I have a reverse SSH server in Cisco router(runs IOS operating system) and it listens on port 2001:
C1841#sh control-plane host open-ports Active internet connections (servers and established) Prot Local Address Foreign Address Service State tcp *:22 *:0 SSH-Server LISTEN tcp *:23 *:0 Telnet LISTEN tcp *:2001 *:0 SSH-Server LISTEN C1841#
In other words, if I connect to port 2001(
ssh 10.10.10.2 -l root -p 2001), then I'm able to access RS-232 console port of another device which is connected to AUX port of the router. However, instead of
ssh 10.10.10.2 -l root -p 2001 I can simply execute
ssh root:firstname.lastname@example.org. This feature is also described in this blog post. Am I correct that this is not a feature of OpenSSH client, but instead Cisco IOS parses the username in a way that integer after colon is taken as a line number(line number 1 us usually AUX port in IOS)?