How To Disable IPv6 In Ubuntu 9.10 Karmic Koala

The easy way: if you use Firefox, you can just disable IPv6 in Firefox. Type about:config and search for:

network.dns.disableIPv6

and toggle it to TRUE.

The 'hard' way: disable IPv6 system-wide: you must edit the GRUB. Be very careful, and edit it correctly or else your system might not boot!

1. Open a terminal and type the following command (if you don't use Gedit, replace it with your text editor such as Kate, etc).

sudo gedit /etc/default/grub

2. And search for this:

GRUB_CMDLINE_LINUX

Modify it so it looks like this:

GRUB_CMDLINE_LINUX="ipv6.disable=1"

3. Now, let's update the GRUB:

sudo update-grub2

Or if you don't use GRUB 2, do:

sudo update-grub

4. And finally, restart your system.