Making Atheros 9k usable on Ubuntu 11.04

This is a quick post to document a problem that I have had with my atheros WiFi card on Ubuntu 11.04 (Natty Narwhal). I installed Natty on my servers as soon as it became available and the installation was a breeze. All my servers were up and running in no time.

I delayed the Natty upgrade a bit on my laptop because it contains way more custom repositories than my servers, and I did not know if anything was going to break after the upgrade. I finally took the plunge this afternoon and made the upgrade.

The first thing I noticed was that my Internet connection slowed to a crawl. Most of my requests timed out and I could not even browse my local network. A bit of Googling solved the problem: apparently, the new kernel and atheros driver did not play nice with hardware encryption.

So I modified the atheros config file to disable hardware encryption at module load time. Here is the script I used

sudo -s

echo "options ath9k nohwcrypt=1" > /etc/modprobe.d/ath9k.conf

reboot

That’s it. After the reboot, my WiFi connection worked perfectly. Hope this post helps anyone who is having similar problems.