Attacks on computer networks are increasing and are more sophisticated than ever in today's network environment. One step to address the growing wave of attacks is the availability of a system that can trace attack packets back to their original sources, regardless of invalid or manipulated source addresses. This project presents an innovative use of these maps to influence IP tracing in general and packet marking schemes in particular. The trust-based deterministic packet marking approach is capable of tracing attacks that consist of only a few packets. Since a trust relationship is maintained between routers to disclose the attacker's information, the overall effort for tracing will be minimal. Furthermore, a service provider can implement this scheme without revealing its internal network topology.