wg(4) listen on a specific interface / address

[Pierre Emeriaud]

Howdy misc@,

I have a fairly complicated setup with lots of interfaces, a couple of
rdomains etc.

I'd like wireguard to listen only on an IP address, not all. But if my
understanding of ifconfig(8) is correct, this doesn't seem possible
currently:

wgport port
             Set the UDP port that the tunnel operates on.  _The interface will
             bind to INADDR_ANY and IN6ADDR_ANY_INIT._

I guess this the reason for the following behaviour?

$ doas ifconfig wg0 wgport 53
ifconfig: SIOCSWG: Address already in use
(the error message is generic I guess - but confusing imho)

$ netstat -natfinet | grep 53
tcp          0      0  127.0.0.1.53           *.*                    LISTEN
udp          0      0  127.0.0.1.53           *.*

$  netstat -T1 -natfinet | grep 53
udp          0      0  127.0.0.1.53           *.*

Is there a way to circumvent this restriction? (is there a reason
behind it maybe?)

thanks
--
pierre