Dropbear turns into zombie process after killing

[Jeroen van der Vegt]

Hi Matt,


I found the issue, and indeed it had nothing to do with dropbear.
Apparently, 'init' was only  half-way its start-up procedure. One of the
scripts in ::sysinit:: had a loop like this though:

while /bin/true; do
        /bin/sh
done

which prevented 'init' from finishing completely. It also triggered a 'Job
control turned off' warning on the serial console, but I had no clue what it
meant. I did find out about the command 'kill 0' command though, which
allowed me to break out of the while-loop and make 'init' finish its work,
removing all zombie processes with it.


Sorry to bother you,

Jeroen van der Vegt	 
System designer 
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> -----Original Message-----
> From: dropbear-bounces at ucc.asn.au [mailto:dropbear-bounces at ucc.asn.au] On
> Behalf Of Matt Johnston
> Sent: vrijdag 21 november 2008 0:10
> To: Jeroen van der Vegt
> Cc: dropbear at ucc.asn.au
> Subject: Re: Dropbear turns into zombie process after killing
> 
> On Thu, Nov 20, 2008 at 04:54:14PM +0100, Jeroen van der Vegt wrote:
> > Hello,
> >
> >
> > We're using Dropbear 0.51 to create a tunnel from an embedded ARM device
> to
> > a server (running openSSH). We use the precompiled dropbear version from
> > Debian, and ssh is symlinked to dbclient.
> > The tunnel is constructed in a script using this command:
> >
> > 	# ssh -i /etc/dropbear/dropbear_rsa_host_key $USER@$REMOTEHOST -L \
> > 		$LOCALPORT:127.0.0.1:$REMOTEPORT -f -N
> >
> > A tunnel created this way works fine. When the script is done, the
> tunnel
> > should be removed. We simply kill all instances of 'ssh' for this.
> > Unfortunately, this results in a zombie dropbear process on our ARM
> device.
> 
> How are you running that command? Cleaning up zombie
> processes is the responsibility of the parent process that
> spawns a process (using waitpid() etc, most shells etc would
> take care of it). I don't think there's much that the
> Dropbear client could be doing (or not doing) that would
> influence whether it's zombified?
> 
> Matt