From owner-freebsd-questions@FreeBSD.ORG Sun Apr 18 12:37:05 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8FC8316A4CE for ; Sun, 18 Apr 2004 12:37:05 -0700 (PDT) Received: from ux1sjc1.calicat.org (ux1sjc1.calicat.org [69.36.243.12]) by mx1.FreeBSD.org (Postfix) with SMTP id 61C1843D31 for ; Sun, 18 Apr 2004 12:37:05 -0700 (PDT) (envelope-from sfisher@ux1sjc1.calicat.org) Received: (qmail 50714 invoked by uid 1001); 18 Apr 2004 19:37:04 -0000 Date: Sun, 18 Apr 2004 12:37:04 -0700 From: Stephen Fisher To: freebsd-questions@freebsd.org Message-ID: <20040418193704.GA50421@ux1sjc1.calicat.org> References: <407BFD3D.6030206@daleco.biz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <407BFD3D.6030206@daleco.biz> User-Agent: Mutt/1.4.1i Subject: Re: Interpreting ping response? (the POD lives??) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 18 Apr 2004 19:37:05 -0000 On Tue, Apr 13, 2004 at 09:46:21AM -0500, Kevin D. Kinsey, DaleCo, S.P. wrote: > Can anyone help me interpret the following output? I read the ping > manpage, but came to the end before I learned much that helps me > here.... > [/home/kdk] [16:25] > #sudo ping -s 2048 app > PING app.southuni.com (192.168.0.80): 2048 data bytes > 36 bytes from app.southuni.com (192.168.0.80): Destination Host Unreachable > Vr HL TOS Len ID Flg off TTL Pro cks Src Dst > 4 5 00 05dc 07bd 0 0000 3f 01 1677 192.168.0.2 192.168.0.80 The device (router?) is sending a host unreachable message which can be for a variety of reasons, the most common being that there is no route available to the destination. What address are you pinging from though? You are trying to ping with a packet size of 2048 bytes (-s) but the MTU of Ethernet is 1500 bytes. You don't need to understand the information below to troubleshoot this but here is an explanation anyway :) It's just a dump of the IP packet headers that came back in the destination host unreachable message: Vr 4 IP version 4 HL 5 Packet header length TOS 0 Type of Service: Routine traffic Len 05dc Packet length in hex (1500 bytes) ID 07bd Identification - unique number to tell the ICMP packets apart Flg 0 Flags - 3 bits: 0 (reserved), 0 (fragment if necessary), 0 (last fragment) Off 0000 Fragment offset (not used since it is not a fragment) TTL 3f Time to Live in hex (63 hops) - number of hops before packet is discarded Pro 01 IP protocol type (01 = ICMP, what ping uses) Cks 1677 Packet header checksum Src Source address that sent the "host unreachable" message Dst Recipient of the "host unreachable" message - your machine -- Stephen Fisher San Jose, CA USA