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Date:      Thu, 30 Dec 2021 08:11:00 +0000
From:      Steve O'Hara-Smith <steve@sohara.org>
To:        Michael Sierchio <kudzu@tenebras.com>
Cc:        Kurt Hackenberg <kh@panix.com>, "questions@FreeBSD.org" <questions@freebsd.org>
Subject:   Re: ipfw syntax clarification
Message-ID:  <20211230081100.61aa3ed3f093be97dd8a88d5@sohara.org>
In-Reply-To: <CAHu1Y73puvD4kNDonRYv1sDujVyFh3ncF2OVs9eF35K04O3Jmw@mail.gmail.com>
References:  <8b2c341d-10e6-51a2-0654-86f4394865c7@tundraware.com> <Yc1MxCxJ6Mk6bsdf@rain.home> <CAHu1Y72AgMjVhv_qE1C529NcQbGOi0O-4vRTKNeO2PHK=_t%2BVQ@mail.gmail.com> <20211230070529.9dba7412d68b6c417251058d@sohara.org> <CAHu1Y73puvD4kNDonRYv1sDujVyFh3ncF2OVs9eF35K04O3Jmw@mail.gmail.com>

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On Wed, 29 Dec 2021 23:16:45 -0800
Michael Sierchio <kudzu@tenebras.com> wrote:

> On Wed, Dec 29, 2021 at 11:05 PM Steve O'Hara-Smith <steve@sohara.org>
> wrote:
> 
> > On Wed, 29 Dec 2021 22:32:20 -0800
> > Michael Sierchio <kudzu@tenebras.com> wrote:
> >
> > > Actual location of IP addresses
> > > is something known to the CDNs (Akamai, Cloudflare, AWS, etc.) and is
> > > somewhat proprietary.
> >
> >         Even they only guess based on what they can find out about who
> > controls which block,
> 
> 
> Not so – the location DB used by the large CDNs are empirical, and based
> on RTT of probes which happen all the time from many different geo
> locations. It's pretty easy to infer where the targets are.  These are

	This is what I call guessing based on what they can find out -
nobody tells them where the IP addresses are used and if the fibre running
out of a router near a border happens to cross that border (or the block
of IPs routed down it is spread across that border by a VPN) then there's no
way to tell by RTT measurements and the CDN will guess wrong, which happens
all the time.

--  
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/



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