Fast command line option
If you want to force the apt-get to use IPv4 or IPv6 only one time, follow these steps. This feature is available after the 0.9.7.9~exp1 version of apt-get. First, make sure your version of apt-get is newer than 0.9.7.9~exp1 by running the following command:
apt-get --version
The result will be something like this:
apt 1.0.1ubuntu2 for amd64 compiled on Oct 28 2014 20:55:14
If the version checks out, then you can force IPv4 with:
apt-get -o Acquire::ForceIPv4=true update
or IPv6:
apt-get -o Acquire::ForceIPv6=true update
This will update the repositories resolving the URLs in sources.list to IPv4 only.
Persistent option
To make the setting persistent, create the file 99force-ipv4 in /etc/apt/apt.conf.d/.
sudoedit /etc/apt/apt.conf.d/99force-ipv4
Put the following contents in it:
Acquire::ForceIPv4 "true";
Save the file, and you're good to go. If you want to force IPv6 instead, change the 4 to 6 in the file name and settings. To choose between one of them, test with the fast method and see which works better.
