Wireshark mailing list archives

Re: Adding verification functionality to SIP dissector


From: Peter Wu <peter () lekensteyn nl>
Date: Thu, 23 Feb 2017 22:21:53 +0100

On Thu, Feb 23, 2017 at 12:49:51PM -0800, Guy Harris wrote:
On Feb 23, 2017, at 11:56 AM, Erik de Jong <erikdejong () gmail com> wrote:

During my day job I have noticed that sometimes combinations of
certain platforms have trouble dealing with SIP digest
authorization. Reasons for this range from bugs in the SIP stack to
wrong escapes for special characters in configuration files
generated for automated set provisioning. I have written a Lua
script that will allow me to enter credentials and check if the
digest hash in a SIP authorization line is indeed the correct hash
for those credentials.  I've written a proof of concept where this
functionality is added to the SIP dissector itself and I'm wondering
whether this is appropriate to submit for review or that these kind
of diagnostics are better left in an external script as it is not
really a dissection of the packet.

1) We already do validation of checksums in dissectors.

2) Wireshark is a packet *analyzer*, not a packet *dissector*.

So there's no reason *not* to do digest hash checks in Wireshark, and if the dissector is the best place, there's no 
reason not to do them there.

Validation of the protocol fields (like checksums) can be done without
external input and would be nice. On violation, these could add "expert
info" to the tree.

But for Authorization digests in SIP, this would require external input
(credentials), possibly through a preference (filename or UAT). I think
it is better as separate script (since the input format can be different
depending on the user), but wouldn't object if a patch is proposed.
-- 
Kind regards,
Peter Wu
https://lekensteyn.nl
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