Socket Programming

[krellor]

I was wondering if anyone could help point me in the right direction on this question. I am writing a network application in C/C++ that requires closing ports, and keeping them closed until a specified condition is met, or the program is terminated. I am learning socket programming, but am reasonabley fluent in C/C++. My problem is that I know the commands used for closing ports, and how to setup multiplexing, etc... but I do not know of a way to keep a port closed to other applications. (i.e. I close port 80, but internet explorer just re-creates the connection.) I develop with winsock, and *nix headers, so a solution/resource that applies to either platform would be helpful. Any help is appreciated.