Block a Local Port

I need your help.If anybody can give me the solution of my Query that is:- I want to block a local port so that no service can run on this port.like if I want to stop ftp service on my computer then I'll have to block port no:21 but ques is how? How I can stop this service from running.If you have some code snippet for this or some other dll or exe to whom I can send the coomand with a port number then plz send it to [email protected]

Thanks

If you want to stop a service (FTP, MAIL) then you can use the net command:
[Highlight=VB]
net stop "Name of the service"
[/vbocde]
run that in a dos-box or use the SHELL command from VB.