ZMap is a fast single packet network scanner for network surveys
Cross-platform, C implementation of the IETF QUIC protocol
Communication framework for data-centric high-performance applications
Packet generator and packet editor for Windows, Linux, BSD, and macOS
Very fast network stress tool
tcptrace analyzes packet tcp connections and provides analysis
Xplico is a Network Forensic Analysis Tool (NFAT)
PCAP from another point of view
Linux Server and Data-Center WAN Optimization
Hexadecimal and raw packet injector and sniffer.
Zero copy MMAP linux network drivers
...has moved to packetpeeper.org
A simple packet sniffer for local networks
Simple Multi Protocol Packet Sniffer - SMPPS
Example for a sercos III Network Driver