Few home inventions have changed the way we live the way the Internet and the pervasiveness of wireless connectivity have. The technology is in the hands of millions who literally don’t know the power, or the vulnerability, they have exposed themselves to. I’m sure if you’re reading this, you’ve read at least one article from some network security expert claiming that no wireless network can be made 100% safe. I believe that’s true, just like every home can’t be made 100% safe. But you can install simple tools to help you detect intruders and keep yourself safe while at home, around the pool, with your laptop (not that I would ever do such a thing).
There are many sophisticated ways to secure your wireless network. Some require installations on your PCs that are accessing the Internet as well as your router, some require long, complex passwords, that you hopefully never forget, along with Linksys wrt 1900 ac manual that you must go through in order to use these routers effectively. I’m going to summarize how to use your computers’ Media Access Control address (MAC address) to determine who’s on your network, and then take action against any unauthorized computer. Think of the MAC address as the physical address of any computer (or computer-like device) that’s on your wired or wireless network. Or more specifically, the actual piece of hardware in the computer-like device that is talking to the network. This number is unique. Mostly. It’s true that it’s relatively easy for someone who really knows what they’re doing to “spoof”, or fakes a MAC address, but if that guy is living next door to you, he’s getting into your network anyway. Bake him some cookies, bring him a Diet Dr. Pepper and make nice. You’ll thank me later.
First things first. In order to know who or what is on your network, you have to know what’s going on on your network. I recommend a free download called AirSnare (http://www.download.com/AirSnare/3640-2092_4-10255195.html). AirSnare works on Windows (any current version) and is very easy to install. The downside is that if your network card isn’t supported (I’ve never personally run into this) then the program won’t run. AirSnare basically watches your network and shows you all the MAC addresses that are on your network. Now comes the fun stuff. You get to track down the MAC addresses for each network device you own. This is my favorite part of the game, I always find new devices on my network that surprise me. In the past, I’ve tracked down my Nintendo Wii, Xbox 360, iPhone, and an iTouch that all have access to my network.
Once you start up AirSnare, select your network card, right-click and select “start”. This will start the network monitoring and show all MAC addresses in red. Those are the potential bad guys. So now we’ve got to figure out who’s friendly and who’s not. Use your PC’s command prompt (Start- gt;run- gt;”cmd”) and type “ipconfig /all”. This will show you, among other things, your network cards and settings for your computer. Under something like “Ethernet Adapter wireless network connection,” you’ll see a “Physical Address” section. The format will be 00-00-00-00-00-00, where there will be a combination of numbers and the letters A-F (hexadecimal). Find the set of numbers and letters that match one of the many on the list of AirSnare. Now, go back to the AirSnare interface and right click and add that MAC address, and give it a meaningful name while you’re at it. Go around to every PC connected to your network and do the same “ipconfig /all” command and gather all the known MAC addresses. Go to your network router, turn it over and look for the address on the bottom of it, add those to AirSnare (there will be more than one, just add them all to be safe). Any wireless printers you have will have a MAC address. You can see that this process can be a little time consuming, but it will also open your eyes to all the devices that are on your network.
Now, for any MAC address that you can’t find a device for, take the first three couplets of the address (00-00-00), and find the manufacturer via an Internet search. Hardware vendors purchase the base MAC address so that they can be identified globally. Do a quick Google search for “MAC address vendor” and you’ll see many web sites that allow you to enter the first 6 digits of the MAC address and return the vendor. That’s how I found my Xbox 360 and iPhone. I knew that I only have two devices in my house made by Microsoft and Apple, so I knew those MAC addresses were safe and added them to my safe list.
The next step is to log in to your wireless router and turns on MAC address filtering. This will essentially only allow access to MAC addresses that you enter into the router. All you need to do is make sure your router has a SOLID password (upper and lowercase letters with at least one number) and your network will be secure to anyone except that weirdly geeky neighbor, but he likes you now that you brought him cookies and Diet Dr. Pepper, remember? Every wireless router worth its salt has this capability. I’ll walk through the procedure on a Linksys WRT54G, but this will be identical on any Linksys product, and very similar on any other manufacturer’s router.
First things first. You do have a password that’s not “admin” on your router, right? 90% of routers are hacked due to the simple fact that people buy them, take them home, and turn them on with default settings. This means that if I know the defaults for the router you have, I can get into your router, and that’s bad. So I’m going to assume that you have you’re router secured, and you’ve logged in. Under your router’s “wireless” tab you’ll see something that designates “MAC Filter” or something to that nature. You’ll want to enable this feature, and make sure you choose “permit only clients…” not “prevent clients”. This will determine whether you lock yourself out of your router, or it works like a champ. No simply click on the edit/add button, and add your MAC addresses into the given space. Some routers will want a colon between the couplets like 00:00:00:00:00:00, some will be fine with dashes like shown above.
Once you have added all your MAC addresses, save your changes, and your router will reboot. You should now be able to connect just like you did before. If you want to test your new configuration, remove one of the MAC addresses, and try to browse the Internet from that device. It will no longer connect. The good thing about this type of security is that someone will try to connect, and their system will timeout trying. They don’t get a message back saying their MAC is unknown, they just don’t get to connect. It’s called “security by obscurity” and it’s pretty effective.
That’s it, you’re (mildly) secure. I make a practice of running AirSnare once a month, just to make sure no one is sniffing around my network, or more likely because of MAC address filtering, that I haven’t added a computer and forgotten to update my settings. Once you get comfortable with AirSnare, you can start to look at some of the traffic that goes across your network, and you will quickly see how easy it is to track and locate strange behavior. But that is another story.