Access Controls Lists(ACL)

Access Controls  Lists(ACL):

ACL is a set of rules which will allow or deny the traffic moving through the router.

It is a layer 3 security which controls the flow of traffic from one router to another.

It is also called as packet filtering firewall.

ACL is two type:

1.Standard ACL: standard access controls  Lists(ACLs) are the oldest type of access control lists. Standard IP access lists are used to permit/deny traffic only based on source IP address of the IP datagram packets.

Standard Access Control list can be created by using the access-list IOS command.

Function:

The access list number range is 1 -99

Can block a network, host and subnet

Two way communication is stopped

All services are blocked.

Implemented closest to the destination.

Filtering is done based on only source IP address.

2.Extended ACL: Extended Access Control Lists allow you to permit or deny traffic from specific IP addresses to a specific destination IP address and port.it also allows you to specify different types of traffic such as ICMP(Internet Control message Protocol) TCP(Transmission control protocol)UDP(User datagram protocol)

Function:

The access list number range is 100 -199

Can block a network, host ,subnet and service

one way communication is stopped

selected services can be blocked.

Implemented closest to the source.

Checks source, destination, protocol, port no