Harald Welte

OpenPCD is an open-source RFID reader design platform that is available for free. It serves as a reference for designing and building RFID readers.

Netfilter Userspace Packet Logging is a software solution that enables logging of packet data by acting as a middleman between the kernel and the network stack. The tool can be used to monitor and analyze network traffic for security or other purposes.

Iptables: a Linux packet control tool.

Free tools for Linux system administrators to interact with Connection Tracking System are available through a set of userspace software programs.