Access lists

Another post from times when I was preparing to my CCNA exam. This time my notes about ACLs in Cisco routers.

• ACLs provide IP route filtering


• ACLs identify interesting traffic for DDR


• ACLs provide lists for NAT


• 1-99 standard lists


• 100-199 and 2000–2699 extended lists


• For extended acls filter packets as close to the source as possible


• For standard acls filter packets as close to the destination as possible


• One access list can be configured per direction for each layer 3(IP, IPX…) protocol on interface

Configure ACL on line:

line vty 0 4

access class 3 in

Configure ACL on interface:

ip access-group

Show which access list and which direction is set:

show ip interface