Date: Sun, 11 Apr 2021 14:32:05 -0700 From: Matt Joras <matt.joras@gmail.com> To: Michael Sierchio <kudzu@tenebras.com> Cc: "freebsd-ipfw@freebsd.org" <freebsd-ipfw@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: How to support QUIC with ipfw Message-ID: <CADdTf%2BhJz-ZWMMTvKBW%2B9xOWKRpE7h_k1sga5JVvTY6C_aSkGQ@mail.gmail.com> In-Reply-To: <CAHu1Y72E9xH7Z0ZUK5dh44FekFeRyQbWDmUKG8PaVwRB4J=gWA@mail.gmail.com> References: <CAHu1Y73zGYPmsDu6YhzES0FHkZPpVdxL==h_zoRrjdDr9UTQVQ@mail.gmail.com> <CADdTf%2BgpB6D2pZKOtbs1Kqc0rSOztUR3rnjZCunYxzX-uocFYw@mail.gmail.com> <CAHu1Y72E9xH7Z0ZUK5dh44FekFeRyQbWDmUKG8PaVwRB4J=gWA@mail.gmail.com>
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Hi Michael, On Sun, Apr 11, 2021 at 2:27 PM Michael Sierchio <kudzu@tenebras.com> wrote= : > > On Sun, Apr 11, 2021 at 2:20 PM Matt Joras <mjoras@freebsd.org> wrote: > > > Hi Michael, > > > > On Sun, Apr 11, 2021, 1:25 PM Michael Sierchio <kudzu@tenebras.com> wro= te: > > > >> Hi, all. I noticed my firewall was dropping what seemed to be unsolic= ited > >> UDP connections from Google and Facebook, but this turned out to be QU= IC > >> traffic. The traffic can be initiated by the browser (or other support= ing > >> software) or the server. The problem is that dynamic rules generally > >> don't > >> cut it =E2=80=93 udp traffic here is predominantly NTP and DNS, and th= e 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 initiat= ing > > these connections. I'm not an ipfw user, the best generic firewall stra= tegy > > 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. 4= 43 > > will cover the vast majority of Internet cases, as QUIC is only being u= sed > > 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 =E2= =80=93 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 i= n > a fraction of that time. 30 seconds is forever =E2=80=93 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," Brahm=C4=81 said, "even after ten thousand explanations, a fool i= s no > wiser, but an intelligent person requires only two thousand five hundred.= " > > - The Mah=C4=81bh=C4=81rata Matt Joras
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