I'm running some very long jobs on a machine that I'm SSH'd in. However, sometimes after a few hours in the session, I no longer have permissions to run simple commands that I previously could. That is, when I type commands as simple as cd .. or ls ., I'm getting permission denied errors. Opening files or running programs yields the same result as well.

The only way to resolve this is to completely log out of my SSH session and reconnect. I seem to remember that there's some way to reauthorize my credentials within an SSH session; I can't seem to find it though. Is there any way that I can reauthorize myself when this happens?

EDIT: the problem has been resolved. It was about Kerberos authentication and not an SSH issue itself. Answer below.

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    There is no way ssh connection wish to "reauthorize". It seems to be an issue behind the connection itself, like you have this server more complex than it sounds. Maybe it has homedir on NFS share or something like that? – kab00m Mar 29 '20 at 0:10
  • I fixed my problem -- you were right, it wasn't an ssh issue, but rather dealing with Kerberos. – tchainzzz Mar 30 '20 at 3:57

I've resolved my problem -- as @kab00m correctly pointed out, it's not about ssh "reauthorization," since that's impossible. The issue was that the server I'm using utilizes Kerberos tickets to authenticate to an AFS cell. I had a long job going on in a tmux session, and detached + logged out. Since I had logged out of my session, even when I ssh'ed back and reattached myself, I was no longer authenticated because the Kerberos ticket was destroyed on logout.

I opened up a new pane in my tmux session, and then a simple kinit && aklog got things going again. That is what I was looking for. Sorry for the poor original wording of the question -- it really wasn't a problem with SSH after all.

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