Can't block mac address

hello all i have a computer on my network that needs to be removed but it will not let me. it is in somone elses house. they have broken into my wireless router several times. i need that computer off my network as i am running servers and everything.the funny thing is that i can't block their mac address with my linksys router. i have a picutre of the computer on my ip table.

 

enable the mac filter so only your mac is allowed access. also, secure your wireless obviously.

 

wireless is secured i enabled mac address filter to be told that that is an invalid mac address (thats what i am getting out of the error)

 

are you trying to filter your neighbors mac to be disallowed? try to configure your mac filter to only allow the address you specify. so youd have to enter each mac of each computer you want on wireless. if your neighbors mac isnt in the filter, it wont be able to connect. then change your security key, because somehow they have it if theyre on your secured wireless...

 

What encryption are you using on the wireless (WEP/WPA/WPA2)? I'd recommend WPA2 with AES. If they were smart enough to actually crack the encryption of your wireless network, chances are they are smart enough to change the MAC address of their wireless card.

 

How important is the information to you? Personal or business?
Purely from a security standpoint, I would be inclined to reset the whole network from router through computers. Make sure the router's default log-in username and password are changed. If this guy has had access to your network several times, it's hard to tell what information he has gleaned from you.

Agree with that whole heartedly if you are going to use wireless. KingSteve's recommendation to allow only your specific MAC's is valid also.