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

[Niksa Baldun <niksa.baldun@xxxxxxxxx>]

Hmmm, no, on my system all iaxmodem processes were still in memory, but
one pseudo-tty was missing. So the resetmodem script will not do much good.

Nonetheless, I understand the gist of the problem now, so I will monitor
it further and find a solution. I appreciate your help immensely.

Regards,

Niksa


On 03/22/2010 01:49 PM, Lee Howard wrote:
> 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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