iperf3
iperf3: A TCP, UDP, and SCTP network bandwidth measurement tool
...It supports TCP, UDP, and SCTP testing, making it useful for a wide range of network troubleshooting and benchmarking scenarios. The tool reports throughput, bitrate, packet loss, and other measurement details for each test. iperf3 was redesigned from the original iperf with a smaller codebase, a cleaner architecture, and library functionality that can be used by other programs. It includes features such as zero-copy mode, optional JSON output, protocol tuning, buffer tuning, and timing controls. Overall, it is a trusted utility for network engineers, research networks, developers, and administrators who need reliable active bandwidth testing.