configuration/advertising a prefix difficulties, another method, forwarding, accept_ra

[Mikaela]

I was having difficulties with the current instructions, until I started advertising router address instead of the prefix. To adjust the example config:

interface eth0
{
     AdvSendAdvert on;
     prefix 300:1111:2222:3333::1/64 {
         AdvOnLink on;
         AdvRouterAddr on;
         AdvAutonomous on;
     };
     route 200::/7 {};
};

I added 1 to the end of the prefix and told radvd that it's the router address instead of prefix by adding AdvRouterAddr on;.

Other potential issues:

• forwarding has to be allowed in the firewall, in ufw this is in/etc/default/ufw which should say DEFAULT_FORWARD_POLICY="ACCEPT"
• when forwarding is enabled, Linux stops accepting router announcements potentially breaking clearnet IPv6 unless explicitly configured to do otherwise sysctl -w net.ipv6.conf.all.accept_ra=2

[Mikaela]

On another machine I cannot reproduce the config in the original issue, but just by adding AdvRouterAddr on; (to the example) I got it to work.

Fun thing to note is that the interface address doesn't need to be added as accept_ra=2 seems to autoconfigure that too 😁