Router Security Strategies: Securing IP Network Traffic Planes

Appendix B. IP Protocol Headers

Many network attacks are accomplished by manipulating or spoofing the packet header fields within TCP/IP protocols. With few exceptions, these protocol header fields can be manipulated or spoofed by an attacker to achieve one of two broad goals: circumvent security policies (to steal or modify data), or cause a denial of service (DoS) condition somewhere within the network. The fact that protocol header value manipulation and spoofing can be used to accomplish these goals is made possible because of the following reasons:

• Protocol weaknesses: Many protocol definitions are insufficiently specific or lack inherent security mechanisms, leaving them exposed to manipulation and spoofing. For example, ICMP is designed ...