As we enter the age of universal electronic connectivity in which viruses, hackers, electronic eavesdropping, and electronic fraud can threaten the prosperity and productivity of corporations and individuals, security is increasingly important. Fortunately, the discipline of network security has matured, leading to the development of practical, available applications to enforce network security. This book provides an integrated, comprehensive, up-to-date coverage of internet-based security tools and applications vital to any treatment of data communications or networking.