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What is port address and its function

Question asked by Issack Kalange in #Hacking and Security on Jun 13, 2019
Issack Kalange
Issack Kalange · Jun 13, 2019

What is port address and its functions

Posted in: #Hacking and Security
Jeffery Simon
Jeffery Simon · Jun 13, 2019
Rank D2 - MASTER

@Issack Kalange Are you looking for the textbook definition?

In the internet protocol suite, a port is an endpoint of communication in an operating system.

A port is always associated with an IP address of a host and the protocol type of the communication. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number.

Does this answer your question? 

Kaustubh Katdare
Kaustubh Katdare · Jun 14, 2019
Rank A1 - PRO

Think of port address as the unique 'door' where the other computers connected to the network can communicate with the host computer. It's a number that's generated by the operating system on the host computer.

Some of the port numbers are dedicated to specific functions and are universally agreed upon. For example, http works on port 80 and 25 is dedicated to SMTP. Now a days, http is being deprecated in favor of the more secure HTTPS (S stands for Secure) which works on port 443.

As @Jeffery Simon said, it's a 16 bit number, which means port numbers will range from 0 - 65,535. The initial port numbers, up to 1024 are typically reserved for the privileged services; like the ones I mentioned above. 

I hope this gives you a better idea of port addresses (port numbers). Here's a list of some of the most commonly used port addresses -

Port Number ---


1TCP Port Service Multiplexer (TCPMUX)
5Remote Job Entry (RJE)
18Message Send Protocol (MSP)
20FTP -- Data
21FTP -- Control
22SSH Remote Login Protocol
25Simple Mail Transfer Protocol (SMTP)
42Host Name Server (Nameserv)
49Login Host Protocol (Login)
53Domain Name System (DNS)
69Trivial File Transfer Protocol (TFTP)
70Gopher Services
103X.400 Standard
108SNA Gateway Access Server
115Simple File Transfer Protocol (SFTP)
118SQL Services
119Newsgroup (NNTP)
137NetBIOS Name Service
139NetBIOS Datagram Service
143Interim Mail Access Protocol (IMAP)
150NetBIOS Session Service
156SQL Server
179Border Gateway Protocol (BGP)
190Gateway Access Control Protocol (GACP)
194Internet Relay Chat (IRC)
197Directory Location Service (DLS)
389Lightweight Directory Access Protocol (LDAP)
396Novell Netware over IP
444Simple Network Paging Protocol (SNPP)
458Apple QuickTime
546DHCP Client
547DHCP Server

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