smoltcp - Standalone, event-driven TCP/IP stack that is designed for bare-metal, real-time systems.
tcpgoon - Test concurrent connections towards a server listening to a TCP port.
Warp speed Data Transfer (WDT) - Embeddedable library (and command line tool) aiming to transfer data between 2 systems as fast as possible over multiple TCP paths.
netscanner - TCP/UDP scanner to find open or closed ports.
MASSCAN - TCP port scanner, spews SYN packets asynchronously, scanning entire Internet in under 5 minutes.
clobber - TCP load testing tool, written in async Rust.
TCPause - Zero-downtime proxy for TCP and UNIX sockets written in Go.
Toxiproxy - TCP proxy to simulate network and system conditions for chaos and resiliency testing.