Lookup table with alerts for new devices plugged into network -- as an app.

[raugugliaro]

I am trying to develop an app that will continually monitor my network and alert me when a new, never seen before device is plugged in to the LAN.

My thought is to use Splunk Stream and monitor ARP messages coming across the wire. I would then keep a lookup table updated with all the MAC addresses that have been seen so far and alert when I see a new one.

Any thoughts on this approach?
Any major hurdles I may not have thought of?
Any alternative methods that anyone can think of?

[starcher]

Make a kvstore backed lookup. Where the key is the mac address and has a column for lastSeen. Have a search that updates the lookup.

Use the lookup like this

index=myindex sourcetype=myarp data | lookup macTracker macaddress OUTPUTNEW lastSeen isFound | where isnull(isFound) 

That would give you events where the mac has never been seen before.