[Bug 121] New: ssh hangs on exit (not damon, nor background)

Nicolas Williams Nicolas.Williams at ubsw.com
Wed Feb 20 08:43:13 EST 2002

This sounds like the SIGCHLD race bug.

Check if the sshd has a defunct child when hanging - if so, send SIGCHLD
to the sshd and watch the connection close.

Search the list. Patches have been posted.



On Wed, Feb 20, 2002 at 08:24:45AM +1100, bugzilla-daemon at mindrot.org wrote:
> http://bugzilla.mindrot.org/show_bug.cgi?id=121
>            Summary: ssh hangs on exit (not damon, nor background)
>            Product: Portable OpenSSH
>            Version: 3.0.2p1
>           Platform: Other
>         OS/Version: other
>             Status: NEW
>           Severity: normal
>           Priority: P2
>          Component: ssh
>         AssignedTo: openssh-unix-dev at mindrot.org
>         ReportedBy: joshua.mehlman at morganstanley.com
> ssh running on Solaris 2.8 ocasionaly hangs on exit. I run the command
> ssh -v server hostname 
> we have also seen this with different commands and even just getting a shell.
> (note I have tryed with -t, -n and of course without the -v and a -v -v -v give
> no more info)
> and about 1 time out of 1000 it hangs.
> The verbose output is as follows:
> debug1: Sending command: hostname
> debug1: channel 0: open confirm rwindow 0 rmax 16384
> debug1: channel 0: rcvd eof
> debug1: channel 0: output open -> drain
> server
> debug1: channel 0: obuf empty
> debug1: channel 0: output drain -> closed
> debug1: channel 0: close_write
> Then comes the hang. Note that this is differnt than the bg file wait issue.
> an netstat on the client:
> client# netstat -a | grep server
> client.34819        server.ssh         17520      0 33580      0 ESTABLISHED
> client.34820        server.ssh         17520      0 33580      0 TIME_WAIT
> and one on the server:
> server# netstat -a | grep client
> server.full.domain.name.com.ssh client.34819        33580      0 17520      0
> and some ps :
> client# ps -ef | grep hostname
>     root 19944  2917  0 12:32:19 ?        0:01 /usr/local/bin/ssh -n -v server
> hostname
> server# ps -ef | grep ssh
>     root  3439 10524  0 12:32:21 ?        0:01 /services/ssh/sbin/sshd
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