Hi Michael, On Sun, Apr 11, 2021 at 2:27 PM Michael Sierchio <ku...@tenebras.com> wrote: > > On Sun, Apr 11, 2021 at 2:20 PM Matt Joras <mjo...@freebsd.org> wrote: > > > Hi Michael, > > > > On Sun, Apr 11, 2021, 1:25 PM Michael Sierchio <ku...@tenebras.com> wrote: > > > >> Hi, all. I noticed my firewall was dropping what seemed to be unsolicited > >> UDP connections from Google and Facebook, but this turned out to be QUIC > >> traffic. The traffic can be initiated by the browser (or other supporting > >> software) or the server. The problem is that dynamic rules generally > >> don't > >> cut it – udp traffic here is predominantly NTP and DNS, and the dynamic > >> rule lifetime for UDP is very short (3-6 s). And of course they don't > >> work > >> at all for traffic initiated by the server side. > >> > > > > QUIC connections aren't initiated by the server. The browser is initiating > > these connections. I'm not an ipfw user, the best generic firewall strategy > > would be to have some sort of flow tracking for ~30s for UDP flows > > associated with tuples originating on the client for remote port 443. 443 > > will cover the vast majority of Internet cases, as QUIC is only being used > > at scale for HTTP/3. > > > > > Hej, Matt. Thanks. That's a solution that occurred to me, but it means a > ton of dynamic rules will get instantiated for ephemeral DNS lookups – 3 > seconds is a very long time for a conversation with a DNS server, because > it has probably recursed from the root zone all the way to the A record in > a fraction of that time. 30 seconds is forever – well, since UDP doesn't > have an analogue to a FIN or RST, the rule doesn't go away when the > conversation does.
Is it not possible to do the dynamic rule instantiation for select UDP ports, i.e. 443? That may cause issues if DNS-over-HTTP/3 becomes a thing, but at least for now it would exclude DNS. > > I'll get some metrics on it. Thanks again. > > > -- > > "Well," Brahmā said, "even after ten thousand explanations, a fool is no > wiser, but an intelligent person requires only two thousand five hundred." > > - The Mahābhārata Matt Joras _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
