Date: Sun, 18 Apr 2004 12:37:04 -0700 From: Stephen Fisher <StephenTFisher@yahoo.com> To: freebsd-questions@freebsd.org Subject: Re: Interpreting ping response? (the POD lives??) Message-ID: <20040418193704.GA50421@ux1sjc1.calicat.org> In-Reply-To: <407BFD3D.6030206@daleco.biz> References: <407BFD3D.6030206@daleco.biz>
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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.... > <kdk@eli> [/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
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