Apparently, I can enable IPv6 in two ways. To test, I first confirm it's not enabled currently.
$ ping6 -c 1 ::1 socket: Address family not supported by protocol I then enable it immediately
$ sudo modprobe ipv6 And ping6 -c 1 ::1 now works. To enable it at boot, I append ipv6 on a single line to /etc/modules, then reboot. However, it's unclear if IPv6 is working now.
$ ping6 -c 1 ::1 connect: Cannot assign requested address N.B. it's a different error to the first one. If informative, the original enabling doesn't work now either.
$ sudo modprobe ipv6 $ ping6 -c 1 ::1 connect: Cannot assign requested address How can I enable IPv6 at boot?
EDIT
Here are the contents of /etc/network/interfaces. It's a static IP.
auto lo iface lo inet loopback iface eth0 inet static address 192.168.1.91 netmask 255.255.255.0 gateway 192.168.1.254 allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface default inet dhcp
192.168.1.91part?dhcpcd. But why IP4 in a question about IP6?