From owner-freebsd-security@FreeBSD.ORG Wed Apr 21 13:41:55 2004 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E4F3616A4CE for ; Wed, 21 Apr 2004 13:41:55 -0700 (PDT) Received: from smtp3b.sentex.ca (smtp3b.sentex.ca [205.211.164.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id A8CD543D49 for ; Wed, 21 Apr 2004 13:41:55 -0700 (PDT) (envelope-from mike@sentex.net) Received: from avscan1.sentex.ca (avscan1.sentex.ca [199.212.134.11]) by smtp3b.sentex.ca (8.12.11/8.12.11) with ESMTP id i3LKftY8079523; Wed, 21 Apr 2004 16:41:55 -0400 (EDT) (envelope-from mike@sentex.net) Received: from lava.sentex.ca (pyroxene.sentex.ca [199.212.134.18]) by avscan1.sentex.ca (8.12.10/8.12.10) with ESMTP id i3LKfs3x095048; Wed, 21 Apr 2004 16:41:54 -0400 (EDT) (envelope-from mike@sentex.net) Received: from simian.sentex.net (simeon.sentex.ca [192.168.43.27]) by lava.sentex.ca (8.12.11/8.12.11) with ESMTP id i3LKfssb045439; Wed, 21 Apr 2004 16:41:54 -0400 (EDT) (envelope-from mike@sentex.net) Message-Id: <6.0.3.0.0.20040421163904.0738d960@209.112.4.2> X-Sender: mdtpop@209.112.4.2 (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 6.0.3.0 Date: Wed, 21 Apr 2004 16:43:48 -0400 To: Charles Swiger From: Mike Tancsa In-Reply-To: <75226E9B-93D3-11D8-90F9-003065ABFD92@mac.com> References: <6.0.3.0.0.20040420125557.06b10d48@209.112.4.2> <6.0.3.0.0.20040420144001.0723ab80@209.112.4.2> <200404201332.40827.dr@kyx.net> <20040421111003.GB19640@lum.celabo.org> <6.0.3.0.0.20040421121715.04547510@209.112.4.2> <20040421165454.GB20049@lum.celabo.org> <6.0.3.0.0.20040421132605.0901bb40@209.112.4.2> <48FCF8AA-93CF-11D8-9C50-000393C94468@sarenet.es> <6.0.3.0.0.20040421161217.05453308@209.112.4.2> <75226E9B-93D3-11D8-90F9-003065ABFD92@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Virus-Scanned: by amavisd-new cc: freebsd-security@freebsd.org Subject: Re: Other possible protection against RST/SYN attacks (was Re: TCP RST attack X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Security issues [members-only posting] List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Apr 2004 20:41:56 -0000 At 04:35 PM 21/04/2004, Charles Swiger wrote: >On Apr 21, 2004, at 4:14 PM, Mike Tancsa wrote: >>What side effects if any are there? Why is the default 64 and not some >>other number like 255... > >The default TTL gets decremented with every hop, which means that a packet >coming in with a TTL of 255 had to be sent by a directly connected >system. [ip_ttl is an octet, so it can't hold a larger TTL value.] A >packet with a TTL of 64 could have been many hops away. Thanks, I realize that. My question is, what unintended consequences might happen if the default is changed to 255 from 64. As one poster said, if a packet generated by that host had a ttl of 255, it would bounce around a lot more if it was trying to reach a host with a bad route somewhere. I am no IP expert, but I have been around long enough to know that these default values get set only after long arduous debates and often there are tradeoffs by raising or lowering a value. I guess I am trying to find that original debate to see what I might be in for by implementing this with my peers who request it. ---Mike