On the other hand, that huge footprint carries a risk of malevolent intrusion that increases with its size. A network footprint is more or less a product of the access point deployment. And the primary entry in a WLAN for an intruder is, of course, the access point (AP).
That's why the management of a network footprint requires a constant balancing act between territorial expansion and controlling the increasing security risks. Simply, network footprint expansion is synonymous with increasing security risk. As you expand and increase your network, you must give corresponding diligence to security issues.
As your network grows, there are some specific initiatives you should make standard:
Curtail informal network expansion
When APs are added, they should be added according to a formal procedure that includes:
Wireless expansion via AP is so simple that it is a temptation to just pop an AP in as easily as we move a lamp in our office. But the issues and risks are exactly what they would be -- and then some -- if we were running network cable to a new floor of our building.
Control local AP footprints
While your network has a footprint, so do individual APs. Here are some rules of thumb for providing good coverage while preventing leakage:
Maintain a proper client/AP ratio
Another aspect of network footprint control is individual AP effectiveness in context. It's very important that you keep a proper ratio of clients to APs. A good rule of thumb is 20:1 as an upper limit. Keep in mind that your effective AP range, the geography of the room, and possible sources of interference will not likely be more than 150 feet. Plan the number and placement of APs according to these rules.
Final thoughts
Increase your wireless network's effective resolution with an eye toward security when you fine-tune AP signal strength. There's a balance between a strong signal that makes the AP effective in the area where it's placed and a signal so strong that it leaks to the highway outside. Attention to this detail can prevent an intrusion.
Remember that rogue access points essentially represent unplanned, uncontrolled footprints. An axiom of control system theory is that you can't control what you can't observe. Since rogue APs can slip into even the best-planned wireless networks, resolve to keep a constant watch for them. You can detect rogue APs with a number of freely available utilities.
