How to get SSH connection info programatically?

Murali Mohan · 05-06-2006, 08:47 AM

User U1 on machine M1 logged onto machine M2 via ssh as user U2 and running a Perl program P2.
Within the perl program P2, will I be able to know that U1 on M1 is ruuning this program? If so, how?
Thanks,
Murali Mohan.

ioerror · 05-06-2006, 09:00 AM

ssh sets a few environment variables SSH_CLIENT, SSH_CONNECTION and a few others, you could maybe use one/some of those. SSH_CONNECTION consists of "source_ip source_port dest_ip dest_port", SSH_CLIENT has "source_ip source_port dest_port" so either of those should suffice to determine M1, but I can't think of any way offhand to determine which user (U1) initiated the session (other than maybe logging in from M2 to M1 and running ps).

Murali Mohan · 05-06-2006, 09:30 AM

Thank you for you response..
I tried, but, I notice that these variables, SSH_CLIENT, SSH_CONNECTION and SSH_TTY are set on M1. The program that is being invoked is running on M2. Will that program be able to access these variables?

ioerror · 05-06-2006, 10:16 AM

They should be set on the remote side (M2). At least, they are when I log in remotely. This:

Code:

ssh <M2> echo \$SSH_CONNECTION

should print the ip addresses and ports. If they aren't printed, then I don't know why, it works for me?

Murali Mohan · 05-17-2006, 06:34 PM

I am sorry I didnot notice well. It was giving me the remote IP

Next, how can I get the remote user?

ioerror · 05-19-2006, 03:52 AM

That is less straightforward, I don't think ssh provides that information, so there is no way to get it directly. Probably the easiest way would be to wrap ssh in a shell script that set a REMOTE_USER variable.