How To Prevent Other Network User From Accessing Your PC

How To Prevent Other Network User From Accessing Your PC

Apr 20, 2011

Wonder how you can do this to your internet, file or even multimedia server? Do you want those annoying colleagues of yours out? Well read on, it’s very easy. 🙂

At first, I really didn’t know that it will work. During my early days working as a network/system admin, I was given the task of eliminating ‘rogue’ access to the department’s internet server. The problem is that the ‘privileged’ users always share their ‘password’ to others. This generosity of theirs makes the ‘internet’ service almost unusable. The service tends to become slow because of ‘multiple’ connections brought by sharing passwords. When questioned about how did the the other users obtained their password, they just said that they don’t know. What the hell?

I can’t help to think that it’s their intention to bring the service down. For what reason? I really don’t know. But it ignites the fire residing in me to find the answers to this problem. The problem gave me the challenges to prove that I can ‘conquer’ the network. It inspires me a lot in such a way that I can see those sad faces in front of their monitor waiting and waiting for their favorite site to pop up( sounds bad huh? 😉 ).

Prevent hackers from accessing your PC

Prevent hackers from accessing your PC

I enlist the help of Almighty Google to find the right information. During my research, I stumble upon a term ‘IP Address-to-MAC Address binding’. Hmmmm. I read on the comments and found out that it is possible. I’m not gonna explain all the intricate details on how the thing work. I’ll just show you how to do it with some little explanation. Promise, just a little. Alright? 😛

In a networked computer, there are two things a ‘computer’ must know to communicate to other network devices. The first one is the ‘IP Address’, type ‘ipconfig /all’ to see what’s your IP. It will look something like this.

 "IPv4 Address. . . . . . . . . . . :"

This one was taken from a Windows 7 machine, on Windows XP it’s just “IP Address”. The second one is the MAC address, type getmac and you should see like this.

 "A0-3C-B5-56-E7-DD   \Device\Tcpip_{BEB89E0F-0BC0-42A1-A7D8-C2E9B31ACBF6}"

The “A0-3C-B5-56-E7-DD” is the MAC address.

Therefore, you need to know the IP address of the machine you need to disallow access to your server. In this example, I’m going to assume that ‘’ is the IP address of the machine you need to ‘block’ access from.

[Remote Machine]

IP Address:

MAC Address: 34-6D-0A-56-E2-55

Open your command console then type ‘arp -s 00-00-00-00-00-00’. Verify the command if it’s successful or not by running ‘arp -a’. You should see output similar to this:

Internet Address---Physical Address------Type</p>

Remember that these settings will ‘gone’ away if you restart your server. So if you want to retain the settings, you can ‘write’ the command you used on a *.cmd file and then schedule the file to run every time the computer boots up. 💡

Note: In your *.cmd file just put this line of code -> ‘arp -s 00-00-00-00-00-00’ (without the qoutes) to ban a particular IP from accessing your PC. You can put as many as you can as needed. 😀

What we do is that we introduce a ‘fake’ MAC address in combination to the ‘real’ IP address we want to block on our precious server. And since we ‘manually’ specify the IP Address-to-MAC Address bind, any computer with ‘’ will not be able to ‘change’ the binding dynamically (that is why you can see ‘static’). Since that computer cannot change a ‘static’ entry, that computer will not be able to communicate to the server. As a result, the computer will be cast away from communicating with the server. 😀

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