Interpreting ping response? (the POD lives??)

JJB Barbish3 at
Tue Apr 13 11:30:56 PDT 2004

Check the archives, I remember seeing the question asked about what
the ping response fields mean about 2+ years ago.

-----Original Message-----
From: owner-freebsd-questions at
[mailto:owner-freebsd-questions at]On Behalf Of Kevin D.
Kinsey, DaleCo, S.P.
Sent: Tuesday, April 13, 2004 1:08 PM
To: freebsd-questions at
Subject: Re: Interpreting ping response? (the POD lives??)

Rob wrote:

> Kevin D. Kinsey, DaleCo, S.P. wrote:
>> can you tell me what might be happening?
>> <kdk at eli> [/home/kdk] [16:25]
>> #sudo ping -s 2048 app
>> PING ( 2048 data bytes
>> 36 bytes from ( Destination Host
>> Unreachable
> This may indicate that the computer is behind a firewall, that
> response
> to ping.

Well, yes; I am somewhat aware of that.  Can you tell
me what the hieroglyphics mean?

 >Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
 >4  5  00 05dc 07bd   0 0000  3f  01 1677

There is, AFAIK, no firewall here; the situation:
the two hosts are on the same private Class C,
and "app" is an application server running an OS that
is neither a *BSD nor M$ stuff.  The crux of the issue
is that "app" responded normally to pings of 56, 128, 256,
512, and 1024 bytes, and then when the 2048 byte packet
was sent, we got this response and the whole shop went
offline, hence the subtitle to this post (the POD lives??)
The shop has problems similar to this rather frequently,
and my next step is probably to put an old-style hub on
the wire right next to "app" with a lil' FBSD box that I
can run ethereal or tcpdump on, but it may not do me
much good until I can learn how to read this stuff a little

I want to blame the OS or the app vendor, or the M$
Windows client that connects to it.  Fortunately for us,
the only FreeBSD machine in this scenario is the one doing
the attacking.  I'll probably be hunting for clues (and
harping the blues) elsewhere, as it doesn't appear to be
related to FreeBSD at all, but as I frequent this list
I thought I might gain a bit of insight by asking.

Thanks for your response :-)

Kevin Kinsey
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