Erratic TCP behaviour ... pb w/ outgoing connections

[Frenchie]

Hi,

I upgraded last week from an older version of Knoppix to an French version of Knoppix called "Kaella" based on Knoppix 5.0 (using kernel Linux CineboxII 2.6.17 #4 SMP PREEMPT Wed May 10 13:53:45 CEST 2006 i686 GNU/Linux). In fact, I just blindly did a knoppix-install onto my hard drive, configured everything to my liking, set up some samba shares, installed webmin, started sshd and started watching a DVD with kaffeine. Very satisfied with myself I thought I'd just install a couple of packages to get xmms working with .ape files. That was when I realized that my machine was having trouble accessing the Internet. Let me try to explain because the details are quite strange :

1/ I am using an ADSL router so I just configured an IP address, gateway and DNS server as I do with all my other computers (I have three of them on my network). My network card uses the 3C59x module.

2/ I am able to ssh to my Knoppix FROM another machine TO my Knoppix machine, the samba shares work fine, I started an apache server and I'm able to browse to it, webmin is OK too.

3/ The trouble starts when I try to connect FROM my Knoppix TO any other machine whether it be on my local network or on the Internet. The strange thing is that I am able to ping, do traceroutes (ICMP). My DNS lookup gives good results (UDP). It is when I try to do anything with TCP that I have problems. apt times out, Firefox hangs, lynx hangs, wget hangs.

4/ I had a look at the network traffic with Ethereal and found that the SYN/ACK is ok, the http GET is transmitted and the TCP ACK comes back from the remote server then NOTHING ... no more packets ... radio silence. My browser just says "Host contacted waiting for reply" then waits forever.

5/ Strangely enough, some sites DO work. I am able to browse http://www.google.com but not http://www.yahoo.com. I'm able to browse http://www.free.fr/ but not http://www.wanadoo.fr/ etc. I used google to search "English version" to get a wide variety of (geographically) unrelated sites and am able to browse about 1 in 20 or so. VERY ERRATIC !!

6/ I tried other TCP protocols such as smtp, ftp, ssh, imap, pop with the same results.

7/ I tried booting my Knoppix live CD on other machines with different network cards with exactly the same results.

8/ I tried booting Knoppix 4.0 on my machine and everything works fine.

9/ I thought it might be an iptables problem ... nope ! It's OK.

I have spend a few days looking for people who have seemingly the same type of problem and they are very few and far between. Could we compare some notes ? I'd really like to get this narrowed down to something logically plausible. I can't think of anything else to try (short of hacking the kernel).

I am in the process of downloading the vanilla KNOPPIX_V5.0.1CD-2006-06-01-EN.iso to give it a try too. It shouldn't be long before I can try that.

Has anyone else experienced this ? Is everyone else surfing OK ? I find it hard to believe that this is an isolated case.

[Frenchie]

Hi,

I am in the process of downloading the vanilla KNOPPIX_V5.0.1CD-2006-06-01-EN.iso to give it a try too. It shouldn't be long before I can try that.

OK I just finished downloading KNOPPIX_V5.0.1CD-2006-06-01-EN.iso and am having the same problems. I definitely DO have an issue here.

Any suggestions and/or help would be appreciated.

[ockham23]

Some routers work fine with windows clients, but not with linux clients. Try this:
Get the IP addresses of your ISP's name servers (you can find them using the router's web interface ["Diagnostics"] or from the ISP's web site) and add them to /etc/resolv.conf. This should solve the problem.

[Frenchie]

I just configured another adsl router and found that everything works fine ...

It seems that the problem has something to do with my Triway V2 router. I think I might as well give up and either change routers or change distributions.