Screenshot 11:3:12 8:54 PM

Did you know that the first six characters of a MAC address will tell you the manufacturer of the device?  (or at least who made the network interface)

Example:  The MAC address of my Control4 HC-300 is 00:0F:FF:13:06:4E.

Go to this website and enter 00:0F:FF and see what it tells you.

 

This isn’t foolproof…. for example, while almost every Control4 device I’ve worked with has had a 00:0F:FF MAC address prefix, the HC-1000 was manufactured by a different company and has a different MAC prefix.  But almost all of the time I can look at a list of MAC addresses on a network and instantly see which ones are Control4 devices.

Also, most PCs and DVRs won’t have a MAC prefix that matches up to the name on the outside of the box.  If you search that site for the MAC from a Digimerge DVR, you’ll end up with whoever made the Ethernet interface.  Still, it’s helpful to know.  Sometimes you know “a device” is “at that IP address”, but you don’t know what it is or WHERE it is (we found a Linksys router hooked up and stuffed behind a cash register that ‘no one knew about’…).  Figuring out the manufacturer by the MAC can help to identify what it is.

At that same job with the Linksys behind the cash register we were having trouble figuring out what IP’s the credit card machines were getting.  A quick search revealed that the manufacturer for that MAC address was called “something-or-other Payment Services”.  Took a guess that it was the CC machines and we were right.  We were then able to give them the static DHCP reservations we wanted.

How do I find a MAC address?

On a Mac

One quick way is this… ping the IP address of the device (this forces your computer to learn the MAC address of the device).  Stop the ping from repeating forever by hitting control-C.  Next, type in “arp” followed by a space and the IP address that you just pinged.  It should look something like this:

The “arp” command stands for Address Resolution Protocol.  Whenever someone is talking about ARP, they are talking about the conversion of an IP address to a MAC address or vice-versa.  This is actually a HUGE concept in networking, but you can do a lot without even knowing it exists.

note – On a Mac, typing “arp -a” will display a list of every MAC address that your computer has in its memory.

On Windows

Same concept, different syntax.  Ping the IP first to make sure your computer learns the MAC of the device, then type “arp -a” followed by a space and the IP address.  Like this:


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