Cisco ASA: How To See Who Is SSH'ed Into Your ASA

Just to see the SSH sessions that are connected, you can take a look with the 'show ssh sessions' command.  It will show you who is logged in, plus the encryption standards used.  Pretty good for verification.

ASA# show ssh sessions

SID Client IP       Version Mode Encryption Hmac     State            Username
1   4.2.2.194  2.0     IN   aes256-cbc sha1     SessionStarted   skillen
                            OUT  aes256-cbc sha1     SessionStarted   skillen
ASA#