A problem with tcp checksums (evident in PPP)

Matan Ziv-Av (matan@arava.co.il)
Sat, 9 Jan 1999 00:46:46 +0200 (IST)

Using 2.2.0-pre5, I can't connect to some sites (freshmeat,
dejanews, Alan Cox's site), though other sites work normaly, All I
tried other than http (telnet to a few hosts, nntp to one host, ftp to
a few hosts) did work.
At the same time dmesg show bad checksums for packets from the sites
I can't access, but not from other sites.
(The warnings don't find their way to my /var/log dir unfortunately).
The problem does not exist in kernel 2.0.36.
I'm sure the problem is with checksum, since when I change line 1644
of linux/net/ipv4/tcp_ipv4.c from
if(tcp_v4_check(th,len,skb->nh.iph->saddr,skb->nh.iph->daddr...
to
if(0&tcp_v4_check(th,len,skb->nh.iph->saddr,skb->nh.iph->daddr...

and then recompile and reboot the new kernel, I can access those
sites.

--
Matan Ziv-Av.        zivav@cs.bgu.ac.il


        ש"דח הז לאמש םעפה םג
Vote MAKI - The Israeli Communist Party




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