Note that this will only get the addresses of devices on the local Ethernet segment. Not every device will respond to a broadcast ping.

If you want MAC addresses of devices beyond the current Ethernet segment (ie devices that are a router hop or more away) then you will have to get that device to volunteer the MAC address information by using a SNMP query or by installing your own special client software on each of those remote devices.

I think you're going to have to take a different tack on this one. E.g. If you have Cisco Catalysts, you might be able to poll them for their CAM tables, and pull back connected info from that, but the best way to get these addresses is probably by polling a hardware information program resident on each PC.

Net::Address::Ethernet essentially returns the MAC address of physically installed ethernet cards on the machine. Not on other machines. If you can get the program to run on the other machines remotely, then you might be able to poll them all. Do you have some bulk distribution mechanism for the PCs?

Wish I could be more help,
-v

Update: see monarch's post, below, for excellent info about SNMP polling and segment restrictions.

• use Net::DNS to enumerate all the hosts listed
• for each host use Net::ARP to find the addresses of the hosts on the local segment
• If there are hosts on the "other side" of a router, use SNMP to retrieve those from the router or run this program on each segment

The core router in this scenerio would be the only device that is aware of all other devices that are communicating on the network, and it needs to maintain an ARP cache.

You should be able to get the contents of the ARP cache, which contains MAC to IP address mappings, either via SNMP, or via telent.

if you /msg me, I could share a crude but functional perl script that I have that collects this information using Net::Telnet, from an Enterasys router.

That script may not be portable to other routers (or even work on some simple routers or that don't support SNMP). Nor would the router know about MAC's that haven't passed a packet through. But it gave me a good idea.

Assuming this all on a local net and the subnets are not firewalled from each other (ie. no firewall between the local subnets - Firewalls between the local net and the internet would be fine). Just ping each ip in the net. If this is your local net you should have no problem getting the network info.

Then all you have to do poll you local ARP table. Which far easier than wirting a custom router poller.



grep

One dead unjugged rabbit fish later

Your first paragraph makes valid points, but your conclusion :
-- all you have to do poll you local ARP table --
will not work if you have multiple routed subnets, because of proxy ARP.

     "For every complex problem, there is a simple answer ... and it is wrong." --H.L. Mencken