Tuesday, July 22, 2008

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

This post is to ask Linux Experts to answer the puzzle above.

Situation (puzzle):

At home, I use Airtel DSL Broadband connection to access internet.
Hardware used: US Robotics ADSL router modem.

When I connect my Ubuntu notebook to this router modem, I am unable to access the web. Also, surprisingly (rather shockingly) only google owned websites are accessible. e.g. I can access google.com, orkut.com etc. No other site can be accessed. I do not get an error message but the browser does not return any thing.

ssh, ping also do not work.

Solution:
After reading various posts on the web, I learnt that the following command solves the problem. As root, run :
'echo 0 > /proc/sys/net/ipv4/tcp_window_scaling'

After this, all sites are accessible.

Questions for the Experts?
a. What is the issue here?
b. What does the above command do?
Looking for guidance.

P.S. There is nothing wrong with Ubutnu or my notebook setup, Fedora also behaves in the same manner. Other users also faced the same problem at my house.