OSPF Output filter mot filtering /32 Networks

Hi Gang

I have a bit a strange issue with OSPF and google did not spit out any obvious soltuion.

On a mikrotik (7.22.2), I have two WireGuard instances. One running witn IP 192.168.10.0/24 another one with 192.168.11.0/24

An OSPF Instance is set-up to redistribute connected + ospf and has one configured static ptmp peer (over wireguard) to which I want to announce the local networks.

On that ptmp peer i receive two routes which I don’t understand:

  • 192.168.10.1/32
  • 192.168.11.1/32

Both /32 routed do not exist on the originating mikrotik.

I built an output filter: if (dst-len == 32 && afi ipv4) {reject;}

This does not remove those routes from being announced.

if (dst in 192.168.0.0/16) {reject;}

Also not removing the routes.

When I manually add a 192.168.12.1/32 route it is being removed by the filter.

On the receiving mikrotik, I can remove the /32 routes with an input filter, but my goal is not to announce them at all.

Is there anything (like using a static ptmp peer) preventing those routes from being output filtered?

Update: Realized that Multicast works over Wireguard (if you add that range to allowed ip’s) - this solved the issue. So I guess in ptp the /32 of both endpoints get forcefully announced without means to block.

-Benoit-