Standard Access Control Lists, syntax of access-list IOS command to create a Standard Access Control List (ACL)

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

Standard Access Control Lists (ACLs) can be created by using the "access-lists" IOS command. The syntax of "access-list" IOS command to create a Standard Access Control List is shown below.

access-list [Access_list_number] [permit | deny] [IP_address] [wildcard mask (optional)]

The arguments are explained in detail below.

Access_list_number: For Standard Access Control List, Access list number must be between 1–99 or 1300–1999.

permit | deny: Whether to permit or deny traffic.

IP_address: An IP address to filter the traffic.

wildcard mask: Instead of specifying a single IP address, you can also permit or deny networks/subnets entirely or partly by using wildcard masks, also known as inverse masks. Wildcard mask is optional in above IOS command.

Click the following link to learn more about Access Control List (ACL) wildcard masks.