The inefficiencies of current intrusion detection system against fraudulent cyber activities attracts the attention of computer gurus, also known as “hackers” to exploit known weakness on a particular host or network. These hackers are expert programmers who mainly focus on how the Internet works, and they interact with each other to know its strengths and weaknesses. Then they develop advanced tools which an average attacker with little background can use to know the liveness, reachability and running service on the network. Once an attacker identifies these details, he can accurately launch an effective attack and get maximum benefit out of it with less probability of attack detection. In this paper, a system that opens ports on a firewall by generating a connection attempt on a set of pre-specified closed ports is established. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host that sent the connection attempts to connect over specific port(s). This conceals and protects network services which are running on the computer.