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Improve this questionWhy is 22 the default port number for SFTP? Is there any specific reason for this?
It's the default SSH port and SFTP is usually carried over an SSH tunnel.
Why is 21 the default port for FTP? Or 80 the default for HTTP? It is a convention.
From Wikipedia:
Applications implementing common services often use specifically reserved, well-known port numbers for receiving service requests from client hosts. This process is known as listening and involves the receipt of a request on the well-known port and reestablishing one-to-one server-client communications on another private port, so that other clients may also contact the well-known service port. The well-known ports are defined by convention overseen by the Internet Assigned Numbers Authority (IANA).
Source
So as others mentioned, it's a convention.
Not authoritative, but interesting: 21 is FTP, 23 is telnet. 22 is SSH...something in between (that can take the place of both).
Ahem, because 22 is the port number for ssh and has been for ages?
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