Re: 2.1.103 won't connect to ftp.kernel.org
ak@muc.de
Sun, 31 May 1998 18:08:38 +0200
On Sun, May 31, 1998 at 05:32:01PM +0200, Carsten Gross wrote:
> Hello Andi and Developer list
>
> [Cc'ed to the List]
>
> Thanks for your answer.
>
> In article <k2ogwemx8u.fsf@zero.aec.at>,
> ak@muc.de (Andi Kleen) writes:
> [Description of my problem...and:]
> > Now it starts to be come strange. The other end floods us with ACKs.
> >
> > Can't see yet why. Is this reproducible? If yes, could you change ncftp
> > to set the SO_DEBUG option on the socket
>
> Yes, it is reproducible. I've fetched ncftp 2.4.3 (This version is a lot
> newer than my installed version) from a redhat mirror at
> ftp.rz.uni-karlsruhe. This server isn't a problem for me at all, I
> downloaded the 200 kbyte in one or two minutes.
>
> I compiled ncftp with the following line added around Row 494 (and at the
> top of the function, I set int flag = 1):
>
> if (setsockopt(sockfd, SOL_SOCKET, SO_DEBUG, &flag, sizeof(flag))<0) {
> perror("setsockopt");
> exit(1);
> }
>
> This version of ncftp has a timeout handling. It stops itselfs connecting
> after 30 seconds, but the problem remains:
>
> python:/home/carsten/ncftp-2.4.3#./ncftp ftp.kernel.org
> (hanging, the prompt returns after 30 seconds with exit status 7)
[...]
That's very strange. Could you try to turn off RFC1323
(echo 0 > /proc/sys/net/ipv4/tcp_rfc1323), SACK (the same for
tcp_sack) and pmtu discovery (echo 1 > ..../ip_no_pmtu_disc)
It would be interesting if any combination of these flags works.
The only thing that looks strange in your packet are the timestamps,
maybe the PAWS old packet check discards them.
-Andi
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