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Bug#498409: marked as done (Some TCP connections are not established, incoming SYN/ACK-package is seemingly not regarded as valid.)

Your message dated Thu, 11 Sep 2008 13:34:14 +0200
with message-id <20080911113414.GL31207@baikonur.stro.at>
and subject line Re: Bug#498409: bug invalid
has caused the Debian Bug report #498409,
regarding Some TCP connections are not established, incoming SYN/ACK-package is seemingly not regarded as valid.
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
498409: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498409
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: linux-image-2.6.18-6-686

(On Debian Stable)

Trying to connect to some hosts via TCP, no connection is
established. SYN packages are sent repeatedly although a package with
no flag should (?) be sent to accept the connection since the
SYN/ACK-package corresponding to the SYN-package already arrived.

This is an example 'tcpdump' output while doing 'telnet
www.wikipedia.org 80' (the same happens while trying to connect from a
web browser):

(some empty lines inserted to make it better readable)

till:/home/olaf# tcpdump -i ppp0 -vvv host www.wikipedia.org
tcpdump: listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes

19:36:01.309287 IP (tos 0x10, ttl  64, id 15523, offset 0, flags [DF], proto: TCP (6), length: 44) p54B8C1A5.dip.t-dialin.net.45289 > rr.knams.wikimedia.org.www: S, cksum 0x4d02 (correct), 575226067:575226067(0) win 5808 <mss 1452>

19:36:01.359890 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:04.305824 IP (tos 0x10, ttl  64, id 15524, offset 0, flags [DF], proto: TCP (6), length: 44) p54B8C1A5.dip.t-dialin.net.45289 > rr.knams.wikimedia.org.www: S, cksum 0x4d02 (correct), 575226067:575226067(0) win 5808 <mss 1452>

19:36:04.357651 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:05.664477 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:10.306201 IP (tos 0x10, ttl  64, id 15525, offset 0, flags [DF], proto: TCP (6), length: 44) p54B8C1A5.dip.t-dialin.net.45289 > rr.knams.wikimedia.org.www: S, cksum 0x4d02 (correct), 575226067:575226067(0) win 5808 <mss 1452>

19:36:10.356971 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:11.664530 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:22.306952 IP (tos 0x10, ttl  64, id 15526, offset 0, flags [DF], proto: TCP (6), length: 44) p54B8C1A5.dip.t-dialin.net.45289 > rr.knams.wikimedia.org.www: S, cksum 0x4d02 (correct), 575226067:575226067(0) win 5808 <mss 1452>

19:36:22.358369 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

19:36:22.376944 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.36826: S, cksum 0xa0f5 (correct), 4219996580:4219996580(0) ack 301537506 win 5840 <mss 1452>

19:36:23.665007 IP (tos 0x0, ttl  49, id 0, offset 0, flags [DF], proto: TCP (6), length: 44) rr.knams.wikimedia.org.www > p54B8C1A5.dip.t-dialin.net.45289: S, cksum 0xf2c0 (correct), 1073551891:1073551891(0) ack 575226068 win 5840 <mss 1452>

12 packets captured
16 packets received by filter
0 packets dropped by kernel
till:/home/olaf# 

Thus the kernel behaves as if the peer would not respond at all. Not
quite, since the SYN/ACK packages of the peer are logged (why?). This
is the corresponding part of the 'messages' log file:

Sep  9 19:36:01 till kernel: IN=ppp0 OUT= MAC= SRC=91.198.174.2 DST=84.184.193.165 LEN=44 TOS=0x00 PREC=0x00 TTL=49 ID=0 DF PROTO=TCP SPT=80 DPT=45289 WINDOW=5840 RES=0x00 ACK SYN URGP=0 
Sep  9 19:36:22 till last message repeated 5 times
Sep  9 19:36:22 till kernel: IN=ppp0 OUT= MAC= SRC=91.198.174.2 DST=84.184.193.165 LEN=44 TOS=0x00 PREC=0x00 TTL=49 ID=0 DF PROTO=TCP SPT=80 DPT=36826 WINDOW=5840 RES=0x00 ACK SYN URGP=0 
Sep  9 19:36:23 till kernel: IN=ppp0 OUT= MAC= SRC=91.198.174.2 DST=84.184.193.165 LEN=44 TOS=0x00 PREC=0x00 TTL=49 ID=0 DF PROTO=TCP SPT=80 DPT=45289 WINDOW=5840 RES=0x00 ACK SYN URGP=0 

The problem does _not_ occur from a different computer with a faster
internet connection (with linux-image-2.6.18-6-amd64 of Debian Stable).

Olaf

--- End Message ---
--- Begin Message --- 
On Thu, Sep 11, 2008 at 12:57:28PM +0200, Olaf Till wrote:
> Forgive me ... I did not realize that 'tcpdump' will show incoming
> packages although they do no pass the firewall. It was the firewall
> which caused the 'problem'; some of its configuration escaped my
> attention. Sorry, please mark this bug invalid. Olaf

closing.

--- End Message ---
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