How to get the incoming ssh/telnets clients local IP address from a shell script or C

Question

I need a way to obtain a local (not WAN) address of an incoming telnet or ssh session using a shell script or C.

Answer 1

This can be done in several ways, depending on what OS/ssh daemon/telnet daemon you're using. Here are two approaches:

• OpenSSH publishes the clients ip (and ports) in the environment variable SSH_CLIENT.
• Use the utmpx database (the same as who uses), as explained here: whoamIP - Find hostname/IP of current remote shell user