FreeBSD if_wg POINTTOPOINT and MULTICAST behaviour

Toke Høiland-Jørgensen toke at
Fri Apr 16 09:35:46 UTC 2021

Stefan Haller <stefan.haller at> writes:

> Hi Jason,
> On Thu, Apr 15, 2021 at 06:05:03PM -0600, Jason A. Donenfeld wrote:
>> I spent the day playing around with bird and babel and sorted out
>> FreeBSD's v6 situation. Basically, ff00::/8 addresses are treated
>> differently, and they're blocked unless the interface sets
>> IFF_MULTICAST. So I've committed
>> to do this.
> That is also what I observed. Without IFF_MULTICAST I see the following
> error in bird's log:
> bird[8045]: babel1: Socket error: IPV6_MULTICAST_IF: Can't assign requested address
> bird[8045]: babel1: Cannot open socket for wg1
>> Stefan - please let me know if those work for you. In my testing thus
>> far, things seem to work for me.
> After applying Toke's patch for bird and your Wireguard patch in
> a7a84a17faf784 everything is working as before (with minor config
> changes).
> Just for the record, my previous configuration looked like this (using
> POINTTOPOINT interfaces, I use ifconfig to set the peer address):
>> [Interface]
>> ...
>> Address = fe80::5/64
>> PostUp = ifconfig %i inet
> My new configuration without POINTTOPOINT, but only a single peer
> directly attached to other side of the wg tunnel:
>> [Interface]
>> ...
>> Address =, fe80::5/64
>> PostUp = route add -iface %i
> So for me everything works as expected again. A big thanks to all of you for
> figuring out what was going wrong and getting it fixed so quickly.

Great! You're welcome :)


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