Truth be told I was baffled by how poor a job Canonical did on Karmic, and this is just one of the bazillion issues that you might encounter, so keep an eye out for others. After much head-scratching and Googling around for answers, I’ve finally managed to setup Karmic to work properly on a regular desktop after a fresh install. The problem, as reported many times on the Ubuntu Forums, is largely based on the fact that the network settings on Karmic were horrible to begin with. At least for Australia. The steps below are absolutely essential before you begin doing anything silly and risk destroying your Karmic installation.
Unless your DNS supports IPv6, chances are you will not be able to do anything that concerns the Internet, such as browsing, IMs, apt-get, or even Software Center. Without these Karmic is pretty much a crippled OS. You need to disable IPv6 in favour of the old IPv4 protocol. To do this, open up /etc/sysctl.conf in your favourite text editor and append this line to the end of the file:
net.ipv6.conf.all.disable_ipv6 = 1
This will disable IPv6 on all applications that you have, such as Pidgin (if you decide to hate Empathy and revert to old Pidgin), Skype, and weather forecasts.
This leaves only the settings on Firefox. Type “about:config” in the address bar, promise that you’ll be careful when prompted, and find a field that says:
and set it to true (you can double click on it).
The steps above will make your applications use IPv4. The last step in configuring the network is to set your machine to use OpenDNS nameservers. Follow the well-documented instructions on the Ubuntu Forums.
Despite these settings, however, I’ve run into trouble trying to download applications from the default Australian server. If this applies to you, you’ll need to configure Software Sources to download from the server that you can download from. Go to System > Administration > Software Sources and on the first tab where it says “Download from:”, select “Other…” and click “Select Best Server”. This will administer a bulkload of tests on all servers that you can reach and find the fastest one that you can download from. Select the server once the tests are done.
And that’s it! Hopefully with these, you will have a uber-fast, Internet-friendly Karmic OS to boot! There might be other things you’ll need to sort out, such as webcam capabilities and enabling Alt+Shift+Tab for windows navigation, but I’ll leave it to you to figure it out.