Using Sequence Numbers in Named ACLs

Router(config)#ip access-list extended serveraccess2	Creates an extended named ACL called serveraccess2
Router(config-ext-nacl)#10 permit tcp any host 131.108.101.99 eq smtp	Uses a sequence number of 10 for this line
Router(config-ext-nacl)#20 permit udp any host 131.108.101.99 eq domain	Sequence number of 20 will be applied after line 10
Router(config-ext-nacl)#30 deny ip any any log	Sequence number 30 will be applied after 20
Router(config-ext-nacl)#exit
Router(config)#int fa 0/0
Router(config-if)#ip access-group serveraccess2 out	Applies this ACL to the FastEthernet Interface 0/0 in an outbound direction
Router(config-if)#exit
Router(config)#ip access-list extended serveraccess2
Router(config-ext-nacl)#25 permit tcp any host 131.108.101.99 eq ftp	Sequence number of 25 places this line after line 20 and before line 30
Router(config-ext-nacl)#exit

Tip:

Sequence numbers are used to allow for easier editing of your ACL's. The preceding example used numbers 10, 20, and 30 in the ACL lines. If I needed to add another line to this ACL, it would have previously been added after the last linemy line 30. If I needed a line to go closer to the top, I would have had to remove the entire ACL and then reapply it with the lines in the correct order. Now I can enter in a new line with a sequence number, placing it in the correct location.

Note:

The sequence-number argument was added in IOS version 12.2(14)S. It was integrated into Cisco IOS Software Release 12.2(15)T.