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From: Tim Adye <T DOT J DOT Adye AT rl DOT ac DOT uk>
Subject: ssh-agent doesn't die
To: <cygwin AT cygwin DOT com>
Message-ID: <319e26c0-32f0-40b7-2137-c7de170a3486@rl.ac.uk>
Date: Fri, 27 Sep 2019 00:42:44 +0100
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Hi,

I have noticed a (new?) problem with using ssh-agent to start a session, 
eg. with

   ssh-agent xterm &

When the xterm (or whatever) command completes, the ssh-agent process is 
still left running in the background. It should stop once its subprocess 
is done.

As a simple test example, consider:

/bin/ssh-agent /bin/sleep 10

While the sleep is still running, ps shows:

       PID    PPID    PGID     WINPID   TTY         UID    STIME COMMAND
      1694    1693    1694       1576  ?          22534 00:01:10 
/usr/bin/ssh-agent
      1653       1    1653      11740  cons1      22534 00:00:37 
/usr/bin/bash
      1693    1653    1693       1552  cons1      22534 00:01:10 
/usr/bin/sleep

One oddity is that ssh-agent is listed as a subprocess of sleep, not the 
other way round. pstree shows this clearly:

?-+-bash---pstree
   `-bash---sleep---ssh-agent

Once the sleep finishes, ps shows:

       PID    PPID    PGID     WINPID   TTY         UID    STIME COMMAND
      1694    1693    1694       1576  ?          22534 00:01:10 
/usr/bin/ssh-agent
      1653       1    1653      11740  cons1      22534 00:00:37 
/usr/bin/bash

ie. ssh-agent is still running, though its PPID no longer exists.

I'm using the latest release versions of cygwin and openssh:

Cygwin Package Information
Package              Version        Status
cygwin               3.0.7-1        OK
openssh              8.0p1-2        OK

with Windows 10 1803 (2019-09 update). I use Sophos AV 10.8 with HitmanPro.

Previously, I haven't had this problem: ssh-agent stopped when it's 
subprocess stopped. I updated from Cygwin 2.10-1 (and contemporaneous 
openssh) fairly recently, and it's possible the problem started then. Or 
it could have been a Windows minor update, AV update, or some other 
setting change I made. Sorry I couldn't pin it down further.

Is it just me that sees this, or could it be a bug in ssh-agent or Cygwin?

If it is just me, my first suspicion would be HitmanPro, which 
previously caused silent failures with an earlier version of Cygwin (I 
reported in cygwin-patches AT cygwin DOT com, June 2018). That bug is fixed, 
but maybe this is something new. If we can rule out a more general 
Cygwin bug, I can ask my IT support to try disabling the HitmanPro to test.

Thanks,
Tim.


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