[TriLUG] MS Web Host drops connecions from Linux clients

[Brian Phelps]

In summary, disabling RFC1323 in the clients TCP stack covers up the
error in the NAT/router's TCP stack implementation of window_scaling.
This can be done by adding the following in /etc/sysctl.conf:
net.ipv4.tcp_window_scaling=0

and then running:
user at host:~# sysctl -p /etc/sysctl.conf

On Tue, Nov 17, 2009 at 10:56 PM, Brian Phelps <brphelps at ieee.org> wrote:
> I don't know how to repost a twitter conversation but here goes.  It
> reads backwards to forwards, which is annoying, like twitter often is,
> so start at the >>>>>
>
> electronjunkie
>
> @kernelslacker Thanks! I'll tell Abdel to upgrade the NAT for his
> server/domain. Whether he knows what that means is a different story.
>
> kernelslacker
>
> @electronjunkie right. The local side is just performing a perfectly
> valid optimisation that the remote end doesn't handle.
>
> electronjunkie
>
> @kernelslacker Meaning the router on their end I take it.
>
> kernelslacker
>
> @electronjunkie just a hunch. I've seen it before. some crappy routers
> have broken scaling implementations
>
> electronjunkie
>
> @kernelslacker Genius! Why would this server shit itself when
> tcp_window_scaling is enabled? More importantly, what pointed this out
> to you?
>
> kernelslacker
>
> electronjunkie
>
> The last response I had from abdel claimed the problem was me. See
> this interesting thread for why thats not the case:
> http://bit.ly/2wJ95R
>
> @electronjunkie site seems to load fine if you disable the
> tcp_window_scaling sysctl. Looks like crap hardware on the remote end.
>
> electronjunkie
>
> The last response I had from abdel claimed the problem was me. See
> this interesting thread for why thats not the case:
> http://bit.ly/2wJ95R
>
> electronjunkie
>
>>>>>>
> Start here and read up
>
>
> Entire site that timeouts on TCP layer only to Linux Clients
> http://www.keydigital.com/ Contact abdel at keydigital.com and ask to fix
> it.
> On Fri, Nov 6, 2009 at 7:30 AM, Brian Phelps <brphelps at ieee.org> wrote:
>> Haven't heard back at all since I posted his last response.  I sent this to
>> him this morning:
>>
>>>
>>> Abdel,
>>> I was wondering if you happened to figure out what the bug is in your web
>>> server/firewall that is causing problems with non-Microsoft operating
>>> systems.  I have not heard back from you on this and I would like to know
>>> where this issue rests, and if you are still working on a fix for this bug.
>>>
>>> Thanks
>>>
>> On Wed, Nov 4, 2009 at 10:40 AM, John Broome <jbroome at gmail.com> wrote:
>>>
>>> Christopher L Merrill wrote:
>>>>
>>>> Lee Fickenscher wrote:
>>>>>
>>>>> Could it be due to all the asp on their site?
>>>>
>>>> It is certainly not a problem that is inherent to ASP. Most likely,
>>>> something
>>>> is looking at the User-Agent HTTP header and puking when it sees Linux.
>>>> It could be at the firewall, the web server, or deep in their
>>>> application.
>>>
>>> Ubuntu 9.10 here.  Tried site with no modifications and wouldn't load (or
>>> was taking a very long time).
>>>
>>> Changed user agent to IE7 and i got the page up except for the residential
>>> image on the LH side, and the 'government' and 'entertainment' images below.
>>>
>>> so strange.
>>>
>>> Someone wget their entire site, host it on apache and see what happens. :)
>>> --
>>> TriLUG mailing list        : http://www.trilug.org/mailman/listinfo/trilug
>>> TriLUG FAQ  : http://www.trilug.org/wiki/Frequently_Asked_Questions
>>
>>
>