This article provides a brief description of the Extended ACL Established Keywords. Before discussing the topic let’s summarize the overall topic connected to the topic.

Access control lists are a group of conditions that are wrapped together by a particular name or number. The conditions used in this group are the number. And these conditions are used to avoid traffic on routes. Through these conditions, we can avoid or filter traffic. ACL is a combined feature of IOS software which helps to reduce traffic jams in IOS devices.

Extended Access Control List is one of the ACL used to filter the traffic in the network. Extended ACL is the firewall protection that needs to be created to protect the filtering packet from the network. The port number, protocol, source address, and destination address are used to configure the extended ACL. The range of numbers assigned is from 100-199 and can expand up to 2000-2699.

The extended access control lists are near to the source address network. Extended ACL with named can have the flexibility to delete the rules. The extended ACL can be created using an IOS command named an access-list. Extended ACL can be configured using an IOS command named access-group command. To use access-list to an interface access-group commands are applied. To remove the extended access control list from the statement use the no command

Unique numbers are referred to as port numbers. The numbers are unique for certain keywords and are only used to refer to those words. For example, the port number used by web traffic is 80 and the port number of telnet is 23. The range from 0 and 1023 are well-known port numbers.

Some of the keywords and the port numbers are shown below:

Port Name                                           Keyword

FTP Data (TCP port number 20)      ftp-data

FTP Control (TCP port number 21)  ftp

Telnet (TCP port number 23)            telnet

The operators like Less than (lt), Greater than (gt), Not equal to (neq), Equal to (eq), Range of port numbers (range) are used in the working of extended access control lists.

To develop a connection with the Transmission Control Protocol (TCP) established keywords are used. These established connections are taken as TCP protocol which originates traffic in the network, not from the outside. This can be meant as the packets contain the TCP segments which has reset bit (RST) and acknowledgment (ACK) bit set.

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