Re: [tkined] [Q] IP network discovery

Benoit Papillault (papilla@cs.tamu.edu)
Mon, 8 Jun 1998 11:11:40 -0500 (CDT)

On Mon, 8 Jun 1998, Lu Shan wrote:

> Could any tell me another mehod to find the network structure, such
> as using SNMP? You know, in Scotty, it is done by ICMP but many
> networks disallow the ICMP, so I have to choose another way.

First: If you are trying to discover the topology of a network that you
can't access.... it means that perhaps your are doing bad things or your
network has not been properly configured. I do not know many networks
disallowing ICMP.

Second: Many ways exists in fact to discover the topology of a network.
You can use SNMP of course, but it's like ICMP, you must have SNMP agent
nearly everywhere in order to work. You can use UDP/TCP by modifying the
TTL value and waiting for "ICMP time exceeded" packets. You can use
"broadcast UDP", I mean sending a packet to 1.2.3.255 for example. You can
also also try to connect to a well known port (TCP port 7 or UDP port 7).
But, try to make a list of what information is available first, and then
we can discuss on how to use this information to draw a network structure.

As far as I am concerned, I use SNMP on our ATM switches. And it works
great!

Benoit Papillault

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