how do I get computers that are not mine off of my network?

[primo1]

how do I get computers that are not mine off of my network? I'm in an office building and have other computers on my network.

 

[diplo]

Wireless or wired network? You're going to want to employ some sort of ACL or blacklist by logging into either a router and / or switch depending on your network topology. You'll have to identify the hosts that you don't want on your network and blacklist their MAC addresses. So if you have Alice-PC on the network and you don't want her there, open command prompt and ping Alice-PC to get her IP. When that comes back, match that PCs IP to its MAC address by looking at your ARP table (do an "arp -a" from the command prompt). This is a simple scenario as to how you could go about doing this, yours may vary.

 

[primo1]

Great, thanks Diplo, I will try this.

 

[Layback Bear]

primo1 how did these computers get on your network?
Did these computers on your network come from a workplace domain/network?

 

[primo1]

Yes its a network at my job. I don't know bow but they are wireless piggybacking from my router I suppose.

 

[UsernameIssues]

You said "my router".... so I assume that you are in charge of the network - correct?

What is the make/model of the router?
Is the router also your Wireless Access Point (WAP)?
If not, what is the make/model of your WAP?

What is the security type for your WAP:
WEP?
WPA?
WPA2?
Other?
Or wide open - requiring no security key to join the network?

If you are using a security key (or pass phrase), you should probably change it.

 

[UsernameIssues]

Wireless or wired network? You're going to want to employ some sort of ACL or blacklist by logging into either a router and / or switch depending on your network topology. You'll have to identify the hosts that you don't want on your network and blacklist their MAC addresses. So if you have Alice-PC on the network and you don't want her there, open command prompt and ping Alice-PC to get her IP. When that comes back, match that PCs IP to its MAC address by looking at your ARP table (do an "arp -a" from the command prompt). This is a simple scenario as to how you could go about doing this, yours may vary.

White listing might be simpler - it all depends on info that we don't have yet

 

[AddRAM]

Yep, change the key, then reboot the router.

You must be connected to the wap with an ethernet cable.

 

[diplo]

I'm going to agree with "Usernameissues", if it's a smaller business and the wireless network is for business use, whitelisting is probably your way to go if your hardware has that functionality. If it's a small enough business and your employees can keep a password to themselves, a whitelist may not even be necessary, just change the password quarterly or something. It's worth mentioning that MAC filters aren't perfect ( a MAC address can be spoofed by a determined attacker ) but for most purposes they work.

 

[Mark Phelps]

You might want to consider installing Who's on my WiFi app. I did that at home when I suspected that neighbors were leeching off my WiFi. When you install it, you run a scan and it finds all the clients on the network, reporting their IP addresses and Mac addresses. You mark the ones "known" to you. It runs in the backround and whenever a new Mac address appear that is not "known", you get a real-time alert. I used this to build a table of Mac addresses for my router.