Utility to open TCP port to listen state

netcat should do what you want. Have it listen on you machine and echo stuff to STDOUT:

nc -4 -k -l -v localhost 1026

when you want it to close when the connection ends, don't use -k

You have

TCP Listen: http://www.allscoop.com/tcp-listen.php

Port Peeker: http://www.linklogger.com/portpeeker.htm

Microsoft's Command-line utility Portqry.exe

Try iperf. There is a version for Windows. You can just run it like iperf -s -p 1234, and it will listen on port 1234. You can then connect to that port from a remote machine by doing something like:

telnet 192.168.1.1 1234

iperf -c 192.168.1.1 1234

portqry -n 192.168.1.1 -e 1234

You would need to obtain iperf.exe or portqry.exe for the last two. iPerf isn't strictly designed for this task, but it's great for troubleshooting connectivity, bandwidth availability, stress testing links, etc.

It looks like this utility will do exactly what you want, even displaying the received data if you like: http://www.drk.com.ar/builder.php

It has a GUI rather than just a command line, an advantage for some.