Log SSH activity

Maybe you can make sshd use a logging shell like rootsh?

You can try with snoopy. After you install it, will logs all input command that calls execve to syslog. you'll only find it in the repos for hardy and precise.

You can install it from here.

I don't think SSHD logs commands while the user is logged in.

you can check who logged in by checking

/var/log/auth.log

and cross reference it to their history

/home/sshuser/.bash_history

history will have commands local or remote though.

I have a similar problem and wrote the tool log-user-session which stores all shell output into a root-only accessible session log file. It can be enabled via forced command on sshd_conf or ~/.ssh/authorized keys (see documentation).