Despite the uncertainty regarding the best security practices for wireless networking, many organizations are interested in or are already deploying wireless LAN technology.
A majority of the concerns revolve around the inherent flaws in wireless security. However, since these networks are popular for the ease of installation and use, organizations will continue to deploy them regardless of the flaws. Following are a few sensible solutions that can help prevent wireless LAN users from taking one step forward in technology only to take two steps backwards in security.
Wireless security is not as simple as turning on encryption. If you are not even aware that your users are secretly setting up an unprotected wireless network inside your organization, you may have a more serious problem on your hands.
One solution for securing wireless LANs is to implement a three-pronged approach from the technical, physical and administrative perspectives.
The first security approach obviously focuses on securing the technology itself as best you can, such as activating the appropriate security features built into the wireless devices. Here are just a few suggestions to ensure this approach is effective:
- Activate the wired equivalent privacy (WEP) encryption features that come with the wireless access point. Although the implementation does have its problems and is not the strongest form of encryption, using a lock is better than using no lock at all. It can keep out the casual intruders.
- Change the default settings that come with the wireless access points. Change the service set identifier (SSID), the password, and the IP addresses that were set by the manufacturer. Keeping these default settings will unfortunately make it easier for an outsider to hack into your wireless network because these settings are already public knowledge. It's like using a lock but with the key still inside it.
- Do not plug wireless access points directly into the internal network inside the firewall. Doing so can give wireless hackers an easy entry into your network. Plug them instead into a buffer zone or 'demilitarized zone' (DMZ) of their own outside of the main firewall. Most of us already have firewalls; we should take advantage of these protective barriers, especially for wireless environments.
The physical security approach deals with protecting the wireless equipment itself from tampering and theft. It also includes eliminating unauthorized equipment that does not belong on your network. Suggestions include:
- Perform periodic radio frequency site surveys to identify wireless access points that are authorized, and those that are not. Unauthorized, or 'rogue' access points can compromise the security of your network and must be removed. Not knowing that rogue access points even exist indicates your organization may not have the skills, the means or the tools to combat the new frontier of wireless hacking. It's time to get started.
- Place your access points as close to the center of your facility or building as possible. Placing them near the exterior wall of your building can cause your wireless signals to 'bleed' excessively outside of your facility, providing people outside with a strong enough signal to hack into your network.
- Monitor radio interference from other sources and other access points. With the right tools to perform a radio frequency site survey, you can spot potential problems caused by common household devices or even other access points that can disrupt your wireless network. For example, cordless phones commonly found in homes and small offices may share the same frequency band as your wireless network (2.4GHz). Talking on these phones can kick everyone off the wireless network.
Also, if you have wireless access points that are close to each other, set them at least five wireless channels apart so they don't compete and interfere with each other. For example, if your first access point is using channel 1, the second should use at least channel 6, and the third, channel 11. Otherwise your users will perpetually complain about connection problems.
Finally, the administrative approach focuses on the people in the organization who use wireless, making sure they play a role in its security. Suggestions include:
- Set up a clear and comprehensive policy on wireless devices and enforce it. It's hard to prohibit your users from setting up their own wireless networks if you don't have a written policy restricting them. If you want a secure environment, there is no room for ambiguity. Policies are a must - the more people you have following a sensible policy, the greater the strength of your security.
- Set up proper procedures for purchasing, installing and maintaining wireless devices. It's usually better to have a centralized department accountable for the wireless equipment than to have the users do it on their own. Users will probably not set up the equipment consistently or securely, leaving behind holes where outsiders can hack in. Without accountability, there is no real security.
This list of suggestions is not meant to be all encompassing, but rather is just a beginning. The intent is to focus on more than one approach. To effectively protect a wireless network requires serious planning and effort - it is not just a trivial exercise of turning on encryption and hoping for the best. It involves people and policies as well as technology. The goal is to set up a wireless environment so it does not become an attractive target for exploitation and a magnet for hackers.
Dennis Seymour Lee, CISSP, is a lead instructor for (ISC)2 and is president of Digital Solutions & Video, Inc.