Wireless Networking Security
Types of Security Problems
There are many goals for attacks. Don't assume your network is safe just
because you don't do critical work on it.
- Snooping. Reading private mail and other personal files.
- Destroying or corrupting computer data: Making files unusable,
or making a whole computer unusable.
- Stealing computer data: Taking credit card numbers, email
addresses, company information, etc.
- Stopping computer from functioning properly: Blocking incoming
traffic so that intended users cannot get access, etc.
- Misusing computer resources: Sending spam without you knowing
it, etc.
- Pranks: practical jokes, breaking in just because it's a
challenge.
While wireless networking with Windows XP is great, you have to be mindful
of the fact that it works like radio broadcasts: anyone with the proper
motivation and equipment can "listen" to your wireless communications. You
should secure your network by carrying out all of these steps:
- Change the default Service Set Identifier (SSID). The software that
came with your Wireless Access Point (WAP) will allow you to change the
SSID (the SSID is the name that appears for the wireless network when
Windows XP detects the network).
- Stop your WAP from broadcasting your SSID. This means that anyone who
wants to connect to your WAP will need to know the SSID in advance; they
can't just get within range and pick up the name automatically. On
some Access Points to turn off SSID broadcasting set your home AP to
closed network. This turns off the SSID broadcasting feature
on the AP.
- Evaluate whether to turn on Wired Equivalent Privacy (WEP) or Wi-Fi
Protected Access (WPA) on your home network. WEP is a protocol that
encrypts data as it travels across a wireless network, making it unreadable
even if it's intercepted. If you use one machine both at home and at work,
you may need to turn WEP on for your home network and turn it off when on
the work network. Yes, WEP has been cracked, but it takes time and
effort. WPA is wireless security with far greater protection than WEP. It
avoids most of WEP's vulnerabilities. WPA is effectively unbreakable with
current technology [more info].
- Use MAC address controls. Your WAP software allows you to specify which
wireless network cards are allowed to use it, based on the Media Access
Control (MAC) address. Every computer has a different MAC address assigned
to its network card.
While no security scheme is perfect, carrying out the above steps is like
locking your doors before you go to bed and turning on your alarm system.
With enough determination, a bad guy can still get in - but you've made it
harder.
If one day you notice one or more strange computers on your wireless
network its probably your neighbors' with a wireless access point installed.
Hopefully you have secured your wireless network with an encrypted WEP and
hid the ID of your access point as instructed above. Is there a way to notify
your neighbors' that they are broadcasting all over the neighborhood? Yes
there is a way if your know what their IP addresses are.
Wireless security is a huge issue. Best practices dictate using Wired
Equivalent Privacy (WEP) encryption and changing the default SSID and default
administrator password, but it's very common for people to leave their
wireless access points (WAPs) with the default configurations. This leaves
the networks to which these WAPs are connected wide open for anyone to
connect to. There are several ways you can let people know that they have an
open WAP, but you have to be careful because "no good deed goes unpunished."
You have to make sure you don't access any resources on their networks, or
else you could be prosecuted in some jurisdictions. One thing you could do,
without accessing anything on the other network, is use the Messenger
Service. Open a command prompt and type the following:
Net send COMPUTERNAME Your Wireless Access Point is Unprotected!
and press ENTER. The COMPUTERNAME is the name of the computer you're
seeing in your My Network Places window. If your neighbor left the Messenger
Service running (and they probably did, if they left the WAPs unprotected),
they will get the message.
NOTE: Do you have multiple Wireless Access Points (WAPs) in your home or
business? If so, you need to be aware that Windows XP SP1 ignores the
preference order you set in your wireless configuration properties if one WAP
broadcasts its SSID and the other doesn't.
If you are interested in learning more:
Firewall and Perimeter Security
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