot configure the dns keyword if you configure a destination address. See the CLI configuration guide for more information.

dynamic

Configures dynamic NAT or PAT for the source addresses. The destination translation is always static.

extended

(Optional) Enables extended PAT for a PAT pool. Extended PAT uses 65535 ports per service , as opposed to per IP address, by including the destination address and port in the translation information. Normally, the destination port and address are not considered when creating PAT translations, so you are limited to 65535 ports per PAT address. For example, with extended PAT, you can create a translation of 10.1.1.1:1027 when going to 192.168.1.7:23 as well as a translation of 10.1.1.1:1027 when going to 192.168.1.7:80.

flat [ include-reserve ]

(Optional) Enables use of the entire 1024 to 65535 port range when allocating ports. When choosing the mapped port number for a translation, the ASA uses the real source port number if it is available. However, without this option, if the real port is not available, by default the mapped ports are chosen from the same range of ports as the real port number: 1 to 511, 512 to 1023, and 1024 to 65535. To avoid running out of ports at the low ranges, configure this setting. To use the entire range of 1 to 65535, also specify the include-reserve keyword.

inactive

(Optional) To make this rule inactive without having to remove the command, use the inactive keyword. To reactivate it, reenter the whole command without the inactive keyword.

interface [ ipv6 ]

(Optional) Uses the interface IP address as the mapped address. If you specify ipv6 , then the IPv6 address of the interface is used.

For the dynamic NAT source mapped address, if you specify a mapped object or group followed by the interface keyword, then the IP address of the mapped interface is only used if all other mapped addresses are already allocated.

For dynamic PAT, you can specify interface alone for the source mapped address.

For static NAT with port translation (source or destination), be sure to also configure the service keyword.

For this option, you must configure a specific interface for the mapped_ifc .

This option is not available in transparent mode.

line

(Optional) Inserts a rule anywhere in section 1 of the NAT table. By default, the NAT rule is added to the end of section 1 (see the CLI configuration guide for more information). If you want to add the rule into section 3 instead (after the network object NAT rules), then use the after-auto line option.

mapped_dest_svc_obj

(Optional) For dynamic NAT/PAT, specifies the mapped destination port (the destination translation is always static). See the service keyword for more information.

mapped_object

Identifies the mapped network object or object group ( object network or object-group network ).

For dynamic NAT, you typically configure a larger group of addresses to be mapped to a smaller group.

Note The mapped object or group cannot contain a subnet.

You can share this mapped IP address across different dynamic NAT rules, if desired.

You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

For dynamic PAT, configure a group of addresses to be mapped to a single address. You can either translate the real addresses to a single mapped address of your choosing, or you can translate them to the mapped interface address. If you want to use the interface address, do not configure a network object for the mapped address; instead use the interface keyword.

For static NAT, the mapping is typically one-to-one, so the real addresses have the same quantity as the mapped addresses. You can, however, have different quantities if desired. For more information, see the CLI configuration guide.

mapped_src_real_dest_svc_obj

(Optional) For static NAT, specifies the either the mapped source port, the real destination port, or both together. See the service keyword for more information.

net-to-net

(Optional) For static NAT 46, specify net-to-net to translate the first IPv4 address to the first IPv6 address, the second to the second, and so on. Without this option, the IPv4-embedded method is used. For a one-to-one translation, you must use this keyword.

no-proxy-arp

(Optional) For static NAT, disables proxy ARP for incoming packets to the mapped IP addresses.

pat-pool mapped_obj

(Optional) Enables a PAT pool of addresses; all addresses in the object are used as PAT addresses. You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

real_dest_svc_obj

(Optional) For dynamic NAT/PAT, specifies the real destination port (the destination translation is always static). See the service keyword for more information.

real_ifc

(Optional) Specifies the name of the interface where packets may originate. For source option. For the source option, the origin_ifc is the real interface. For the destination option, the real_ifc is the mapped interface.

real_object

Identifies the real network object or object group ( object network or object-group network ). You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

real_src_mapped_dest_svc_obj

(Optional) For static NAT, specifies the either the real source port, the mapped destination port, or both together. See the service keyword for more information.

round-robin

(Optional) Enables round-robin address allocation for a PAT pool. By default, all ports for a PAT address will be allocated before the next PAT address is used. The round-robin method assigns an address/port from each PAT address in the pool before returning to use the first address again, and then the second address, and so on.

route-lookup

(Optional) For identity NAT in routed mode, determines the egress interface using a route lookup instead of using the interface specified in the NAT command. If you do not specify interfaces in the NAT command, a route lookup is used by default.

service

(Optional) Specifies the port translation.

  • Dynamic NAT and PAT—Dynamic NAT and PAT do not support (additional) port translation. However, because the destination translation is always static, you can perform port translation for the destination port. A service object ( object service ) can contain both a source and destination port, but only the destination port is used in this case. If you specify the source port, it will be ignored.
  • Static NAT with port translation—You should specify either the source or the destination port for both service objects. You should only specify both the source and destination ports if your application uses a fixed source port (such as some DNS servers); but fixed source ports are rare.

For source port translation, the objects must specify the source service. The order of the service objects in the command in this case is service real_port mapped_port . For destination port translation, the objects must specify the destination service. The order of the service objects in this case is service mapped_port real_port . In the rare case where you specify both the source and destination ports in the object, the first service object contains the real source port/mapped destination port; the second service object contains the mapped source port/real destination port. See the “Usage Guidelines” section for more information about “source” and “destination” terminology.

For identity port translation, simply use the same service object for both the real and mapped ports (source and/or destination ports, depending on your configuration). The “not equal” ( neq ) operator is not supported.

NAT only supports TCP or UDP. When translating a port, be sure the protocols in the real and mapped service objects are identical (both TCP or both UDP).

source

Configures translation for the source address.

static

Configures static NAT or static NAT with port translation.

unidirectional

(Optional) For static NAT, makes the translarion unidirection from the source to the destination; the destination addresses cannot initiate traffic to the source addresses. This option might be useful for testing purposes.

 
Defaults

  • By default, the rule is added to the end of section 1 of the NAT table.
  • The default value of real_ifc and mapped_ifc is any , which applies the rule to all interfaces.
  • (8.3(1), 8.3(2), and 8.4(1)) The default behavior for identity NAT has proxy ARP disabled. You cannot configure this setting. (8.4(2) and later) The default behavior for identity NAT has proxy ARP enabled, matching other static NAT rules. You can disable proxy ARP if desired.
  • If you specify an optional interface, then the ASA uses the NAT configuration to determine the egress interface. (8.3(1) through 8.4(1)) The only exception is for identity NAT, which always uses a route lookup, regardless of the NAT configuration. (8.4(2) and later) For identity NAT, the default behavior is to use the NAT configuration, but you have the option to always use a route lookup instead.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.3(1)

This command was introduced.

8.3(2)

When migrating from a pre-8.3 NAT exemption configuration, the keyword unidirectional is added for the resulting static identity NAT rule.

8.4(2)/8.5(1)

The no-proxy-arp , route-lookup , pat-pool , and round-robin keywords were added.

The default behavior for identity NAT was changed to have proxy ARP enabled, matching other static NAT rules.

For pre-8.3 configurations, the migration of NAT exempt rules (the nat 0 access-list command) to 8.4(2) and later now includes the following keywords to disable proxy ARP and to use a route lookup: no-proxy-arp and route-lookup . The unidirectional keyword that was used for migrating to 8.3(2) and 8.4(1) is no longer used for migration. When upgrading to 8.4(2) from 8.3(1), 8.3(2), and 8.4(1), all identity NAT configurations will now include the no-proxy-arp and route-lookup keywords, to maintain existing functionality. The unidirectional keyword is removed.

8.4(3)

The extended , flat , and include-reserve keywords were added.

When using a PAT pool with round robin allocation, if a host has an existing connection, then subsequent connections from that host will use the same PAT IP address if ports are available.

This feature is not available in 8.5(1).

9.0(1)

NAT now supports IPv6 traffic, as well as translating between IPv4 and IPv6. Translating between IPv4 and IPv6 is not supported in transparent mode. We added the interface ipv6 option and the net-to-net option.

 
Usage Guidelines

Twice NAT lets you identify both the source and destination address in a single rule. Specifying both the source and destination addresses lets you specify that a source address should be translated to A when going to destination X, but be translated to B when going to destination Y, for example.


Note For static NAT, the rule is bidirectional, so be aware that “source” and “destination” are used in commands and descriptions throughout this guide even though a given connection might originate at the “destination” address. For example, if you configure static NAT with port translation, and specify the source address as a Telnet server, and you want all traffic going to that Telnet server to have the port translated from 2323 to 23, then in the command, you must specify the source ports to be translated (real: 23, mapped: 2323). You specify the source ports because you specified the Telnet server address as the source address.


The destination address is optional. If you specify the destination address, you can either map it to itself (identity NAT), or you can map it to a different address. The destination mapping is always a static mapping.

Twice NAT also lets you use service objects for static NAT with port translation; network object NAT only accepts inline definition.

For detailed information about the differences between twice NAT and network object NAT, see the CLI configuration guide.

Twice NAT rules are added to section 1 of the NAT rules table, or if specified, section 3. For more information about NAT ordering, see the CLI configuration guide.

Mapped Address Guidelines

The mapped IP address pool cannot include:

  • The mapped interface IP address. If you specify any interface for the rule, then all interface IP addresses are disallowed. For interface PAT (routed mode only), use the interface keyword instead of the IP address.
  • (Transparent mode) The management IP address.
  • (Dynamic NAT) The standby interface IP address when VPN is enabled.
  • Existing VPN pool addresses.

Prerequisites

  • For both the real and mapped addresses, configure network objects or network object groups (the object network or object-group network command). Network object groups are particularly useful for creating a mapped address pool with discontinuous IP address ranges or multiple hosts or subnets. You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.
  • For static NAT with port translation, configure TCP or UDP service objects (the object service command).

Objects and object groups used in NAT cannot be undefined; they must include IP addresses.

Clearing Translation Sessions

If you change the NAT configuration, and you do not want to wait for existing translations to time out before the new NAT information is used, you can clear the translation table using clear xlate command. However, clearing the translation table disconnects all of the current connections.

PAT Pool Guidelines

  • DNS rewrite is not applicable for PAT because multiple PAT rules are applicable for each A-record, and the PAT rule to use is ambiguous.
  • If available, the real source port number is used for the mapped port. However, if the real port is not available, by default the mapped ports are chosen from the same range of ports as the real port number: 0 to 511, 512 to 1023, and 1024 to 65535. Therefore, ports below 1024 have only a small PAT pool that can be used. (8.4(3) and later, not including 8.5(1) or 8.6(1)) If you have a lot of traffic that uses the lower port ranges, you can now specify a flat range of ports to be used instead of the three unequal-sized tiers: either 1024 to 65535, or 1 to 65535.
  • (8.4(3) and later, not including 8.5(1) or 8.6(1)) If you use the same PAT pool object in two separate rules, then be sure to specify the same options for each rule. For example, if one rule specifies extended PAT and a flat range, then the other rule must also specify extended PAT and a flat range.

Extended PAT for a PAT Pool Guidelines

  • Many application inspections do not support extended PAT. See the configuration guide for a complete list of unsupported inspections.
  • If you enable extended PAT for a dynamic PAT rule, then you cannot also use an address in the PAT pool as the PAT address in a separate static NAT-with-port-translation rule. For example, if the PAT pool includes 10.1.1.1, then you cannot create a static NAT-with-port-translation rule using 10.1.1.1 as the PAT address.
  • If you use a PAT pool and specify an interface for fallback, you cannot specify extended PAT.
  • For VoIP deployments that use ICE or TURN, do not use extended PAT. ICE and TURN rely on the PAT binding to be the same for all destinations.

Round robin for a PAT Pool Guidelines

  • (8.4(3) and later, not including 8.5(1) or 8.6(1)) If a host has an existing connection, then subsequent connections from that host will use the same PAT IP address if ports are available. Note : This “stickiness” does not survive a failover. If the ASA fails over, then subsequent connections from a host may not use the initial IP address.
  • (8.4(2), 8.5(1), and 8.6(1)) If a host has an existing connection, then subsequent connections from that host will likely use different PAT addresses for each connection because of the round robin allocation. In this case, you may have problems when accessing two websites that exchange information about the host, for example an e-commerce site and a payment site. When these sites see two different IP addresses for what is supposed to be a single host, the transaction may fail.

NAT and IPv6

You can use NAT to translate between IPv6 networks, and also to translate between IPv4 and IPv6 networks (routed mode only). We recommend the following best practices:

  • NAT66 (IPv6-to-IPv6)—We recommend using static NAT. Although you can use dynamic NAT or PAT, IPv6 addresses are in such large supply, you do not have to use dynamic NAT. If you do not want to allow returning traffic, you can make the static NAT rule unidirectional (twice NAT only).
  • NAT46 (IPv4-to-IPv6)—We recommend using static NAT. Because the IPv6 address space is so much larger than the IPv4 address space, you can easily accommodate a static translation. If you do not want to allow returning traffic, you can make the static NAT rule unidirectional (twice NAT only). When translating to an IPv6 subnet (/96 or lower), the resulting mapped address is an IPv4-embedded IPv6 address, where the 32-bits of the IPv4 address is embedded after the IPv6 prefix. For example, if the IPv6 prefix is a /96 prefix, then the IPv4 address is appended in the last 32-bits of the address. For example, if you map 192.168.1.0/24 to 201b::0/96, then 192.168.1.4 will be mapped to 201b::0.192.168.1.4 (shown with mixed notation). If the prefix is smaller, such as /64, then the IPv4 address is appended after the prefix, and a suffix of 0s is appended after the IPv4 address.
  • NAT64 (IPv6-to-IPv4)—You may not have enough IPv4 addresses to accommodate the number of IPv6 addresses. We recommend using a dynamic PAT pool to provide a large number of IPv4 translations.

Examples

The following example includes a host on the 10.1.2.0/24 network that accesses two different servers. When the host accesses the server at 209.165.201.11, the real address is translated to 209.165.202.129: port . When the host accesses the server at 209.165.200.225, the real address is translated to 209.165.202.130: port .

ciscoasa(config)# object network myInsideNetwork
ciscoasa(config-network-object)# subnet 10.1.2.0 255.255.255.0
 
ciscoasa(config)# object network DMZnetwork1
ciscoasa(config-network-object)# subnet 209.165.201.0 255.255.255.224
 
ciscoasa(config)# object network PATaddress1
ciscoasa(config-network-object)# host 209.165.202.129
 

ciscoasa(config)# nat (inside,dmz) source dynamic myInsideNetwork PATaddress1 destination static DMZnetwork1 DMZnetwork1

 

ciscoasa(config)# object network DMZnetwork2
ciscoasa(config-network-object)# subnet 209.165.200.224 255.255.255.224
 
ciscoasa(config)# object network PATaddress2
ciscoasa(config-network-object)# host 209.165.202.130
 

ciscoasa(config)# nat (inside,dmz) source dynamic myInsideNetwork PATaddress2 destination static DMZnetwork2 DMZnetwork2

 

The following example shows the use of source and destination ports. The host on the 10.1.2.0/24 network accesses a single host for both web services and Telnet services. When the host accesses the server for Telnet services, the real address is translated to 209.165.202.129: port . When the host accesses the same server for web services, the real address is translated to 209.165.202.130: port .

ciscoasa(config)# object network myInsideNetwork
ciscoasa(config-network-object)# subnet 10.1.2.0 255.255.255.0
 
ciscoasa(config)# object network TelnetWebServer
ciscoasa(config-network-object)# host 209.165.201.11
 
ciscoasa(config)# object network PATaddress1
ciscoasa(config-network-object)# host 209.165.202.129
 
ciscoasa(config)# object service TelnetObj
ciscoasa(config-network-object)# service tcp destination eq telnet
 

ciscoasa(config)# nat (inside,outside) source dynamic myInsideNetwork PATaddress1 destination static TelnetWebServer TelnetWebServer service TelnetObj TelnetObj

 

ciscoasa(config)# object network PATaddress2
ciscoasa(config-network-object)# host 209.165.202.130
 
ciscoasa(config)# object service HTTPObj
ciscoasa(config-network-object)# service tcp destination eq http
 

ciscoasa(config)# nat (inside,outside) source dynamic myInsideNetwork PATaddress2 destination static TelnetWebServer TelnetWebServer service HTTPObj HTTPObj

 

The following example shows the use of static interface NAT with port translation. Hosts on the outside access an FTP server on the inside by connecting to the outside interface IP address with destination port 65000 through 65004. The traffic is untranslated to the internal FTP server at 192.168.10.100:6500 through :65004. Note that you specify the source port range in the service object (and not the destination port) because you want to translate the source address and port as identified in the command; the destination port is “any.” Because static NAT is bidirectional, “source” and “destination” refers primarily to the command keywords; the actual source and destination address and port in a packet depends on which host sent the packet. In this example, connections are originated from outside to inside, so the “source” address and port of the FTP server is actually the destination address and port in the originating packet.

ciscoasa(config)# object service FTP_PASV_PORT_RANGE

ciscoasa(config-service-obvject)# service tcp source range 65000 65004

 

ciscoasa(config)# object network HOST_FTP_SERVER

ciscoasa(config-network-obvject)# host 192.168.10.100

 

ciscoasa(config)# nat (inside,outside) source static HOST_FTP_SERVER interface service FTP_PASV_PORT_RANGE FTP_PASV_PORT_RANGE

 

The following example configures dynamic NAT for an IPv6 inside network 2001:DB8:AAAA::/96 when accessing servers on the IPv4 209.165.201.1/27 network as well as servers on the 203.0.113.0/24 network:

ciscoasa(config)# object network INSIDE_NW

ciscoasa(config-network-object)# subnet 2001:DB8:AAAA::/96

 

ciscoasa(config)# object network MAPPED_1

ciscoasa(config-network-object)# range 209.165.200.225 209.165.200.254

 

ciscoasa(config)# object network MAPPED_2

ciscoasa(config-network-object)# range 209.165.202.129 209.165.200.158

 

ciscoasa(config)# object network SERVERS_1

ciscoasa(config-network-object)# subnet 209.165.201.0 255.255.255.224

 

ciscoasa(config)# object network SERVERS_2

ciscoasa(config-network-object)# subnet 203.0.113.0 255.255.255.0

 

ciscoasa(config)# nat (inside,outside) source dynamic INSIDE_NW MAPPED_1 destination static SERVERS_1 SERVERS_1

ciscoasa(config)# nat (inside,outside) source dynamic INSIDE_NW MAPPED_2 destination static SERVERS_2 SERVERS_2

 

The following example configures interface PAT for inside network 192.168.1.0/24 when accessing outside IPv6 Telnet server 2001:DB8::23, and Dynamic PAT using a PAT pool when accessing any server on the 2001:DB8:AAAA::/96 network.

ciscoasa(config)# object network INSIDE_NW

ciscoasa(config-network-object)# subnet 192.168.1.0 255.255.255.0

 

ciscoasa(config)# object network PAT_POOL

ciscoasa(config-network-object)# range 2001:DB8:AAAA::1 2001:DB8:AAAA::200

 

ciscoasa(config)# object network TELNET_SVR

ciscoasa(config-network-object)# host 2001:DB8::23

 

ciscoasa(config)# object service TELNET

ciscoasa(config-service-object)# service tcp destination eq 23

 

ciscoasa(config)# object network SERVERS

ciscoasa(config-network-object)# subnet 2001:DB8:AAAA::/96

 

ciscoasa(config)# nat (inside,outside) source dynamic INSIDE_NW interface ipv6 destination static TELNET_SVR TELNET_SVR service TELNET TELNET

ciscoasa(config)# nat (inside,outside) source dynamic INSIDE_NW pat-pool PAT_POOL destination static SERVERS SERVERS

 

 

 
Related Commands

Command
Description

clear configure nat

Removes the NAT configuration (both twice NAT and network object NAT).

show nat

Displays NAT policy statistics.

show nat pool

Displays information about NAT pools.

show running-config nat

Shows the NAT configuration.

show xlate

Displays NAT session (xlate) information.

nat (object)

To configure NAT for a network object, use the nat command in object network configuration mode. To remove the NAT configuration, use the no form of this command.

For dynamic NAT and PAT:

nat [ ( real_ifc , mapped_ifc ) ] dynamic
{ mapped_inline_host_ip [ interface [ ipv6 ]] | [ mapped_obj ] [ pat-pool mapped_obj [ round-robin ] [ extended ] [ flat [ include-reserve ]]] [ interface [ ipv6 ]]} [ dns ]

no nat [ ( real_ifc , mapped_ifc ) ] dynamic
{ mapped_inline_host_ip [ interface [ ipv6 ]] | [ mapped_obj ] [ pat-pool mapped_obj [ round-robin ] [ extended ] [ flat [ include-reserve ]]] [ interface [ ipv6 ]]} [ dns ]

For static NAT and static NAT with port translation:

nat [ ( real_ifc , mapped_ifc ) ] static { mapped_inline_ip | mapped_obj | interface [ ipv6 ]} [ net-to-net ] [ dns | service { tcp | udp } real_port mapped_port ] [ no-proxy-arp ] [ route-lookup ]

no nat [ ( real_ifc , mapped_ifc ) ] static { mapped_inline_ip | mapped_obj | interface [ ipv6 ]} [ net-to-net ] [ dns | service { tcp | udp } real_port mapped_port ] [ no-proxy-arp ] [ route-lookup ]

 
Syntax Description

( real_ifc , mapped_ifc )

(Optional) For static NAT, specifies the real and mapped interfaces. If you do not specify the real and mapped interfaces, all interfaces are used. You can also specify the keyword any for one or both of the interfaces. Be sure to include the parentheses in your command. In transparent mode, you must specify the real and mapped interfaces; you cannot use any .

dns

(Optional) Translates DNS replies. Be sure DNS inspection ( inspect dns ) is enabled (it is enabled by default). This option is not available if you specify the service keyword (for static NAT). For more information, see the CLI configuration guide.

dynamic

Configures dynamic NAT or PAT.

extended

(Optional) Enables extended PAT for a PAT pool. Extended PAT uses 65535 ports per service , as opposed to per IP address, by including the destination address and port in the translation information. Normally, the destination port and address are not considered when creating PAT translations, so you are limited to 65535 ports per PAT address. For example, with extended PAT, you can create a translation of 10.1.1.1:1027 when going to 192.168.1.7:23 as well as a translation of 10.1.1.1:1027 when going to 192.168.1.7:80.

flat [ include-reserve ]

(Optional) Enables use of the entire 1024 to 65535 port range when allocating ports. When choosing the mapped port number for a translation, the ASA uses the real source port number if it is available. However, without this option, if the real port is not available, by default the mapped ports are chosen from the same range of ports as the real port number: 1 to 511, 512 to 1023, and 1024 to 65535. To avoid running out of ports at the low ranges, configure this setting. To use the entire range of 1 to 65535, also specify the include-reserve keyword.

interface [ ipv6 ]

(Optional) For dynamic NAT, if you specify a mapped IP address, object, or group followed by the interface keyword, then the IP address of the mapped interface is only used if all of the other mapped addresses are already allocated.

For dynamic PAT, if you specify the interface keyword instead of a mapped IP address, object, or group, then you use the interface IP address for the mapped IP address. You must use this keyword when you want to use the interface IP address; you cannot enter it inline or as an object.

If you specify ipv6 , then the IPv6 address of the interface is used.

For static NAT with port translation, you can specify the interface keyword if you also configure the service keyword.

For this option, you must configure a specific interface for the mapped_ifc .

You cannot specify interface in transparent mode.

mapped_inline_host_ip

Specifies the mapped address as an inline value. If you specify dynamic , then using a host IP address configures dynamic PAT.

mapped_inline_ip

For static NAT, specifies the mapped IP address as an inline value. The netmask or range for the mapped network is the same as that of the real network. For example, if the real network is a host, then this address will be a host address. In the case of a range, then the mapped addresses include the same number of addresses as the real range. For example, if the real address is defined as a range from 10.1.1.1 through 10.1.1.6, and you specify 172.20.1.1 as the mapped address, then the mapped range will include 172.20.1.1 through 172.20.1.6.

mapped_obj

Specifies the mapped IP address(es) as a network object ( object network ) or object group ( object-group network ). You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

For dynamic NAT, the object or group cannot contain a subnet. You can share this mapped object across different dynamic NAT rules, if desired. See the “Mapped Address Guidelines” section for information about disallowed mapped IP addresses.

For static NAT, typically you configure the same number of mapped addresses as real addresses for a one-to-one mapping. You can, however, have a mismatched number of addresses. For more information, see the CLI configuration guide.

mapped_port

(Optional) Specifies the mapped TCP or UDP port. You can specify ports by either a literal name or a number in the range of 0 to 65535.

net-to-net

(Optional) For NAT 46, specify net-to-net to translate the first IPv4 address to the first IPv6 address, the second to the second, and so on. Without this option, the IPv4-embedded method is used. For a one-to-one translation, you must use this keyword.

no-proxy-arp

(Optional) For static NAT, disables proxy ARP for incoming packets to the mapped IP addresses.

pat-pool mapped_obj

(Optional) Enables a PAT pool of addresses; all addresses in the object are used as PAT addresses. You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

real_port

(Optional) For static NAT, specifies the real TCP or UDP port. You can specify ports by either a literal name or a number in the range of 0 to 65535.

round-robin

(Optional) Enables round-robin address allocation for a PAT pool. By default, all ports for a PAT address will be allocated before the next PAT address is used. The round-robin method assigns an address/port from each PAT address in the pool before returning to use the first address again, and then the second address, and so on.

route-lookup

(Optional) For identity NAT in routed mode, determines the egress interface using a route lookup instead of using the interface specified in the NAT command. If you do not specify interfaces in the NAT command, a route lookup is used by default.

service { tcp | udp }

(Optional) For static NAT with port translation, specifies the protocol for port translation. Only TCP and UDP are supported.

static

Configures static NAT or static NAT with port translation.

 
Defaults

  • The default value of real_ifc and mapped_ifc is any , which applies the rule to all interfaces.
  • (8.3(1), 8.3(2), and 8.4(1)) The default behavior for identity NAT has proxy ARP disabled. You cannot configure this setting. (8.4(2) and later) The default behavior for identity NAT has proxy ARP enabled, matching other static NAT rules. You can disable proxy ARP if desired.
  • If you specify an optional interface, then the ASA uses the NAT configuration to determine the egress interface. (8.3(1) through 8.4(1)) The only exception is for identity NAT, which always uses a route lookup, regardless of the NAT configuration. (8.4(2) and later) For identity NAT, the default behavior is to use the NAT configuration, but you have the option to always use a route lookup instead.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Object network configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.3(1)

This command was introduced.

8.4(2)/8.5(1)

The no-proxy-arp , route-lookup , pat-pool , and round-robin keywords were added.

The default behavior for identity NAT was changed to have proxy ARP enabled, matching other static NAT rules.

When upgrading to 8.4(2) from 8.3(1), 8.3(2), and 8.4(1), all identity NAT configurations will now include the no-proxy-arp and route-lookup keywords, to maintain existing functionality.

8.4(3)

The extended , flat , and include-reserve keywords were added.

When using a PAT pool with round robin allocation, if a host has an existing connection, then subsequent connections from that host will use the same PAT IP address if ports are available.

This feature is not available in 8.5(1).

9.0(1)

NAT now supports IPv6 traffic, as well as translating between IPv4 and IPv6. Translating between IPv4 and IPv6 is not supported in transparent mode. We added the interface ipv6 option and the net-to-net option.

 
Usage Guidelines

When a packet enters the ASA, both the source and destination IP addresses are checked against the network object NAT rules. The source and destination address in the packet can be translated by separate rules if separate matches are made. These rules are not tied to each other; different combinations of rules can be used depending on the traffic.

Because the rules are never paired, you cannot specify that a source address should be translated to A when going to destination X, but be translated to B when going to destination Y. Use twice NAT for that kind of functionality (twice NAT lets you identify the source and destination address in a single rule).

For detailed information about the differences between twice NAT and network object NAT, see the CLI configuration guide.

Network object NAT rules are added to section 2 of the NAT rules table. For more information about NAT ordering, see the CLI configuration guide.

Depending on the configuration, you can configure the mapped address inline if desired or you can create a network object or network object group for the mapped address (the object network or object-group network command). Network object groups are particularly useful for creating a mapped address pool with discontinous IP address ranges or multiple hosts or subnets. You cannot use an object group with both IPv4 and IPv6 addresses; the object group must include only one type of address.

Objects and object groups used in NAT cannot be undefined; they must include IP addresses.

You can only define a single NAT rule for a given object; if you want to configure multiple NAT rules, you need to create multiple objects that specify the same IP address, for example, object network obj-10.10.10.1-01 , object network obj-10.10.10.1-02 , and so on.

Mapped Address Guidelines

The mapped IP address pool cannot include:

  • The mapped interface IP address. If you specify any interface for the rule, then all interface IP addresses are disallowed. For interface PAT (routed mode only), use the interface keyword instead of the IP address.
  • (Transparent mode) The management IP address.
  • (Dynamic NAT) The standby interface IP address when VPN is enabled.
  • Existing VPN pool addresses.

Clearing Translation Sessions

If you change the NAT configuration, and you do not want to wait for existing translations to time out before the new NAT information is used, you can clear the translation table using clear xlate command. However, clearing the translation table disconnects all of the current connections.

PAT Pool Guidelines

  • DNS rewrite is not applicable for PAT because multiple PAT rules are applicable for each A-record, and the PAT rule to use is ambiguous.
  • If available, the real source port number is used for the mapped port. However, if the real port is not available, by default the mapped ports are chosen from the same range of ports as the real port number: 0 to 511, 512 to 1023, and 1024 to 65535. Therefore, ports below 1024 have only a small PAT pool that can be used. (8.4(3) and later, not including 8.5(1) or 8.6(1)) If you have a lot of traffic that uses the lower port ranges, you can now specify a flat range of ports to be used instead of the three unequal-sized tiers: either 1024 to 65535, or 1 to 65535.
  • (8.4(3) and later, not including 8.5(1) or 8.6(1)) If you use the same PAT pool object in two separate rules, then be sure to specify the same options for each rule. For example, if one rule specifies extended PAT and a flat range, then the other rule must also specify extended PAT and a flat range.

Extended PAT for a PAT Pool Guidelines

  • Many application inspections do not support extended PAT. See the configuration guide for a complete list of unsupported inspections.
  • If you enable extended PAT for a dynamic PAT rule, then you cannot also use an address in the PAT pool as the PAT address in a separate static NAT-with-port-translation rule. For example, if the PAT pool includes 10.1.1.1, then you cannot create a static NAT-with-port-translation rule using 10.1.1.1 as the PAT address.
  • If you use a PAT pool and specify an interface for fallback, you cannot specify extended PAT.
  • For VoIP deployments that use ICE or TURN, do not use extended PAT. ICE and TURN rely on the PAT binding to be the same for all destinations.

Round robin for a PAT Pool Guidelines

  • (8.4(3) and later, not including 8.5(1) or 8.6(1)) If a host has an existing connection, then subsequent connections from that host will use the same PAT IP address if ports are available. Note : This “stickiness” does not survive a failover. If the ASA fails over, then subsequent connections from a host may not use the initial IP address.
  • (8.4(2), 8.5(1), and 8.6(1)) If a host has an existing connection, then subsequent connections from that host will likely use different PAT addresses for each connection because of the round robin allocation. In this case, you may have problems when accessing two websites that exchange information about the host, for example an e-commerce site and a payment site. When these sites see two different IP addresses for what is supposed to be a single host, the transaction may fail.
  • Round robin, especially when combined with extended PAT, can consume a large amount of memory.

NAT and IPv6

You can use NAT to translate between IPv6 networks, and also to translate between IPv4 and IPv6 networks (routed mode only). We recommend the following best practices:

  • NAT66 (IPv6-to-IPv6)—We recommend using static NAT. Although you can use dynamic NAT or PAT, IPv6 addresses are in such large supply, you do not have to use dynamic NAT. If you do not want to allow returning traffic, you can make the static NAT rule unidirectional (twice NAT only).
  • NAT46 (IPv4-to-IPv6)—We recommend using static NAT. Because the IPv6 address space is so much larger than the IPv4 address space, you can easily accommodate a static translation. If you do not want to allow returning traffic, you can make the static NAT rule unidirectional (twice NAT only). When translating to an IPv6 subnet (/96 or lower), the resulting mapped address is an IPv4-embedded IPv6 address, where the 32-bits of the IPv4 address is embedded after the IPv6 prefix. For example, if the IPv6 prefix is a /96 prefix, then the IPv4 address is appended in the last 32-bits of the address. For example, if you map 192.168.1.0/24 to 201b::0/96, then 192.168.1.4 will be mapped to 201b::0.192.168.1.4 (shown with mixed notation). If the prefix is smaller, such as /64, then the IPv4 address is appended after the prefix, and a suffix of 0s is appended after the IPv4 address.
  • NAT64 (IPv6-to-IPv4)—You may not have enough IPv4 addresses to accommodate the number of IPv6 addresses. We recommend using a dynamic PAT pool to provide a large number of IPv4 translations.

Examples

Dynamic NAT Examples

The following example configures dynamic NAT that hides 192.168.2.0 network behind a range of outside addresses 2.2.2.1-2.2.2.10:

ciscoasa(config)# object network my-range-obj
ciscoasa(config-network-object)# range 2.2.2.1 2.2.2.10
ciscoasa(config)# object network my-inside-net
ciscoasa(config-network-object)# subnet 192.168.2.0 255.255.255.0
ciscoasa(config-network-object)# nat (inside,outside) dynamic my-range-obj
 

The following example configures dynamic NAT with dynamic PAT backup. Hosts on inside network 10.76.11.0 are mapped first to the nat-range1 pool (10.10.10.10-10.10.10.20). After all addresses in the nat-range1 pool are allocated, dynamic PAT is performed using the pat-ip1 address (10.10.10.21). In the unlikely event that the PAT translations are also use up, dynamic PAT is performed using the outside interface address.

ciscoasa(config)# object network nat-range1
ciscoasa(config-network-object)# range 10.10.10.10 10.10.10.20
 
ciscoasa(config-network-object)# object network pat-ip1
ciscoasa(config-network-object)# host 10.10.10.21
 
ciscoasa(config-network-object)# object-group network nat-pat-grp
ciscoasa(config-network-object)# network-object object nat-range1
ciscoasa(config-network-object)# network-object object pat-ip1
 
ciscoasa(config-network-object)# object network my_net_obj5
ciscoasa(config-network-object)# subnet 10.76.11.0 255.255.255.0
ciscoasa(config-network-object)# nat (inside,outside) dynamic nat-pat-grp interface
 

The following example configures dynamic NAT with dynamic PAT backup to translate IPv6 hosts to IPv4. Hosts on inside network 2001:DB8::/96 are mapped first to the IPv4_NAT_RANGE pool (209.165.201.1 to 209.165.201.30). After all addresses in the IPv4_NAT_RANGE pool are allocated, dynamic PAT is performed using the IPv4_PAT address (209.165.201.31). In the event that the PAT translations are also used up, dynamic PAT is performed using the outside interface address.

ciscoasa(config)# object network IPv4_NAT_RANGE
ciscoasa(config-network-object)# range 209.165.201.1 209.165.201.30
 
ciscoasa(config-network-object)# object network IPv4_PAT
ciscoasa(config-network-object)# host 209.165.201.31
 
ciscoasa(config-network-object)# object-group network IPv4_GROUP
ciscoasa(config-network-object)# network-object object IPv4_NAT_RANGE
ciscoasa(config-network-object)# network-object object IPv4_PAT
 
ciscoasa(config-network-object)# object network my_net_obj5
ciscoasa(config-network-object)# subnet 2001:DB8::/96
ciscoasa(config-network-object)# nat (inside,outside) dynamic IPv4_GROUP interface
 

Dynamic PAT Example

The following example configures dynamic PAT that hides the 192.168.2.0 network behind address 2.2.2.2:

ciscoasa(config)# object network my-inside-net
ciscoasa(config-network-object)# subnet 192.168.2.0 255.255.255.0
ciscoasa(config-network-object)# nat (inside,outside) dynamic 2.2.2.2
 

The following example configures dynamic PAT that hides the 192.168.2.0 network behind the outside interface address:

ciscoasa(config)# object network my-inside-net
ciscoasa(config-network-object)# subnet 192.168.2.0 255.255.255.0
ciscoasa(config-network-object)# nat (inside,outside) dynamic interface
 

The following example configures dynamic PAT with a PAT pool to translate the inside IPv6 network to an outside IPv4 network:

ciscoasa(config)# object network IPv4_POOL

ciscoasa(config-network-object)# range 203.0.113.1 203.0.113.254

ciscoasa(config)# object network IPv6_INSIDE

ciscoasa(config-network-object)# subnet 2001:DB8::/96
ciscoasa(config-network-object)# nat (inside,outside) dynamic pat-pool IPv4_POOL
 

Static NAT Examples

The following example configures static NAT for the real host 1.1.1.1 on the inside to 2.2.2.2 on the outside with DNS rewrite enabled.

ciscoasa(config)# object network my-host-obj1
ciscoasa(config-network-object)# host 1.1.1.1
ciscoasa(config-network-object)# nat (inside,outside) static 2.2.2.2 dns
 

The following example configures static NAT for the real host 1.1.1.1 on the inside to 2.2.2.2 on the outside using a mapped object.

ciscoasa(config)# object network my-mapped-obj
ciscoasa(config-network-object)# host 2.2.2.2
 
ciscoasa(config-network-object)# object network my-host-obj1
ciscoasa(config-network-object)# host 1.1.1.1
ciscoasa(config-network-object)# nat (inside,outside) static my-mapped-obj
 

The following example configures static NAT with port translation for 1.1.1.1 at TCP port 21 to the outside interface at port 2121.

ciscoasa(config)# object network my-ftp-server
ciscoasa(config-network-object)# host 1.1.1.1
ciscoasa(config-network-object)# nat (inside,outside) static interface service tcp 21 2121
 

The following example maps an inside IPv4 network to an outside IPv6 network.

ciscoasa(config)# object network inside_v4_v6
ciscoasa(config-network-object)# subnet 10.1.1.0 255.255.255.0
ciscoasa(config-network-object)# nat (inside,outside) static 2001:DB8::/96
 

The following example maps an inside IPv6 network to an outside IPv6 network.

ciscoasa(config)# object network inside_v6
ciscoasa(config-network-object)# subnet 2001:DB8:AAAA::/96
ciscoasa(config-network-object)# nat (inside,outside) static 2001:DB8:BBBB::/96
 

Identity NAT Examples

The following example maps a host address to itself using an inline mapped address:

ciscoasa(config)# object network my-host-obj1

ciscoasa(config-network-object)# host 10.1.1.1

ciscoasa(config-network-object)# nat (inside,outside) static 10.1.1.1

 

The following example maps a host address to itself using a network object:

ciscoasa(config)# object network my-host-obj1-identity

ciscoasa(config-network-object)# host 10.1.1.1

 

ciscoasa(config-network-object)# object network my-host-obj1

ciscoasa(config-network-object)# host 10.1.1.1

ciscoasa(config-network-object)# nat (inside,outside) static my-host-obj1-identity

 

 
Related Commands

Command
Description

clear configure nat

Removes the NAT configuration (both twice NAT and network object NAT).

show nat

Displays NAT policy statistics.

show nat pool

Displays information about NAT pools.

show running-config nat

Displays the NAT configuration.

show xlate

Displays xlate information.

nat (vpn load-balancing)

To set the IP address to which NAT translates the IP address of this device, use the nat command in VPN load-balancing configuration mode. To disable this NAT translation, use the no form of this command.

nat ip-address

no nat [ ip-adddress ]

 
Syntax Description

ip-address

The IP address to which you want this NAT to translate the IP address of this device.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

VPN load-balancing configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

You must first use the vpn load-balancing command to enter VPN load-balancing mode.

In the no nat form of the command, if you specify the optional ip-address value, the IP address must match the existing NAT IP address in the running configuration.

Examples

The following is an example of a VPN load-balancing command sequence that includes a nat command that sets the NAT-translated address to 192.168.10.10:

ciscoasa(config)# interface GigabitEthernet 0/1
ciscoasa(config-if)# ip address 209.165.202.159 255.255.255.0
ciscoasa(config)# nameif test
ciscoasa(config)# interface GigabitEthernet 0/2
ciscoasa(config-if)# ip address 209.165.201.30 255.255.255.0
ciscoasa(config)# nameif foo
ciscoasa(config)# vpn load-balancing
ciscoasa(config-load-balancing)# nat 192.168.10.10
ciscoasa(config-load-balancing)# priority 9
ciscoasa(config-load-balancing)# interface lbpublic test
ciscoasa(config-load-balancing)# interface lbprivate foo
ciscoasa(config-load-balancing)# cluster ip address 209.165.202.224
ciscoasa(config-load-balancing)# cluster port 9023
ciscoasa(config-load-balancing)# participate
ciscoasa(config-load-balancing)# participate

 
Related Commands

Command
Description

vpn load-balancing

Enter VPN load-balancing mode.

nat-assigned-to-public-ip

To automatically translate a VPN peer’s local IP address back to the peer’s real IP address, use the nat-assigned-to-public-ip command in tunnel-group general-attributes configuration mode. To disable the NAT rules, use the no form of this command.

nat-assigned-to-public-ip interface

no nat-assigned-to-public-ip interface

 
Syntax Description

interface

Specifies the interface where you want to apply NAT.

 
Command Default

This command is disabled by default.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Tunnel-group general-attributes configuration

  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.4(3)

We introduced this command.

 
Usage Guidelines

In rare situations, you might want to use a VPN peer’s real IP address on the inside network instead of an assigned local IP address. Normally with VPN, the peer is given an assigned local IP address to access the inside network. However, you might want to translate the local IP address back to the peer’s real public IP address if, for example, your inside servers and network security is based on the peer’s real IP address.

You can enable this feature on one interface per tunnel group. Object NAT rules are dynamically added and deleted when the VPN session is established or disconnected. You can view the rules using the show nat command.

Data Flow

The following steps describe the packet flow through the ASA when this feature is enabled:

1. The VPN peer sends a packet to the ASA.

The outer source/destination consists of the peer public IP address/ASA IP address. The encrypted inner source/destination consists of the VPN-assigned IP address/inside server address.

2. The ASA decrypts the packet (removing the outer source/destination).

3. The ASA performs a route lookup for the inside server, and sends the packet to the inside interface.

4. The automatically created VPN NAT policy translates the VPN-assigned source IP address to the peer public IP address.

5. The ASA sends the translated packet to the server.

6. The server responds to the packet, and sends it to the peer’s public IP address.

7. The ASA receives the response, and untranslates the destination IP address to the VPN-assigned IP address.

8. The ASA forwards the untranslated packet to the outside interface where it is encrypted, and an outer source/destination is added consisting of the ASA IP address/peer public IP address.

9. The ASA sends the packet back to the peer.

10. The peer decrypts and processes the data.

Limitations

Because of routing issues, we do not recommend using this feature unless you know you need this feature; contact Cisco TAC to confirm feature compatibility with your network. See the following limitations:

  • Only supports Cisco IPsec and AnyConnect client.
  • Return traffic to the public IP addresses must be routed back to the ASA so the NAT policy and VPN policy can be applied.
  • If you enable reverse route injection (see the set reverse-route command), only the VPN-assigned IP address is advertised.
  • Does not support load-balancing (because of routing issues).
  • Does not support roaming (public IP changing).

Examples

The following example enables NAT to the public IP for the “vpnclient” tunnel group:

ciscoasa# ip local pool client 10.1.226.4-10.1.226.254
ciscoasa# tunnel-group vpnclient type remote-access
ciscoasa# tunnel-group vpnclient general-attributes
ciscoasa(config-tunnel-general)# address-pool client
ciscoasa(config-tunnel-general)# nat-assigned-to-public-ip inside
 

The following is sample output from the show nat detail command showing an automatic NAT rule from peer 209.165.201.10 with assigned IP 10.1.226.174:

ciscoasa# show nat detail
 
Auto NAT Policies (Section 2)
1 (outside) to (inside) source static _vpn_nat_10.1.226.174 209.165.201.10
translate_hits = 0, untranslate_hits = 0
Source - Origin: 10.1.226.174/32, Translated: 209.165.201.10/32

 
Related Commands

Command
Description

show nat

Shows current xlates.

tunnel-group general-attributes

Sets general attributes for a tunnel group.

debug menu webvpn 99

For AnyConnect SSL sessions, the VPN NAT interface is stored in the session.

debug menu ike 2 peer_ip

For Cisco IPsec client sessions, the VPN NAT interface is stored in the SA.

debug nat 3

Shows debug messages for NAT.

nat-rewrite

To enable NAT rewrite for IP addressess embedded in the A-record of a DNS response, use the nat-rewrite command in parameters configuration mode. To disable this feature, use the no form of this command.

nat-rewrite

no nat-rewrite

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

NAT rewrite is enabled by default. This feature can be enabled when inspect dns is configured even if a policy-map type inspect dns is not defined. To disable, no nat-rewrite must explicitly be stated in the policy map configuration. If inspect dns is not configured, NAT rewrite is not performed.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Parameters configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.2(1)

This command was introduced.

 
Usage Guidelines

This feature performs NAT translation of A-type Resource Record (RR) in a DNS response.

Examples

The following example shows how to enable NAT rewrite in a DNS inspection policy map:

ciscoasa(config)# policy-map type inspect dns preset_dns_map
ciscoasa(config-pmap)# parameters
ciscoasa(config-pmap-p)# nat-rewrite
 

 
Related Commands

Command
Description

class

Identifies a class map name in the policy map.

class-map type inspect

Creates an inspection class map to match traffic specific to an application.

policy-map

Creates a Layer 3/4 policy map.

show running-config policy-map

Display all current policy map configurations.

nbns-server (tunnel-group webvpn attributes mode)

To configure an NBNS server, use the nbns-server command in tunnel-group webvpn configuration mode. To remove the NBNS server from the configuration, use the no form of this command.

The ASA queries NBNS servers to map NetBIOS names to IP addresses. WebVPN requires NetBIOS to access or share files on remote systems.

nbns-server { ipaddr | hostname } [ master ] [ timeout timeout ] [ retry retries ]

no nbns-server

 
Syntax Description

hostname

Specifies the hostname for the NBNS server.

ipaddr

Specifies the IP address for the NBNS server.

master

Indicates that this is a master browser, rather than a WINS server.

retry

Indicates that a retry value follows.

retries

Specifies the number of times to retry queries to NBNS servers. The ASA recycles through the list of servers the number of times you specify here before sending an error message. The default value is 2; the range is 1 through 10.

timeout

Indicates that a timeout value follows.

timeout

Specifies the amount of time the ASA waits before sending the query again, to the same server if there is only one, or another server if there are multiple NBNS servers. The default timeout is 2 seconds; the range is 1 to 30 seconds.

 
Defaults

No NBNS server is configured by default.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Tunnel-group webvpn configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

7.1(1)

Moved from webvpn mode to tunnel-group webvpn configuration mode.

 
Usage Guidelines

In Release 7.1(1), if you enter this command in webvpn configuration mode, it is transformed to the same command in tunnel-group webvpn-attributes configuration mode.

Maximum of 3 server entries. The first server you configure is the primary server, and the others are backups, for redundancy.

Use the no option to remove the matching entry from the configuration.

Examples

The following example shows how to configure the tunnel-group “test” with an NBNS server that is a master browser with an IP address of 10.10.10.19, a timeout value of 10 seconds, and 8 retries. It also shows how to configure an NBNS WINS server with an IP address of 10.10.10.24, a timeout value of 15 seconds, and 8 retries.

ciscoasa(config)# tunnel-group test type webvpn
ciscoasa(config)# tunnel-group test webvpn-attributes
ciscoasa(config-tunnel-webvpn)# nbns-server 10.10.10.19 master timeout 10 retry 8
ciscoasa(config-tunnel-webvpn)# nbns-server 10.10.10.24 timeout 15 retry 8
ciscoasa(config-tunnel-webvpn)#
 

 
Related Commands

Command
Description

clear configure group-policy

Removes the configuration for a particular group policy or for all group policies.

show running-config group-policy

Displays the running configuration for a particular group policy or for all group policies.

tunnel-group webvpn-attributes

Specifies the WebVPN attributes for the named tunnel-group.

nbns-server (webvpn mode)

To configure an NBNS server, use the nbns-server command in tunnel-group webvpn configuration mode. To remove the NBNS server from the configuration, use the no form of this command.

The ASA queries NBNS servers to map NetBIOS names to IP addresses. WebVPN requires NetBIOS to access or share files on remote systems.

nbns-server { ipaddr | hostname } [ master ] [ timeout timeout ] [ retry retries ]

no nbns-server

 
Syntax Description

hostname

Specifies the hostname for the NBNS server.

ipaddr

Specifies the IP address for the NBNS server.

master

Indicates that this is a master browser, rather than a WINS server.

retry

Indicates that a retry value follows.

retries

Specifies the number of times to retry queries to NBNS servers. The ASA recycles through the list of servers the number of times you specify here before sending an error message. The default value is 2; the range is 1 through 10.

timeout

Indicates that a timeout value follows.

timeout

Specifies the amount of time the ASA waits before sending the query again, to the same server if there is only one, or another server if there are multiple NBNS servers. The default timeout is 2 seconds; the range is 1 to 30 seconds.

 
Defaults

No NBNS server is configured by default.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Tunnel-group webvpn configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

7.1(1)

Moved from webvpn mode to tunnel-group webvpn configuration mode.

 
Usage Guidelines

This command is deprecated in webvpn configuration mode. The nbns-server command in tunnel-group webvpn-attributes configuration mode replaces it. In Release 7.1(1), if you enter this command in webvpn configuration mode, it is transformed to the same command in tunnel-group webvpn-attributes mode.

Maximum of 3 server entries. The first server you configure is the primary server, and the others are backups, for redundancy.

Use the no option to remove the matching entry from the configuration.

Examples

The following example shows how to configure an NBNS server that is a master browser with an IP address of 10.10.10.19, a timeout value of 10 seconds, and 8 retries. It also shows how to configure an NBNS WINS server with an IP address of 10.10.10.24, a timeout value of 15 seconds, and 8 retries.

ciscoasa(config)# webvpn
ciscoasa(config-webvpn)# nbns-server 10.10.10.19 master timeout 10 retry 8
ciscoasa(config-webvpn)# nbns-server 10.10.10.24 timeout 15 retry 8

neighbor

To define a static neighbor on a point-to-point, non-broadcast network, use the neighbor command in router configuration mode. To remove the statically defined neighbor from the configuration, use the no form of this command.

neighbor ip_address [ interface name ]

no neighbor ip_address [ interface name ]

 
Syntax Description

interface name

(Optional) Specifies the interface name, as specified by the nameif command, through which the neighbor can be reached.

ip_address

Specifies the IP address of the neighbor router.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Router configuration

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

9.0(1)

Multiple context mode is supported.

 
Usage Guidelines

The neighbor command is used to advertise OSPF routes over VPN tunnels. One neighbor entry must be included for each known non-broadcast network neighbor. The neighbor address must be on the primary address of the interface.

The interface option needs to be specified when the neighbor is not on the same network as any of the directly connected interfaces of the system. Additionally, a static route must be created to reach the neighbor.

Examples

The following example defines a neighbor router with an address of 192.168.1.1:

ciscoasa(config-router)# neighbor 192.168.1.1
 

 
Related Commands

Command
Description

router ospf

Enters router configuration mode.

show running-config router

Displays the commands in the global router configuration.

neighbor (EIGRP)

To define an EIGRP neighbor router with which to exchange routing information, use the neighbor command in router configuration mode. To remove a neighbor entry, use the no form of this command.

neighbor ip_address interface name

no neighbor ip_address interface name

 
Syntax Description

interface name

The interface name, as specified by the nameif command, through which the neighbor can be reached.

ip_address

IP address of the neighbor router.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Router configuration

  • Yes

  • Yes

 
Command History

Release
Modification

8.0(2)

This command was introduced.

 
Usage Guidelines

You can use multiple neighbor statements to establish peering sessions with specific EIGRP neighbors. The interface through which EIGRP exchanges routing updates must be specified in the neighbor statement. The interfaces through which two EIGRP neighbors exchange routing updates must be configured with IP addresses from the same network.


Note Configuring the passive-interface command for an interface suppresses all incoming and outgoing routing updates and hello messages on that interface. EIGRP neighbor adjacencies cannot be established or maintained over an interface that is configured as passive.


EIGRP hello messages are sent as unicast messages to neighbors defined using the neighbor command.

Examples

The following example configures EIGRP peering sessions with the 192.168.1.1 and 192.168.2.2 neighbors:

ciscoasa(config)# router eigrp 100
ciscoasa(config-router)# network 192.168.0.0
ciscoasa(config-router)# neighbor 192.168.1.1 interface outside
ciscoasa(config-router)# neighbor 192.168.2.2 interface branch_office
 

 
Related Commands

Command
Description

debug eigrp neighbors

Displays debug information for EIGRP neighbor messages.

show eigrp neighbors

Displays the EIGRP neighbor table.

neighbor activate

To enable the exchange of information with a Border Gateway Protocol (BGP) neighbor, use the neighbor activate command in address-family configuration mode. To disable the exchange of an address with a BGP neighbor, use the no form of this command.

neighbor ip_address activate

no neighbor ip_address activate

 
Syntax Description

ip_address

IP address of the neighbor router.

 
Defaults

Address exchange with BGP neighbors is enabled by default for the IPv4 address family. You cannot enable address exchange for any other address families.


Note Address exchange for the IPv4 address family is enabled by default for each BGP routing session defined by the neighbor remote-as command; unless you configure the no bgp default ipv4-activate command before configuring the neighbor remote-as command, or you disable address exchange with a specific neighbor by using the no neighbor activate command.


 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

You can use this command to advertise address information in the form of an IP prefix. The address prefix information is known as Network Layer Reachability Information (NLRI) in BGP.

Examples

The following example enables address exchange for IPv4 address family unicast for the BGP neighbor 172.16.1.1:

ciscoasa(config)# router bgp 50000
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.1.1 remote-as 4
ciscoasa(config-router-af)# neighbor 172.16.1.1 activate
 
 

 
Related Commands

Command
Description

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

neighbor advertisement-interval

To set the minimum route advertisement interval (MRAI) between the sending of BGP routing updates, use the neighbor advertisement-interval command in address-family configuration mode. To restore the default value, use the no form of this command

neighbor ip_address advertisement-interval seconds

no neighbor ip_address advertisement-interval seconds

 
Syntax Description

ip_address

IP address of the neighbor router.

seconds

Minimum time interval between sending BGP routing updates.

Valid values are between 0 and 600.

 
Defaults

eBGP sessions not in a VRF: 30 seconds

eBGP sessions in a VRF: 0 seconds

iBGP sessions: 0 seconds.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

When the MRAI is equal to 0 seconds, BGP routing updates are sent as soon as the BGP routing table changes.

Examples

The following example sets the minimum time between sending BGP routing updates to 10 seconds:

ciscoasa(config-router-af)# neighbor 172.16.1.1 advertisement-interval 10
 

 
Related Commands

Command
Description

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor default-originate

To allow a BGP speaker (the local router) to send the default route 0.0.0.0 to a neighbor for use as a default route, use the neighbor default-originate command in address-family configuration mode. To send no route as a default, use the no form of this command.

neighbor ip_address default-originate [route-map route-map name]

no neighbor ip_address default-originate [route-map route-map name]

 
Syntax Description

ip_address

IP address of the neighbor router.

route-map route-map name

(Optional) Name of the route map. The route map allows route 0.0.0.0 to be injected conditionally.

 
Defaults

No default route is sent to the neighbor.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command does not require the presence of 0.0.0.0 in the local router. When used with a route map, the default route 0.0.0.0 is injected if the route map contains a match ip address clause and there is a route that matches the IP access list exactly. The route map can also contain other match clauses.

You can use standard or extended access lists with the neighbor default-originate command.

Examples

In the following example, the local router injects route 0.0.0.0 to the neighbor 72.16.2.3 unconditionally:

ciscoasa(config-router-af)# neighbor 172.16.2.3 default-originate

 
Related Commands

Command
Description

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor description

To associate a description with a neighbor, use the neighbor description command in address-family configuration mode. To remove the description, use the no form of this command.

neighbor ip_address description text

no neighbor ip_address description text

 
Syntax Description

ip_address

IP address of the neighbor router.

text

Text (upto 80 characters in length) that describes the neighbor.

 
Defaults

There is no description of the neighbor.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

Examples

In the following example, the description of the neighbor is “peer with example.com”:

ciscoasa(config-router-af)# neighbor 172.16.2.3 description peer with example.com

 
Related Commands

Command
Description

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor disable-connected-check

To disable connection verification to establish an eBGP peering session with a single-hop peer that uses a loopback interface, use the neighbor disable-connected-check command in address-family configuration mode. To enable connection verification for eBGP peering sessions, use the no form of this command.

neighbor ip_address disable-connected-check

no neighbor ip_address disable-connected-check

 
Syntax Description

ip_address

IP address of the neighbor router.

 
Defaults

A BGP routing process will verify the connection of single-hop eBGP peering session (TTL=254) to determine if the eBGP peer is directly connected to the same network segment by default. If the peer is not directly connected to same network segment, connection verification will prevent the peering session from being established.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

The neighbor disable-connected-check command is used to disable the connection verification process for eBGP peering sessions that are reachable by a single hop but are configured on a loopback interface or otherwise configured with a non-directly connected IP address.

This command is required only when the neighbor ebgp-multihop command is configured with a TTL value of 1. The address of the single-hop eBGP peer must be reachable. The neighbor update-source command must be configured to allow the BGP routing process to use the loopback interface for the peering session.

Examples

In the following example, a single-hop eBGP peering session is configured between two BGP peers that are reachable on the same network segment through a local loopback interfaces on each router:

BGP Peer 1

ciscoasa(config)# interface loopback1
ciscoasa(config-if)# ip address 10.0.0.100 255.255.255
ciscoasa(config-if)# exit
ciscoasa(config)# router bgp 64512
ciscoasa(config-router)# neighbor 192.168.0.200 remote-as 65534
ciscoasa(config-router)# neighbor 192.168.0.200 ebgp-multihop 1
ciscoasa(config-router)# neighbor 192.168.0.200 update-source loopback2
ciscoasa(config-router)# neighbor 192.168.0.200 disable-connected-check
 
BGP Peer 2
ciscoasa(config)# interface loopback2
ciscoasa(config-if)# ip address 192.168.0.200 255.255.255
ciscoasa(config-if)# exit
ciscoasa(config)# router bgp 65534
ciscoasa(config-router)# neighbor 10.0.0.100 remote-as 64512
ciscoasa(config-router)# neighbor 10.0.0.100 ebgp-multihop 1
ciscoasa(config-router)# neighbor 10.0.0.100 update-source loopback1
ciscoasa(config-router)# neighbor 10.0.0.100 disable-connected-check
 

 
Related Commands

Command
Description

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

neighbor ebgp-multihop

Accepts or initiates BGP connections to external peers residing on networks that are not directly connected.

neighbor distribute-list

To distribute BGP neighbor information as specified in an access list, use the neighbor distribute-list command in address-family configuration mode. To remove an entry, use the no form of this command.

neighbor ip_address distribute-list {access-list-name} {in | out}

no neighbor ip_address distribute-list {access-list-name} {in | out}

 
Syntax Description

ip_address

IP address of the neighbor router.

access-list-name

Name of a standard access list.

in

Access list is applied to incoming advertisements to that neighbor

out

Access list is applied to outgoing advertisements to that neighbor

 
Defaults

No BGP neighbor is specified.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

Using a distribute list is one of several ways to filter advertisements. Advertisements can also be filtered by using the following methods:

  • Autonomous system path filters can be configured with the ip as-path access-list and neighbor filter-list commands.
  • The access-list (IP standard) commands can be used to configure standard access lists for the filtering of advertisement
  • The route-map (IP) command can be used to filter advertisements. Route maps may be configured with autonomous system filters, prefix filters, access lists and distribute lists.

Standard access lists may be used to filter routing updates. However, in the case of route filtering when using classless inter-domain routing (CIDR), standard access lists do not provide the level of granularity that is necessary to configure advanced filtering of network addresses and masks.

Examples

In the following example, BGP neighbor information in the standard access-list distribute-list-acl is applied to incoming advertisements to the neighbor 172.16.4.1.

ciscoasa(config)#router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0
ciscoasa(config-router-af) neighbor 172.16.4.1 distribute-list distribute-list-acl in

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

network

Specifies the networks to be advertised by BGP.

access-list permit

Specifies packets to forward.

access-list deny

Species packets to deny.

neighbor ebgp-multihop

To accept and attempt BGP connections to external peers residing on networks that are not directly connected, use the neighbor ebgp-multihop command in address-family configuration mode. To return to the default, use the no form of this command.

neighbor ip_address ebgp-multihop [ttl]

no neighbor ip_address ebgp-multihop

 
Syntax Description

ip_address

IP address of the neighbor router.

ttl

(Optional) Time to live.

Valid values are between 1 and 255 hops.

 
Defaults

Only directly connected neighbors are allowed.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This feature should be used only under the guidance of Cisco technical support staff. To prevent the creation of loops through oscillating routes, the multihop will not be established if the only route to the multihop peer is the default route (0.0.0.0).

Examples

The following example allows connections to or from neighbor 10.108.1.1, which resides on a network that is not directly connected:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af) neighbor 10.108.1.1 ebgp-multihop

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor filter-list

To set up a BGP filter, use the neighbor filter-list command in address-family configuration mode. To disable this function, use the no form of this command.

neighbor ip_address filter-list access-list-name {in | out}

no neighbor ip_address filter- list acces s-list-name {in | out}

 
Syntax Description

ip_address

IP address of the neighbor router.

access-list-name

Name of an autonomous system path access list. You define this access list with the as-path access-list command.

in

Access list is applied to incoming routes.

out

Access list is applied to outgoing routes.

 
Command Default

No BGP filter is used.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command establishes filters on both inbound and outbound BGP routes.


Note Do not apply both a neighbor distribute-list and a neighbor prefix-list command to a neighbor in any given direction (inbound or outbound). These two commands are mutually exclusive, and only one command ( neighbor distribute-list or neighbor prefix-list) can be applied to each inbound or outbound direction.


Examples

In the following address-family configuration mode example, the BGP neighbor with IP address 172.16.1.1 is not sent advertisements about any path through or from the adjacent autonomous system 123:

ciscoasa(config)# as-path access-list as-path-acl deny _123_
ciscoasa(config)# as-path access-list as-path-acl deny ^123$
ciscoasa(config)#router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0
ciscoasa(config-router-af)# neighbor 192.168.6.6 remote-as 123
ciscoasa(config-router-af)# neighbor 172.16.1.1 remote-as 47
ciscoasa(config-router-af)# neighbor 172.16.1.1 filter-list as-path-acl out

 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

network

Specifies the network to be advertised by the BGP routing process.

neighbor local-as

To customize the AS_PATH attribute for routes received from an external Border Gateway Protocol (eBGP) neighbor, use the neighbor local-as command in address-family configuration mode. To disable AS_PATH attribute customization, use the no form of this command.

neighbor ip_address local-as [autonomous-system-number [no-prepend [replace-as [dual-as]]]

no neighbor ip_address local-as

 
Syntax Description

ip_address

IP address of the neighbor router.

autonomous-system-number

(Optional) Number of an autonomous system to prepend to the AS_PATH attribute. The range of values for this argument is any valid autonomous system number from 1 to 65535.

Note With this argument, you cannot specify the autonomous system number from the local BGP routing process or from the network of the remote peer.

For more details about autonomous system number formats, see the router bgp command.

no-prepend

(Optional) Does not prepend the local autonomous system number to any routes received from the eBGP neighbor.

replace-as

(Optional) Replaces the real autonomous system number with the local autonomous system number in the eBGP updates. The autonomous system number from the local BGP routing process is not prepended.

dual-as

(Optional) Configures the eBGP neighbor to establish a peering session using the real autonomous system number (from the local BGP routing process) or by using the autonomous system number configured with the autonomous-system-number argument (local-as).

 
Command Default

The autonomous system number from the local BGP routing process is prepended to all external routes by default.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

The neighbor local-as command is used to customize the AS_PATH attribute by adding and removing autonomous system numbers for routes received from eBGP neighbors. The configuration of this command allows a router to appear to external peers as a member of another autonomous system for the purpose of autonomous system number migration. This feature simplifies the process of changing the autonomous system number in a BGP network by allowing the network operator to migrate customers to new configurations during normal service windows without disrupting existing peering arrangements.


Caution BGP prepends the autonomous system number from each BGP network that a route traverses to maintain network reachability information and to prevent routing loops. This command should be configured only for autonomous system migration, and should be de-configured after the transition has been completed. This procedure should be attempted only by an experienced network operator. Routing loops can be created through improper configuration.

This command can be used for only true eBGP peering sessions. This command does not work for two peers in different sub-autonomous systems of a confederation.

To ensure a smooth transition, we recommend that all BGP speakers within an autonomous system that is identified using a 4-byte autonomous system number, be upgraded to support 4-byte autonomous system numbers.

Examples

Local-AS Example

The following example establishes peering between Router 1 and Router 2 through autonomous system 300, using the local-as feature:

Router 1 (Local router)

ciscoasa(config)# router bgp 100
ciscoasa(config-router)# address-family ipv4 unicast
ciscoasa(config-router-af)# neighbor 172.16.1.1 remote-as 200
ciscoasa(config-router-af)# neighbor 172.16.1.1 local-as 300
 
Router 2 (Remote router)
 
ciscoasa(config)# router bgp 200
ciscoasa(config-router)# address-family ipv4 unicast
ciscoasa(config-router-af)# neighbor 10.0.0.1 remote-as 300
 

No-prepend keyword configuration Example

The following example configures BGP to not prepend autonomous system 500 to routes received from the 192.168.1.1 neighbor:

ciscoasa(config)# router bgp 400
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 192.168.0.0
ciscoasa(config-router-af)# neighbor 192.168.1.1 local-as 500 no-prepend
 

Replace-as keyword configuration Example

The following example strips private autonomous system 64512 from outbound routing updates for the 172.20.1.1 neighbor and replaces it with autonomous system 600:

ciscoasa(config)# router bgp 64512
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.20.1.1 local-as 600 no-prepend replace-as
ciscoasa(config-router-af)# neighbor 172.20.1.1 remove-private-as
 

Dual-as keyword configuration Example

The following examples show the configurations for two provider networks and one customer network. Router 1 belongs to autonomous system 100, and Router 2 belongs to autonomous system 200. Autonomous system 200 is being merged into autonomous system 100. This transition needs to occur without interrupting service to Router 3 in autonomous system 300 (customer network). The neighbor local-as command is configured on router 1 to allow Router 3 to maintain peering with autonomous system 200 during this transition. After the transition is complete, the configuration on Router 3 can be updated to peer with autonomous system 100 during a normal maintenance window or during other scheduled downtime.

Router 1 Configuration (Local Provider Network)

ciscoasa(config)# router bgp 100
ciscoasa(config-router)# address-family pv4
ciscoasa(config-router-af)# no synchronization
ciscoasa(config-router-af)# bgp router-id 100.0.0.11
ciscoasa(config-router-af)# neighbor 10.3.3.33 remote-as 300
ciscoasa(config-router-af)# neighbor 10.3.3.33 local-as 200 no-prepend replace-as dual-as
 

Router 2 Configuration (Remote Provider Network)

ciscoasa(config)# router bgp 200
ciscoasa(config-router)# address-family pv4
ciscoasa(config-router-af)# bgp router-id 100.0.0.11
ciscoasa(config-router-af)# neighbor 10.3.3.33 remote-as 300
 

Router 3 Configuration (Remote Customer Network)

ciscoasa(config)# router bgp 300
ciscoasa(config-router)# address-family pv4
ciscoasa(config-router-af)# bgp router-id 100.0.0.3
ciscoasa(config-router-af)# neighbor 10.3.3.11 remote-as 200
 

To complete the migration after the two autonomous systems have merged, the peering session is updated on Router 3:

ciscoasa(config-router-af)# neighbor 10.3.3.11 remote-as 100

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

bgp router-id

Configure a fixed router ID for the local Border Gateway Protocol (BGP) routing process.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP neighbor table.

network

Specifies the network to be advertised by the BGP routing process.

synchronization

Enables the synchronization between BGP and your Interior Gateway Protocol (IGP) system

neighbor maximum-prefix

To control how many prefixes can be received from a neighbor, use the neighbor maximum-prefix command in address-family configuration mode. To disable this function, use the no form of this command.

neighbor ip_address maximum-prefix maximum [threshold] [restart restart-interval] [warning-only]

no neighbor ip_address maximum-prefix maximum

 
Syntax Description

ip_address

IP address of the neighbor router.

maximum

Maximum number of prefixes allowed from this neighbor.

threshold

(Optional) Integer specifying at what percentage of maximum the router starts to generate a warning message. The range is from 1 to 100; the default is 75 (percent).

restart

(Optional) Configures the router that is running BGP to automatically reestablish a peering session that has been disabled because the maximum-prefix limit has been exceeded. The restart timer is configured with the restart-interval argument.

restart-interval

(Optional) Time interval (in minutes) that a peering session is reestablished. The range is from 1 to 65535 minutes.

warning-only

(Optional) Allows the router to generate a log message when the maximum is exceeded, instead of terminating the peering.

 
Command Default

This command is disabled by default. There is no limit on the number of prefixes.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command allows you to configure a maximum number of prefixes that a BGP router is allowed to receive from a peer. It adds another mechanism (in addition to distribute lists, filter lists, and route maps) to control prefixes received from a peer.

When the number of received prefixes exceeds the maximum number configured, the router terminates the peering (by default). However, if the warning-only keyword is configured, the router instead only sends a log message, but continues peering with the sender. If the peer is terminated, the peer stays down until the clear bgp command is issued.

Examples

The following example sets the maximum number of prefixes allowed from the neighbor at 192.168.6.6 to 1000:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0
ciscoasa(config-router-af)# neighbor 192.168.6.6 maximum-prefix 1000
 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

network

Specifies the network to be advertised by the BGP routing process.

neighbor next-hop-self

To configure the router as the next hop for a BGP-speaking neighbor, use the neighbor next-hop-self command in address-family configuration mode. To disable this feature, use the no form of this command.

neighbor ip_address next-hop-self

no neighbor ip_address next-hop-self

 
Syntax Description

ip_address

IP address of the neighbor router.

warning-only

(Optional) Allows the router to generate a log message when the maximum is exceeded, instead of terminating the peering.

 
Command Default

This command is disabled by default.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command is useful in unmeshed networks (such as Frame Relay or X.25) where BGP neighbors may not have direct access to all other neighbors on the same IP subnet.

Examples

The following example forces all updates destined for 10.108.1.1 to advertise this router as the next hop:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 10.108.1.1 next-hop-self
 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

neighbor password

To enable message digest5 (MD5) authentication on a TCP connection between two BGP peers, use the neighbor password command in address-family configuration mode. To disable this function, use the no form of this command

neighbor ip_address password [0-7] string

no neighbor ip_address password

 
Syntax Description

ip_address

IP address of the neighbor router.

string

Case-sensitive password of up to 25 characters in length.

The first character cannot be a number. The string can contain any alphanumeric characters, including spaces. You cannot specify a password in the format number-space-anything. The space after the number can cause authentication to fail.

0-7

(Optional) Encryption type. 0-6 is without encryption. 7 is used for encryption.

 
Command Default

MD5 is not authenticated on a TCP connection between two BGP peers.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

You can configure MD5 authentication between two BGP peers, meaning that each segment sent on the TCP connection between the peers is verified. MD5 authentication must be configured with the same password on both BGP peers; otherwise, the connection between them will not be made. Configuring MD5 authentication causes the Cisco ASA software to generate and check the MD5 digest of every segment sent on the TCP connection.

When configuring you can provide a case-sensitive password of up to 25 characters regardless of whether the service password-encryption command is enabled. If the length of password is more than 25 characters, an error message is displayed and the password is not accepted. The string can contain any alphanumeric characters, including spaces. A password cannot be configured in the number-space-anything format. The space after the number can cause authentication to fail. You can also use any combination of the following symbolic characters along with alphanumeric characters:

` ~ ! @ # $ % ^ & * ( ) - _ = + | \ } ] { [ " ` : ; / > < . , ?


Caution If the authentication string is configured incorrectly, the BGP peering session will not be established. We recommend that you enter the authentication string carefully and verify that the peering session is established after authentication is configured.

If a router has a password configured for a neighbor, but the neighbor router does not, a message such as the following will appear on the console while the routers attempt to establish a BGP session between them:

%TCP-6-BADAUTH: No MD5 digest from [peer's IP address]:11003 to [local router's IP address]:179

Similarly, if the two routers have different passwords configured, a message such as the following will appear on the screen:

%TCP-6-BADAUTH: Invalid MD5 digest from [peer's IP address]:11004 to [local router's IP address]:179

Configuring an MD5 Password in an Established BGP Session

If you configure or change the password or key used for MD5 authentication between two BGP peers, the local router will not tear down the existing session after you configure the password. The local router will attempt to maintain the peering session using the new password until the BGP hold-down timer expires. The default time period is 180 seconds. If the password is not entered or changed on the remote router before the hold-down timer expires, the session will time out.


Note Configuring a new timer value for the hold-down timer will only take effect after the session has been reset. So, it is not possible to change the configuration of the hold-down timer to avoid resetting the BGP session.


Examples

The following example configures MD5 authentication for the peering session with the 10.108.1.1 neighbor. The same password must be configured on the remote peer before the hold-down timer expires:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 10.108.1.1 password bla4u00=2nkq
 

The following example configures a password for more than 25 characters when the service password-encryption command is disabled.

ciscoasa(config)# router bgp 200
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# bgp router-id 2.2.2.2
ciscoasa(config-router-af)# neighbor remote-as 3
ciscoasa(config-router-af)# neighbor 209.165.200.225 password 1234567891234567891234567890 % BGP: Password length must be less than or equal to 25.
ciscoasa(config-router-af)# do show run | i password
no service password-encryption
neighbor 209.165.200.225 password 1234567891234567891234567

In the following example an error message occurs when you configure a password for more than 25 characters when the service password-encryption command is enabled.

Router(config)# service password-encryption
Router(config)# router bgp 200
Router(config-router)# bgp router-id 2.2.2.2
Router(config-router)# neighbor 209.165.200.225 remote-as 3
Router(config-router)# neighbor 209.165.200.225 password 1234567891234567891234567890
% BGP: Password length must be less than or equal to 25.
Router(config-router)# do show run | i password service password-encryption
neighbor 209.165.200.225 password 1234567891234567891234567
 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

bgp router-id

Configure a fixed router ID for the local Border Gateway Protocol (BGP) routing process.

neighbor remote-as

Add an entry to the BGP or multiprotocol BGP neighbor table.

neighbor prefix-list

To prevent distribution of Border Gateway Protocol (BGP) neighbor information as specified in a prefix list, use the neighbor prefix-list command in address-family configuration mode. To remove a filter list, use the no form of this command.

neighbor ip_address prefix-list prefix-list-name {in | out}

no neighbor ip_address prefix-list prefix-list-name {in | out}

 
Syntax Description

ip_address

IP address of the neighbor router.

prefix-list-name

Name of a prefix list.

in

Filter list is applied to incoming advertisements from that neighbor.

out

Filter list is applied to outgoing advertisements to that neighbor.

 
Command Default

All external and advertised address prefixes are distributed to BGP neighbors.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

Using prefix lists is one of three ways to filter BGP advertisements. You can also use AS-path filters, defined with the ip as-path access-list global configuration command and used in the neighbor filter-list command to filter BGP advertisements. The third way to filter BGP advertisements uses access or prefix lists with the neighbor distribute-list command.


Note Do not apply both a neighbor distribute-list and a neighbor prefix-list command to a neighbor in any given direction (inbound or outbound). These two commands are mutually exclusive, and only one command (neighbor distribute-list or neighbor prefix-list) can be applied to each inbound or outbound direction..


Examples

The following address-family configuration mode example applies the prefix list named abc to incoming advertisements from neighbor 10.23.4.1:

ciscoasa(config)# router bgp 65200
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 192.168.1.2
ciscoasa(config-router-af)# neighbor 10.23.4.1 prefix-list abc in
 

The following address family router configuration mode example applies the prefix list named CustomerA to outgoing advertisements to neighbor 10.23.4.3:

ciscoasa(config)# router bgp 64800
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 192.168.3.6
ciscoasa(config-router-af)# neighbor 10.23.4.3 prefix-list CustomerA out

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

network

Specifies the network to be advertised by the BGP routing process.

neighbor remote-as

To add an entry to the BGP or multiprotocol BGP neighbor table, use the neighbor remote-as command in the address-family configuration mode. To remove an entry from the table, use the no form of this command.

neighbor ip_address remote-as autonomous-system-number

no neighbor ip_address remote-as autonomous-system-number

 
Syntax Description

ip_address

IP address of the neighbor router.

autonomous-system-number

Number of an autonomous system to which the neighbor belongs in the range from 1 to 65535.

For more details about autonomous system number formats, see the router bgp command.

When used with the alternate-as keyword, up to five autonomous system numbers may be entered.

 
Command Default

There are no BGP or multiprotocol BGP neighbor peers.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

Specifying a neighbor with an autonomous system number that matches the autonomous system number specified in the router bgp global configuration command identifies the neighbor as internal to the local autonomous system. Otherwise, the neighbor is considered external.

By default, neighbors that are defined using the neighbor remote-as command in router configuration mode exchange only unicast address prefixes.

Use the alternate-as keyword is used to specify up to five alternate autonomous systems in which a dynamic BGP neighbor may be identified. BGP dynamic neighbor support allows BGP peering to a group of remote neighbors that are defined by a range of IP addresses. BGP dynamic neighbors are configured using a range of IP addresses and BGP peer groups. After a subnet range is configured and associated with a BGP peer group using the bgp listen command and a TCP session is initiated for an IP address in the subnet range, a new BGP neighbor is dynamically created as a member of that group. The new BGP neighbor will inherit any configuration or templates for the group.

Cisco implementation of 4-byte autonomous system numbers uses asplain—65538 for example—as the default regular expression match and output display format for autonomous system numbers, but you can configure 4-byte autonomous system numbers in both the asplain format and the asdot format as described in RFC 5396. To change the default regular expression match and output display of 4-byte autonomous system numbers to asdot format, use the bgp asnotation dot command followed by the clear bgp * command to perform a hard reset of all current BGP sessions.

Examples

The following example specifies that a router at the address 10.108.1.2 is an internal BGP (iBGP) neighbor in autonomous system number 65200:

ciscoasa(config)# router bgp 65200
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0
ciscoasa(config-router-af)# neighbor 10.108.1.2 remote-as 65200
 

The following example assigns a BGP router to autonomous system 65400, and two networks are listed as originating in the autonomous system. Then the addresses of three remote routers (and their autonomous systems) are listed. The router being configured will share information about networks 10.108.0.0 and 192.168.7.0 with the neighbor routers. The first router is a remote router in a different autonomous system from the router on which this configuration is entered (an eBGP neighbor); the second neighbor remote-as command shows an internal BGP neighbor (with the same autonomous system number) at address 10.108.234.2; and the last neighbor remote-as command specifies a neighbor on a different network from the router on which this configuration is entered (also an eBGP neighbor).

ciscoasa(config)# router bgp 65400
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0
ciscoasa(config-router-af)# network 192.168.7.0
ciscoasa(config-router-af)# neighbor 10.108.200.1 remote-as 65200
ciscoasa(config-router-af)# neighbor 10.108.234.2 remote-as 65400
ciscoasa(config-router-af)# neighbor 172.29.64.19 remote-as 65300
 

The following example configures neighbor 10.108.1.1 in autonomous system 65001 to exchange only unicast routes:

ciscoasa(config)# router bgp 65001
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 10.108.1.1 remote-as 65001
ciscoasa(config-router-af)# neighbor 172.31 1.2 remote-as 65001
ciscoasa(config-router-af)# neighbor 172.16.2.2 remote-as 65002

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

network

Specifies the network to be advertised by the BGP routing process.

neighbor remove private-as

Removes private autonomous system numbers from the eBGP outbound routing updates.

neighbor remove-private-as

To remove private autonomous system numbers from the eBGP outbound routing updates, use the neighbor remove-private-as command in address-family configuration mode. To disable this function, use the no form of this command.

neighbor ip_address remove-private-as [all [replace-as]]

no neighbor ip_address remove-private-as [all [replace-as]]

 
Syntax Description

ip_address

IP address of the neighbor router.

all

(Optional) Removes all private AS numbers from the AS path in outgoing updates.

replace-as

(Optional) As long as the all keyword is specified, the replace-as keyword causes all private AS numbers in the AS path to be replaced with the router's local AS number.

 
Command Default

No private AS numbers are removed from the AS path.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command is available for external BGP (eBGP) neighbors only. The private AS values are 64512 to 65535. When an update is passed to the external neighbor, if the AS path includes private AS numbers, the software will drop the private AS numbers

  • The neighbor remove-private-as command removes private AS numbers from the AS path even if the path contains both public and private ASNs
  • The neighbor remove-private-as command removes private AS numbers even if the AS path contains only private AS numbers. There is no likelihood of a 0-length AS path because this command can be applied to eBGP peers only, in which case the AS number of the local router is appended to the AS path. The neighbor remove-private-as command removes private AS numbers even if the private ASNs appear before the Confederation segments in the AS path.
  • Upon removing private AS numbers from the AS path, the path length of prefixes being sent out will decrease. Because the AS path length is a key element of BGP best path selection, it might be necessary to retain the path length. The replace-as keyword ensures that the path length is retained by replacing all removed AS numbers with the local router's AS number.
  • The feature can be applied to neighbors per address family. Therefore, you can apply the feature to a neighbor in one address family and not in another, affecting update messages on the outbound side for only the address family for which the feature is configured.

Examples

The following example shows a configuration that removes the private AS number from the updates sent to 172.16.2.33. The result is that the AS path for the paths advertised by 10.108.1.1 through AS 100 will contain only "100" (as seen by autonomous system 2051).

ciscoasa(config)# router bgp 100
ciscoasa(config-router)# address-family ipv4 unicast
ciscoasa(config-router-af)# neighbor 10.108.1.1 description peer with private-as
ciscoasa(config-router-af)# neighbor 10.108.1.1 remote-as 65001
ciscoasa(config-router-af)# neighbor 172.16.2.33 description eBGP peer
ciscoasa(config-router-af)# neighbor 172.16.2.33 remote-as 2051
ciscoasa(config-router-af)# neighbor 172.16.2.33 remove-private-as
 
Router-in-AS100# show bgp 10.0.0.0
 
BGP routing table entry for 10.0.0.0/8, version 15
Paths: (1 available, best #1)
Advertised to non peer-group peers:
172.16.2.33
65001
10.108.1.1 from 10.108.1.1
Origin IGP, metric 0, localpref 100, valid, external, best
 
Router-in-AS2501# show bgp 10.0.0.0
BGP routing table entry for 10.0.0.0/8, version 3
Paths: (1 available, best #1)
Not advertised to any peer
2
172.16.2.32 from 172.16.2.32
Origin IGP, metric 0, localpref 100, valid, external, best

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor description

Associates a description with a neighbor

neighbor remote-as

Adds a BGP or multi-protocol BGP routing entry to the routing table.

neighbor route-map

To apply a route map to incoming or outgoing routes, use the neighbor route-map command in address-family configuration mode. To remove a route map, use the no form of this command.

neighbor ip_address route-map map-name {in | out}

no neighbor ip_address route-map map-name {in | out}

 
Syntax Description

ip_address

IP address of the neighbor router.

map-name

Name of a route-map.

in

Applies route map to incoming routes.

out

Applies route map to outgoing routes.

 
Command Default

No route maps are applied to a peer.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

When specified in address-family configuration mode, this command applies a route map to that particular address family only. When specified in router configuration mode, this command applies a route map to IPv4 unicast routes only.

If an outbound route map is specified, it is proper behavior to only advertise routes that match at least one section of the route map.

Examples

The following router configuration mode example applies a route map named internal-map to a BGP incoming route from 172.16.70.24:

ciscoasa(config)# router bgp 5
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.70.24 route-map internal-map in
ciscoasa(config-router-af)# route-map internal-map
ciscoasa(config-route-map)# match as-path 1
ciscoasa(config-route-map)# set local-preference 100

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

match as-path

Matches a BGP autonomous system path that is specified by an access list

route-map

Defines the conditions for redistributing routes from one routing protocol into another.

match as-path

Match a BGP autonomous system path that is specified by an access list.

set local-preference

Specify a preference value for the autonomous system path.

neighbor send-community

To specify that a communities attribute should be sent to a BGP neighbor, use the neighbor send-community command in address-family configuration mode. To remove the entry, use the no form of this command.

neighbor ip_address send-community [both | standard]

no neighbor ip_address send-community [both | standard]

 
Syntax Description

ip_address

IP address of the neighbor router.

both

(Optional) Specifies that both standard and extended communities will be sent.

standard

(Optional) Specifies that only standard communities will be sent.

 
Command Default

No communities attribute is sent to any neighbor.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

Examples

In the following address-family configuration mode example, the router belongs to autonomous system 109 and is configured to send the communities attribute to its neighbor at IP address 172.16.70.23:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.70.23 send-community

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor shutdown

To disable a neighbor, use the neighbor shutdown command in address-family configuration mode. To re-enable the neighbor, use the no form of this command.

neighbor ip_address shutdown

no neighbor ip_address shutdown

 
Syntax Description

ip_address

IP address of the neighbor router.

 
Command Default

No change is made to the status of any BGP neighbor.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

The neighbor shutdown command terminates any active session for the specified neighbor and removes all associated routing information.

To display a summary of BGP neighbors, use the show bgp summary command. Those neighbors with an Idle status and the Admin entry have been disabled by the neighbor shutdown command.

‘State/PfxRcd’ shows the current state of the BGP session or the number of prefixes the router has received from a neighbor. When the maximum number (as set by the neighbor maximum-prefix command) is reached, the string ‘PfxRcd’ appears in the entry, the neighbor is shut down, and the connection is idle.

Examples

The following example disables any active session for the neighbor 172.16.70.23:

ciscoasa(config-router-af)# neighbor 172.16.70.23 shutdown

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables information exchange with a BGP neighbor.

show bgp summary

Displays a summary of BGP neighbor status.

neighbor timers

To set the timers for a specific BGP peer, use the neighbor timers command in address-family configuration mode. To clear the timers for a specific BGP peer , use the no form of this command.

neighbor ip_address timers keepalive holdtime [min- holdtime]

no neighbor ip_address timers

 
Syntax Description

ip_address

IP address of the neighbor router.

keepalive

Frequency (in seconds) with which the Cisco ASA software sends keepalive messages to its peer. The default is 60 seconds.The range is from 0 to 65535.

holdtime

Interval (in seconds) after not receiving a keepalive message that the software declares a peer dead. The default is 180 seconds. The range is from 0 to 65535.

min-holdtime

(Optional) Interval (in seconds) specifying the minimum acceptable hold-time from a BGP neighbor. The minimum acceptable hold-time must be less than, or equal to, the interval specified in the holdtime argument. The range is from 0 to 65535.

 
Command Default

Keepalive time: 60 seconds

Holdtime: 180 seconds

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

  • The timers configured for a specific neighbor override the timers configured for all BGP neighbors using the timers bgp command.
  • When configuring the holdtime argument for a value of less than twenty seconds, the following warning is displayed: A hold time of less than 20 seconds increases the chances of peer flapping.
  • If the minimum acceptable hold-time interval is greater than the specified hold-time, a notification is displayed: Minimum acceptable hold time should be less than or equal to the configured hold time.

Note When the minimum acceptable hold-time is configured on a BGP router, a remote BGP peer session is established only if the remote peer is advertising a hold-time that is equal to, or greater than, the minimum acceptable hold-time interval. If the minimum acceptable hold-time interval is greater than the configured hold-time, the next time the remote session tries to establish, it will fail and the local router will send a notification stating “unacceptable hold time.”


Examples

The following example changes the keepalive timer to 70 seconds and the hold-time timer to 210 seconds for the BGP peer 192.168.47.0:

ciscoasa(config-router-af)# neighbor 192.168.47.0 timers 70 210
 

The following example changes the keepalive timer to 70 seconds, the hold-time timer to 130 seconds, and the minimum hold-time interval to 100 seconds for the BGP peer 192.168.1.2:

ciscoasa(config-router-af)# neighbor 192.168.1.2 timers 70 130 100
 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables exchange of information with a BGP neighbor.

neighbor transport

To enable a TCP transport session option for a Border Gateway Protocol (BGP) session, use the neighbor transport command in router or address-family configuration mode. To disable a TCP transport session option for a BGP session, use the no form of this command.

neighbor ip_address transport {connection-mode {active | passive} | path-mtu-discovery [disable]}

no neighbor ip_address transport {connection-mode {active | passive} | path-mtu-discovery [disable]}

 
Syntax Description

ip_address

IP address of the neighbor router.

connection-mode

Specifies the type of connection - active or passive.

active

Specifies an active connection.

passive

Specifies a passive connection.

path-mtu-discovery

Enables TCP transport path maximum transmission unit (MTU) discovery. TCP path MTU discovery is enabled by default.

disable

Disables TCP path MTU discovery.

 
Command Default

If this command is not configured, TCP path MTU discovery is enabled by default, but no other TCP transport session options are enabled.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

This command is used to specify various transport options. An active or passive transport connection can be specified for a BGP session. TCP transport path MTU discovery can be enabled to allow a BGP session to take advantage of larger MTU links. Use the show bgp neighbors command to determine whether TCP path MTU discovery is enabled.If you use the disable keyword to disable discovery, discovery is also disabled on any peer that inherits the template in which you disabled discovery.

Examples

The following example shows how to configure the TCP transport connection to be active for a single internal BGP (iBGP) neighbor:

ciscoasa(config)# router bgp 45000
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.1.2 remote-as 45000
ciscoasa(config-router-af)# neighbor 172.16.1.2 activate
ciscoasa(config-router-af)# neighbor 172.16.1.2 transport connection-mode active
 

The following example shows how to configure the TCP transport connection to be passive for a single external BGP (eBGP) neighbor:

ciscoasa(config)# router bgp 45000
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 192.168.1.2 remote-as 40000
ciscoasa(config-router-af)# neighbor 192.168.1.2 activate
ciscoasa(config-router-af)# neighbor 192.168.1.2 transport connection-mode passive

 

The following example shows how to disable TCP path MTU discovery for a single BGP neighbor:

ciscoasa(config)# router bgp 45000
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.1.2 remote-as 45000
ciscoasa(config-router-af)# neighbor 172.16.1.2 activate
ciscoasa(config-router-af)# no neighbor 172.16.1.2 transport path-mtu-discovery

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables exchange of information with a BGP neighbor.

neighbor remote-as

Adds an entry to the BGP or multi-protocol BGP routing table.

show bgp neighbor

Displays information about BGP neighbors

neighbor ttl-security

To secure a Border Gateway Protocol (BGP) peering session and to configure the maximum number of hops that separate two external BGP (eBGP) peers, use the neighbor ttl-security command in address-family configuration mode. To disable this feature, use the no form of this command.

neighbor ip_address ttl-security hops hop-count

no neighbor ip_address ttl-security hops hop-count

 
Syntax Description

ip_address

IP address of the neighbor router.

hop-count

Number of hops that separate the eBGP peers. The TTL value is calculated by the router from the configured hop-count argument.

Valid values are a number between 1 and 254.

 
Command Default

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

The neighbor ttl-security command provides a lightweight security mechanism to protect BGP peering sessions from CPU utilization-based attacks. These types of attacks are typically brute force Denial of Service (DoS) attacks that attempt to disable the network by flooding the network with IP packets that contain forged source and destination IP addresses in the packet headers.

This feature leverages designed behavior of IP packets by accepting only IP packets with a TTL count that is equal to or greater than the locally configured value. Accurately forging the TTL count in an IP packet is generally considered to be impossible. Accurately forging a packet to match the TTL count from a trusted peer is not possible without internal access to the source or destination network.

This feature should be configured on each participating router. It secures the BGP session in the incoming direction only and has no effect on outgoing IP packets or the remote router. When this feature is enabled, BGP will establish or maintain a session only if the TTL value in the IP packet header is equal to or greater than the TTL value configured for the peering session. This feature has no effect on the BGP peering session, and the peering session can still expire if keepalive packets are not received. If the TTL value in a received packet is less than the locally configured value, the packet is silently discarded and no Internet Control Message Protocol (ICMP) message is generated. This is designed behavior; a response to a forged packet is not necessary.

To maximize the effectiveness of this feature, the hop-count value should be strictly configured to match the number of hops between the local and external network. However, you should also take path variation into account when configuring this feature for a multihop peering session.

The following restrictions apply to the configuration of this command:

  • This feature is not supported for internal BGP (iBGP) peers.
  • The neighbor ttl-security command cannot be configured for a peer that is already configured with the neighbor ebgp-multihop command. The configuration of these commands is mutually exclusive, and only one of these commands is needed to enable a multihop eBGP peering session. An error message will be displayed in the console if you attempt to configure both commands for the same peering session.
  • The effectiveness of this feature is reduced in large-diameter multihop peerings. In the event of a CPU utilization-based attack against a BGP router that is configured for large-diameter peering, you may still need to shut down the affected peering sessions to handle the attack.
  • This feature is not effective against attacks from a peer that has been compromised inside of your network. This restriction also includes peers that are on the network segment between the source and destination network.

Examples

The following example sets the hop count to 2 for a directly connected neighbor. Because the hop-count argument is set to 2, BGP will accept only IP packets with a TTL count in the header that is equal to or greater than 253. If a packet is received with any other TTL value in the IP packet header, the packet will be silently discarded.

ciscoasa(config-router-af)# neighbor 10.0.0.1 ttl-security hops 2
 

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables exchange of information with a BGP neighbor.

neighbor ebgp-multihop

Accepts and attempts BGP connections to external peers residing on networks that are not directly connected

neighbor version

To configure the ASA software to accept only a particular BGP version, use the neighbor version command in the address-family configuration mode. To use the default version level of a neighbor, use the no form of this command.

neighbor ip_address version number

no neighbor ip_address version number

 
Syntax Description

ip_address

IP address of the neighbor router.

number

BGP version number. The version can be set to 2 to force the software to use only Version 2 with the specified neighbor. The default is to use Version 4 and dynamically negotiate down to Version 2 if requested.

 
Command Default

BGP version 4.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

Entering this command disables dynamic version negotiation.

Examples

The following example locks down to Version 4 of the BGP protocol:

ciscoasa(config)# router bgp 109
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# neighbor 172.16.27.2 version 4

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables exchange of information with a BGP neighbor.

neighbor weight

To assign a weight to a neighbor connection, use the neighbor weight command in address-family configuration mode. To remove a weight assignment, use the no form of this command.

neighbor ip_address weight number

no neighbor ip_address weight number

 
Syntax Description

ip_address

IP address of the neighbor router.

number

Weight to assign.

Valid values are between 0 and 65535.

 
Command Default

Routes learned through another BGP peer have a default weight of 0 and routes sourced by the local router have a default weight of 32768.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration mode

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

All routes learned from this neighbor will have the assigned weight initially. The route with the highest weight will be chosen as the preferred route when multiple routes are available to a particular network.

The weights assigned with the set weight route-map command override the weights assigned using the neighbor weight command.

Examples

The following address-family configuration mode example sets the weight of all routes learned via 172.16.12.1 to 50:

ciscoasa(config-router-af)# neighbor 172.16.12.1 weight 50

 
Related Commands

Command
Description

address-family ipv4

Enters address-family configuration mode.

neighbor activate

Enables exchange of information with a BGP neighbor.

nem

To enable network extension mode for hardware clients, use the nem enable command in group-policy configuration mode. To disable NEM, use the nem disable command. To remove the NEM attribute from the running configuration, use the no form of this command. This option allows inheritance of a value from another group policy.

nem { enable | disable }

no nem

 
Syntax Description

disable

Disables Network Extension Mode.

enable

Enables Network Extension Mode.

 
Defaults

Network extension mode is disabled.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Group-policy configuration

  • Yes

  • Yes

 
Usage Guidelines

Network Extension mode lets hardware clients present a single, routable network to the remote private network over the VPN tunnel. IPsec encapsulates all traffic from the private network behind the hardware client to networks behind the ASA. PAT does not apply. Therefore, devices behind the ASA have direct access to devices on the private network behind the hardware client over the tunnel, and only over the tunnel, and vice versa. The hardware client must initiate the tunnel, but after the tunnel is up, either side can initiate data exchange.

 
Command History

Release
Modification

7.0(1)

This command was introduced.

Examples

The following example shows how to set NEM for the group policy named FirstGroup:

ciscoasa(config)# group-policy FirstGroup attributes
ciscoasa(config-group-policy)# nem enable

 

network

To specify a list of networks for the RIP routing process, use the network command in router configuration mode. To remove a network definition, use the no form of this command.

network ip_addr

no network ip_addr

 
Syntax Description

ip_addr

The IP address of a directly connected network. The interface connected to the specified network will participate in the RIP routing process.

 
Defaults

No networks are specified.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Router configuration

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

7.2(1)

This command was introduced.

9.0(1)

Multiple context mode is supported.

 
Usage Guidelines

The network number specified must not contain any subnet information. There is no limit to the number of network commands you can use on the router. RIP routing updates will be sent and received only through interfaces on the specified networks. Also, if the network of an interface is not specified, the interface will not be advertised in any RIP update.

Examples

The following example defines RIP as the routing protocol to be used on all interfaces connected to networks 10.0.0.0 and 192.168.7.0:

ciscoasa(config)# router rip
ciscoasa(config-router)# network 10.0.0.0
ciscoasa(config-router)# network 192.168.7.0
 

 
Related Commands

Command
Description

router rip

Enters router configuration mode.

show running-config router

Displays the commands in the global router configuration.

network (EIGRP)

To specify a list of networks for the EIGRP routing process, use the network command in router configuration mode. To remove a network definition, use the no form of this command.

network ip_addr [ mask ]

no network ip_addr [ mask ]

 
Syntax Description

ip_addr

The IP address of a directly connected network. The interface connected to the specified network will participate in the EIGRP routing process.

mask

(Optional) The network mask for the IP address.

 
Defaults

No networks are specified.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Router configuration

  • Yes

  • Yes

 
Command History

Release
Modification

8.0(2)

This command was introduced.

 
Usage Guidelines

The network command starts EIGRP on all interfaces with at least one IP address in the specified network. It inserts the connected subnet from the specified network in the EIGRP topology table.

The ASA then establishes neighbors through the matched interfaces. There is no limit to the number of network commands that can be configured on the ASA.

Examples

The following example defines EIGRP as the routing protocol to be used on all interfaces connected to networks 10.0.0.0 and 192.168.7.0:

ciscoasa(config)# router eigrp 100
ciscoasa(config-router)# network 10.0.0.0 255.0.0.0
ciscoasa(config-router)# network 192.168.7.0 255.255.255.0
 

 
Related Commands

Command
Description

show eigrp interfaces

Displays information about interfaces configured for EIGRP.

show eigrp topology

Displays the EIGRP topology table.

network BGP

To specify the networks to be advertised by the Border Gateway Protocol (BGP) routing processes, use the network command in address-family configuration mode. To remove an entry from the routing table, use the no form of this command.

network {network-number [mask network-mask]} [route-map map-tag]

no network {network-number [mask network-mask]} [route-map map-tag]

 
Syntax Description

network-number

Network that BGP or multiprotocol BGP will advertise.

mask network-mask

(Optional) Network or subnetwork mask with mask address.

route-map map-tag

(Optional) Identifier of a configured route map. The route map should be examined to filter the networks to be advertised. If not specified, all networks are advertised. If the keyword is specified, but no route map tags are listed, no networks will be advertised.

 
Defaults

No networks are specified.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Address-family configuration

  • Yes

  • Yes
  • Yes

 
Command History

Release
Modification

9.2(1)

This command was introduced.

 
Usage Guidelines

BGP and multiprotocol BGP networks can be learned from connected routes, from dynamic routing, and from static route sources.

The maximum number of network commands you can use is determined by the resources of the router, such as the configured NVRAM or RAM.

Examples

The following example sets up network 10.108.0.0 to be included in the BGP updates:

ciscoasa(config)# router bgp 65100
ciscoasa(config-router)# address-family ipv4
ciscoasa(config-router-af)# network 10.108.0.0

 
Related Commands

Command
Description

show bgp interfaces

Displays entries in the BGP routing table.

network-acl

To specify a firewall ACL name that you configured previously using the access-list command, use the network-acl command in dynamic-access-policy-record configuration mode. To remove an existing network ACL, use the no form of this command. To remove all network ACLs, use the command without arguments.

network-acl name

no network-acl [ name ]

 
Syntax Description

name

Specifies the name of the network ACL. The maximum number for a name is 240 characters.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Dynamic-access-policy-record configuration

  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.0(2)

This command was introduced.

 
Usage Guidelines

Use this command multiple time to assign multiple firewall ACLs to the DAP record.

The ASA verifies each of the ACLs you specify to make sure they contain only permit rules or only deny rules for the access-list entries. If any of the specified ACLs contain mixed permit and deny rules, then the ASA rejects the command.

The following example shows how to apply a network ACL called Finance Restrictions to the DAP record named Finance.

ciscoasa(config)# dynamic-access-policy-record Finance
ciscoasa(config-dynamic-access-policy-record)# network-acl Finance Restrictions
ciscoasa(config-dynamic-access-policy-record)#
 

 
Related Commands

Command
Description

access-policy

Configures a firewall access policy.

dynamic-access-policy-record

Creates a DAP record.

show running-config dynamic-access-policy-record [ name ]

Displays the running configuration for all DAP records, or for the named DAP record.

network area

To define the interfaces on which OSPF runs and to define the area ID for those interfaces, use the network area command in router configuration mode. To disable OSPF routing for interfaces defined with the address/netmask pair, use the no form of this command.

network addr mask area area_id

no network addr mask area area_id

 
Syntax Description

addr

IP address.

area area_id

Specifies the area that is to be associated with the OSPF address range. The area_id can be specified in either IP address format or in decimal format. When specified in decimal format, valid values range from 0 to 4294967295.

mask

The network mask.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Router configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

For OSPF to operate on the interface, the address of the interface must be covered by the network area command. If the network area command does not cover the IP address of the interface, it will not enable OSPF over that interface.

There is no limit to the number of network area commands you can use on the ASA.

Examples

The following example enables OSPF on the 192.168.1.1 interface and assigns it to area 2:

ciscoasa(config-router)# network 192.168.1.1 255.255.255.0 area 2
 

 
Related Commands

Command
Description

router ospf

Enters router configuration mode.

show running-config router

Displays the commands in the global router configuration.

network-object

To add a host object, a network object, or a subnet object to a network object group, use the network-object command in object-group network configuration mode. To remove network objects, use the no form of this command.

network-object {host ip_address | ip_address mask | object name }

no network-object {host ip_address | ip_address mask | object name }

 
Syntax Description

host ip_address

Specifies a host IP address.

ip_address mask

Specifies the network address and subnet mask.

object name

Specifies a network object ( object network command).

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Object-group network configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.3(1)

The object argument was added to support network objects ( object network command).

 
Usage Guidelines

The network-object command is used with the object-group command to define a host object, a network object, or a subnet object.

Examples

The following example shows how to use the network-object command to create a new host object in a network object group:

ciscoasa(config)# object-group network sjj_eng_ftp_servers
ciscoasa(config-network-object-group)# network-object host sjj.eng.ftp
ciscoasa(config-network-object-group)# network-object host 172.16.56.195
ciscoasa(config-network-object-group)# network-object 192.168.1.0 255.255.255.224
ciscoasa(config-network-object-group)# group-object sjc_eng_ftp_servers
ciscoasa(config)#

 
Related Commands

Command
Description

clear configure object-group

Removes all the object-group commands from the configuration.

group-object

Adds network object groups.

object network

Adds a network object.

object-group network

Defines network object groups.

service-object

Adds a service object to a service object group.

show running-config object-group

Displays the current object groups.

nop

To define an action when the No Operation IP option occurs in a packet with IP Options inspection, use the nop command in parameters configuration mode. To disable this feature, use the no form of this command.

nop action {allow | clear}

no nop action {allow | clear}

 
Syntax Description

allow

Instructs the ASA to allow a packet containing the No Operation IP option to pass.

clear

Instructs the ASA to clear the No Operation IP option from a packet and then allow the packet to pass.

 
Defaults

By default, IP Options inspection, drops packets containing the No Operation IP option.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Parameters configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

8.2(2)

This command was introduced.

 
Usage Guidelines

This command can be configured in an IP Options inspection policy map.

You can configure IP Options inspection to control which IP packets with specific IP options are allowed through the ASA. Configuring this inspection instructs the ASA to allow a packet to pass or to clear the specified IP options and then allow the packet to pass.

The Options field in the IP header can contain zero, one, or more options, which makes the total length of the field variable. However, the IP header must be a multiple of 32 bits. If the number of bits of all options is not a multiple of 32 bits, the No Operation (NOP) or IP Option 1 is used as “internal padding” to align the options on a 32-bit boundary.

Examples

The following example shows how to set up an action for IP Options inspection in a policy map:

ciscoasa(config)# policy-map type inspect ip-options ip-options_map
ciscoasa(config-pmap)# parameters
ciscoasa(config-pmap-p)# eool action allow
ciscoasa(config-pmap-p)# nop action allow
ciscoasa(config-pmap-p)# router-alert action allow
 

 
Related Commands

Command
Description

class

Identifies a class map name in the policy map.

class-map type inspect

Creates an inspection class map to match traffic specific to an application.

policy-map

Creates a Layer 3/4 policy map.

show running-config policy-map

Display all current policy map configurations.

nt-auth-domain-controller

To specify the name of the NT Primary Domain Controller for this server, use the nt-auth-domain-controller command in aaa-server host configuration mode. To remove this specification, use the no form of this command.

nt-auth-domain-controller string

no nt-auth-domain-controller

 
Syntax Description

string

Specifies the name, up to 16 characters long, of the Primary Domain Controller for this server.

 
Defaults

No default behaviors or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Aaa-server host configuration

  • Yes
  • Yes
  • Yes
  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

This command is valid only for NT Authentication AAA servers. You must have first used the aaa-server host command to enter host configuration mode. The name in the string variable must match the NT entry on the server itself.

Examples

The following example configures the name of the NT Primary Domain Controller for this server as “primary1”:

ciscoasa(config)# aaa-server svrgrp1 protocol nt
ciscoasa(configaaa-sesrver-group)# aaa-server svrgrp1 host 1.2.3.4
ciscoasa(config-aaa-server-host)# nt-auth-domain-controller primary1
ciscoasa(config-aaa-server-host)#

 
Related Commands

Command
Description

aaa server host

Enters aaa server host configuration mode so that you can configure AAA server parameters that are host-specific.

clear configure aaa-server

Remove all AAA command statements from the configuration.

show running-config aaa-server

Displays AAA server statistics for all AAA servers, for a particular server group, for a particular server within a particular group, or for a particular protocol.

ntp authenticate

To enable authentication with an NTP server, use the ntp authenticate command in global configuration mode. To disable NTP authentication, use the no form of this command.

ntp authenticate

no ntp authenticate

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

If you enable authentication, the ASA only communicates with an NTP server if it uses the correct trusted key in the packets (see the ntp trusted-key command). The ASA also uses an authentication key to synchronize with the NTP server (see the ntp authentication-key command).

Examples

The following example configures the ASA to synchronize only to systems that provide authentication key 42 in their NTP packets:

ciscoasa(config)# ntp authenticate
ciscoasa(config)# ntp authentication-key 42 md5 aNiceKey
ciscoasa(config)# ntp trusted-key 42
 

 
Related Commands

Command
Description

ntp authentication-key

Sets an encrypted authentication key to synchronize with an NTP server.

ntp server

Identifies an NTP server.

ntp trusted-key

Provides a key ID for the ASA to use in packets for authentication with an NTP server.

show ntp associations

Shows the NTP servers with which the ASA is associated.

show ntp status

Shows the status of the NTP association.

ntp authentication-key

To set a key to authenticate with an NTP server, use the ntp authentication-key command in global configuration mode. To remove the key, use the no form of this command.

ntp authentication-key key_id md5 key

no ntp authentication-key key_id [ md5 [0 | 8] key ]

 
Syntax Description

0

(optional) Indicates <key_value> is plain text. Format is plain text if 0 or 8 is not present.

8

(optional) Indicates <key_value> is encrypted text. Format is plain text if 0 or 8 is not present.

key

Sets the key value as a string up to 32 characters in length.

key_id

Identifies a key ID between 1 and 4294967295. You must specify this ID as a trusted key using the ntp trusted-key command.

md5

Specifies the authentication algorithm as MD5, which is the only algorithm supported.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

To use NTP authentication, also configure the ntp authenticate command.

Examples

The following example enables authentications, identifies trusted key IDs 1 and 2, and sets authentication keys for each trusted key ID:

ciscoasa(config)# ntp authenticate
ciscoasa(config)# ntp trusted-key 1
ciscoasa(config)# ntp trusted-key 2
ciscoasa(config)# ntp authentication-key 1 md5 aNiceKey
ciscoasa(config)# ntp authentication-key 2 md5 aNiceKey2
 

 
Related Commands

Command
Description

ntp authenticate

Enables NTP authentication.

ntp server

Identifies an NTP server.

ntp trusted-key

Provides a key ID for the ASA to use in packets for authentication with an NTP server.

show ntp associations

Shows the NTP servers with which the ASA is associated.

show ntp status

Shows the status of the NTP association.

ntp server

To identify an NTP server to set the time on the ASA, use the ntp server command in global configuration mode. To remove the server, use the no form of this command.

ntp server ip_address [ key key_id ] [ source interface_name ] [ prefer ]

no ntp server ip_address [ key key_id ] [ source interface_name ] [ prefer ]

 
Syntax Description

ip_address

Sets the IP address or hostname of the NTP server.

key key_id

If you enable authentication using the ntp authenticate command, sets the trusted key ID for this server. See also the ntp trusted-key command.

source interface_name

Identifies the outgoing interface for NTP packets if you do not want to use the default interface in the routing table. Because the system does not include any interfaces in multiple context mode, specify an interface name defined in the admin context.

prefer

Sets this NTP server as the preferred server if multiple servers have similar accuracy. NTP uses an algorithm to determine which server is the most accurate and synchronizes to that one. If servers are of similar accuracy, then the prefer keyword specifies which of those servers to use. However, if a server is significantly more accurate than the preferred one, the ASA uses the more accurate one. For example, the ASA uses a server of stratum 2 over a server of stratum 3 that is preferred.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was modified to make the source interface optional.

 
Usage Guidelines

You can identify multiple servers; the ASA uses the most accurate server. In multiple context mode, set the NTP server in the system configuration only.

Examples

The following example identifies two NTP servers and enables authentication for the key IDs 1 and 2:

ciscoasa(config)# ntp server 10.1.1.1 key 1 prefer
ciscoasa(config)# ntp server 10.2.1.1 key 2
ciscoasa(config)# ntp authenticate
ciscoasa(config)# ntp trusted-key 1
ciscoasa(config)# ntp trusted-key 2
ciscoasa(config)# ntp authentication-key 1 md5 aNiceKey
ciscoasa(config)# ntp authentication-key 2 md5 aNiceKey2
 

 
Related Commands

Command
Description

ntp authenticate

Enables NTP authentication.

ntp authentication-key

Sets an encrypted authentication key to synchronize with an NTP server.

ntp trusted-key

Provides a key ID for the ASA to use in packets for authentication with an NTP server.

show ntp associations

Shows the NTP servers with which the ASA is associated.

show ntp status

Shows the status of the NTP association.

ntp trusted-key

To specify an authentication key ID to be a trusted key, which is required for authentication with an NTP server, use the ntp trusted-key command in global configuration mode. To remove the trusted key, use the no form of this command. You can enter multiple trusted keys for use with multiple servers.

ntp trusted-key key_id

no ntp trusted-key key_id

 
Syntax Description

key_id

Sets a key ID between 1 and 4294967295.

 
Defaults

No default behavior or values.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Global configuration

  • Yes
  • Yes
  • Yes

  • Yes

 
Command History

Release
Modification

7.0(1)

This command was introduced.

 
Usage Guidelines

To use NTP authentication, also configure the ntp authenticate command. To synchronize with a server, set the authentication key for the key ID using the ntp authentication-key command.

Examples

The following example enables authentications, identifies trusted key IDs 1 and 2, and sets authentication keys for each trusted key ID:

ciscoasa(config)# ntp authenticate
ciscoasa(config)# ntp trusted-key 1
ciscoasa(config)# ntp trusted-key 2
ciscoasa(config)# ntp authentication-key 1 md5 aNiceKey
ciscoasa(config)# ntp authentication-key 2 md5 aNiceKey2
 

 
Related Commands

Command
Description

ntp authenticate

Enables NTP authentication.

ntp authentication-key

Sets an encrypted authentication key to synchronize with an NTP server.

ntp server

Identifies an NTP server.

show ntp associations

Shows the NTP servers with which the ASA is associated.

show ntp status

Shows the status of the NTP association.

num-packets

To specify the number of request packets sent during an SLA operation, use the num-packets command in sla monitor protocol configuration mode. To restore the default value, use the no form of this command.

num-packets number

no num-packets number

 
Syntax Description

number

The number of packets sent during an SLA operation. Valid values are from 1 to 100.

Note When all the packets specified as the number argument (in this command) are lost, the tracked route has failed.

 
Defaults

The default number of packets sent for echo types is 1.

 
Command Modes

The following table shows the modes in which you can enter the command:

 

Command Mode
Firewall Mode
Security Context
Routed
Transparent
Single
Multiple
Context
System

Sla monitor protocol configuration

  • Yes

  • Yes

 
Command History

Release
Modification

7.2(1)

This command was introduced.

 
Usage Guidelines

Increase the default number of packets sent to prevent incorrect reachability information due to packet loss.

Examples

The following example configures an SLA operation with an ID of 123 that uses an ICMP echo request/response time probe operation. It sets the payload size of the echo request packets to 48 bytes and the number of echo requests sent during an SLA operation to 5. All 5 packets must be lost before the tracked route is removed

ciscoasa(config)# sla monitor 123
ciscoasa(config-sla-monitor)# type echo protocol ipIcmpEcho 10.1.1.1 interface outside
ciscoasa(config-sla-monitor-echo)# num-packets 5
ciscoasa(config-sla-monitor-echo)# request-data-size 48
ciscoasa(config-sla-monitor-echo)# timeout 4000
ciscoasa(config-sla-monitor-echo)# threshold 2500
ciscoasa(config-sla-monitor-echo)# frequency 10
ciscoasa(config)# sla monitor schedule 123 life forever start-time now
ciscoasa(config)# track 1 rtr 123 reachability
 

 
Related Commands

Command
Description

request-data-size

Specifies the size of the request packet payload.

sla monitor

Defines an SLA monitoring operation.

type echo

Configures the SLA operation as an echo response time probe operation.