Transmission triggers anti-SYN-Flood countermeasures and Wi-Fi connection is killed often

[mercutio22]

Binary package hint: transmission

I get repeated messages like these: "[26088.392579] possible SYN flooding on port 20767. Sending cookies." And then my wireless connection dies every time transmission is running.

20767 is the chosen forwarded por fot transmission.

ProblemType: Bug
Architecture: amd64
Dependencies:

DistroRelease: Ubuntu 9.04
NonfreeKernelModules: nvidia
Package: transmission None [modified: /var/lib/dpkg/info/transmission.list]
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: transmission
Uname: Linux 2.6.30-020630-generic x86_64
UnreportableReason: This is not a genuine Ubuntu package

[Krzysztof Klimonda (kklimonda)]

Thanks for your report. Unfortunately you are using a custom kernel and transmission packages. Can you downgrade to the supported versions and see if the problem persists?

[Charles Kerr (charlesk)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

I don't think this is a Transmission bug. If you Google for that error message you
can find it being caused by KTorrent[1] and Deluge[1] too. According to [3], your
machine thinks it's under attack because of the high rate of incoming connections.
SYN cookies are there to try to maintain a usable network connection despite such
an attack. The poster there gives instructions on how to disable the warning.

[1] http://www.linuxquestions.org/questions/showthread.php?p=2621661#post2621661
[2] http://ubuntuforums.org/showpost.php?p=7973243&postcount=7
[3] http://ubuntuforums.org/showpost.php?p=7815082&postcount=2,

[mercutio22 (macabro22)]

I am using the X-updates ppa: https://launchpad.net/~ubuntu-x-swat/+archive/x-updates/ I need the 2.6.30 kernel and latest nvidia drivers to solve compiz issues. You may close the bug and I will hope this doesn't happen when karmic is released. If it helps I would willingly downgrade the transmission package and post more info if that helps.

How exactly can I do it?

[Krzysztof Klimonda (kklimonda)]

I actually think the easiest approach would be to keep it until you can test out version from Karmic. Hopefully the problem is fixed in newer release.

[Charles Kerr (charlesk)]

mercutio22: Could you try this out in the latest Karmic beta?

[mercutio22 (macabro22)]

On Sat, 2009-10-10 at 09:14 +0000, charles wrote:

> mercutio22: Could you try this out in the latest Karmic beta?

Charles I will try ASAP. I am a little busy with my thesis at the
moment.

>

--

[Charles Kerr (charlesk)]

We'd like to figure out what's causing this bug for you, but we haven't heard back from you in a while. Could you please provide the requested information? Thanks!

[mercutio22 (macabro22)]

Hi Charles,

Sorry to take so long, I completely forgot about this.

I am now using Karmic and I am not getting repeated messages about SYN floods. I only found one in my kern.log from 2 days ago (november 8th). The connection is much more stable but I still get disconnected sometimes.

Network manager prompts me for my WPA password and wont reconnect till I type it but I am not sure if this problem is related. I remember reading a bug post where a developer named Alexander Sacks mentioned this is standard behavior in response to wi-fi oscillation.

I attach my kern.log

[Charles Kerr (charlesk)]

Hi Mercutio22,

I think this new issue is a separate matter, which has already been reported and is a duplicate of bug #427102. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report.

I'm glad that the anti-syn flood issue is fixed in Karmic. I'm marking this ticket accordingly.

Please feel free to report any other bugs you may find.