What is port?

By | 24 October, 2013

What is port? Port is important for application as a ‘door’ to access the application. Any network related application will assign one port to allow incoming or outgoing data.

Port range from 1 – 65535 (port no 0 is reserved and can’t be used).The port numbers are divided into three ranges:

1) well-known ports (0 – 1023)
2) registered ports (1024 – 49151)
3) dynamic or private ports (49152 – 65535)

Example of well-known ports :

20 & 21: File Transfer Protocol (FTP)
22: Secure Shell (SSH)
23: Telnet remote login service
25: Simple Mail Transfer Protocol (SMTP)
53: Domain Name System (DNS) service
80: Hypertext Transfer Protocol (HTTP) used in the World Wide Web
110: Post Office Protocol (POP3)
119: Network News Transfer Protocol (NNTP)
143: Internet Message Access Protocol (IMAP)
161: Simple Network Management Protocol (SNMP)
194: Internet Relay Chat (IRC)
443: HTTP Secure (HTTPS)
465: SMTP Secure (SMTPS)

We can test or access via telnet command as per below :

telnet port

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