Ports

Application Ports

Hardware port: Refers to the physical interface where a cable must be connected.
Software port: A point of entry for communication using a specific protocol.

The software port is also called an application port because it matches a 16-bit coded number (ranging from 1 to 65536) with an application.

Port 21: FTP protocol – A file transfer protocol.
Port 22: SSH protocol – Used for almost all remote machine connections. It encrypts exchanges to make intercepted information unreadable.
Ports 25, 465, 587: SMTP protocol – A protocol for sending messages.
Port 53: DNS protocol – Matches an IP address with a domain name and vice versa.
Port 67 (server), 68 (client): DHCP protocol – Automatically assigns an IP address (and associated addressing configurations such as subnet mask and gateway address) to a node on the network that requests it.