Wireless Networks are being inexpensive and easy to install so most people are moving to Wireless technology.
unfortunately,unlike the Wired Network , WLAN are vulnerable and easy to hack especially if they are not well configured .

if you own an unsecured wireless network , hackers can steal your bandwidth,personal information and even use your computer as a Zombie .

protect a wireless Network is necessary for everyone using a wireless connection .

Encrypting The Wireless Connection :

the first thing you have to do is to check if your Wireless network is secure or no , to do that ,click with your mouse on the wireless connection icon in the bottom right of screen and go to "view wireless networks" (on windows) , if your wireless network is unsecured , you should see under you wireless connection Name(SSID) something like "unsecured wireless network" , otherwise ,you will see a lock icon with "security-enbaled...(wireless encryption you use : wep,wpa ,wpa2 ...)".

even if you see the lock icon , it's too early to quit this article :) , this is just the first defense line for your Wi-Fi network .
in fact there are different systems to Encrypt data between your Wireless Devices ( router <-> computer for example) .
the most commons are Wep,WPA,WPA2 .

there are three kinds of Wep(Wired Equivalent Privacy) Encryption :64bit,128bit,256bit .The longer key gives a slightly higher level of security but not enough , in general , WEP encryption is easy to crack so consider to change it to WPA(Wireless Protected Access) or WPA2 which provide more security level.

also,make sure to choose a solid Key with more than 10 characters and contains both letters and numbers .

but how to do that ??

an essential step to protect Wireless Network is to change the encryption system and password, to do that, you should enter to the wireless router configuration page via browser ,to do that you need the router ip ,username and password.

to find out the router ip in windows , enter to command via start->run then type "cmd" , in command , type "ipconfig" , the router ip is right after the "default gateway" (for exmaple "default gateway.....:192.168.1.1 ").

in MAC , open the terminal window then type ifconfig . take a look at lines that start with "inet" ,The IP addresses will appear on these lines.

enter this ip in the browser , it will ask you for the username and password,you can find here default routers passwords for most common routers , in general , they are provided with router guide book .

for linksys routers ,you can find the password management window in administration->Management .

for D-link routers: go to the tab Tools->Admin .

if you own a netgear,the router password window is located under Setup->Wireless Settings.

you can browse the router guide if you have a router from another brand.

MAC Filtering To Improve Security:

Securing A Wireless Network By MAC Filtering is a great way for people who use always the same devices to connect to wireless Network .
if your router support MAC Filtering (most routers these days include this feature), you can restrict access for only certain devices with "known" MAC addresses .

to find out your laptop MAC addresses , you can take a look here
http://www-dcn.fnal.gov/DCG-Docs/mac/ .

after creating a list of allowed MAC addresses , go to router web configuration interface and enter them .

MAC Filtering is an excellent way to protect wireless network but it's not reliable for people who share their wireless connection between devices that change usually because every time a new device would connect , you have to add its MAC addresses in the router "Allow List".

i would also to write about a common mistake I see these days made by many people:

certain are enabling Mac Filtering only without a Wireless Encryption to achieve a better performance ( no need to encrypt every packet ),in this case, what I need to know is only a mac addresses of any of your allowed devices (no hard to get in general), then using this Mac addresses to connect to your network(by adjusting network adapter card settings) and that's it , your computer identify me as one of your devices and give me full control.

Mixing A good wireless Encryption with MAC Addresses filtering is a perfect way to secure a wireless network in most cases.