What your users are doing in their SSH sessions? Do you want to see, whats happening there?
Try the following:
# cat /dev/vcs1
This will show you what happenening on the first console. If someone is typing, you’ll be able to get an output of their keystrokes.
Note: You should have “root” access for this.
Replace /dev/vcs1 with /dev/vcs2 or /dev/vcs3 and so on for other consoles.