From owner-freebsd-net@freebsd.org Sun Nov 24 16:02:47 2019 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6D3161B31B8 for ; Sun, 24 Nov 2019 16:02:47 +0000 (UTC) (envelope-from vas@sibptus.ru) Received: from admin.sibptus.ru (admin.sibptus.ru [IPv6:2001:19f0:5001:21dc::10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 47LZgn0GK5z49kp for ; Sun, 24 Nov 2019 16:02:43 +0000 (UTC) (envelope-from vas@sibptus.ru) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sibptus.ru; s=20181118; h=In-Reply-To:Message-ID:Subject:To:From:Date; bh=GxdEWvb2bivDelJ4pgqLs51qaygLpkAHzZYHnuwCsH8=; b=cjdGNovkKuverhMYJuifGmSbMA kCd/WKh5PZgmdcpACW0wBHF83Y9X0ILW4DeardOv4sid73y54NJiOsfadpti6kKm/QWAUGp8wFb9r nDl2khsh6Pc96eQbCFF+DYfBJu6UMQPNwUpcL0CJCE4rIMY1bffv/+JJweuTvaJLoTo8=; Received: from vas by admin.sibptus.ru with local (Exim 4.92.3 (FreeBSD)) (envelope-from ) id 1iYuLR-0004VJ-CI for freebsd-net@freebsd.org; Sun, 24 Nov 2019 23:02:41 +0700 Date: Sun, 24 Nov 2019 23:02:41 +0700 From: Victor Sudakov To: freebsd-net@freebsd.org Subject: Re: Several hosts behind a caching resolver Message-ID: <20191124160241.GA17008@admin.sibptus.ru> References: <20191124123451.GA6593@admin.sibptus.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="FL5UXtIhxfXey3p5" Content-Disposition: inline In-Reply-To: X-PGP-Key: http://admin.sibptus.ru/~vas/ X-PGP-Fingerprint: 10E3 1171 1273 E007 C2E9 3532 0DA4 F259 9B5E C634 User-Agent: Mutt/1.12.2 (2019-09-21) X-Rspamd-Queue-Id: 47LZgn0GK5z49kp X-Spamd-Bar: -------- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=sibptus.ru header.s=20181118 header.b=cjdGNovk; dmarc=pass (policy=none) header.from=sibptus.ru; spf=pass (mx1.freebsd.org: domain of vas@sibptus.ru designates 2001:19f0:5001:21dc::10 as permitted sender) smtp.mailfrom=vas@sibptus.ru X-Spamd-Result: default: False [-8.41 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[sibptus.ru:s=20181118]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.20)[multipart/signed,text/plain]; TO_DN_NONE(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; RCPT_COUNT_ONE(0.00)[1]; IP_SCORE(-3.31)[ip: (-9.85), ipnet: 2001:19f0:5000::/38(-4.93), asn: 20473(-1.72), country: US(-0.05)]; DKIM_TRACE(0.00)[sibptus.ru:+]; DMARC_POLICY_ALLOW(-0.50)[sibptus.ru,none]; SIGNED_PGP(-2.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:20473, ipnet:2001:19f0:5000::/38, country:US]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 Nov 2019 16:02:47 -0000 --FL5UXtIhxfXey3p5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Eugene Grosbein wrote: > >=20 > > Several hosts of the local network use a FreeBSD server with BIND or > > local-unbound as a caching resolver. Let's call it "Resolver A." > > Resolver A forwards all queries to another resolver, e.g. 8.8.8.8 or > > some other, let's call it "Resolver B." > >=20 > > Can the operator of Resolver B figure out how many clients there are > > behind Resolver A, or obtain any other information about the hosts on > > the said local network (like their operating system etc)? In other > > words, does Resolver A effectively anonymize the queries, or is some > > information about the internal network leaking? >=20 > No anonymization via unencrypted DNS. >=20 > The query itself reveals most data about clients. Windows OSes send queri= es > for MS-specific domains periodically, Android for its domains, > FreeBSD for pkg.freebsd.org or svn.freebsd.org etc. This is a good point. >=20 > If a there are multiple recursive queries for both of MS/Androis/MacOS-sp= ecific domains, > this means there are many clients behind this local resolver. If there are multiple recursive queries for MS domains only, do you think the operator of Resolver B can tell if there are 10 or 100 MS clients behind Resolver A?=20 --=20 Victor Sudakov, VAS4-RIPE, VAS47-RIPN 2:5005/49@fidonet http://vas.tomsk.ru/ --FL5UXtIhxfXey3p5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJd2qmhAAoJEA2k8lmbXsY0uHYH/194Ilnrq6+5U/W6n4uWZvxy 5XewcN9NyF94f+J72wVgLLcGDQVKu+uJGoL1s6TKvcHrhOrG6zqR59wBAorDdLXA GgrIMzqrmgVjDbdfZi9gqgwa/XSDsOUxfhhdPAaDYdh1ynhXVVvVNuLUZWB78BVc xfnXwnFOz3yzVroQ6xxSi1qcx7XguzR0FcC/zSxS169ho6/T2m4tdb1Vudcd/SBR ddpBG3Oc8CFADkzGwA85y0YFZ5sdB2QZAcIEu5DS75//R4prMz8sLo54NZxld7Ja N9xHRYMZz8NkQMgwwMpkKhSZXj4QHn+NMAKOKF7QQtIu1EWcMY9txLFoSs7lKuw= =UGCT -----END PGP SIGNATURE----- --FL5UXtIhxfXey3p5--