2007/4/20, Nathan Smith <ndansmith@gmail.com>:
The symptoms (broken TCP traffic to some sites)
depend entirely upon the sites you are connecting to and how your
connections are routed.
We saw that affected users are sending TCP data with bad checksum (this could apply to udp and/or icmp too? anyone to check?).
Then, some router on the Internet can decide to drop such bad packet. I noticed Linux doesn't drop but Checkpoint does.
Another point, note that the bad checksum is always good_checksum+0100
"""
[bad tcp cksum 3de5 (->3ce5)!]
[bad tcp cksum 322d (->312d)!]
[bad tcp cksum 25ad (->24ad)!]
"""
I guess this is the checksum algorithm that is incompatible with -O2. Even if I won't check the source code :p
However, using tcpdump I can tell that some machines apparently do not
experience this problem, so it may be processor-specific (which makes
sense given that it is an optimization problem). I use a Pentium M.
What are other people using that have been affected by the problem?
Mine is pentium-4
--
Camille Huot