Monday, August 3, 2009

Easy PCLinuxOS Solution to Weird HTTPS Annoyance in Centos 5.3

pclinuxos tweak on centos to fix https annoyance

Background:
Couple of months back I had installed PCLinuxOS 2009.1 in ONSIS, Noida. For almost 2 months after installation ONSISians had a joyride with PCLinuxOS. But slowly PCLinuxOS started to hang after some hours of working, and afterwards hangs became frequent. And finally we gave up on it and moved to Centos 5.3. We had to compromise on usability for the sake of stability.

The Problem:
Though Centos 5.3 worked like a charm it gave rise to some weird problems, the most annoying of which was the inability to open any HTTPS websites. On the same network Windows XP and PCLinuxOS had no problem opening https websites but Centos did not move. We scanned the firewall settings, browser setting; visited several forums (fedora, rhel, mandriva, pclinuxos, etc.) but to no avail. We checked for 443 port, there was no blockage there. We checked for konqueror and firefox setting, there was nothing wrong either.

The Solution:
Suddenly something brilliant stuck to your System Admin Tarun Pandey's mind. He tried to dig deep into the pclinuxos network settings (which opens https sites flawlessly) and came up with a big point – PCLinuxOS advanced network setting has disabled tcp_window_scaling. He did the same on Centos 5.3 by putting an extra line net.ipv4.tcp_window_scaling=0 at end of /etc/sysctl.conf file, and lo, after rebooting Centos opened up all the https websites.

The Question:
Though the problem was solved. I am interested to know how disabling tcp_window_scaling solved this weird https problem. So far, I have no cue.

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