ssh tunnel as a daemon

[Patrick Nelson]

One way I tried is using pidof like this in the script sshtun:

---snip---
while [ true ]; do
 pidof ssh
 if [ $? -eq 1 ]; then
  ssh -nN2g -c $Crypt $LPort:$LHost $RUser@$RHost -L $RPort:$LHost:$LPort
 fi
 sleep 5
done
---snip---

which appears to work, recreating the ssh tunnel when it drops off. 
Thoughts, questions, anecdotes?


On Sat, 2004-06-12 at 11:47, Patrick Nelson wrote:
> FC2 Uptodate
> 
> I'm trying to figure out how to daemon'ize a script that I have to start
> an ssh port forwading tunnel.  Here is how I'm doing it:
> 
> the script (name is sshtun):
> ---snip---
> while [ true ]; do
>  ssh -nN2g -c $Crypt $LPort:$LHost $RUser@$RHost -L $RPort:$LHost:$LPort
> done
> ---snip---
> 
> the init script (sshtund):
> ---snip---
> daemon $ProgramFull
> ....
> killproc $ProgramFull
> ---snip---
> 
> The problem:
> When I call service sshtund start, the ssh process does go to the
> background and sshtund never exits.
> 
> So I tried this with the init:
> ---snip---
> $ProgramFull &
> ....
> killproc $ProgramFull
> ---snip---
> 
> but then service sshtund stop doest work.  So I changed the stop section
> of the init to:
> 
> ---snip---
> $ProgramFull &
> ....
> killall -qgs 9 $ProgramName
> ---snip---
> 
> where ProgramName is sshtun.  And this works but all further processing
> of the init script (everything that follows the killall) doesn't get
> done and the init script returns.
> 
> So, it appears that the ssh is holding the init script and tie'ing it to
> the ssh command but I can not seem to separate the init script from the
> program it calls (not sure if it is  possible).  OK thats cool, So I can
> give the ssh command (in the script sshtun) the -f option to put ssh in
> the background.  But I have to get rid of the while-do-done which
> creates my real problem.  So, my question is:
> 
> Is there a best practice on scripting a process to make sure a
> background process is running?  Or when a background process drops off
> it triggers an event that would attempt to start it up again?  Any ideas
> would help.
>