November 16, 2006
At work, we installed a Linksys RV016 Router + VPN solution. After one of our sys admins setup and turned on the firewall rules, I lost the ability to browse certain sites including slashdot.org, news.yahoo.com, and many others. But, many sites were fine.
I spent some time trying to figure out what the problem was, and realized that with the firewall disabled, everything was ok, but when it was on, I had troubles. Some web pages or images would load part way.
Other things I noticed included:
So, I had tracked it down to a kernel related change somewhere between 2.6.13 through 2.6.17.
I was able to route around the issue by using another point of entry, but that was a temporary fix. Eventually, I sought help on the Fedora mailing list and was pointed to a discussion on lkml (linux kernel mailing list). This led to a fix.
The workaround was to turn off tcp_window_scaling. To test this, do this:
echo 0 > /proc/sys/net/ipv4/tcp_window_scalingand to make it permanent add this line to /etc/sysctl.conf:
net.ipv4.tcp_window_scaling = 0
Comments are currently closed.