Port in Computer Networking allows a computer listen or transmit information on these ports. A port is distinguished by its number and corresponds a standard. This port in Port in Computer Networking is also known as the port number. These corresponds to the transport layer of the OSI model.
Port in Computer Networking : Basics
The word Port in Computer Networking originated from the Latin word porta, which means door. For simplicity, we can consider Port in Computer Networking as doors of a server giving access to the operating system ( Linux, Microsoft Windows , Mac OS X and so on). A program must have the access to the operating system and should open the port to enter the operating system. This is how we can connect to a remote server and run commands through SSH/Telnet clients.
Due to abstraction layer, we can run multiple software servers on the same machine and even simultaneous software in client and server model.
Standard Port in Computer Networking
There are 256 assigned numbers known as Port in Computer Networking, among this number, only few are actually needed for day to day work.
The number of Port in Computer Networking is expressed in 16 bits, which means that there is a maximum of 65,536 ports on a computer. Port assignment is done by the operating system on request by a software.
When an user wants to communicate with software, the user needs to know the port number. The ports used by the services are to be known by users, the main Port in Computer Networking used in client server model are reserved, so they are a standard number.
On a UNIX or UNIX like Operating System, the file inside /etc/ services lists these services, the best known and most used Port in Computer Networking are :
- Port 20 and Port 21 : For the exchange of files via FTP
- Port 22 : For access to a Secure Shell Secure Shell (SSH) and also for exchanging files via FTP over SSH (SFTP)
- Port 23: For telnet
- Port 25 : For sending an e-mail via SMTP
- Port 53 : For the resolution of domain name addresses
- Port 67 and Port 68 : To connect to the DHCP
- Port 80 : HTTP GET request through a web browser
- Port 110 : For e-mail via POP
- Port 143 : For e-mail via IMAP
- Port 389 : For connection to an LDAP
- Port 443 : HTTP connections using SSL
- Port 500 : For IPsec key exchange
- Port 636 : For Connecting to an LDAP by SSL / TLS
- Port 1723 : For the use of VPN
- Port 3306 : For connecting to MySQL
- Port 3389 : For Remote connection protocol
- Port 6667 : For IRC
Most softwares do the communication with the above mentioned Port in Computer Networking.