I have had a look online but can't seem to find what I want. I can find RDP clients for Linux but that is not what I want. I am looking for some software so that a Linux server can be used as a relay or proxy.
The idea is that the Windows server is on a local network and has no direct access to the internet. It all goes through this Linux server which is acting like a hardware firewall and proxy for other things. When people want to connect to the Windows server, the idea is that they would connect to the IP of the Linux server which would then relay the request to the Windows server, meaning the end user logs in via RDP to the Windows server through the Linux server.
To try explaining it visually, the connection would look similar to this:
Client --> Linux --> Windows
I want to make is so the client doesn't have to do anything special, just simply connect to the IP as they normally would for RDP. The Linux server would basically be receiving the request (on port 3389) and simply forwarding it all to the Windows server.
I'm not sure if I've explained myself well enough so if anything needs clarifying, please let me know.