TCP Listen – Firewall Testing Tool

This is a handy little program for testing and troubleshooting.

Enter a port to listen on and it will show incoming connections to that port. This can be useful if you are trying to setup connectivity through a firewall or a router.

This could also be used as a security tool to make it appear you are running a service on a standard port, by having the tool respond, while the services is really running on a different port.

Very small single file is only 48k in size.

Get TCP Listen

TCP Listen

Similar Posts

38 Comments

  1. Hi,

    Is it possible to listen multiple ports at same time. Or can it take source ports from a flat file and listen to all at once.

  2. Hi. Does this create a listener process on the port, similar in the way NetCat does, or does this snoop the interface?

  3. THANK YOU!!! If you ever want to enhance it, I suggest to add a multiport (add) system like splited with commas or an interval (x1,x2,x3,…,xn for different ports or y1-y2 for all ports between y1 and y2) or reading from a csv file, or any other simple way. A port stopper would be cool too, and show which IP the incoming connection came from would allow other purposes. And please note Note that this tool is really really great just as it is.

  4. Great Thanks. Similar to other comments, a way to add multiple ports, or a port range. Even from a .txt file would be good.

    How about a command line option referencing the text file of ports to start monitoring at open.

    Nice simple reliable program. Thanks.

  5. would there be any chance of a version able to output results in a TXT file? I have to capture raw data from point of sale sources to create a parsers for a data event monitoring solution.

      1. Agreed. Trying to run this on 2012 R2 or 2016 and don’t want to have to use versions of .NET lower than 4.x.

  6. Cool tool but once I try to connect to the port on the 2nd or 3rd time it says an error occured, the port may be in use when running nmap scan against it that specific port

  7. Thanks a ton. Really handy when I needed this, and an awesome project to add to my collection of tools to write

  8. The program opens on Server 2016, but I can’t get a source computer to connect to any ports I put in. It says it’s listening too. Just wondering if it works for others on Server 2016. Thanks ahead!

Leave a Reply

Your email address will not be published. Required fields are marked *