[Borealid]

I used RFC1918 addresses as examples only.

10.7.7.7 shouldn't get dropped, because it's supposed to be routed over the VPN. The DHCP server shouldn't be able to cause VPN-bound traffic to be dropped, in my opinion.

As I replied to one of your other comments, I don't think making the attack go from privacy-breach to denial-of-service is "preventing" the attack: you've only partially mitigated it. Full mitigation requires more than the firewall rules you've described.

Said differently, a malicious DHCP server should not be able to denial-of-service traffic within your VPN (or, by selectively pushing routes and then observing the impact on generated traffic, probabalistically determine the IPs with which you're communicating!).

[banister]

Ok. Well, the attack is so rare that i don't believe putting mitigations against the DoS is worth the effort. The mitigations are not that trivial (though it's arguable that just removing the route is kind of trivial, but still not worth it IMO). Better a DoS than a leak in any case :)