Re: PROBLEM: networking - port 80 not accessible on eth0

Re: PROBLEM: networking - port 80 not accessible on eth0

[Ilpo Järvinen]

Added netdev though this is unlikely to end up being dev related.

On Fri, 9 Jan 2009, Orgad Shaneh wrote:

> ---------- Forwarded message ----------
> From: Orgad Shaneh <orgads@gmail.com>
> Date: Fri, Jan 9, 2009 at 8:20 AM
> Subject: PROBLEM: networking - port 80 not accessible on eth0
> To: linux-kernel@vger.kernel.org
> 
> 
> I have a "VIA Technologies, VIA Technologies, Inc. VT6102 [Rhine-II]"
> NIC connected to an ECI B-FOCuS 270PR ADSL model. I used fedora since
> version 5. On FC5 (using kernel 2.6.15) the modem functioned as a
> router, and it worked fine.
> 
> When I upgraded to FC6 (which was published with kernel 2.6.18) I
> couldn't access any websites. I found out that I can access https, ftp
> etc. but not http. I figured out that for some reason, port 80 was
> blocked. When using VMWare with Windows, I could access websites.
> 
> I configured the modem to be a bridge, and I'm connecting through
> pppoe. This way it works. Anyway, although I can access websites on
> ppp0, I cannot access the modem itself (for configuration), which is
> on eth0 port 80.
> 
> I attached a tcpdump when trying to connect to the modem (the same
> applies for websites, when the modem is configured as a gateway):
> 
> After trying some different distributions (fedora up to 9, ubuntu 8.04
> and 8.10), the problem remains. That's what leads me to the conclusion
> that the problem is in the kernel.

Unlikely so, more likely the router is broken and some kernel TCP settings 
got changed in the newer kernels. I took a short look into the provided 
tcpdump and the modem negotiates tcp connection ok but then goes dead 
silent.

Your could try playing around with tcp_window_scaling sysctl,
most likely the modem has some problem related to it.


-- 
 i.