A method and system for tracing internet protocol packets is disclosed. One aspect of the method involves generating traceback packets containing information relating to their origin, destination, and encountered devices. The generated traceback packets can differ depending on the network configuration and Internet traffic scenarios. Another aspect involves analyzing incoming Internet traffic and generating traceback packets based on the performed analysis. Another aspect involves discovering a denial-of-service attack. Another aspect involves modifying operational parameters in response to the attack. One aspect of the system involves traceback servers, which can collect and provide traceback information to the public or on a private network. Another aspect involves the dissemination of traceback information to interested and/or authorized parties.