Re: [gentoo-bsd] TCP (FTP) problem - some sites - while emerging

["Camille Huot" <cam@gentoo.org>]

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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

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