4 Command Line Interface

This is a more comprehensive example. It denies any TCP packets in which the SYN bit is ON, and permits all other packets. It then sets the ingress mask to check the deny rule first, and finally binds port 1 to this ACL. Note that once the ACL is bound to an interface (i.e., the ACL is active), the order in which the rules are displayed is determined by the associated mask.

Switch(config)#access-list ip extended 6 Switch(config-ext-acl)#permit any any Switch(config-ext-acl)#deny tcp any any control-flag 2 2 Switch(config-ext-acl)#end

Console#show access-list

IP extended access-list A6: permit any any

deny tcp any any control-flag 2 2 Console#configure Switch(config)#access-list ip mask-precedence in

Switch(config-ip-mask-acl)#mask protocol any any control-flag 2 Switch(config-ip-mask-acl)#end

Console#sh access-list

IP extended access-list A6: permit any any

deny tcp any any control-flag 2 2 IP ingress mask ACL:

mask protocol any any control-flag 2 Console#configure Console(config)#interface ethernet 1/1 Console(config-if)#ip access-group A6 in Console(config-if)#end

Console#show access-list

IP extended access-list A6:

deny tcp any any control-flag 2 2 permit any any

IP ingress mask ACL:

mask protocol any any control-flag 2 Console#

show access-list ip mask-precedence

This command shows the ingress or egress rule masks for IP ACLs.

Syntax

show access-list ip mask-precedence [in out]in – Ingress mask precedence for ingress ACLs.out – Egress mask precedence for egress ACLs.

Command Mode

Privileged Exec

Example

Console#show access-list ip mask-precedence IP ingress mask ACL:

mask host any

mask 255.255.255.0 any Console#

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