Marlborough Wi-Fi

Wi-Fi Security Presentation

A local computer company ran a seminar on wireless security this evening and I decided to pay a visit to see what I could pick up. They covered the main points very well but ran into some serious flaws when presenting the information.

Basically the summary of the presentation was the following:

• Locate the access point centrally
• Change the admin password (strong)
• Change the SSID and disable broadcast
• Disable DHCP and use fixed IP addresses
• Enable MAC filtering
• Enable WPA encryption

All good points covered well for home and small business users. The main worry I have was they suggested the last four ideas in that priority i.e. that cloaking the SSID was the single biggest security factor (and even quoted that it is highly effective when used by itself), followed by disabling DHCP. Sorry guys, but that’s just dead wrong.

Based on my experience, this is more how I would prioritise this list:

• Enable encryption, preferably WPA
• Disable SSID broadcast
• Change the admin password
• Locate your access point centrally, away from windows and roads
• Use MAC filtering
• Disable DHCP (actually not recommended unless you need to)

Here’s why:

SSID cloaking prevents your SSID from displaying if you run a casual site survey, or use Netstumbler for wardriving. Disabling DHCP means you don’t hand anyone addresses casually, but it won’t hide your IP range. MAC filtering also works as a casual deterrent but anyone can change the MAC address of their wireless card in seconds in Windows or Linux without requiring third-party software.

Kismet is the de facto standard software for wardriving and it will display the above three items (SSID, IP range and MAC addresses) in seconds on an unencrypted network the moment any data is broadcast, which is pretty much constantly on a typical Windows network. You don’t have to do any fiddling or magic, that’s just how it works. No effort required. Not only that, Kismet will happily collect all that raw data floating through the air for easy viewing later. What about those passwords on insecure websites? Even your email? It all comes up in plain readable English!

Encryption is the number one priority. The moment most malicious wardrivers spot encrypted networks, they move on to easier targets as most networks are not worth the time to crack. It also effectively hides all of the above mentioned information so you dont have to configure a pile of different options. While WEP is relatively easy to crack it still puts off the majority of crackers as it adds an extra hurdle. Most access points and clients out there nowdays support WPA-PSK, which offeres much more advanced security for home and small business users when set up properly. If you use a strong passkey over about 20 characters long the immense amount of time it takes to crack the key is almost impossible. As a bonus it’s also the easiest to get set up.

The person running the seminar made out it adversly affects performance, however this is also untrue. Most access points and clients made over the last few years include more than enough processing power to handle this task effortlessly. Sure there is still an overhead but it is very small, and not enough to affect casual network usage such as internet browsing. What is more important to you anyway? Security or an insignificant speed decrease when copying large files?

Food for thought. I’ll get a security page up on this site soon to assist visitors. In the mean time there is loads of information out there on the web, just ask Google.

This entry was posted on Tuesday, March 28th, 2006 at 18:19 NZST and is filed under Security. It has been viewed 2084 times. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.