What can I do when my SSH session is stuck?

Question

Sometimes my ssh session in the terminal hangs. How can I exit the ssh session and reconnect?

Answer 1

Type ~. (i.e. tilde, period) at the beginning of a line. In other words, press Enter, then ~, then .. (In some languages, you may need to press Shift or Alt to enter the ~ character.)

Generally speaking, the ~ character is an escape character in an SSH session when you type it at the beginning of a line. Type Enter then ~? to see the list of escape commands. The most common ones are

• ~. to terminate the connection
• ~^Z (press ~ then Ctrl+Z) to suspend the connection and type a command locally (run the command fg to return to the SSH session)

If you want a tilde at the beginning of a line, press ~ twice.

Answer 2

All you need to do to exit an ssh session is type exit at the prompt.

Try entering Shift+`+.

Answer 3

If your session is hung and the prompt is no longer responsive you can just kill the Terminal instance and all child processes associated with that instance, of which your ssh session is one, should get axed along with it.

If you're really wanting to be thorough though you can open a new Terminal instance, look for ssh sessions in the process list, and kill them via the command line:

> ps -ef  |grep ssh
501  1332   142   0 20Dec11 ??         0:01.33 /usr/bin/ssh-agent -l
501 57172 57150   0  1:58pm ttys000    0:00.01 grep ssh
501 57139 57133   0  1:57pm ttys002    0:00.03 ssh -i/Users/ian/code/ec2-keys/id_rsa-gsg-keypair someuser@someinstance.amazonaws.com

> kill 57139

If that doesn't work try:

> kill -9 57139

Don't kill the ssh-agent process.

Or you can open Activity Monitor and search there for sessions and hit the kill button for them: