I am experimenting running some VM's with ipv6 fully disabled in 14.04. Nothing magic but I have no current use for 6 and considering security I figured I would disable it until/unless at some future time I need it. I used a procedure described over at ubuntu forums: To disable ipv6 open /etc/sysctl.conf using any text editor, insert the following lines at the end. net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 If still ipv6 not disabled, then the problem is sysctl.conf still not activated, to solve it you can do the following, Open terminal(Ctrl+Alt+T) and type the following command, sudo sysctl -p You will get result in terminal as, net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 After that if you check, $ cat /proc/sys/net/ipv6/conf/all/disable_ipv6 You will get result as, 1 If you get result as 1, ipv6 disabled successfully. **This was of course really easy to do. I was wondering if there have been any investigations of ways that ipv6 could be maliciously turned backed on remotely? I am still going to leave my firewall imposing blocks on ipv6.