Sometimes it may be necessary to identify the SSH client that you are currently running and it’s corresponding version number. Use ssh –V to identify the version number. Please note that Linux comes with OpenSSH.
The following examples indicates that this particular system is using OpenSSH:
$ ssh -V OpenSSH_3.9p1, OpenSSL 0.9.7a Feb 19 2003 (or) $ ssh -V OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
The following example indicates that this particular system is using SSH2:
$ ssh -V ssh: SSH Secure Shell 18.104.22.168 (non-commercial version) on i686-pc-linux-gnu
Note: It is upper-case V in “ssh -V”