Quick, what does MAC stand for? 

Even after decades working with computers, I still forget. No one really remembers "Media Access Controller", because we call them NICs. MAC is just short for "MAC Address". Frankly, more often than not I think of MAC as "Machine Address Code". Makes more frelling sense to me.

But for those who have no clue what I'm talking about, MAC does indeed stand for "Media Access Controller", it relates to Network Interface Cards and we don't really care about Media Access Controllers because no one calls them that, we call them NICs or Network Cards. Got that?

Here's what everyone in IT means when they refer to a MAC: 00:11:AA:44:F1:DD

Every network controller needs a MAC address, regardless of what kind of networking it does. MAC addresses are need for layer 2 networking. If you don't know what that means, you can review the OSI model or just ignore it because it's not important. Just know that MAC addresses (or MACs) are just as critical to computer networks as IP addresses. And just like IP addresses, MACs are assigned by a central authority. The IEEE.

<cue ominous crack of thunder>

MAC addresses are 6 bytes long (or 48 bits), compared to IPv4 addresses which are 4 bytes long (or 32 bits) . Which provides an enormously huge amount of address space. Also, IEEE haven't frivoled away the MAC space like IANA did, the tools... Anyways, IEEE assigns MAC address space in 24 bit chunks. Anyone can apply for one, though it's pretty useless unless you plan to make networking equipment of some sort. These chunks are called Organizational Unit Identifiers or OUIs. I call them "MAC prefixes" because it's always the first 3 bytes of a MAC address. IAB's are the same idea, except it's a 36 bit chunk leaving only 12 bits of space for use by the assignee.

Now the great thing about all this is unlike with IP address space assignments, which are dynamic and fluctuating and a pain in the ass to look-up, the MACs are pretty stable. You'll notice space assigned to Digital Electronics Corporation, which hasn't existed with that name for years. IEEE proves a single, easy to get file with every OUI assigned, including organization name and address. Sweet! This is especially useful to network engineers and information security dudes, as it makes it possible to figure out what a rogue device is by just studying the packets. A MAC assigned to Xerox is most likely a printer, Cisco MACs are going to be routers, switches or firewalls, and an Apple MAC is probably a Macintosh. Or... maybe an iPhone.

See, there's a lot more things with network interfaces then there was just ten years ago. When IEEE was originally handing out OUIs to companies, it was all big iron dinosaurs like Xerox, Digital Electronics Corporation, Cray, and so-on. Even with the initial surge of networking in the workplace, you still dealt with computers. But now thanks to WiFi, Bluetooth and slobbering, uncontrollable capitalism we have refrigerators with network cards. Cellphones have MAC addresses. So do home video game consoles, electronic badge readers for doors, a growing number of cars and a small but expensive number of medical devices.

It's only going to increase. And eventually, a MAC prefix isn't going to make it very easy to tell what exactly something is.

Which is the whole point of DeepMac.