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(ASCEND) Re: traceroute
>>>Doesn't traceroute use unpredictable random UDP ports, so that traceroute
>>>will automatically fail most of the time if you block all but well known
>>>UDP ports, and fail always if you block all UDP ports?
>>
>>If it does work that way (and that sounds familiar) it would explain why
>>I can't get a filter to work at the P50. It makes the problem at the P75
>>even more baffling.
>There are varying methods of writing traceroute. With that said the method
>which should work all the time is generating ICMP echo request packets with
>the IP header's TTL field set to 1, then 2, then 3, and so on ...
>
>At this point the machine sending the request should be recieving ICMP
>error replies indicating Time Exceeded. Eventually the machine should
>recieve an echo reply indicating the end point, traceroute completed.
>
>This method uses the Network Layer, therefore no UDP/TCP (Transport layer)
>ports come into the equation.
The traceroute I'm using is on NetBSD. It uses a fixed port but, you can tell
it which port to use. It doesn't randomly pick a port or change ports.
In reviewing the traceroute man page I noticed that *** represents a gateway
all of my frontline NetBSD machines are gateways. So I tried tracerouting to
my wifes Win95 machine and it works just fine. So that ends that mystery.
Later,
Paul
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