[hobbit] Re: Conn test problems

Hobbit User in Richmond hobbit at epperson.homelinux.net
Mon Jan 14 19:36:00 CET 2008


The question was "But, I don't understand, how the traceroute works when
the host is up, but when the host is down it times out???" and remarked on
the 30 lines of output in a time out situation.

Although I cited Fedora 8 as the page I was quoting, the traceroute
documentation for most any modern distro contains the explanation about
the 30-hop default and the behavior when the tracerouted host is not
reached.  Sorry if I wasn't clear.

On Mon, January 14, 2008 13:19, Josh Luthman wrote:
> Then I don't see how the FC8 traceroute documentation would be relevant,
> as Michael stated that he can do one from the shell but errors out in
> Hobbit.
>
> Am I missing something here?
>
> On 1/14/08, Hobbit User in Richmond <hobbit at epperson.homelinux.net>
> wrote:
>>
>> Presumably.
>>
>> On Mon, January 14, 2008 12:40, Josh Luthman wrote:
>>> Wouldn't the traceroute used by Hobbit be the same command as the
>> shell?
>>>
>>> On 1/14/08, Hobbit User in Richmond <hobbit at epperson.homelinux.net>
>>> wrote:
>>>>
>>>> Actually, ICMP echo-request and echo-reply packets are almost
>> certainly
>>>> not an issue here, nor is packet-filtering/firewalling.  In current
>>>>  implementations, traceroute by default uses UDP packets to
>>>> abitrary
>> and
>>>> unlikely-to-respond ports, varying the TTL and using the ICMP type
>> 11
>>>> (Time Exceeded) from hops along the way to map the routing path.
>>>>
>>>> The manpage in Fedora 8 says "We start our probes with a ttl of one
>>>>
>> and
>>>> increase by one until we...got to the "host", or hit a max (which
>>>> defaults to  30  hops)".
>>>>
>>>> So, the behavior you're seeing is as documented.  If a firewall
>>>> were
>> an
>>>> issue in sending/receiving the packets used by traceroute, you'd
>>>> see the 30-hop behavior whether the host was up or down.
>>>>
>>>> On Mon, January 14, 2008 11:17, Michael A. Price wrote:
>>>>> Josh,
>>>>>
>>>>>
>>>>>
>>>>> Thanks for helping... The source/destination is on a closed
>>>>> network, sorry...and I don't own the router...
>>>>>
>>>>>
>>>>>
>>>>> But, I don't understand, how the traceroute works when the host
>>>>> is up, but when the host is down it times out???
>>>>>
>>>>>
>>>>>
>>>>> If it works when the host is up, then you would think the ACL on
>>%



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