You pay a pretty penny for that super fast internet connection, but you aren't seeing anywhere close to the speeds promised by your Internet service provider. It could be any number of problems. One thing that will suck the life out of your bandwidth are wireless freeloaders. They will hop on to any wireless network connection they can find and use your bandwidth to their heart's content.
How can you tell if someone is connected to your wireless network without your permission?
1. Log on to the administrative interface on your wireless router / wireless access point
In order to view the current active wireless connections using your wireless access point you will need to log in to the administrative console of your wireless router. Check your router manufacturer's user guide for detailed instructions.
2. Click on the wireless configuration / status page from your router's admin console
While all routers are different, usually the list of active wireless clients is provided on either the 'wireless configuration' page or the 'wireless status' page on most wireless routers. Look for a list of wireless clients.
You should see a table with two columns. One column will show the Media Access Control (MAC) address which is a unique identifier assigned to the network interface of whatever device is connected to your network. The other column should contain the IP addresses that were assigned to the devices by your router.
If you have DHCP enabled on your router then your router will automatically assign an IP address to any client that is authenticated (whether they hacked their way in or not). Only after the router gives the client an IP is the client able to connect to resources on your network and reach the internet.
3. Count your wireless devices
Do you only have a laptop and a smartphone that use your wireless access point yet you see 20 different clients listed in the wireless clients table? If the numbers aren't adding up, then you may have some rogue wireless clients or you may just have some devices that you forgot had wireless connections such as your XBOX or your Wi-Fi enabled camcorder.
4. Look up the MAC addresses of any suspicious devices to see what they are
So you've counted up all your wireless devices and there are two more than you think you are supposed to have. It's time to lookup the MAC addresses to see who made the device so you can learn what it might be. Visit a MAC Vendor lookup site such as MACVendorLookup.com and enter the MAC address of the suspicious device. The site will tell you who the manufacturer of the device-in-question is. If it says "Dell Inc." and you don't own any Dell computers then, chances are, someone is hijacking your connection and freeloading off your Wi-Fi.
5. Lock out the wireless freeloaders
If someone is using your wireless network without your permission then one of two things has happened, you've either turned off security completely and are allowing anyone to connect to your access point or someone has cracked your wireless encryption or cracked / guessed your wireless password.
The best way to get rid of unauthorized wireless users is to first ensure that you are using the latest wireless encryption mechanism (currently WPA2). Once you are using the latest and greatest security then you should change your wireless network's name to something other than the default because hackers have tools that make cracking the password of a known network name a fairly simple task.
After you've chosen a good network name that is not on the list of the Top 1000 Most Common SSIDs then you should create a strong wireless network password (also known as a Pre Shared Key). Performing these steps should get rid of all the freeloaders who are using your network.
Don't forget that you'll have to give out your new wireless network name and password to all your legitimate / authorized users so they can rejoin your network after you've purged all the leeches.