Need to block any IP on a computer by coding in .Net (C#). Anyone know the best/easiest way to do this?

Question

I am playing around with a way to kick cheaters in Modern Warfare 2 (when you are the host). So far I have been able to use winpcap to sniff packages to identify the player names and their IPs.

The next thing I need is a way to block all traffic (or just the target IPs UDP traffic to my machine). Hence the player will timeout/lagout.

Does anyone know of an available library that lets me do this easily. I could go about doing this the hard way and install Windows DDK and mess around in C++ to create a low level NDIS driver, but being überly rusty on C++ and all the typical compile issues that comes when compiling template code for this, I really prefer some ready coded library for this.

Or maybe someone has a better idea that would work?

Solution: Use Windows Firewall. Easy API to create and remove rules on the fly. http://stackoverflow.com/questions/1242566/any-way-to-turn-the-internet-off-in-windows-using-c

And a a test program that does this now works. I kicked 2 people out of the game :))

Answer 1

You should be able to put an invalid entry for that IP into the Windows Hosts file. Here's some C# code that might work for you.

This place discusses a way to use IPSec to filter IP addresses. It's very manual though. Here's the process:

Under Local Security Settings / IP Security Policies

1. Create a new IP Filter list
2. Source IP is My IP address
3. Destination (in this example) is 129.74.250.101 (nd.edu)
4. Protocol is any
5. Create a new IP Security Policy (use Kerberos 5 authentication)
6. Add an IP Security Rule (this rule is not a tunnel) (all network connections)
7. Add the new IP filter list that you just created. (require security)
8. Assign the new policy

If you could figure out how to do that in C#, you're a winner.

Answer 2

Are you running a firewall? Maybe you could use the firewall's API to reject connection requests from the offending host. For example, the "Windows Firewall with Advanced Security" API is probably available on a lot of PCs.