From owner-freebsd-net@FreeBSD.ORG Sat Jul 3 00:12:05 2004 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CAF0A16A4CE for ; Sat, 3 Jul 2004 00:12:05 +0000 (GMT) Received: from relay.pair.com (relay.pair.com [209.68.1.20]) by mx1.FreeBSD.org (Postfix) with SMTP id 3997143D41 for ; Sat, 3 Jul 2004 00:12:05 +0000 (GMT) (envelope-from silby@silby.com) Received: (qmail 58446 invoked from network); 3 Jul 2004 00:11:56 -0000 Received: from niwun.pair.com (HELO localhost) (209.68.2.70) by relay.pair.com with SMTP; 3 Jul 2004 00:11:56 -0000 X-pair-Authenticated: 209.68.2.70 Date: Fri, 2 Jul 2004 19:11:55 -0500 (CDT) From: Mike Silbersack To: David Malone In-Reply-To: <200406291413.ab33924@salmon.maths.tcd.ie> Message-ID: <20040702190516.Q65076@odysseus.silby.com> References: <200406291413.ab33924@salmon.maths.tcd.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed cc: freebsd-net@freebsd.org Subject: Re: RANDOM_IP_ID sysctl? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 03 Jul 2004 00:12:05 -0000 On Tue, 29 Jun 2004, David Malone wrote: > It seems to me that RANDOM_IP_ID might be better as a sysctl rather > than a kernel option. Would anyone mind if I changed this? > > David. I'd rather see a sysctl that switched between incremental frag IDs and arc4random() based IDs, followed by the removal of RANDOM_IP_ID. For more info, see: http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/netinet/ip_id.c (I think we're still using the old code that's collision prone.) Given that we're in a 16-bit space anyway, it's simpler to just use arc4random and stop pretending that we can avoid collisions. Remember: An IP ID collision is equivalent to a packet being lost; this is not a big deal. Mike "Silby" Silbersack