VOO in bridge mode with IPv6 (optional: and prefix delegation!)

Despite old threads that can be seen on VOO’s forum, VOO do not seem to use SLAAC in bridge mode (anymore?), but DHCPv6. Also VOO only gives a /64 prefix so you can’t do internal subnets 🙁

Important: my outgoing (WAN) interface directly connected to the VOO modem in bridge mode is enx000ec6ec03b3 . My internal LAN interface is br0 (it’s a bridge between my actual eth0 LAN interface and a WiFi access point using hostapd, but that’s for another day).

This tutorial assumes Ubuntu 18.04:

sudo apt install wide-dhcpv6-client

sudo vi /etc/wide-dhcpv6/dhcp6c.conf

interface enx000ec6ec03b3 {
  send ia-na 1;
  send ia-pd 1;
  request domain-name-servers;
  request domain-name;
  script "/etc/wide-dhcpv6/dhcp6c-script";
};

# Only for prefix delegation
id-assoc pd 1 {
  prefix-interface br0 { #internal facing interface (LAN)
    sla-id 0; # subnet. Combined with ia-pd to configure the subnet for this interface.
    ifid 1; #IP address "postfix". if not set it will use EUI-64 address of the interface. Combined with SLA-ID'd prefix to create full IP address of interface.
    sla-len 0; # Number of prefix bits assigned. Sadly this is 0 with voo... 
    };
  };

  id-assoc na 1 {
  # id-assoc for eth1
};

sudo vi /etc/default/wide-dhcpv6-client

INTERFACES="enx000ec6ec03b3"

sudo service wide-dhcpv6-client restart

At this point you should get an IPv6 address:

enx000ec6ec03b3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 109.89.XXX  netmask 255.255.255.0  broadcast 109.89.XXXX
        inet6 2a02:2788:XXXXXXXXX:8458  prefixlen 128  scopeid 0x0<global>
        inet6 fe80::20e:c6ff:feec:3b3  prefixlen 64  scopeid 0x20<link>
        ether 00:0e:c6:ec:03:b3  txqueuelen 1000  (Ethernet)
        RX packets 1358557038  bytes 1701875645905 (1.7 TB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 648168501  bytes 176987273193 (176.9 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Enable prefix delegation

Actually enable the prefix delegation with radvd:

sudo apt-get install radvd

sudo vi /etc/radvd.conf

interface br0 # LAN interface
{
  AdvManagedFlag off; # no DHCPv6 server here.
  AdvOtherConfigFlag off; # not even for options.
  AdvSendAdvert on;
  AdvDefaultPreference high;
  AdvLinkMTU 1280;
  prefix ::/64 #pick one non-link-local prefix assigned to the interface and start advertising it
  {
    AdvOnLink on;
    AdvAutonomous on;
  };
};

sudo service radvd restart

Some configuration is taken and adapted from https://www.ipcalypse.ca/?p=204

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