[exim] Now exim segfault in a very strange way :-/ (was: Re:…

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Autor: Marc Schiffbauer
Datum:  
To: exim-users
Alte Treads: Re: [exim] Why does exim4 stat /boot and /proc/<pid>/mounts very often?
Betreff: [exim] Now exim segfault in a very strange way :-/ (was: Re: Why does exim4 stat /boot and /proc/<pid>/mounts very often?)
* Philip Hazel schrieb am 17.12.04 um 10:28 Uhr:
> On Thu, 16 Dec 2004, Marc Schiffbauer wrote:
>
> > > > Run a SMTP message receive in debug mode and see if you can see how the
> > > > accesses match up with exim operations.
> > >
> > > Ultimately, I guess, you may have to strace it.
> >
> > which would be the best exim call to test that?
>
> strace is the Linux command for running a program and tracing all its
> system calls. If you are using Solaris, the equivalent program is called
> truss. The output tends to be voluminous, but it might give a clue as to
> when the stat() calls of interest take place.
>


Hi Philip,

sorry if I my question was a bit misleading. I know strace.. but I
wondered how to call exim with strace on a production box that is
already running the exim daemon to reproduce the stat() calls..

I stopped exim and then started it as root like this:

strace -qff /usr/sbin/exim4 -bdf -q30m 2>&1 | tee /tmp/exim.trace

.. but when I tried to send a mail exim segfaulted...

And now something VERY strange was going to happen (at least to me):

Because this is a production server I decided to defer that test to
tonight.

I started exim "normal" again. It listens on port 25 and runs the
queue etc. as usual.

Now I tried to send an email (using my local exim3 that connects to
the exim 4.34 that we are talking about). But that did not work
anymore! (after the strace call on the production box)

I ran the exim3 queue again:

---------------------------
root@lisa:~# exim -qff -v
Single queue run
LOG: 0 MAIN
Start queue run: pid=1872 -qff
delivering message 1CfGI1-0008Np-00 (queue run pid 1872 fd 5)
Connecting to mail.schiffbauer.net [212.112.227.138.25] ... connected
LOG: 0 MAIN
Remote host mail.schiffbauer.net [212.112.227.138] closed connection after initial connection
LOG: 0 MAIN
== schiffbauer@??? T=remote_smtp defer (-19): Remote host
mail.schiffbauer.net [212.112.227.138] closed connection after initial connection
LOG: 0 MAIN
End queue run: pid=1872 -qff
---------------------------

stracing the production exim4 via "strace -f -p <pid>" shows that it
segfaults on any connection attempt by my exim3. I also tried
thunderbird or telnet:

--------------------------------------
root@lisa:~# telnet schiffbauer.net 25
Trying 212.112.227.138...
Connected to schiffbauer.net.
Escape character is '^]'.
Connection closed by foreign host.
root@lisa:~#
-------------------------------------

I tried to reboot the exim4 server, looked for unusual stuff in
/var/spool/exim4 but looks all normal... the problem persists.

I tried to connect with or without TLS.

I asked a friend to try that telnet call.
Success. (?!!??) I use dialup for my internet connection
via some different providers... so I changed the provider... and
(STRANGE!) it worked now for me too... exim3 could empty its queue
and deliver the testmessage to my production box.

Reverting back to the other provider restores the problem although I
got a different IP.

I even tried a third provider which works for me as well (telnet).

Wtf can cause this??? I am totally clueless. I will have to send
taht mail now with that second provider to make it work...

I logged one of that strace calls where it was segfaulting. Is that
of interest for you?

-a confused Marc

-- 
°    <M3rlin-> what is the legal age to buy alcoholic in england ? °
°  <p5Ds13a06> you cant buy alcoholics                             °
°  <p5Ds13a06> but if you wink the right way,                      °
°              some of them will follow you home for free          °