More TCP checksum problems

Aaron Turner <[email protected]> Wed, 2 Jun 2004 17:12:34 -0700
Newsgroups gmane.comp.security.libnet
Message-ID <[email protected]>
Not sure if this is related to the earlier reports of problems w/ TCP
checksums (I deleted the emails, and the list archives seem to be
empty), but here it goes...

First, I'm using libnet 1.1.2.1 on debian w/ kernel 2.6.6.  I have TWO
libnet handles in my app (both LIBNET_RAW4 injection).

Basically, if I open two handles, libnet always seems to want to calc
TCP checksums for packets sent with the first handle, even when I hard
code the checksum to a non-zero value (I don't use
libnet_toggle_checksum()).  It does however seem to correctly set the
checksums for the 2nd handle.  If I play with the order of libnet_init()
and libnet_destroy() I can get libnet to do various odd things where the
checksum isn't what it should be as I've coded it.

However, if I only use one handle (kinda messy since I'm sending so many
different looking packets), it seems to work fine.

Any ideas what's going on?

-- 
Aaron Turner <aturner at pobox.com|synfin.net>  http://synfin.net/
They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety. -- Benjamin Franklin
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