[tproxy] tproxy race condition? [RESEND]

jim@minter.demon.co.uk jim@minter.demon.co.uk
Mon, 20 Dec 2004 13:42:22 +0000

Hi Krisztian!

> > Sorry :o(.  I'm currently recompiling the kernel with a larger log
> > buffer and will rerun the tests and post an updated tarball.
>   I'm afraid it won't help much, but let's see.

OK, http://www.minter.demon.co.uk/tproxy-bug-2.tar.bz2 [3.1M] is available; the system log files are considerably longer this time, but it's possible that you'll find that they're still not complete :o/

> > >   Could you try what happens if you omit the ITP_ONCE flag from the
> > > FLAGS setsockopt(), and set only ITP_CONNECT?
> > 
> > OK, in this case we don't get any un-NATted packets at the remote
> > host, but sooner or later one of the processes gets stuck in a
> > connect() call and never returns: presumably every time it attempts to
> > issue a SYN packet, this packet gets lost somewhere?  Maybe with
> > proper logging it will be clearer what's going on here.
>   OK, thanks. So, in the meantime I reproduced the problem (and tested
> without ITP_ONCE as well). Seems interesting, since I get a lot of
> "failed to apply NAT mapping" errors...

The above tarball also has a log of a run without the ITP_ONCE flag.  It's encouraging that you've been able to reproduce the problem at your end -- was it on an SMP box?

By "failed to apply NAT mapping" error, I assume you mean the "IP_TPROXY: error applying NAT mapping" error?  Just to confirm, I'm not getting any of these error messages at all (perhaps because I've configured NAT reservations off?)