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Asked: 2017-05-15 19:28:56 +0800 CST

ssh, agent forwarding stops working after a few days ...

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I've been facing an interesting issue for a few weeks now. Part of our fleet is only reachable via a jump-host.

In the past I had no issues w/ logging into the jump-host from my workstation using ssh -A and maintain a session for extended periods of time [yes, I know that's bad practice, not here for a lecture on a foul habit =}], and connect on from there to other machines w/o password entry as expected.

Now every so often going to my uxterm with the active session to the jump host gives me a 

Permission denied (publickey)

If I disconnect, and w/o restarting the agent connect to the jump host again, all works as before.

How do I diagnose what's going on there?

Extra information: my workstation is Ubuntu 16.04, the jump host is 14.04, recently upgraded from 12.04.

ssh

1 Answers

  1. When using agent forwarding, ssh actually forwards the UNIX socket to a directory in /tmp and the sets SSH_AUTH_SOCK to point to it.

    Effectively, thus means that only a new remote shell will inherit SSH_AUTH_SOCK. Older sessions, will keep pointing to a socket that no longer exists. You could just export it again if you don't want to open a new shell

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