p.sen
TCP/UDP Network Test Utility
P.SEN is a utility to allow sending and receiving TCP and UDP packets and is available for Windows and Linux. It's designed to be very easy to use while still providing enough features for power users to do what they need. It is completely free (no ads / no bundleware) and opensource. Some knowledge of a basic network protocols is a prerequisite to using it. Beyond that, P.SEN was designed to be very easy to use.