[CentOS] NMAP - reveal MAC address

Thu May 8 20:00:52 UTC 2008
Flaherty, Patrick <pflaherty at wsi.com>

> >> The main function of a switch is to keep irrelevant 
> packets away from
> >> hosts, but packets to unknown (to the switch) hosts get sent 
> >> everywhere, just like a Hub would do.
> >>
> >
> >yes - thanks all, it appears its a cross network 'issue'
> >
> >thanks
> If you're trying to get a MAC address across your own switches, you
> could try walking the switch's forwarding table (assuming SNMP
> availability).  It's a cheesy way but works!

If you have CDP enabled switches, try one of the magic auto discovery
programs out there. I use  NetDisco (netdisco.org), but there is also
nTop and a ton of commercial apps. CDP is cisco, but all the major
vendors have a similar protocol. NetDisco has a web interface listing
what macs/vlans showed up on what ports, duplex mismatches, and all your
switch os/patch levels.