Re: Only some websites will open - Ubuntu

On Fri, 08 Jun 2007 13:43:55 +0100, The Natural Philosopher wrote:

>echo 0 > /proc/sys/net/ipv4/tcp_default_win_scale

root-at-deltree:~# uname -r
2.6.21.3a
root-at-deltree:~# echo 0 > /proc/sys/net/ipv4/tcp_default_win_scale
-bash: /proc/sys/net/ipv4/tcp_default_win_scale: No such file or directory

Grant.

kubismo-at-gmail.com wrote:
> On Jun 8, 8:43 am, The Natural Philosopher wrote:
>
>> problem. If you're unsure whether this is the problem you are having,
>> you can test it by executing:
>>
>> echo 0 > /proc/sys/net/ipv4/tcp_default_win_scale
>>
>> To make the setting permanent, edit /etc/sysctl.conf and add:
>>
>> net.ipv4.tcp_default_win_scale = 0
>
> I am indeed running a recent kernel (Linux ubuntu 2.6.20-16-generic #2
> SMP Wed May 23 01:46:23 UTC 2007 i686 GNU/Linux) so perhaps this might
> be the problem, but unfortunately this didn't fix it. I don't seem to
> have a tcp_default_win_scale file on my system and editing the
> sysctl.conf (with a reboot) didn't seem to change anything.
>
>
Well i'd say that is 'strong hints' that that is the problem.

another ubuntu specific fix is this one

"There are 2 quick fixes. First you can simply turn off windows scaling
all together by doing

echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

but that limits your window to 64k. Or you can limit the size of your
TCP buffers back to pre 2.6.17 kernel values which means a wscale value
of about 2 is used which is acceptable to most broken routers.

echo "4096 16384 131072" > /proc/sys/net/ipv4/tcp_wmem
echo "4096 87380 174760" > /proc/sys/net/ipv4/tcp_rmem

The original values would have had 4MB in the last column above which is
what was allowing these massive windows."

It seems that different kernels call things by different names..

However not sure how to translate the above to a boot time setup..

Perhaps in sysctl.conf try

net.ipv4.tcp_window_scaling = 0

and reboot?

Yipppeeee!

That did it (i.e. editing the .conf file with reboot - it wouldn't let
me run the echo "4096..." etc)

Thanks a million!



On Jun 8, 10:07 am, The Natural Philosopher wrote:

> echo "4096 16384 131072" > /proc/sys/net/ipv4/tcp_wmem
> echo "4096 87380 174760" > /proc/sys/net/ipv4/tcp_rmem
>
> The original values would have had 4MB in the last column above which is
> what was allowing these massive windows."
>
> It seems that different kernels call things by different names..
>
> However not sure how to translate the above to a boot time setup..
>
> Perhaps in sysctl.conf try
>
> net.ipv4.tcp_window_scaling = 0
>
> and reboot?

kubismo-at-gmail.com wrote:
> Yipppeeee!
>
> That did it (i.e. editing the .conf file with reboot - it wouldn't let
> me run the echo "4096..." etc)
>
> Thanks a million!
>
>

But did it FIX THE PROBLEM?


>
> On Jun 8, 10:07 am, The Natural Philosopher wrote:
>
>> echo "4096 16384 131072" > /proc/sys/net/ipv4/tcp_wmem
>> echo "4096 87380 174760" > /proc/sys/net/ipv4/tcp_rmem
>>
>> The original values would have had 4MB in the last column above which is
>> what was allowing these massive windows."
>>
>> It seems that different kernels call things by different names..
>>
>> However not sure how to translate the above to a boot time setup..
>>
>> Perhaps in sysctl.conf try
>>
>> net.ipv4.tcp_window_scaling = 0
>>
>> and reboot?
>
>

Well, there might still be a wonky router somewhere up the line but
since I'm the only person on our little community network with an
issue it's probably good enough for us.

Whether this counts as a Ubuntu bug, is another question. Since other
versions of Linux and Windows XP have no problems with our network,
I'd say that yeah maybe there is some kind of flaw in this release of
Ubuntu. I'm reporting it as a bug on Launchpad (#119338 if anyone's
interested).


On Jun 8, 10:41 am, The Natural Philosopher wrote:

>
> But did it FIX THE PROBLEM?

On Fri, 08 Jun 2007 06:37:52 -0700, kubismo wrote:

> On Jun 8, 8:43 am, The Natural Philosopher wrote:
>
>> problem. If you're unsure whether this is the problem you are having,
>> you can test it by executing:
>>
>> echo 0 > /proc/sys/net/ipv4/tcp_default_win_scale
>
>>
>> To make the setting permanent, edit /etc/sysctl.conf and add:
>>
>> net.ipv4.tcp_default_win_scale = 0
>
> I am indeed running a recent kernel (Linux ubuntu 2.6.20-16-generic #2
> SMP Wed May 23 01:46:23 UTC 2007 i686 GNU/Linux) so perhaps this might
> be the problem, but unfortunately this didn't fix it. I don't seem to
> have a tcp_default_win_scale file on my system and editing the
> sysctl.conf (with a reboot) didn't seem to change anything.

I am running FC6 kernel 2.6.20-1.2952.fc6 and had the same problem
reaching my home site. Following the instructions I changed
/proc/sys/net/ipv4/tcp_win_scale=1 back to =0 by hand and now all works ok.

Many thanks for the info greatly appreciated

Keith

The Natural Philosopher wrote:
> Well i'd say that is 'strong hints' that that is the problem.


YES!!! You're right. It works for me on Fedora 6 (I can't test it on
Kubuntu 7.04 right now). Thank you very much. I couldn't find the answer
anywhere since Fedora 6 came out.

Though I still don't understand why with two computers with Kubuntu 7.04
in the same network one of them had the problem and not the other. Maybe
the network adapter driver modifying the window scaling?.


> another ubuntu specific fix is this one


As I said, it fixed it on Fedora 6, so it's not a Ubuntu specific solution.


> "There are 2 quick fixes. First you can simply turn off windows scaling
> all together by doing
>
> echo 0 > /proc/sys/net/ipv4/tcp_window_scaling



I couldn't do it this way on the Live CD, even with sudo. It gave me
permissions problems. Why?


Cheers,
//.arce

Just to add a little more to this, when I submitted my bug I got a
message saying it was a dupe which lead me to this page

https://bugs.launchpad.net/ubuntu/+s....17/+bug/59331

kubismo-at-gmail.com wrote:
> Well, there might still be a wonky router somewhere up the line but
> since I'm the only person on our little community network with an
> issue it's probably good enough for us.
>
> Whether this counts as a Ubuntu bug, is another question. Since other
> versions of Linux and Windows XP have no problems with our network,
> I'd say that yeah maybe there is some kind of flaw in this release of
> Ubuntu. I'm reporting it as a bug on Launchpad (#119338 if anyone's
> interested).
>
>
Oh..the article I quoted was specific.

The problem is that Linux saw fit to invoke a dusty corner of the TCP/IP
spec, quite correctly.

Sadly half the routers out there had never contemplated its use..

What the Linux kernel author SHOULD do in my opinion is to do what the
original InterOp was for..check his implementation against all known
routers, and if they are broke, which they are, patch his code to work
around them.

He won't of course, because He Is Right And They Are Wrong.

However its open source, and some damned sysadmin will get tired of
patching every server and come up with a code fix that will end up in
the next release.

> On Jun 8, 10:41 am, The Natural Philosopher wrote:
>
>> But did it FIX THE PROBLEM?
>

kubismo-at-gmail.com wrote:
> Just to add a little more to this, when I submitted my bug I got a
> message saying it was a dupe which lead me to this page
>
> https://bugs.launchpad.net/ubuntu/+s....17/+bug/59331
>
>

Well I am pleased that the discussion finally narrowed it down to what
it was likely to be, and it turned out it was a known problem with a
simple enough workaround.

Of course speed will be reduced on gigabit LAN traffic, but thats the
price you pay sometimes.