Estimates show that up to 800-900 million people depend on IPv4 for their daily communications needs. Since the inception of the Internet, IPv4 has assumed an unprecedented importance in the global scale. IPv4 implementations are found in almost all modern computer systems. This includes routers, switches, firewalls, desktop and server systems, laptops, PDAs, cell phones and other mobile systems, as well as a large number of various embedded systems. All of these devices are vulnerable to exploitation through externally-supplied malformed protocol data. Effects of malicious data range from transient parsing errors to complete system takeovers. As IPv4 and its associated protocols (TCP, UDP, ICMP, IGMP, ARP) are in an extremely crucial role in modern society, the dependability and reliability of IPv4 implementations must be verified. IPv4 implementations are often tightly coupled with the underlying operating system, which means that serious flaws in IPv4 protocol handling may easily result in total system compromises. Defensics IPv4 Test Suite helps prevent this by making IPv4 implementations more robust.