Re: Scan for "outsider" Pcs on network

On 2 Mar 2006 23:47:59 -0000, dhamm@jackofallgames.com
<dhamm@jackofallgames.com> wrote:
> Is there a way to setup a scan and be notified of an
> intruding pc that is physically plugged into the network?
> When you have an enviroment with a large amount of network
> jacks, it's hard to make sure the ones no longer in use are turned
> off, and that no "visitors" have sat down to use your network
> connections, esp. if you have a large amount of contractors in and
> out. It got me to searching the net, and so far I have found one
> cemmercial product that can do it, but nothing else. Any suggestions?

Just one suggestion:

Write a script that visits all of your switches/routers and gets their
tables of pairs of ports and MAC addresses, then dump them into a
database. Schedule it to do this periodically, say every 5-10 minutes.
Kind of a roll-your-own distributed arpwatch, but it's what I'm doing
by hand for our 6 48-port Cisco switches. Unfortunately, I don't have
the scripting knowledge (Expect? PERL? Something else? SNMP, telnet or
maybe some other query method?) to do this, though I know people have
done it.

And, of course, the obligatory plea to share if you have such a script.

Kurt

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