Fwd: Bug#284729: libnet1: UDP checksums are bogus in odd sized packets

Domenico Andreoli <[email protected]> Wed, 8 Dec 2004 23:18:14 +0100
Newsgroups gmane.comp.security.libnet
Message-ID <[email protected]>
hi Mike, hi all,

here is a bug reported to libnet debian package. full log is available
at http://bugs.debian.org/284729.

i saw similar bug has been reported few days ago against tcp checksum.
is this the same bug? could you please hand me the solution in order
to let me fix the debian package? that's because i don't know if you'll
release the next version in time for sarge ;)

cheers
domenico

----- Forwarded message from Ulisses <[email protected]> -----

Date: Wed, 08 Dec 2004 13:06:06 +0100
To: Debian Bug Tracking System <[email protected]>
Subject: Bug#284729: libnet1: UDP checksums are bogus in odd sized packets

...

If I send UDP packets using libnet and I let libnet to checksum them I
found that the checksums are wrong. I have verified this with 
tethereal -V.

Using the same procedure with packets having an even size are always ok.

Please note that:

 + I have used tcpdump and tcpdump doesn't report udp checksum errors.
 + Using my own udp checksum routine and capturing packets from
   the network, odd sized packets from the network are ok but capturing 
   libnet generated packets gives wrong udp checksums.

So I think both libnet and tcpdump are wrong and my routine and
tethereal's are right.

I hope this helps

	Ulisses

----- End forwarded message -----


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