topic Re: ssh hang in Operating System - HP-UX

ssh hang

Ray Brewer — Mon, 22 Nov 2004 15:54:35 GMT

We are having a problem with ssh hanging in the following scenario:

1. Login to server A - either telnet, CDE, etc
2. ssh to server B - "ssh serverB"
3. Run a swinstall or launch an application
4. Exit from server b - either "exit" or "ctrl D"

While exiting server B the terminal session hangs and never returns to the command prompt on server A. You then need to kill the session on server B. After killing the session you are returned to a command prompt on server A. This only happens if you launch a daemon, start an application, or install a new application via swinstall. Other standard commands like cd ,mkdir, cat, etc. work fine. I think it has something to do with associating a process with a tty then trying to exit but am not sure. Any Ideas? Any help would be appreciated?
Thanks
Ray

Re: ssh hang

Sanjay_6 — Mon, 22 Nov 2004 16:00:53 GMT

Hi Ray,

Did you leave a active process running over there on serverB

http://www.openssh.com/faq.html#3.10

Hope this helps.

Regds

Re: ssh hang

Ray Brewer — Mon, 22 Nov 2004 16:26:06 GMT

Sinjay,

Yes gernerally there is always a process such as a daemon started beforethe exit occurs. I will take a look at the link you provided.

Thanks!
Ray

Re: ssh hang

Ray Brewer — Mon, 22 Nov 2004 16:27:04 GMT

Sanjay,

Sorry for mis-spelling your name!!

Ray

Re: ssh hang

Michael Selvesteen_2 — Thu, 16 Dec 2004 07:05:01 GMT

Hi,

Try recent version of HP Secure Shell ( A.03.81.002). I tried out your scenario but it worked correctly for me.

I tried the following

# ssh sonnet
# sleep 20 &
[1] 7904
# exit
You have running jobs
# ctrl + D
logout root
Connection to sonnet closed.
#

--
M
logout root
Connection to sonnet closed.

Re: ssh hang

NMCI Group — Wed, 16 Feb 2005 15:53:55 GMT

That doesn't seem to replicate the problem. If you were to type "ssh sonet 'sleep 20 & exit'" it would hang. Another way to replicate the issue is to ssh sonet, then mwa stop, then mwa start, assuming you have measureware. Then if you try to exit it hangs on me every time. I am running the most recent version of HPUX Secure Shell.

Re: ssh hang

Ray Brewer — Wed, 16 Feb 2005 16:48:12 GMT

We found a solution to our problem thanks to a little help from HP. We added this line to the script we were running and it worked to release the session.

exec > /dev/null < /dev/null 2>&1

Here is a sample script that illustrates how to place the entry into a script. The return code can be anything you want. We used 3 to help prove we could capture the return code we were looking for.

#!/bin/sh
exec > /dev/null < /dev/null 2>&1

sleep 30 &

return 3