Configuring Standard Access Control Lists (S-ACLs)
Access Control List (ACL) is a security feature that allows you to filter the network traffic based on configured statements. An ACL can be used to filter either inbound or outbound traffic on an interface. Once you applied an access list on a router, the router examine every packet moving from interface to another interface in the specified direction and takes the appropriate action.
Standard access lists
A Standard access list can use only the source IP address in an IP packet to filter the network traffic. Standard access lists are typically used permit or deny an entire system or network. They cannot be used to filter individual protocol or services such as FTP and Telnet.