From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Yx7iM-0006uP-Ar for bitcoin-development@lists.sourceforge.net; Tue, 26 May 2015 05:47:46 +0000 X-ACL-Warn: Received: from resqmta-po-02v.sys.comcast.net ([96.114.154.161]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:AES128-SHA:128) (Exim 4.76) id 1Yx7iL-0005hW-8z for bitcoin-development@lists.sourceforge.net; Tue, 26 May 2015 05:47:46 +0000 Received: from resomta-po-18v.sys.comcast.net ([96.114.154.242]) by resqmta-po-02v.sys.comcast.net with comcast id YVnd1q0055E3ZMc01VnfGE; Tue, 26 May 2015 05:47:39 +0000 Received: from crushinator.localnet ([IPv6:2601:6:4800:47f:1e4e:1f4d:332c:3bf6]) by resomta-po-18v.sys.comcast.net with comcast id YVne1q00B2JF60R01VneLz; Tue, 26 May 2015 05:47:39 +0000 From: Matt Whitlock To: Peter Todd Date: Tue, 26 May 2015 01:47:37 -0400 Message-ID: <2558087.GVnsa68lBj@crushinator> User-Agent: KMail/4.14.8 (Linux/3.18.11-gentoo; KDE/4.14.8; x86_64; ; ) In-Reply-To: <20150526051546.GB23502@savin.petertodd.org> References: <23111107.dfGN69SrR9@crushinator> <20150526051546.GB23502@savin.petertodd.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Score: 0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [96.114.154.161 listed in list.dnswl.org] 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1Yx7iL-0005hW-8z Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Zero-Conf for Full Node Discovery X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 May 2015 05:47:46 -0000 On Tuesday, 26 May 2015, at 1:15 am, Peter Todd wrote: > On Tue, May 26, 2015 at 12:52:07AM -0400, Matt Whitlock wrote: > > On Monday, 25 May 2015, at 11:48 pm, Jim Phillips wrote: > > > Do any wallets actually do this yet? > > > > Not that I know of, but they do seed their address database via DNS, which you can poison if you control the LAN's DNS resolver. I did this for a Bitcoin-only Wi-Fi network I operated at a remote festival. We had well over a hundred lightweight wallets, all trying to connect to the Bitcoin P2P network over a very bandwidth-constrained Internet link, so I poisoned the DNS and rejected all outbound connection attempts on port 8333, to force all the wallets to connect to a single local full node, which had connectivity to a single remote node over the Internet. Thus, all the lightweight wallets at the festival had Bitcoin network connectivity, but we only needed to backhaul the Bitcoin network's transaction traffic once. > > Interesting! > > What festival was this? The Porcupine Freedom Festival ("PorcFest") in New Hampshire last summer. I strongly suspect that it's the largest gathering of Bitcoin users at any event that is not specifically Bitcoin-themed. There's a lot of overlap between the Bitcoin and liberty communities. PorcFest draws somewhere around 1000-2000 attendees, a solid quarter of whom have Bitcoin wallets on their mobile devices. The backhaul was a 3G cellular Internet connection, and the local Bitcoin node and network router were hosted on a Raspberry Pi with some Netfilter tricks to restrict connectivity. The net result was that all Bitcoin nodes (lightweight and heavyweight) on the local Wi-Fi network were unable to connect to any Bitcoin nodes except for the local node, which they discovered via DNS. I also had provisions in place to allow outbound connectivity to the API servers for Mycelium, Blockchain, and Coinbase wallets, by feeding the DNS resolver's results in real-time into a whitelisting Netfilter rule utilizing IP Sets. For your amusement, here's the graphic for the banner that I had made to advertise the network at the festival (*chuckle*): http://www.mattwhitlock.com/bitcoin_wifi.png