On Mon, Dec 30, 2013 at 11:25 PM, Bill Oliver <vendor@billoblog.com> wrote:

In linux, is it possible to dictate two different actions upon login with different passwords?


Short answer: no.

Longer answer: in computing almost anything is possible if you really want to achieve it. Given that on Unix-style systems, including Linux, the login program can be changed, you can modify the source to do what you want. Of course you'll need to have superuser privileges to install it in place of the system standard. Note that doing this may well open a can of worms, e.g. you might have to modify the format of the password file (and hence the library routines that access it), possibly fiddle with SElinux settings, etc. etc.

If the conditions are relaxed slightly you can get a partial solution using the standard login: write a Shell startup script (.profile or whatever) that allows the user to discriminate between the two modes, e.g. by using a timeout, detecting the initial state of the Shift (or Control or whatever) key etc., in a way that is hopefully non-obvious to an observer. Probably not reliable enough for serious use.

Conclusion: better look for some other way to cover your tracks, and note that a forensic investigation can be carried out without having you log in at all.

poc