Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing. All servers and clients may run simultaneously.
Packet Sender was designed to be very easy to use
while still providing enough features for power users.
Using its command line tool or hotkeys
Using the built-in UDP / TCP / SSL clients
using the built-in UDP / TCP / SSL servers
by having 2 Packet Senders talk to each other
by sending customers a portable Packet Sender with pre-defined settings and packets
Send SSL and then analyze the traffic log.
Packet Sender is open source. It will always be free.