In computer networking, the term IP address spoofing or IP spoofing refers to the creation of Internet Protocol (IP) packets with a forged source IP address, called spoofing, with the purpose of concealing the identity of the sender or impersonating another computing system. The IP spoofing security weakness was published by S. M. Bellovin (1989). However, not much attention has been paid to the security weaknesses of the TCP/IP protocol by the general public. This is changing as more people and companies are connecting to the Internet to conduct business. This thesis is on ―Today's Impact on Communication System by IP Spoofing and Its Detection and Prevention‖. This paper contains an overview of IP address and IP Spoofing and its background. It also shortly discusses various types of IP Spoofing, how they attack on communication system. This paper also describes some methods to detection and prevention methods of IP spoofing and also describes impacts on communication system by IP Spoofing.