Re: 2.1.103 won't connect to ftp.kernel.org

Carsten Gross (carsten@wohnheim.uni-ulm.de)
Sun, 31 May 1998 17:32:01 +0200


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)

netstat -to shows during the hang (Sorry for long lines):
python:~>netstat -to
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State Timer
tcp 0 0 python.wohnheim.un:1141 linux.kernel.org:ftp ESTABLISHED off (0.00/0)
tcp 54 0 python.wohnheim.un:1129 sol.wohnheim.uni-u:nntp CLOSE_WAIT off (0.00/0)
tcp 0 0 python.wohnheim.un:1101 drakonis.wo:netbios-ssn ESTABLISHED off (0.00/0)

The connection to 'drakonis' was correctly established, but without traffic
at the moment of capture. The connection to 'sol' was really closing at this
moment.

The Kernel-debug logfile shows only:
May 31 17:21:44 python kernel: sk->rspace = 65535
May 31 17:22:14 python kernel: sk->rspace = 65535

And, after stopping tcpdump, there are some logs from the WD8013
chipset multicast bug:
May 31 17:22:54 python kernel: Multicast filter read/write mismap 0
[..]

tcpdump again:
17:21:40.786923 python.wohnheim.uni-ulm.de.1141 > linux.kernel.org.ftp:
S 2143537654:2143537654(0) win 31856 <mss 1460,sackOK,timestamp 2766374 0,
nop,wscale 0> (DF)

17:21:43.777919 python.wohnheim.uni-ulm.de.1141 > linux.kernel.org.ftp:
S 2143537654:2143537654(0) win 31856 <mss 1460,sackOK,timestamp 2766674 0,
nop,wscale 0> (DF)

17:21:44.325176 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
S 2022962574:2022962574(0) ack 2143537655 win 31856 <mss 1460,sackOK,
timestamp 41977505 0,nop,wscale 0> (DF)

17:21:44.325347 python.wohnheim.uni-ulm.de.1141 > linux.kernel.org.ftp:
.. ack 1 win 31856 <nop,nop,timestamp 2766728 41977505> (DF)

17:21:44.520272 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 1 win 31856 <nop,nop,timestamp 41977540 2766374> (DF) [tos 0x10]

17:21:46.223728 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 1 win 31856 <nop,nop,timestamp 41977801 2766674> (DF) [tos 0x10]

17:21:46.428658 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 1 win 31856 <nop,nop,timestamp 41977840 2766674> (DF) [tos 0x10]

17:21:47.341197 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 1 win 31856 <nop,nop,timestamp 41977870 2766728> (DF) [tos 0x10]

[This is the point where ncftp gives up, it's nearly 30 (here 34) seconds
since starting ncftp:]

17:22:14.318437 python.wohnheim.uni-ulm.de.1141 > linux.kernel.org.ftp:
F 1:1(0) ack 1 win 31856 <nop,nop,timestamp 2769728 41977870> (DF)

17:22:18.250768 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 2 win 31856 <nop,nop,timestamp 41980853 2769728> (DF) [tos 0x10]

17:22:18.254879 linux.kernel.org.ftp > python.wohnheim.uni-ulm.de.1141:
.. ack 2 win 31856 <nop,nop,timestamp 41980853 2769728> (DF) [tos 0x10]

I cannot understand why my computer doesn't answer to ftp.kernel.org. Is
this problem reproducible for someone else?

Regards

Carsten

-- 
unzip ; touch ; finger ; mount ; gasp ; yes ; umount ; sleep
Carsten Gross                     carsten@sol.wohnheim.uni-ulm.de
Wohnheim Heilmeyersteige        Sebastian Kneipp Weg 6, 89075 Ulm

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu