Ipv6 - Connect : Network is unreachable

How to know if IPv6 is configured and working on ubuntu?

Run the command:

[ -f /proc/net/if_inet6 ] && echo 'IPv6 OK' || echo 'No IPv6'

If the output is

IPv6 OK

Then your system can work with IPV6.

Now run the command:

lsmod | grep -qw ipv6 && echo "IPv6 kernel driver loaded and configured." || echo "IPv6 not configured and/or driver loaded on the system."

If the output is:

IPv6 kernel driver loaded and configured.

This means the IPV6 is configured and you can use it but if(and this is your case from comment above) the answer is

IPv6 not configured and/or driver loaded on the system.

this means IPV6 is not configured in your system, and for that you can't use IPV6 yet.

How to enable IPV6 in Ubuntu

Run this command:

sudo modprobe ipv6

Now test if this works:

lsmod | grep ipv6

The outpu should be like :

ipv6                  XXXX xX

source and more information :http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/systemcheck-kernel.html