does anyone knows a keylogger for SSH accounts on linux?
my system shouldn't have too much SSH activity (i give jailshell to all my users, but 5% or less of them uses it) so it wouldn't be a pain to analyse those logs... and i think that's an important monitoring
If you want a keylogger that will work across all PC operating systems you should check out the hardware keyloggers available from keyghost (search google for keyghost).
There is no version for USB keyboards yet (small rectangular plug), but if the machine you want to monitor has a PS/2 keyboard (most common type, small round plug) then it works sweet.
These keylogger are not like software, so they cannot be found using software scanners. They do not need any software to be installed at all to record or retrieve the keystrokes. They simply play them back at high speed into any text editor.