How to disable ipv6 in ubuntu

here is an small howto

Before disabling



and after




$ip addr show lo
1: lo: mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo


see no ipv6