Kubuntu

Here’s a quick list of handling the passwords / passphrases for an encrypted disk:

Manual way (persistent till the next boot):

sudo echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6

Persistent way:

Add the kernel parameter to the sysctl.conf:

sysctl -a |grep net.ipv6.conf.all.disable_ipv6

zero: not disabled by default

set it to 1:

sudo echo net.ipv6.conf.all.disable_ipv6 = 1 >> /etc/sysctl.conf
sudo sysctl -p

source: http://ubuntuforums.org/showthread.php?t=1140536