Wireshark-dev: Re: [Wireshark-dev] Looking for a developer to code an ANSI/ITU mixed decoding m
From: Jean Gottschalk <[email protected]>
Date: Wed, 23 May 2012 14:01:03 -0700

this is great news. I am running 1.6.7 at the moment (which does not show the heuristic option). Is this sufficient, or do I need a higher version?
Then I can test it with our traces and let you know what I see, and we can go from there.

To answer your question: we only need SCCP, however all of our traces are usually M3UA (or M2PA) and I can provide you with more sample traces if necessary.

There will definitely be a few beers from us when this works!

Best regards,

Jean Gottschalk

Telecom North America Inc

On Wed, May 23, 2012 at 8:48 AM, Jeff Morriss <[email protected]> wrote:
Jean Gottschalk wrote:

we often run traces on our network with MTP3/M3UA packets that are mixed between ANSI and ITU in the same trace.

In Wireshark, under the MTP3 decoder, we have to select whether to decode packets as ANSI or ITU, but not both at the same time. When selecting ANSI, all ITU packets are unreadable, and vice-versa.

I'm assuming that Wireshark is somehow aware that a packet could not be properly decoded using 1 mode, and if so, it could be smart enough to try with the other mode to see if that works better, and that on a packet by packet basis.

We are looking for a wireshark developer who could code such enhancement for us, for a fee, and contribute it to the wireshark project. It could be a called "Auto" mode and try all available flavors when any packet cannot be decoded.

Please contact me directly if you are interested in doing this.

Aww nuts... I already implemented (most of) this for free!  (Well, maybe I can get Anders to buy me a beer at Sharkfest for that ;-).)

In the current trunk (or 1.7.1 if you want a (development) release), MTP3 has a preference called "Try to determine the MTP3 standard heuristically".  When enabled, MTP3 will try to automatically determine the MTP3 standard (ANSI, ITU, China, or Japan).

But, this only works for MTP3 (not M3UA) and only when the payload is SCCP.  I tried it for M3UA but because the SCCP payload always starts at the same offset (because the M3UA message format does not depend on the MTP3 standard) the heuristics generally weren't effective.  (Admittedly I didn't have many ANSI M3UA captures to try it against; maybe if I had more I could come up with some ideas to improve it.)

Do you need it to work for non-SCCP traffic too?