Extended Access Control List
CCNA R & S

Extended Access Control List (ACL) Operators

As we all know that extended access control lists are used to filter the traffic present in the network. And in previous sections, we have discussed different types of access control lists and how to create and configure all those access control lists and the TCP and UDP protocols which are mainly used. Here before discussing the different operators let’s create an overview of the access control list and the extended access control list and the different port numbers and the names. To know more about the Extended Access Control List (ACL) Operators, keep reading this article till the end.

Rules used to reduce network traffic and network attack. ACLs are used to filter the incoming and outgoing network. The ACL contains two types of list and the Extended Control List is one among them. 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.in network traffic moves like packets and each packet contains a small piece of data.

In an extended control list, they can differentiate the IP traffic, unlike the Standard Access Control List. In Extended ACL they use both source and destination address and the port number to differentiate the IP traffic. Here we can define which IP address needs to be allowed or get denied and the range is from 100-199 and 2000-2699. Extended control list filter packets which are near to source address. Otherwise, if the extended access control lists are placed in the destination network they will use the bandwidth till the packets reach the destination and the unwanted traffic will get filtered till the final destination.

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. The range from 1024 and 49151 are registered port numbers, and there is one more port number named dynamic or private port number and ranges from 49152 through 65535. The reserved number which is used to identify the protocol is known as the protocol number while the port is a unique number. An example of protocol number is for EIGRP is 88 for IP 4 is the protocol number used.

To permit and delete the traffic in the network the extended access control list uses port numbers to verify it. To filter all those traffic based on the port numbers operators are used. So here in this section, it explains the functions of each of the operators used in the working of extended access control lists.

Operators used are:

Less than                                 lt

Greater than                            gt

Not equal to                            neq

Equal to                                   eq

Range of port numbers           range

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