How to find MAC addresses on network?

[Jason Crain]

Chris G wrote:
> Is there a (reasonably) straightforward way of finding the MAC
> addresses of systems (well, strictly, interfaces) on a network?
> 
> arping works for some but not all of my hardware, presumably some
> things (like my HP printer) don't respond to arping.  What can I use
> to find the MAC address of the printer?
> 

arp-scan works well:

~$ sudo arp-scan 192.168.0.0/24
Interface: eth0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.6 with 256 hosts 
(http://www.nta-monitor.com/tools/arp-scan/)
192.168.0.3     00:12:17:44:0a:3b       Cisco-Linksys, LLC
192.168.0.133   00:1f:d0:8d:64:24       (Unknown)