Named ACL Support for Noncontiguous Ports on an Access Control Entry
The Named ACL Support for Noncontiguous Ports on an Access Control Entry feature allows you to specify noncontiguous ports in a single
access control entry, which greatly reduces the number of entries
required in an access control list when several entries have the
same source address, destination address, and protocol, but differ
only in the ports.
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Prerequisites for Named ACL Support for Noncontiguous Ports on an Access Control Entry
Before you configure the ACL Support for Filtering IP Options feature, you must
understand the concepts of the IP access lists.- "IP Access List Overview"
- "Creating an IP Access List and Applying It to an Interface"
Information About Named ACL Support for Noncontiguous Ports on an Access Control Entry
Benefits of Using the Named ACL Support for Noncontiguous Ports on an Access Control Entry Feature
This feature greatly reduces the number of access control entries (ACEs) required in an access control list to handle multiple entries for the same source address, destination address, and protocol. If you maintain large numbers of ACEs, use this feature to consolidate existing groups of access list entries wherever it is possible and when you create new access list entries. When you configure access list entries with noncontiguous ports, you will have fewer access list entries to maintain.
How to Configure Named ACL Support for Noncontiguous Ports on an Access Control Entry
Configuring an Access Control Entry with Noncontiguous Ports
Perform this task to create access list entries that use noncontiguous TCP or UDP port numbers. Although this task uses TCP ports, you could use the UDP syntax of the
permit and
deny commands to filter noncontiguous UDP ports.
Although this task uses a
permit command first, use the
permit and
deny commands in the order that achieves your filtering goals.
 Note |
The ACL—Named ACL Support for Noncontiguous Ports on an Access Control Entry feature can be used only with named, extended ACLs.
|
SUMMARY STEPS1.
enable
2.
configure
terminal
3.
ip
access-list
extended
access-list-name
4.
[sequence-number]
permit
tcp
source
source-wildcard [operator
port [port]]
destination
destination-wildcard [operator [port]] [established
{match-any |
match-all} {+ |
-}
flag-name] [precedence
precedence] [tos
tos] [log] [time-range
time-range-name] [fragments]
5.
[sequence-number]
deny
tcp
source
source-wildcard [operator
port [port]]
destination
destination-wildcard [operator [port]] [established
{match-any |
match-all} {+ |
-}
flag-name] [precedence
precedence] [tos
tos] [log] [time-range
time-range-name] [fragments]
6.
Repeat Step 4 or Step 5 as necessary, adding statements by sequence number where you planned. Use the
no
sequence-number command to delete an entry.
7.
end
8.
show
ip
access-lists
access-list-name
DETAILED STEPS | Command or Action | Purpose |
---|
Step 1 |
enable
Example:
|
Enables privileged EXEC mode.
- Enter your password if prompted.
|
Step 2 |
configure
terminal
Example:
Device# configure terminal
|
Enters global configuration mode.
|
Step 3 |
ip
access-list
extended
access-list-name
Example:
Device(config)# ip access-list extended acl-extd-1
|
Specifies the IP access list by name and enters named access list configuration mode.
|
Step 4 | [sequence-number]
permit
tcp
source
source-wildcard [operator
port [port]]
destination
destination-wildcard [operator [port]] [established
{match-any |
match-all} {+ |
-}
flag-name] [precedence
precedence] [tos
tos] [log] [time-range
time-range-name] [fragments]
Example:
Device(config-ext-nacl)# permit tcp any eq telnet ftp any eq 450 679
|
Specifies a
permit statement in named IP access list configuration mode.
- Operators include
lt (less than),
gt (greater than),
eq (equal),
neq (not equal), and
range (inclusive range).
- If the operator is positioned after the source and source-wildcard arguments, it must match the source port. If the operator is positioned after the destination and destination-wildcard arguments, it must match the destination port.
- The
range operator requires two port numbers. You can configure up to 10 ports after the
eq and
neqoperators. All other operators require one port number.
- To filter UDP ports, use the UDP syntax of this command.
|
Step 5 | [sequence-number]
deny
tcp
source
source-wildcard [operator
port [port]]
destination
destination-wildcard [operator [port]] [established
{match-any |
match-all} {+ |
-}
flag-name] [precedence
precedence] [tos
tos] [log] [time-range
time-range-name] [fragments]
Example:
Device(config-ext-nacl)# deny tcp any neq 45 565 632
|
(Optional) Specifies a
deny statement in named access list configuration mode.
- Operators include
lt (less than),
gt (greater than),
eq (equal),
neq (not equal), and
range (inclusive range).
- If the
operator is positioned after the
source and
source-wildcard arguments, it must match the source port. If the
operator is positioned after the
destination and
destination-wildcard arguments, it must match the destination port.
- The
range operator requires two port numbers. You can configure up to 10 ports after the
eq and
neqoperators. All other operators require one port number.
- To filter UDP ports, use the UDP syntax of this command.
|
Step 6 | Repeat Step 4 or Step 5 as necessary, adding statements by sequence number where you planned. Use the
no
sequence-number command to delete an entry.
|
Allows you to revise the access list.
|
Step 7 |
end
Example:
Device(config-ext-nacl)# end
|
(Optional) Exits named access list configuration mode and returns to privileged EXEC mode.
|
Step 8 |
show
ip
access-lists
access-list-name
Example:
Device# show ip access-lists kmd1
|
(Optional) Displays the contents of the access list.
|
Consolidating Access List Entries with Noncontiguous Ports into One Access List Entry
Perform this task to consolidate a group of access list entries with noncontiguous ports into one access list entry.
Although this task uses TCP ports, you could use the UDP syntax of the
permit and
deny commands to filter noncontiguous UDP ports.
Although this task uses a
permit command first, use the
permit and
deny commands in the order that achieves your filtering goals.
SUMMARY STEPS1.
enable
2.
show
ip
access-lists
access-list-name
3.
configure
terminal
4.
ip
access-list
extended
access-list-name
5.
no
[sequence-number]
permit
protocol
source
source-wildcard
destination
destination-wildcard[option
option-name] [precedence
precedence][tos
tos] [log] [time-range
time-range-name] [fragments]
6.
[sequence-number]
permit
protocol
source
source-wildcard[operator
port[port]]
destination
destination-wildcard[operator
port[port]] [option
option-name] [precedence
precedence][tos
tos] [log] [time-range
time-range-name] [fragments]
7.
Repeat Steps 5 and 6 as necessary, adding
permit or
deny statements to consolidate access list entries where possible. Use the
no
sequence-number command to delete an entry.
8.
end
9.
show
ip
access-lists
access-list-name
DETAILED STEPS | Command or Action | Purpose |
---|
Step 1 |
enable
Example:
|
Enables privileged EXEC mode.
- Enter your password if prompted.
|
Step 2 |
show
ip
access-lists
access-list-name
Example:
Device# show ip access-lists mylist1
|
(Optional) Displays the contents of the IP access list.
- Review the output to see if you can consolidate any access list entries.
|
Step 3 |
configure
terminal
Example:
Device# configure terminal
|
Enters global configuration mode.
|
Step 4 |
ip
access-list
extended
access-list-name
Example:
Device(config)# ip access-list extended mylist1
|
Specifies the IP access list by name and enters named access list configuration mode.
|
Step 5 |
no
[sequence-number]
permit
protocol
source
source-wildcard
destination
destination-wildcard[option
option-name] [precedence
precedence][tos
tos] [log] [time-range
time-range-name] [fragments]
Example:
Device(config-ext-nacl)# no 10
|
Removes the redundant access list entry that can be consolidated.
- Repeat this step to remove entries to be consolidated because only the port numbers differ.
- After this step is repeated to remove the access list entries 20, 30, and 40, for example, those entries are removed because they will be consolidated into one
permit statement.
- If a
sequence-number is specified, the rest of the command syntax is optional.
|
Step 6 | [sequence-number]
permit
protocol
source
source-wildcard[operator
port[port]]
destination
destination-wildcard[operator
port[port]] [option
option-name] [precedence
precedence][tos
tos] [log] [time-range
time-range-name] [fragments]
Example:
Device(config-ext-nacl)# permit tcp any neq 45 565 632 any eq 23 45 34 43
|
Specifies a
permit statement in named access list configuration mode.
- In this instance, a group of access list entries with noncontiguous ports was consolidated into one
permit statement.
- You can configure up to 10 ports after the
eq and
neq operators.
|
Step 7 | Repeat Steps 5 and 6 as necessary, adding
permit or
deny statements to consolidate access list entries where possible. Use the
no
sequence-number command to delete an entry.
|
Allows you to revise the access list.
|
Step 8 |
end
Example:
Device(config-std-nacl)# end
|
(Optional) Exits named access list configuration mode and returns to privileged EXEC mode.
|
Step 9 |
show
ip
access-lists
access-list-name
Example:
Device# show ip access-lists mylist1
|
(Optional) Displays the contents of the access list.
|
Configuration Examples for Named ACL Support for Noncontiguous Ports on an Access Control Entry
Example: Creating an Access List Entry with Noncontiguous Ports
The following access list entry can be created because up to ten ports can be entered after the
eq and
neq operators:
ip access-list extended aaa
permit tcp any eq telnet ftp any eq 23 45 34
end
Enter the
show
access-lists command to display the newly created access list entry.
Device# show access-lists aaa
Extended IP access list aaa
10 permit tcp any eq telnet ftp any eq 23 45 34
Example: Consolidating Some Existing Access List Entries into One Access List Entry with Noncontiguous Ports
The
show
access-lists command is used to display a group of access list entries for the access list named abc:
Device# show access-lists abc
Extended IP access list abc
10 permit tcp any eq telnet any eq 450
20 permit tcp any eq telnet any eq 679
30 permit tcp any eq ftp any eq 450
40 permit tcp any eq ftp any eq 679
Because the entries are all for the same
permit statement and simply show different ports, they can be consolidated into one new access list entry. The following example shows the removal of the redundant access list entries and the creation of a new access list entry that consolidates the previously displayed group of access list entries:
ip access-list extended abc
no 10
no 20
no 30
no 40
permit tcp any eq telnet ftp any eq 450 679
end
When the
show
access-lists command is reentered, the consolidated access list entry is displayed:
Device# show access-lists abc
Extended IP access list abc
10 permit tcp any eq telnet ftp any eq 450 679
Additional References for Named ACL Support for Noncontiguous Ports on an Access Control Entry
Related Documents
Table 1 Standards and RFCs
Standards/RFCs
|
Title
|
RFC 791
|
Internet Protocol
|
RFC 793
|
Transmission Control Protocol
|
Technical Assistance
Description
|
Link
|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.
|
http://www.cisco.com/cisco/web/support/index.html
|
Feature Information for
Named ACL Support for Noncontiguous Ports on an Access Control Entry
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 2 Feature Information for ACL
Support for Filtering IP Options
Feature Name
|
Releases
|
Feature
Information
|
Named ACL
Support for Noncontiguous Ports on an Access Control Entry
|
Cisco IOS 15.2(2)E
|
The Named
ACL Support for Noncontiguous Ports on an Access Control Entry feature allows
you to specify noncontiguous ports in a single access control entry, which
greatly reduces the number of entries required in an access control list when
several entries have the same source address, destination address, and
protocol, but differ only in the ports.
|