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How To Tell If Someone Is Using Your Wireless Network

There are many reasons you should learn how to check if someone is on your wireless network.  We all know there are security risks associated with it (someone can hack your computer or your internet use stealing important personal information).  There can also be legal implications.  For instance, your neighbor could be doing something illegal and the authorities may accidentally trace the activity back to your equipment.

Although you're not guilty, proving this can be lengthy, difficult, and frustrating.  Also, does your internet provider like the idea of the neighborhood using your internet service instead of paying for the service themselves?  This could be construed as stealing from the service provider.

In any case, it is good to know how to check if someone is on your wireless network.  In this article I would like to show you how anyone can tell if someone is logging on.

To find people on your wireless network, the process will be different depending on your router's manufacturer but the basic idea is similar.  Personally, I use a LinkSys because I think their routers are the best.  That is why the screenshots in this article will be from a LinkSys interface.

There are two main methods to tell if someone has been on your wireless network.  You can check the logs to see if someone's been on there recently or you can check out the DHCP Clients Table to see computers currently connected to your network.  Let's go through both, shall we?

First Things First, What's Your IP Address?

The first step is to identify your own IP address (you'd hate tracking and being nervous about your own shadow, right?).  Finding out your own IP address (a.k.a. your LAN IP address) is quite simple.

• Click the start button
• Click run (in Vista, just type in the Start Search box)
• Type cmd then click OK.
• Type ipconfig when you are given the prompt.  Your IP address will look something like this: "IPv4……………….: [THEN A STRING OF NUMBERS]"  If you need to get a better visual, check out the screenshot below:

Go ahead and keep that window open because we'll need more information from it soon.  Now onto the mission before us!

Check The Log To See If Someone's Been On

The first way to see if someone's been leeching off your wireless network is to check the logs for unknown IP addresses.

Log into your router by entering its IP address into your browser address bar.  Not sure what the IP address is for the router?  One way is to Google the manufacturer and find what the most likely default IP address is.  Another way is to go back to the ipconfig screen and find it listed as "Default Gateway."

If you haven't really set anything up yet, you'll probably be asked to log in with a username and password.

Routers are originally shipped with a default username and password.  To find this out you'll either have to find the documentation that came with the router or use Google to search for the manufacturer and the default login information.

Once in, different routers will have different looks and navigation.  Like I said before, I'm using a LinkSys so that'll be what I will be describing.  You may have to look for similar settings and words to do what you need to.

Let's check out the log by going to the "Administration" tab and then the "Log" sub-tab.  Make sure logging is enabled.  Once that is done, the router will log information.

The information we're interested in for this article is IP addresses that should not be there.  This obviously means that strangers are logging on to your network.  To find this out, click the "Outgoing Log" button.  The LAN IP column shows the IP address for the computers logging on.  Incidentally you can see the site that was accessed in the "Destination URL/IP" column.

This should give you a good idea whether or not someone has been accessing the Internet via your wireless network.

Check The DHCP Clients Table To See If Someone's Currently On

First you must make sure this option is enabled on your router.  Go to the setup tab and look for something similar to "DHCP Server" and make sure "enable" is marked.

Now you can go and check out who's logged on by going to the "Status" tab and the "Local Network" sub-tab and clicking the "DHCP Clients Table" button.

The table that opens offers some useful information about the computers that are connected currently like the Client Host Name (the computers' names), the IP addresses, and the MAC addresses.

So there you have it.  If you want to see who's been leeching off your wi-fi, that's how.  Now, what to do about it?  Secure your network better.  Check out these MakeUseOf articles.  They should be able to help some:

• How To Secure Your D-Link Wireless Router
• Is Your Wireless Network Safe?
• How To Secure Your Wireless Network Connection

Now despite the warnings at the beginning of this article you might not mind others logging on and using your wi-fi.  But now you can at least see what's going on.

Do you have another way of monitoring your wi-fi network?  Please share your tips in the comments.

^ed