Tristan Krakau writes:
> due to the rsync-cygwin-ssh problem when backing up Windows clients
> using 'rsync' as transfer, I tried to use 'rsyncd' through a ssh tunnel
> instead (since the Windows client can only be accessed via ssh).
>
> I found other threads dealing with this topic (e.g.
> http://sourceforge.net/mailarchive/message.php?msg_id=11482919), and all
> the hints there seemed to work fine:
>
> - a ssh tunnel from the backuppc server to the client is created
> - rsync is redirected to the localhost:port and this way connects to
> rsyncd-shares on the client
> - after backing up the host the tunnel is killed again
>
> However, this only works when I manually setup the ssh-tunnel, call
> BackupPC_dump <host> and tear down the tunnel afterwards.
>
> But if I want the tunnel to be set-up by
>
> $Conf{DumpPreUserCmd} = 'ssh -L 5009:localhost:873 -N -f
> [EMAIL PROTECTED]';
>
> the tunnel is created - and the dump is waiting... it simply does not
> continue until the ssh-tunnel is killed (from another shell e.g.). Then
> the backup of course fails because the tunnel is not there and rsyncd
> cannot be contacted.
>
> I also tried putting the ssh -L ... command in another script:
>
> host_prepare.sh:
> ssh -L 5009:localhost:873 -N -f [EMAIL PROTECTED]
> echo Tunnel to host was created
> --
> and it shows that the echo command, like any other command after the
> ssh-command is still executed, which tells that ssh is started in the
> background, but the dump will pause after the script has finished.
>
> Also, using & instead of the -f option with ssh has no effect.
>
> So my question is: How can I make the DumpPreUserCmd start the
> ssh-tunnel in the background and return so the dump can begin while the
> tunnel is there?
>
> I think it could have something to do with the way Perl executes
> commands, maybe it always waits for all child-processes to end?
>
> I really hope someone could give me a hint how to solve this!
Yes, it must have to do with how perl executes these commands.
I'm not near a linux machine right now, so I can't test this.
First, I assume you tried "&" inside host_prepare.sh, since
$Conf{DumpPreUserCmd} is exec'ed directly rather than via
a shell.
The perl code uses the open(F, "-|") form of fork to run you command.
That pipes stdout of the children to perl. So the issue could be
that since stdout of the child (and its children) is still open,
perl continues to wait.
Inside the shell (assuming I've got the /bin/sh syntax right),
I recommend trying to redirect ssh's stdout and stderr to
/dev/null, eg:
ssh -L 5009:localhost:873 -N -f [EMAIL PROTECTED] 1>/dev/null 2>/dev/null
or
ssh -L 5009:localhost:873 -N [EMAIL PROTECTED] 1>/dev/null 2>/dev/null &
Craig
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