Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1VALRs-0003OP-Bw for bitcoin-development@lists.sourceforge.net; Fri, 16 Aug 2013 14:56:20 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.50 as permitted sender) client-ip=209.85.215.50; envelope-from=gmaxwell@gmail.com; helo=mail-la0-f50.google.com; Received: from mail-la0-f50.google.com ([209.85.215.50]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1VALRr-0002IU-HG for bitcoin-development@lists.sourceforge.net; Fri, 16 Aug 2013 14:56:20 +0000 Received: by mail-la0-f50.google.com with SMTP id ek20so1561534lab.37 for ; Fri, 16 Aug 2013 07:56:12 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.152.3.42 with SMTP id 10mr1649337laz.22.1376664972822; Fri, 16 Aug 2013 07:56:12 -0700 (PDT) Received: by 10.112.89.72 with HTTP; Fri, 16 Aug 2013 07:56:12 -0700 (PDT) In-Reply-To: References: Date: Fri, 16 Aug 2013 07:56:12 -0700 Message-ID: From: Gregory Maxwell To: "Warren Togami Jr." Content-Type: text/plain; charset=UTF-8 X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (gmaxwell[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 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: 1VALRr-0002IU-HG Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Gavin's post-0.9 TODO list... 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: Fri, 16 Aug 2013 14:56:20 -0000 On Fri, Aug 16, 2013 at 6:41 AM, Warren Togami Jr. wrote: > If you disallow the same IP and/or subnet from establishing too many TCP > connections with your node, [...] > has almost zero drawbacks, There are whole countries who access the internet from single IP addresses. There are major institution with hundreds or even thousands of hosts that could be running Bitcoin who are visible to the public internet as a single IP address (/single subnet). Most tor traffic exits to the internet from a dozen of the largest exits, common local-network configurations have people addnode-ing local hosts from many systems on a subnet, etc. Prioritizing the availability of inbound slots based on source IP is reasonable and prudent, but it does not have almost zero drawbacks. Outright limiting is even worse. As a protective measure its also neigh useless for IPv6 connected hosts and hidden service hosts. It's also ineffective at attacks which exhaust your memory, cpu, IO, or bandwidth without trying to exhaust your sockets. So I am not opposed to prioritizing based on it (e.g. when full pick an inbound connection to drop based on criteria which includes network mask commonality), but I would not want to block completely based on this.