The SSH (Secure Shell) port is 22. It is not a co-incidence. This is a story I (Tatu Ylonen) haven’t told before. I wrote the initial version of SSH in Spring 1995. It was a time when telnet and FTP were widely used.
Anyway, I designed SSH to replace both
telnet (port 23) and
ftp (port 21). Port 22 was free. It was conveniently between the ports for
ftp. I figured having that port number might be one of those small things that would give some aura of credibility. But how could I get that port number? I had never allocated one, but I knew somebody who had allocated a port.
The basic process for port allocation was fairly simple at that time. Internet was smaller and we were in the very early stages of the Internet boom. Port numbers were allocated by IANA (Internet Assigned Numbers Authority). At the time, that meant an esteemed Internet pioneer called Jon Postel and Joyce K. Reynolds. Among other things, Jon had been the editor of such minor protocol standards as IP (RFC 791), ICMP (RFC 792), and TCP (RFC 793). Some of you may have heard of them.
To me Jon felt outright scary, having authored all the main Internet RFCs!
Anyway, just before announcing
ssh-1.0 in July 1995, I sent this e-mail to IANA:
Read more at SSH