From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAD5BC48BD3 for ; Wed, 26 Jun 2019 20:20:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2A4F2086D for ; Wed, 26 Jun 2019 20:20:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726431AbfFZUUF convert rfc822-to-8bit (ORCPT ); Wed, 26 Jun 2019 16:20:05 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:41058 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726227AbfFZUUE (ORCPT ); Wed, 26 Jun 2019 16:20:04 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id F32D714DB839E; Wed, 26 Jun 2019 13:20:03 -0700 (PDT) Date: Wed, 26 Jun 2019 13:20:03 -0700 (PDT) Message-Id: <20190626.132003.50827799670386389.davem@davemloft.net> To: dave.taht@gmail.com Cc: netdev@vger.kernel.org, gnu@toad.com Subject: Re: [PATCH net-next 1/1] Allow 0.0.0.0/8 as a valid address range From: David Miller In-Reply-To: <1561223254-13589-2-git-send-email-dave.taht@gmail.com> References: <1561223254-13589-1-git-send-email-dave.taht@gmail.com> <1561223254-13589-2-git-send-email-dave.taht@gmail.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 26 Jun 2019 13:20:04 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Dave Taht Date: Sat, 22 Jun 2019 10:07:34 -0700 > The longstanding prohibition against using 0.0.0.0/8 dates back > to two issues with the early internet. > > There was an interoperability problem with BSD 4.2 in 1984, fixed in > BSD 4.3 in 1986. BSD 4.2 has long since been retired. > > Secondly, addresses of the form 0.x.y.z were initially defined only as > a source address in an ICMP datagram, indicating "node number x.y.z on > this IPv4 network", by nodes that know their address on their local > network, but do not yet know their network prefix, in RFC0792 (page > 19). This usage of 0.x.y.z was later repealed in RFC1122 (section > 3.2.2.7), because the original ICMP-based mechanism for learning the > network prefix was unworkable on many networks such as Ethernet (which > have longer addresses that would not fit into the 24 "node number" > bits). Modern networks use reverse ARP (RFC0903) or BOOTP (RFC0951) > or DHCP (RFC2131) to find their full 32-bit address and CIDR netmask > (and other parameters such as default gateways). 0.x.y.z has had > 16,777,215 addresses in 0.0.0.0/8 space left unused and reserved for > future use, since 1989. > > This patch allows for these 16m new IPv4 addresses to appear within > a box or on the wire. Layer 2 switches don't care. > > 0.0.0.0/32 is still prohibited, of course. > > Signed-off-by: Dave Taht > Signed-off-by: John Gilmore > Acked-by: Toke Høiland-Jørgensen Applied, thanks for following up on this.