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. Here before discussing the different port numbers and names let’s create an overview of the access control list and the extended access control list.

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 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.

Port number

The unique numbers used by the applications mainly TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are called port numbers. For example, the port number used by web traffic is 80 and the port number of telnet is 23.

There are two types of port numbers used, and are well-known port numbers and registered port numbers. 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.

One of the main points to notice is that there is a difference in port numbers and protocol numbers. 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.

Commonly used port numbers of TCP are given below, they are:

Port Name                                        Keyword

FTP Data (TCP port number 20)         ftp-data

FTP Control (TCP port number 21)      ftp

Telnet (TCP port number 23)               telnet

SMTP (TCP port number 25)               smtp

HTTP (TCP port number 80)               www

Commonly used port numbers of UDP are given below, they are:

Port Name                                         Keyword

DNS (UDP port number 53)                dns

TFTP (UDP port number 69)               tftp

SNMP (UDP port number 161)          snmp

IP RIP (UDP port number 520)           rip

Also, read…

Download Extended Access Control List, TCP and UDP Port Numbers and Names in pdf – Click here