Every network card in your Mac, whether it’s for Ethernet, Wi-Fi, or even Thunderbolt, has been assigned a unique identifier called a Media Access Control or MAC address. This address can be used to identify a specific computer when it’s on the Internet, so those individuals who are very concerned about privacy sometimes use what’s called “MAC address spoofing” to temporarily mask the MAC address of the computer they’re using. It’s rare, but it’s one of those things you might need to know someday.
Find the MAC address
First, let’s find the existing MAC address for the connection you’re most likely using — a Wi-Fi connection. This is quite simple; just hold down the Option key on your keyboard, then click on the Wi-Fi icon in the Mac menubar:
First, let’s find the existing MAC address for the connection you’re most likely using — a Wi-Fi connection. This is quite simple; just hold down the Option key on your keyboard, then click on the Wi-Fi icon in the Mac menubar:
How far reaching is the MAC address? That is, when does it cease to have network meaning? If the PC on the left in this picture is in a different network A MAC address is a unique number but it is only ever used for direct communication between devices. The Internet doesn't know how to make use of.
Using the option key and Wi-Fi icon to find the interface name and MAC address for Wi-FiThis tells us a few things about the Mac we’re on. First, it’s using an interface with the name of
en1
to connect to Wi-Fi. The MAC address is right below that interface name — in this case, it begins with the hexadecimal address 28:f0:76...
and I’m going to stop right there because I don’t want to encourage hackers to break into my machine!If you need to check the MAC address for other network devices, the System Information utility is very helpful. Launch it from Applications > Utilities > System Information, or from the Apple Menu > About This Mac > System Report. In either case, click on Network, then the specific network hardware you wish to find. On my iMac (see image below), the Ethernet card is listed as
Use the System Information Utility to find other MAC addressesen0
with a MAC address beginning with 38:c9:86...
You can also use the Terminal to find the current MAC address of an interface. Launch Terminal from the Applications > Utilities folder, then type in the command highlighted in yellow below, substituting the correct BSD Device Name (in this case,
en1
):Using Terminal to determine the MAC address of a network interface
Changing the MAC address
Here comes the fun part. Remember, there’s usually no reason for you to change the MAC address unless you have a specific reason to do so. Both of the methods I’m demonstrating here require the use of Terminal. If you’re not comfortable with the OS X command line, perhaps it’s not a good idea to play with MAC addresses…
Here comes the fun part. Remember, there’s usually no reason for you to change the MAC address unless you have a specific reason to do so. Both of the methods I’m demonstrating here require the use of Terminal. If you’re not comfortable with the OS X command line, perhaps it’s not a good idea to play with MAC addresses…
First, let’s change the MAC address to a specific address. It needs to be twelve hexadecimal numbers in groups of two, separated by colons. For example, something like
14:d2:71:11:57:a6
would work.Now at the Terminal prompt, (without the quotes) type in “
sudo ifconfig en1 ether 14:d2:71:11:57:a6'
and press the return key. In this case, Terminal sets the MAC address of en1
(which is the Wi-Fi adapter in my iMac) to the address we selected.The next method changed the MAC address to a randomly chosen address, which is probably the absolute best way to ensure your privacy. Once again in Terminal, type (or copy and paste) the following command, being sure to change the BSD Device Name (en1 or en0) to the interface you wish to change:
openssl rand -hex 6 | sed 's/(..)/1:/g; s/.$//' | xargs sudo ifconfig en1 ether
In my example, that selects a random hexadecimal string that fits the required format and then passes that random string to ifconfig to set the MAC address.
Every time you run this command, it generates and sets a new MAC address for the chosen interface. Realize that any time you restart, the MAC addresses revert to the number originally assigned to the interface, so this is by no means permanent. Some privacy fans make this command a script, then have it run each time the Mac is rebooted. That gives them a new MAC address each time they start their computer.
One other thing: editing your MAC address may cause temporary network issues. It’s a good idea to restart that particular network connection after you change the MAC address to ensure a good connection. For Wi-Fi, that’s simple to do — just click the Wi-Fi menubar icon, select Turn Wi-Fi Off, wait a few seconds, then use the same menu to select Turn Wi-Fi On.
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You may consider using a LAN to connect to the internet. LANs come in two basic varieties: wired and wireless. In a wired network, a cable runs from each computer to a central box, whereas a wireless network uses radio signals rather than wires. Either way, you need a central box.
If all your computers are in one room and you don’t move them (or you’re good at playing home electrician), a wired network is for you; otherwise, wireless is far easier to set up, although the resulting network runs slower. Combos are also possible; most wireless equipment has a few jacks for wires to connect to the computers that are close enough to run cables.
The box in the middle — a hub, switch, or router
For any variety of current LAN, you need a special box that connects everything. Here are the main kinds of boxes you have to choose from:
- A hub or switch is a book-size box with a bunch of jacks for network cables. It serves as a wired connection point that links all your computers into a LAN. A switch has a little extra circuitry to speed things up.
- An access point is the wireless equivalent of a hub, with a radio antenna or two and only one jack to connect to a wired network.
- A router is similar to a hub or an access point (or both) with the addition of Internet-connection smarts, like a firewall.
- Some providers give you a combined modem and router. If they do, you’re all set, no more equipment needed.
Go for a router if your provider didn’t give you one; it’s cheap ($40 to $80), and it saves you days of hair-tearing grief because it keeps most worms out of your network. With a router, none of your computers needs to worry about connecting to the Internet — the router handles it.
Routers come in both wired and wireless versions. The wired versions have varying numbers of jacks, the wireless ones have one jack for the cable to the modem, an antenna for the wireless network, and usually a few jacks for running wires to computers in the same room.
For some perverse reason, wireless routers are usually cheaper than wired, even though the wireless ones include everything the wired ones do plus the wireless radio. So get a wireless router. If you need more jacks than your router has, also get a cheap switch; run a cable from one of its jacks to one of the jacks on your router and it’ll all be one big happy network.
Rent or buy?
Many providers will offer to rent you a modem, a router, or both, typically for the low, low price of $5/month each. This is rarely a good deal. You can buy your own router or modem at a big box store for about $75, and a little arithmetic reveals that you’ll be saving money after a year and a half. Modem and router technology changes slowly, and the ones you get now should serve you for five years or more.
If you have DSL service from the phone company, they will invariably provide the modem at no extra charge because it has to match whatever DSL equipment they use at their end. Cable modems, on the other hand, are totally standardized using a spec called DOCSIS. The only question is whether to get DOCSIS version 2 or 3, with the answer being 3 because it’s faster.
If you get your own router, setting it up is the same as if you got one from your provider. If you buy your own cable modem, the cable company needs to know its MAC address, a 12 character identifier that’s printed on a sticker on the modem. If you buy a modem before you get your service installed, the installer will plug in the modem and call in the MAC address.
If you replace the modem yourself, it’s not much harder. The modem has three connectors, a screw connector for the cable, an RJ-45 multi-pin connector for the Ethernet to your router, and a power connector of some sort, probably a thin wire to a power adapter. Just disconnect the old modem, connect the new modem the same way (use the new power adapter that comes with the new modem), then call your cable company to give them the new MAC address.
The whole process shouldn’t take more than 10 minutes, give or take how long they keep you on hold.