Basics of Wireless Networks

What is wireless networking? How does it work?

A wireless network uses radio signals or microwaves to broadcast data and information. Rather than being transmitted through traditional coaxial, CAT5 ethernet or other standard wired methods, the data is beamed out over the airwaves.

Wireless networks offer advantages for some. Users with personal digital assistant (PDA) handhelds such as Palm Pilots or users with laptops can use wireless technology to allow them the convenience to move about while maintaining their network connectivity. Another pro is the ability for users to network desktop computers at various locations without having to deal with the hassle or expense of running a wired connection to that spot.

There are some cons as well. First- most wired networks operate at 100 mbps- although there are many that operate at 10 mbps still as well. There is also emerging technology for 1 gigabit per second (gbps) networks as well. Most existing wireless technology works at 11 mbps, and some protocols and equipment can operate up to 22 mbps or even 54 mbps. These speeds are affected by obstructions such as walls and floors, interference from other equipment in the same frequency range such as cordless phones and microwave ovens and even weather conditions.

Change Your Wi-Fi Router or Access Point Default Username and Password

Don't Let Just Anyone Alter Your Wi-Fi Settings

Wireless network routers and access points typically come with a built-in web interface that you can access to change the options and configuration settings. Like many other computer applications, accessing it is as simple as knowing the username and password.

The first step in securing your wireless network is the same as the first step for just about everything else in computers and computer networking- always change the defaults. Any attacker can find out what the default username and password is for a given program or device in just a few minutes. The defaults may be great for letting you connect and get the device or program up and running quickly, but in order to keep snoopers or would-be attackers out, you must change the defaults as soon as possible.

Often, the default settings are so common that an attacker doesn't even need to do any research. Many vendors use Admin or Administrator as the username and something like "admin" or "password" as the password. A couple of "educated guesses" and an attacker could infiltrate your wireless router or access point.

Refer to the owner's manual for your particular device to learn how to access the administration and configuration screen, and change the default password as soon as you set the device set up. For guidance in choosing a good, secure password, see Password Security.

Some vendors don't provide a means for changing the username, but if it is possible you should also change the default username. Knowing the username gives an attacker half of the information they need to gain access so leaving it set to the default is a security concern. If you can change it, make it something that won't be easily guessed. Don't use Admin or Administrator and avoid using simple usernames like your own first or last name.

Disable SSID Broadcasting To Protect Your Wireless Network

Don't Announce Your Presence To Strangers

One way to protect your network from unauthorized access is to hide the fact that you have a wireless network at all. By default, wireless network equipment typically broadcasts a beacon signal, announcing its presence to the world and providing key information necessary for devices to connect to it, including the SSID.

The SSID (service set identifier), or network name, of your wireless network is required for devices to connect to it. If you don't want random wireless devices to connect to your network, then you certainly don't want to announce your presence and include one of the key pieces of information they need to do so.

By disabling the broadcasting of the SSID, or even the beacon signal itself, you can hide the presence of your wireless network or at least obscure the SSID itself which is critical for a device to connect to your network.

Refer to the owner's manual for your specific wireless access point or router to learn how to access the configuration and administration screens and disable the beacon signal or the broadcasting of the SSID.

Block Unknown Devices From Connecting To Your Wireless Network

If you have changed the default SSID you have added a piece of the puzzle that an attacker would need to figure out before they could connect to your wireless network, but why stop there?

Most wireless network routers and acces points contain the ability to filter devices based on their MAC address. If you enable MAC address filtering, only the devices with MAC addresses configured in the wireless router or access point will be allowed to connect.

The MAC address is a unique identifier for networking hardware such as wireless network adapters. It is possible to spoof the MAC address, so an attacker could potentially capture details about a MAC address from your network and pretend to be that device to connect to your network, but no casual hacker or curious snooper will go to those lengths so MAC filtering will still protect you from the majority of users.

You can find the MAC address for your network adapters on your devices by following these steps:

1. Click Start and then Run
2. Type command and press Enter
3. Type ipconfig /all in the command prompt window and press Enter
4. Find the line labeled physical access address in the resulting information.

1. That is the MAC address for that adapter.

• If you have more than one network adapter you will need to look at through the results to make sure you get the MAC address from the correct adapter.

Refer to your owner's manual for the wireless network router or access point you are using to learn how to access the configuration and administration screens and enable and configure MAC address filtering to protect your wireless network.

Don't Invite Strange Devices To Play On Your Network

One of the great things about home routers, wired and wireless alike, is that they generally come with the ability to automatically assign IP addresses to devices that try to connect to the network. Since most users don't know anything about IP addresses, subnet masks and other details, it is very efficient and convenient to let the router automatically take care of those details.

The downside to this convenience though is that the router shows no discretion about which devices to assign addresses to. A wireless device that gets within range of your wireless network equipment may be able to acquire an IP address from your router.

For small networks like a home network, you can add some extra protection by turning off the DHCP, or automatic IP addressing, feature of the router and manually assigning static IP addresses.

Refer to your wireless network router or access point owner's manual for details about how to access the administration and configuration screen and disable the DHCP functionality. Once you do that, you will need to configure each one of your wireless network devices with a static IP address rather than for automatically acquiring IP address information using DHCP.

To find out what you current IP address information is, you can follow these steps:

1. Click Start followed by Run.
2. Type command followed by Enter
3. Type ipconfig /all in the command prompt console and press Enter
4. The results displayed will tell you the device's current IP address, Subnet Mask and Default Gateway as well as the current DNS Servers among other things

To reconfigure the IP address settings of a device in Windows, follow these steps:

1. Click Start followed by Control Panel
2. Click Network Connections
3. Locate the device you want to configure
4. Right-click it and select Properties
5. Under the this connection uses the following items: window, scroll to the Internet Protocol (TCP/IP)] entry and click on the Properties button.
6. Select the radio button next to use the following IP address and enter the IP address, subnet mask and default gateway of your choosing (use the information extracted above as a reference)