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Table Of Contents
ip dhcp packet strict-validation
ip dhcp relay information option
ip dhcp relay information option vpn
ip dhcp relay subnet-broadcast
ip dhcp relay sub-option type cisco
ip dhcp snooping information option
ip dhcp snooping verify mac-address
ip verify source dhcp-snooping-vlan
ip verify unicast source reachable-via
I Commands
This chapter describes the Cisco NX-OS security commands that begin with I.
identity policy
To create or specify an identity policy and enter identity policy configuration mode, use the identity policy command. To remove an identity policy, use the no form of this command.
identity policy policy-name
no identity policy policy-name
Syntax Description
policy-name
Name for the identity policy. The name is case sensitive, alphanumeric, and has a maximum of 100 characters.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-admin
VDC userCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to create an identity policy and enter identity policy configuration mode:
switch# configure terminalswitch(config)# identity policy AdminPolicyswitch(config-id-policy)#This example shows how to remove an identity policy:
switch# configure terminalswitch(config)# no identity policy AdminPolicyRelated Commands
identity profile eapoudp
To create the Extensible Authentication Protocol over User Datagram Protocol (EAPoUDP) identity profile and enter identity profile configuration mode, use the identity profile eapoupd command. To remove the EAPoUPD identity profile configuration, use the no form of this command.
identity profile eapoudp
no identity profile eapoudp
Syntax Description
This command has no arguments or keywords.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-admin
VDC userCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to create the EAPoUDP identity profile and enter identity profile configuration mode:
switch# configure terminalswitch(config)# identity profile eapoudpswitch(config-id-policy)#This example shows how to remove the EAPoUDP identity profile configuration:
switch# configure terminalswitch(config)# no identity profile eapoudpRelated Commands
interface policy deny
To enter interface policy configuration mode for a user role, use the interface policy deny command. To revert to the default interface policy for a user role, use the no form of this command.
interface policy deny
no interface policy deny
Syntax Description
This command has no arguments or keywords.
Defaults
All interfaces
Command Modes
User role configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command denies all interfaces to the user role except for those that you allow using the permit interface command in user role interface policy configuration mode.
This command does not require a license.
Examples
This example shows how to enter user role interface policy configuration mode for a user role:
switch# configure terminalswitch(config)# role name MyRoleswitch(config-role)# interface policy denyswitch(config-role-interface)#This example shows how to revert to the default interface policy for a user role:
switch# configure terminalswitch(config)# role name MyRoleswitch(config-role)# no interface policy denyRelated Commands
ip access-class
To configure a virtual teletype (VTY) access control list (ACL) to control access to all IPv4 traffic over a VTY line in the ingress or egress direction, use the ip access-class command. To remove the VTY ACL, use the no form of this command.
ip access-class name {in | out}
no ip access-class name {in | out}
Syntax Description
Defaults
None
Command Modes
Global configuration (config)
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
The VTY ACL feature restricts all traffic on any VTY line. You cannot specify different traffic restrictions for different VTY lines.
Any router ACL can be configured as a VTY ACL.
This command does not require a license.
Examples
This example shows how to configure a VTY ACL to control access to all IPv4 traffic over a VTY line:
switch# configure terminalswitch(config)# ip access-list vtyaclswitch(config-ip-acl)# exitswitch(config)# line vtyswitch(config-line)# ip access-class vtyacl outswitch(config-line)#This example shows how to remove the VTY ACL from all IPv4 traffic over a VTY line:switch# configure terminalswitch(config)# line vtyswitch(config-line)# no ip access-class vtyacl outswitch(config-line)#Related Commands
ip access-group
To apply an IPv4 access control list (ACL) to an interface as a router ACL, use the ip access-group command. To remove an IPv4 ACL from an interface, use the no form of this command.
ip access-group access-list-name {in | out}
no ip access-group access-list-name {in | out}
Syntax Description
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, no IPv4 ACLs are applied to an interface.
You can use the ip access-group command to apply an IPv4 ACL as a router ACL to the following interface types:
•
VLAN interfaces
Note
•
•
•
•
•
•
You can also use the ip access-group command to apply an IPv4 ACL as a router ACL to the following interface types:
•
•
However, an ACL applied to a Layer 2 interface with the ip access-group command is inactive unless the port mode changes to routed (Layer 3) mode. To apply an IPv4 ACL as a port ACL, use the ip port access-group command.
You can also apply an IPv4 ACL as a VLAN ACL. For more information, see the match (VLAN access-map) command on page 388.
The device applies router ACLs on either outbound or inbound traffic. When the device applies an ACL to inbound traffic, the device checks inbound packets against the rules in the ACL. If the first matching rule permits the packet, the device continues to process the packet. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host-unreachable message.
For outbound access lists, after receiving and routing a packet to an interface, the device checks the ACL. If the first matching rule permits the packet, the device sends the packet to its destination. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host unreachable message.
If you delete the specified ACL from the device without removing the ACL from an interface, the deleted ACL does not affect traffic on the interface.
This command does not require a license.
Examples
This example shows how to apply an IPv4 ACL named ip-acl-01 to Ethernet interface 2/1:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip access-group ip-acl-01 inThis example shows how to remove an IPv4 ACL named ip-acl-01 from Ethernet interface 2/1:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# no ip access-group ip-acl-01 inRelated Commands
ip access-list
To create an IPv4 access control list (ACL) or to enter IP access list configuration mode for a specific ACL, use the ip access-list command. To remove an IPv4 ACL, use the no form of this command.
ip access-list access-list-name
no ip access-list access-list-name
Syntax Description
access-list-name
Name of the IPv4 ACL. The name has a maximum of 64 alphanumeric, case-sensitive characters but cannot contain a space or quotation mark.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
No IPv4 ACLs are defined by default.
Use IPv4 ACLs to filter IPv4 traffic.
When you use the ip access-list command, the device enters IP access list configuration mode, where you can use the IPv4 deny and permit commands to configure rules for the ACL. If the ACL specified does not exist, the device creates it when you enter this command.
Use the ip access-group command to apply the ACL to an interface as a router ACL. Use the ip port access-group command to apply the ACL to an interface as a port ACL.
Every IPv4 ACL has the following implicit rule as its last rule:
deny ip any anyThis implicit rule ensures that the device denies unmatched IP traffic.
Unlike IPv6 ACLs, IPv4 ACLs do not include additional implicit rules to enable the neighbor discovery process. The Address Resolution Protocol (ARP), which is the IPv4 equivalent of the IPv6 neighbor discovery process, uses a separate data link layer protocol. By default, IPv4 ACLs implicitly allow ARP packets to be sent and received on an interface.
Use the statistics per-entry command to configure the device to record statistics for each rule in an IPv4 ACL. The device does not record statistics for implicit rules. To record statistics for packets that would match the implicit deny ip any any rule, you must explicitly configure an identical rule.
This command does not require a license.
Examples
This example shows how to enter IP access list configuration mode for an IPv4 ACL named ip-acl-01:
switch# configure terminalswitch(config)# ip access-list ip-acl-01switch(config-acl)#Related Commands
ip arp inspection filter
To apply an ARP access control list (ACL) to a list of VLANs, use the ip arp inspection filter command. To remove the ARP ACL from the list of VLANs, use the no form of this command.
ip arp inspection filter acl-name vlan vlan-list
no ip arp inspection filter acl-name vlan vlan-list
Syntax Description
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to apply an ARP ACL named arp-acl-01 to VLANs 15 and 37 through 48:
switch# configure terminalswitch(config)# ip arp inspection filter arp-acl-01 vlan 15,37-48switch(config)#Related Commands
ip arp inspection log-buffer
To configure the Dynamic ARP Inspection (DAI) logging buffer size, use the ip arp inspection log-buffer command. To reset the DAI logging buffer to its default size, use the no form of this command.
ip arp inspection log-buffer entries number
no ip arp inspection log-buffer entries number
Syntax Description
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, the DAI logging buffer size is 32 messages.
This command does not require a license.
Examples
This example shows how to configure the DAI logging buffer size:
switch# configure terminalswitch(config)# ip arp inspection log-buffer entries 64switch(config)#Related Commands
ip arp inspection trust
To configure a Layer 2 interface as a trusted ARP interface, use the ip arp inspection trust command. To configure a Layer 2 interface as an untrusted ARP interface, use the no form of this command.
ip arp inspection trust
no ip arp inspection trust
Syntax Description
This command has no arguments or keywords.
Defaults
By default, all interfaces are untrusted ARP interfaces.
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
You can configure only Layer 2 Ethernet interfaces as trusted ARP interfaces.
This command does not require a license.
Examples
This example shows how to configure a Layer 2 interface as a trusted ARP interface:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip arp inspection trustswitch(config-if)#Related Commands
ip arp inspection validate
To enable additional Dynamic ARP Inspection (DAI) validation, use the ip arp inspection validate command. To disable additional DAI, use the no form of this command.
ip arp inspection validate {dst-mac [ip] [src-mac]}
ip arp inspection validate {[dst-mac] ip [src-mac]}
ip arp inspection validate {[dst-mac] [ip] src-mac}
no ip arp inspection validate {dst-mac [ip] [src-mac]}
no ip arp inspection validate {[dst-mac] ip [src-mac]}
no ip arp inspection validate {[dst-mac] [ip] src-mac}
Syntax Description
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
You must specify at least one keyword. If you specify more than one keyword, the order is irrelevant.
This command does not require a license.
Examples
This example shows how to enable additional DAI validation:
switch# configure terminalswitch(config)# ip arp inspection validate src-mac dst-mac ipswitch(config)#Related Commands
show ip arp inspection
Displays the DAI configuration status.
show running-config dhcp
Displays DHCP snooping configuration, including DAI configuration.
ip arp inspection vlan
To enable Dynamic ARP Inspection (DAI) for a list of VLANs, use the ip arp inspection vlan command. To disable DAI for a list of VLANs, use the no form of this command.
ip arp inspection vlan vlan-list [logging dhcp-bindings {permit | all | none}]
no ip arp inspection vlan vlan-list [logging dhcp-bindings {permit | all | none}]
Syntax Description
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, the device does not log packets inspected by DAI.
This command does not require a license.
Examples
This example shows how to enable DAI on VLANs 13, 15, and 17 through 23:
switch# configure terminalswitch(config)# ip arp inspection vlan 13,15,17-23switch(config)#Related Commands
ip dhcp packet strict-validation
To enable the strict validation of DHCP packets by the DHCP snooping feature, use the ip dhcp packet strict-validation command. To disable the strict validation of DHCP packets, use the no form of this command.
ip dhcp packet strict-validation
no ip dhcp packet strict-validation
Syntax Description
This command has no arguments or keywords.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command does not require a license.
You must enable DHCP snooping before you can use the ip dhcp packet strict-validation command.
Strict validation of DHCP packets checks that the DHCP options field in DCHP packets is valid, including the "magic cookie" value in the first four bytes of the options field. When strict validation of DHCP packets is enabled, the device drops DHCP packets that fail validation.
Examples
This example shows how to enable the strict validation of DHCP packets:
switch# configure terminalswitch(config)# ip dhcp packet strict-validationswitch(config)#Related Commands
ip dhcp relay
To enable the DHCP relay agent, use the ip dhcp relay command. To disable the DHCP relay agent, use the no form of this command.
ip dhcp relay
no ip dhcp relay
Syntax Description
This command has no arguments or keywords.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to globally enable DHCP snooping:
switch# configure terminalswitch(config)# ip dhcp relayswitch(config)#Related Commands
ip dhcp relay address
To configure the IP address of a DHCP server on an interface, use the ip dhcp relay address command. To remove the DHCP server IP address, use the no form of this command.
ip dhcp relay address IP-address [use-vrf vrf-name]
no ip dhcp relay address IP-address [use-vrf vrf-name]
Syntax Description
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
You can configure up to four DHCP server IP addresses on Layer 3 Ethernet interfaces and subinterfaces, VLAN interfaces, and Layer 3 port channels. In Cisco NX-OS Release 4.0.2 and earlier releases, you can configure only one DHCP server IP address on an interface.
When an inbound DHCP BOOTREQUEST packet arrives on the interface, the relay agent forwards the packet to all DHCP server IP addresses specified on that interface. The relay agent forwards replies from all DHCP servers to the host that sent the request.
This command does not require a license.
Examples
This example shows how to configure two IP addresses for DHCP servers so that the relay agent can forward BOOTREQUEST packets received on the specified Layer 3 Ethernet interface:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip dhcp relay address 10.132.7.120switch(config-if)# ip dhcp relay address 10.132.7.175switch(config-if)#This example shows how to configure the IP address of a DHCP server on a VLAN interface:
switch# configure terminalswitch(config)# interface vlan 13switch(config-if)# ip dhcp relay address 10.132.7.120switch(config-if)#This example shows how to configure the IP address of a DHCP server on a Layer 3 port-channel interface:
switch# configure terminalswitch(config)# interface port-channel 7switch(config-if)# ip dhcp relay address 10.132.7.120switch(config-if)#Related Commands
ip dhcp relay information option
To enable the device to insert and remove option-82 information on DHCP packets forwarded by the relay agent, use the ip dhcp relay information option command. To disable the insertion and removal of option-82 information, use the no form of this command.
ip dhcp relay information option
no ip dhcp relay information option
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the device does not insert and remove option-82 information on DHCP packets forwarded by the relay agent.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
This command does not require a license.
Examples
This example shows how to enable the DHCP relay agent to insert and remove option-82 information to and from packets it forwards:
switch# configure terminalswitch(config)# ip dhcp relay information optionswitch(config)#Related Commands
ip dhcp relay information option vpn
To enable VRF support for the DHCP relay agent, use the ip dhcp relay information option vpn command. To disable VRF support, use the no form of this command.
ip dhcp relay information option vpn
no ip dhcp relay information option vpn
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the device does not support forwarding of DHCP requests to DHCP servers in different VRFs than the VRF that the DHCP client belongs to.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable Option-82 information insertion for the DHCP relay agent (see the ip dhcp relay information option command).
You can configure the DHCP relay agent to forward DHCP broadcast messages from clients in one VRF to DHCP servers in a different VRF. By using a single DHCP server to provide DHCP support to clients in multiple VRFs, you can conserve IP addresses by using a single IP address pool rather than one for each VRF.
If a DHCP request arrives on an interface that you have configured with a DHCP relay address and VRF information and the address of the DCHP server belongs to a network on an interface that is a member of a different VRF, the device inserts Option-82 information in the request and forwards it to the DHCP server in the server VRF. The Option-82 information that the devices adds to a DHCP request relayed to a different VRF includes the following:
•
•
•
When the devices receives the DHCP response message, it strips off the Option-82 information and forwards the response to the DHCP client in the client VRF.
This command does not require a license.
Examples
This example shows how to enable VRF support for the DHCP relay agent, which is dependent upon enabling Option-82 support for the DHCP relay agent, and how to configure a DHCP server address on a Layer 3 interface when the DHCP server is in a VRF named SiteA:
switch# configure terminalswitch(config)# ip dhcp relay information optionswitch(config)# ip dhcp relay information option vpnswitch(config)# interface ethernet 1/3switch(config-if)# ip dhcp relay address 10.43.87.132 use-vrf SiteAswitch(config-if)#Related Commands
ip dhcp relay subnet-broadcast
To configure the Cisco NX-OS device to support the relaying of Dynamic Host Configuration Protocol (DHCP) packets from clients to a subnet broadcast IP address, use the ip dhcp relay subnet-broadcast command. To revert to the default behavior, use the no form of this command.
ip dhcp relay subnet-broadcast
no ip dhcp relay subnet-broadcast
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration mode (config-if)
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
DHCP smart relay and DHCP subnet broadcast support are limited to the first 100 IP addresses of the interface on which they are enabled.
You must configure a helper address on the interface in order to use DHCP smart relay and DHCP subnet broadcast support.
DHCP smart relay and DHCP subnet broadcast support are limited to the first 100 IP addresses of the interface on which they are enabled.
In a vPC environment with DHCP smart relay enabled, the subnet of the primary and secondary addresses of an interface should be the same on both Cisco NX-OS devices.
This command does not require a license.
Examples
This example shows how to configure the Cisco NX-OS device to support the relaying of DHCP packets from clients to a subnet broadcast IP address:
switch# configure terminalswitch(config)# interface ethernet 3/2switch(config-if)# ip dhcp relay subnet-broadcastswitch(config-if)This example shows how to remove configuration for relaying of DHCP packets from clients to a subnet broadcast IP address:switch(config)# interface ethernet 3/2switch(config-if)# no ip dhcp relay subnet-broadcastRelated Commands
feature dhcp
Enables the DHCP feature on the device.
ip dhcp relay
Enable the DHCP relay agent.
ip dhcp relay sub-option type cisco
To enable DHCP to use Cisco proprietary numbers 150, 152, and 151 when filling the link selection, server ID override, and VRF name/VPN ID relay agent option-82 suboptions, use the ip dhcp relay sub-option type cisco command. To disable DHCP's use of these proprietary numbers, use the no form of this command.
ip dhcp relay sub-option type cisco
no ip dhcp relay sub-option type cisco
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled. DHCP uses RFC numbers 5, 11, and 151 for the link selection, server ID override, and VRF name/VPN ID suboptions, respectively.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to enable DHCP to use Cisco proprietary numbers 150, 152, and 151 when filling the link selection, server ID override, and VRF name/VPN ID relay agent option-82 suboptions:
switch# configure terminalswitch(config)# ip dhcp relay sub-option type ciscoswitch(config)#Related Commands
ip dhcp smart-relay
To enable Dynamic Host Configuration Protocol (DHCP) smart relay on a Layer 3 interface, use the ip dhcp smart-relay command. To disable DHCP smart relay on a Layer 3 interface, use the no form of this command.
ip dhcp smart-relay
no ip dhcp smart-relay
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration mode (config-if)
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
The DHCP smart relay agent can be configured independently in default and nondefault VDCs.
Before using the ip dhcp smart-relay global command, you must enable the IP DHCP relay agent using the ip dhcp relay command.
DHCP smart relay and DHCP subnet broadcast support are limited to the first 100 IP addresses of the interface on which they are enabled.
You must configure a helper address on the interface in order to use DHCP smart relay and DHCP subnet broadcast support.
DHCP smart relay and DHCP subnet broadcast support are limited to the first 100 IP addresses of the interface on which they are enabled.
A maximum of 10,000 clients can use DHCP smart relay at any given time.
In a vPC environment with DHCP smart relay enabled, the subnet of the primary and secondary addresses of an interface should be the same on both Cisco NX-OS devices.
This command does not require a license.
Examples
This example shows how to enable DHCP smart relay on a Layer 3 interface:
switch# configure terminalswitch(config)# interface ethernet 7/2switch(config-if)# ip dhcp smart-relayswitch(config-if)#This example shows how to disable DHCP smart relay on a Layer 3 interface:
switch# configure terminalswitch(config)# interface ethernet 7/2switch(config-if)# no ip dhcp smart-relayswitch(config-if)#Related Commands
ip dhcp smart-relay global
Enables the DHCP smart relay globally on the Cisco NX-OS device.
ip dhcp relay
Enable the DHCP relay agent.
ip dhcp smart-relay global
To enable Dynamic Host Configuration Protocol (DHCP) smart relay globally on the Cisco NX-OS device, use the ip dhcp smart-relay global command. To disable DHCP smart relay globally on the Cisco NX-OS device, use the no form of this command.
ip dhcp smart-relay global
no ip dhcp smart-relay global
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Global configuration mode
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
The DHCP smart relay agent can be configured independently in default and nondefault VDCs.
Before using the ip dhcp smart-relay global command, you must enable the IP DHCP relay agent using the ip dhcp relay command.
DHCP smart relay and DHCP subnet broadcast support are limited to the first 100 IP addresses of the interface on which they are enabled.
You must configure a helper address on the interface in order to use DHCP smart relay and DHCP subnet broadcast support.
A maximum of 10,000 clients can use DHCP smart relay at any given time.
In a vPC environment with DHCP smart relay enabled, the subnet of the primary and secondary addresses of an interface should be the same on both Cisco NX-OS devices.
This command does not require a license.
Examples
This example shows how to enable DHCP smart relay globally on the Cisco NX-OS device:
switch# configure terminalswitch(config)# ip dhcp relayswitch(config)# ip dhcp smart-relay globalswitch(config)#This example shows how to disable DHCP smart relay globally on the Cisco NX-OS device:
switch# configure terminalswitch(config)# no ip dhcp smart-relay globalswitch(config)#Related Commands
ip dhcp smart-relay
Enables DHCP smart relay on a Layer 3 interface.
ip dhcp relay
Enable the DHCP relay agent.
ip dhcp snooping
To globally enable DHCP snooping on the device, use the ip dhcp snooping command. To globally disable DHCP snooping, use the no form of this command.
ip dhcp snooping
no ip dhcp snooping
Syntax Description
This command has no arguments or keywords.
Defaults
By default, DHCP snooping is globally disabled.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
The device preserves DHCP snooping configuration when you disable DHCP snooping with the no ip dhcp snooping command.
This command does not require a license.
Examples
This example shows how to globally enable DHCP snooping:
switch# configure terminalswitch(config)# ip dhcp snoopingswitch(config)#Related Commands
ip dhcp snooping information option
To enable the insertion and removal of option-82 information for DHCP packets, use the ip dhcp snooping information option command. To disable the insertion and removal of option-82 information, use the no form of this command.
ip dhcp snooping information option
no ip dhcp snooping information option
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the device does not insert and remove option-82 information.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
This command does not require a license.
Examples
This example shows how to globally enable DHCP snooping:
switch# configure terminalswitch(config)# ip dhcp snooping information optionswitch(config)#Related Commands
ip dhcp snooping trust
To configure an interface as a trusted source of DHCP messages, use the ip dhcp snooping trust command. To configure an interface as an untrusted source of DHCP messages, use the no form of this command.
ip dhcp snooping trust
no ip dhcp snooping trust
Syntax Description
This command has no arguments or keywords.
Defaults
By default, no interface is a trusted source of DHCP messages.
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
You can configure DHCP trust on the following types of interfaces:
•
•
•
This command does not require a license.
Examples
This example shows how to configure an interface as a trusted source of DHCP messages:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip dhcp snooping trustswitch(config-if)#Related Commands
ip dhcp snooping verify mac-address
To enable DHCP snooping MAC address verification, use the ip dhcp snooping verify mac-address command. To disable DHCP snooping MAC address verification, use the no form of this command.
ip dhcp snooping verify mac-address
no ip dhcp snooping verify mac-address
Syntax Description
This command has no arguments or keywords.
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, MAC address verification with DHCP snooping is not enabled.
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
If the device receives a packet on an untrusted interface and the source MAC address and the DHCP client hardware address do not match, address verification causes the device to drop the packet.
This command does not require a license.
Examples
This example shows how to enable DHCP snooping MAC address verification:
switch# configure terminalswitch(config)# ip dhcp snooping verify mac-addressswitch(config)#Related Commands
ip dhcp snooping vlan
To enable DHCP snooping one or more VLANs, use the ip dhcp snooping vlan command. To disable DHCP snooping on one or more VLANs, use the no form of this command.
ip dhcp snooping vlan vlan-list
no ip dhcp snooping vlan vlan-list
Syntax Description
Defaults
By default, DHCP snooping is not enabled on any VLAN.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
To use this command, you must enable the DHCP snooping feature (see the feature dhcp command).
This command does not require a license.
Examples
This example shows how to enable DHCP snooping on VLANs 100, 200, and 250 through 252:
switch# configure terminalswitch(config)# ip dhcp snooping vlan 100,200,250-252switch(config)#Related Commands
ip port access-group
To apply an IPv4 access control list (ACL) to an interface as a port ACL, use the ip port access-group command. To remove an IPv4 ACL from an interface, use the no form of this command.
ip port access-group access-list-name in
no ip port access-group access-list-name in
Syntax Description
access-list-name
Name of the IPv4 ACL, which can be up to 64 alphanumeric, case-sensitive characters.
in
Specifies that the ACL applies to inbound traffic.
Defaults
in
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, no IPv4 ACLs are applied to an interface.
You can use the ip port access-group command to apply an IPv4 ACL as a port ACL to the following interface types:
•
•
You can also use the ip port access-group command to apply an IPv4 ACL as a port ACL to the following interface types:
•
Note
•
•
•
•
•
•
However, an ACL applied to a Layer 3 interface with the ip port access-group command is inactive unless the port mode changes to access or trunk (Layer 2) mode. To apply an IPv4 ACL as a router ACL, use the ip access-group command.
You can also apply an IPv4 ACL as a VLAN ACL. For more information, see the match (VLAN access-map) command on page 388.
The device applies port ACLs to inbound traffic only. The device checks inbound packets against the rules in the ACL. If the first matching rule permits the packet, the device continues to process the packet. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host-unreachable message.
If you delete the specified ACL from the device without removing the ACL from an interface, the deleted ACL does not affect traffic on the interface.
If MAC packet classification is enabled on a Layer 2 interface, you cannot use the ip port access-group command on the interface.
This command does not require a license.
Examples
This example shows how to apply an IPv4 ACL named ip-acl-01 to Ethernet interface 2/1 as a port ACL:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip port access-group ip-acl-01 inThis example shows how to remove an IPv4 ACL named ip-acl-01 from Ethernet interface 2/1:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# no ip port access-group ip-acl-01 inThis example shows how to view the configuration of an Ethernet interface and the error message that appears if you try to apply an IPv4 port ACL to the interface when MAC packet classification is enabled:
switch(config)# show running-config interface ethernet 2/3!Command: show running-config interface Ethernet2/3!Time: Wed Jun 24 13:06:49 2009version 4.2(1)interface Ethernet2/3ip access-group ipacl inmac port access-group macaclswitchportmac packet-classifyswitch(config)# interface ethernet 2/3switch(config-if)# ip port access-group ipacl inERROR: The given policy cannot be applied as mac packet classification is enabled on this portswitch(config-if)#Related Commands
ip radius source-interface
To assign a global source interface for the RADIUS server groups, use the ip radius source-interface command. To revert to the default, use the no form of this command.
ip radius source-interface interface
no ip radius source-interface
Syntax Description
Defaults
Any available interface
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
This command does not require a license.
Examples
This example shows how to configure the global source interface for RADIUS server groups:
switch# configure terminalswitch(config)# ip radius source-interface mgmt 0This example shows how to remove the global source interface for RADIUS server groups:
switch# configure terminalswitch(config)# no ip radius source-interfaceRelated Commands
ip source binding
To create a static IP source entry for a Layer 2 Ethernet interface, use the ip source binding command. To disable the static IP source entry, use the no form of this command.
ip source binding IP-address MAC-address vlan vlan-id interface ethernet slot/port
no ip source binding IP-address MAC-address vlan vlan-id interface ethernet slot/port
Syntax Description
Defaults
None
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, there are no static IP source entries.
This command does not require a license.
Examples
This example shows how to create a static IP source entry associated with VLAN 100 on Ethernet interface 2/3:
switch# configure terminalswitch(config)# ip source binding 10.5.22.7 001f.28bd.0013 vlan 100 interface ethernet 2/3switch(config)#Related Commands
ip tacacs source-interface
To assign a global source interface for the TACACS+ server groups, use the ip tacacs source-interface command. To revert to the default, use the no form of this command.
ip tacacs source-interface interface
no ip tacacs source-interface
Syntax Description
Defaults
Any available interface
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
You must use the feature tacacs+ command before you configure TACACS+.
This command does not require a license.
Examples
This example shows how to configure the global source interface for TACACS+ server groups:
switch# configure terminalswitch(config)# ip tacacs source-interface mgmt 0This example shows how to remove the global source interface for TACACS+ server groups:
switch# configure terminalswitch(config)# no ip tacacs source-interfaceRelated Commands
feature tacacs+
Enables the TACACS+ feature.
show tacacs-server groups
Displays the TACACS+ server group configuration.
ipv6 access-class
To configure a virtual type (VTY) access control list (ACL) to control access to all IPv6 traffic over a VTY line in the ingress or egress direction, use the ipv6 access-class command. To remove the VTY ACL control access from the traffic over a VTY line, use the no form of this command.
ipv6 access-class name {in | out}
no ipv6 access-class name {in | out}
Syntax Description
Defaults
None
Command Modes
Global configuration (config)
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
The VTY ACL feature restricts all traffic on any VTY line. You cannot specify different traffic restrictions for different VTY lines.
Any router ACL can be configured as a VTY ACL.
This command does not require a license.
Examples
This example shows how to configure VTY ACL to control access to all IPv6 traffic over a VTY line:
switch# configure terminalswitch(config)# ip access-list vtyaclswitch(config-ip-acl)# exitswitch(config)# line vtyswitch(config-line)# ipv6 access-class vtyacl1 inswitch(config-line)#This example shows how to remove the VTY ACL from the IPv6 traffic over a VTY line:
switch# configure terminalswitch(config)# line vtyswitch(config-line)# no ipv6 access-class vtyacl1 inswitch(config-line)#Related Commands
ip verify source dhcp-snooping-vlan
To enable IP Source Guard on a Layer 2 Ethernet interface, use the ip verify source dhcp-snooping-vlan command. To disable IP Source Guard on an interface, use the no form of this command.
ip verify source dhcp-snooping-vlan
no ip verify source dhcp-snooping-vlan
Syntax Description
This command has no arguments or keywords.
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, IP Source Guard is not enabled on any interface.
This command does not require a license.
Examples
This example shows how to enable IP Source Guard on an interface:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ip verify source dhcp-snooping-vlanswitch(config-if)#Related Commands
ip source binding
Creates a static IP source entry for the specified Ethernet interface.
show ip verify source
Displays IP-to-MAC address bindings.
ip verify unicast source reachable-via
To configure Unicast Reverse Path Forwarding (Unicast RPF) on an interface, use the ip verify unicast source reachable-via command. To remove Unicast RPF from an interface, use the no form of this command.
ip verify unicast source reachable-via {any [allow-default] | rx}
no ip verify unicast source reachable-via {any [allow-default] | rx}
Syntax Description
any
Specifies loose checking.
allow-default
(Optional) Specifies the MAC address to be used on the specified interface.
rx
Specifies strict checking.
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
You can configure one the following Unicast RPF modes on an ingress interface:
Strict Unicast RPF mode—A strict mode check is successful when the following matches occur:
•
•
If these checks fail, the packet is discarded. You can use this type of Unicast RPF check where packet flows are expected to be symmetrical.
Loose Unicast RPF mode—A loose mode check is successful when a lookup of a packet source address in the FIB returns a match and the FIB result indicates that the source is reachable through at least one real interface. The ingress interface through which the packet is received is not required to match any of the interfaces in the FIB result.
This command does not require a license.
Examples
This example shows how to configure loose Unicast RPF checking on an interface:
switch# configure terminalswitch(config)# interface ethernet 2/3switch(config-if)# ip verify unicast source reachable-via anyThis example shows how to configure strict Unicast RPF checking on an interface:
switch# configure terminalswitch(config)# interface ethernet 2/3switch(config-if)# ip verify unicast source reachable-via rxRelated Commands
ipv6 access-list
To create an IPv6 access control list (ACL) or to enter IP access list configuration mode for a specific ACL, use the ipv6 access-list command. To remove an IPv6 ACL, use the no form of this command.
ipv6 access-list access-list-name
no ipv6 access-list access-list-name
Syntax Description
Defaults
No IPv6 ACLs are defined by default.
Command Modes
Global configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
Use IPv6 ACLs to filter IPv6 traffic.
When you use the ipv6 access-list command, the device enters IPv6 access list configuration mode, where you can use the IPv6 deny and permit commands to configure rules for the ACL. If the ACL specified does not exist, the device creates it when you enter this command.
Use the ipv6 traffic-filter command to apply the ACL to an interface as a router ACL. Use the ipv6 port traffic-filter command to apply the ACL to an interface as a port ACL.
Every IPv6 ACL has the following implicit rules as its last rules:
permit icmp any any nd-napermit icmp any any nd-nspermit icmp any any router-advertisementpermit icmp any any router-solicitationdeny ipv6 any anyUnless you configured an IPv6 ACL with a rule that denies ICMPv6 neighbor discovery messages, the first four rules ensure that the device permits neighbor discovery advertisement and solicitation messages. The fifth rule ensures that the device denies unmatched IPv6 traffic.
Use the statistics per-entry command to configure the device to record statistics for each rule in an IPv6 ACL. The device does not record statistics for implicit rules. To record statistics for packets that would match implicit rules, you must explicitly configure an identical rule for each implicit rule.
Note
This command does not require a license.
Examples
This example shows how to enter IP access list configuration mode for an IPv6 ACL named ipv6-acl-01:
switch# configure terminalswitch(config)# ipv6 access-list ipv6-acl-01switch(config-acl)#Related Commands
ipv6 port traffic-filter
To apply an IPv6 access control list (ACL) to an interface as a port ACL, use the ipv6 port traffic-filter command. To remove an IPv6 ACL from an interface, use the no form of this command.
ipv6 port traffic-filter access-list-name in
no ipv6 port traffic-filter access-list-name in
Syntax Description
access-list-name
Name of the IPv6 ACL, which can be up to 64 alphanumeric, case-sensitive characters.
in
Specifies that the device applies the ACL to inbound traffic.
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, no IPv6 ACLs are applied to an interface.
You can use the ipv6 port traffic-filter command to apply an IPv6 ACL as a port ACL to the following interface types:
•
•
You can also use the ipv6 port traffic-filter command to apply an IPv6 ACL as a port ACL to the following interface types:
•
Note
•
•
•
•
However, an ACL applied to a Layer 3 interface with the ipv6 port traffic-filter command is inactive unless the port mode changes to access or trunk (Layer 2) mode. To apply an IPv6 ACL as a router ACL, use the ipv6 traffic-filter command.
You can also apply an IPv6 ACL as a VLAN ACL. For more information, see the match (VLAN access-map) command on page 388.
The device applies port ACLs to inbound traffic only. The device checks inbound packets against the rules in the ACL. If the first matching rule permits the packet, the device continues to process the packet. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host-unreachable message.
If you delete the specified ACL from the device without removing the ACL from an interface, the deleted ACL does not affect traffic on the interface.
If MAC packet classification is enabled on a Layer 2 interface, you cannot use the ipv6 port traffic-filter command on the interface.
This command does not require a license.
Examples
This example shows how to apply an IPv6 ACL named ipv6-acl-L2 to Ethernet interface 1/3:
switch# configure terminalswitch(config)# interface ethernet 1/3switch(config-if)# ipv6 port traffic-filter ipv6-acl-L2 inThis example shows how to remove an IPv6 ACL named ipv6-acl-L2 from Ethernet interface 1/3:
switch# configure terminalswitch(config)# interface ethernet 1/3switch(config-if)# no ipv6 port traffic-filter ipv6-acl-L2 inswitch(config)# show running-config interface ethernet 2/3!Command: show running-config interface Ethernet2/3!Time: Wed Jun 24 13:13:48 2009version 4.2(1)interface Ethernet2/3ip access-group ipacl inmac port access-group macaclswitchportmac packet-classifyswitch(config)# interface ethernet 2/3switch(config-if)# ipv6 port traffic-filter v6acl inERROR: The given policy cannot be applied as mac packet classification is enabled on this portswitch(config-if)#Related Commands
ipv6 traffic-filter
To apply an IPv6 access control list (ACL) to an interface as a router ACL, use the ipv6 traffic-filter command. To remove an IPv6 ACL from an interface, use the no form of this command.
ipv6 traffic-filter access-list-name {in | out}
no ipv6 traffic-filter access-list-name {in | out}
Syntax Description
Defaults
None
Command Modes
Interface configuration
Supported User Rolesnetwork-admin
vdc-adminCommand History
Usage Guidelines
By default, no IPv6 ACLs are applied to an interface.
You can use the ipv6 traffic-filter command to apply an IPv6 ACL as a router ACL to the following interface types:
•
Note
•
•
•
•
You can also use the ipv6 traffic-filter command to apply an IPv6 ACL as a router ACL to the following interface types:
•
•
However, an ACL applied to a Layer 2 interface with the ipv6 traffic-filter command is inactive unless the port mode changes to routed (Layer 3) mode. To apply an IPv6 ACL as a port ACL, use the ipv6 port traffic-filter command.
You can also apply an IPv6 ACL as a VLAN ACL. For more information, see the match (VLAN access-map) command on page 388.
The device applies router ACLs on either outbound or inbound traffic. When the device applies an ACL to inbound traffic, the device checks inbound packets against the rules in the ACL. If the first matching rule permits the packet, the device continues to process the packet. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host-unreachable message.
For outbound access lists, after receiving and routing a packet to an interface, the device checks the ACL. If the first matching rule permits the packet, the device continues to process the packet. If the first matching rule denies the packet, the device drops the packet and returns an ICMP host-unreachable message.
If you delete the specified ACL from the device without removing the ACL from an interface, the deleted ACL does not affect traffic on the interface.
This command does not require a license.
Examples
This example shows how to apply an IPv6 ACL named ipv6-acl-3A to Ethernet interface 2/1:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# ipv6 traffic-filter ipv6-acl-3A inThis example shows how to remove an IPv6 ACL named ipv6-acl-3A from Ethernet interface 2/1:
switch# configure terminalswitch(config)# interface ethernet 2/1switch(config-if)# no ipv6 traffic-filter ipv6-acl-3A inRelated Commands
