What is Passive Network Measurement

Computer forensic is the practice of collecting, analyzing, and reporting digital evidence in a way that is legally admissible in open court. Network forensics, an offset of computer forensic, is mainly concerned with the monitoring and analysis of network traffic, both local and WAN/internet, in order to identify security incidents and to investigate fraud or network misuse. In this chapter, the authors discuss challenges in creating high-speed network forensic tools and propose NetTrack, a tamper-proof device aimed to produce evidences with probative value via digital signatures for the network traffic. Since digitally signing each IP packet is not efficient, the authors used a specific technique exploiting the Merkle trees to create digital signatures for flows and multicasts and implemented it by using an optimized algorithm for Merkle tree traversal to save space and time. Through experiments, the authors show NetTrack signing is fast as it can produce digital evidence within a short time.