Re: [hylafax-users] Hylafax messing with ssh session

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

I guess it depends on how you run iaxmodem and how the crash occurred.

If you run iaxmodem in daemon-mode, then the parent process should 
restart the child process if it "crashes" such that it terminates.

Thanks,

Lee.


Niksa Baldun wrote:
> Lee,
>
> Many thanks for detailed explanation.
>
> I am unclear on the resetmodem script, however. You are using lsof on
> the pseudo-tty, but if iaxmodem already crashed, that tty will not
> exist. Or am I wrong?
>
> Thanks,
>
> Niksa
>
>
> On 03/22/2010 06:05 AM, Lee Howard wrote:
>   
> > Niksa Baldun wrote:
> >     
> > > I have the strangest of problems. I am using hylafax with a pool of
> > > iaxmodems. Sometimes when I connect to the system using ssh, I keep
> > > getting "ATZ" on the screen and I can't input any commands. Apparently
> > > hylafax thinks that the ssh pseudo console is actually a modem and it
> > > tries to communicate with it.
> > >
> > > When I restart the system, the problem goes away, but I can't find out
> > > what triggers it. How would I go about finding the cause of this? I
> > > tried browsing the system log, but I don't really know what to look for.
> > >       
> > iaxmodem uses pseudo-ttys, but the way that Linux works, iaxmodem
> > cannot request any particular device name for the pseudo-tty.  So we
> > end up with something like /dev/pts/24, but it will vary depending on
> > many things and will not be consistent.  For example, ssh also uses
> > pseudo-ttys, and often the tty numbers are allocated based on a
> > first-come-first-serve basis.
> >
> > In order to achieve a consistent device name iaxmodem creates a
> > symlink to the pseudo-tty, and HylaFAX uses the symlink.
> >
> > If iaxmodem crashes and is not restarted then HylaFAX will be trying
> > to operate on a broken symlink.  And then maybe you log in with ssh
> > and are given the pty that iaxmodem was just using.  Now you'll start
> > to get faxgetty talking to your pty that ssh is using.
> >
> > You can make HylaFAX restart iaxmodems when they "wedge" by putting
> > this in /var/spool/hylafax/etc/resetmodem :
> >
> > -----------------------------------------
> > #!/bin/sh
> >
> > set -x
> > exec 2> /tmp/resetmodem.$$
> >
> >
> > PTY=`ls -l $1 | sed 's/.*-> //g'`
> >
> > IAXPID=`/usr/bin/sudo /usr/sbin/lsof "$PTY" | grep iaxmodem | sed
> > 's/^iaxmodem *\([0-9]*\) .*/\1/g'`
> >
> > /usr/bin/sudo /bin/kill -HUP $IAXPID
> >
> > exit
> > -----------------------------------------
> >
> > Make sure to mark resetmodem as executable (chmod a+x
> > /var/spool/hylafax/etc/resetmodem).
> >
> > You'll also need something like this in your /etc/sudoers file:
> >
> > uucp  ALL = NOPASSWD: /bin/kill
> > uucp  ALL = NOPASSWD: /usr/sbin/lsof
> >
> > Thanks,
> >
> > Lee.
> >
> >
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> >
> >     
>
>
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>
>   


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