From owner-freebsd-hackers Fri Aug 31 17:26:54 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from asdf.dk (electropop.netgroup.dk [195.41.198.44]) by hub.freebsd.org (Postfix) with ESMTP id 045E837B401 for ; Fri, 31 Aug 2001 17:26:52 -0700 (PDT) Received: from asdf.dk (port18.ds1-noe.adsl.cybercity.dk [212.242.52.19]) by asdf.dk (Postfix) with ESMTP id 52EBAB7 for ; Sat, 1 Sep 2001 02:26:50 +0200 (CEST) Message-ID: <3B902B68.E15DFA3E@asdf.dk> Date: Sat, 01 Sep 2001 02:27:20 +0200 From: Hroi Sigurdsson X-Mailer: Mozilla 4.78 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: freebsd-hackers@freebsd.org Subject: Re: Should URL's be pervasive. References: <56710000.999257324@lobster.originative.co.uk> <20010831154300.B27173@dragon.nuxi.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG David O'Brien wrote: > Do you know how traceroute works?? For one, the destination host cannot > be listening on the port used. And you know that each progressive > traceroute packet sent out bumps the destination port by one, to help > trace the ICMP "time exceeded" / "port unreachable" responses. Only UDP traceroute requires that the port not be listened to (otherwise you wouldn't get a packet back). If using TCP you will get a packet back (RST/SYNACK/ICMP-portunreachable etc) whether the port is open or not. In theory at least.. -- Hroi Sigurdsson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message