PortProxy
 
  PortProxy is a TCP connection forwarding service that I wrote in college so that I could run servers from behind a firewall. When I put Linux onto resnet.bryant.edu, I no longer needed this program, but it's still cool if you are running Windows. I also wrote a version that runs as a system tray application in Windows 95.
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Configuration
PortProxy stores its configuration in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PortProxy\Parameters registry key. It can be dynamically configured using a command line interface via a localhost telnet connection to port 256.
When connected to the configuration command line interface, the following commands can be used. Each command is terminated with a newline character. Responses from the server begin with either a plus sign (+) for a positive response or a minus sign (-) for a negative response, similar to DirList Server's protocol.
| Command | Parameters | Meaning | 
|---|---|---|
| + | port intaddr intport 6 | Adds a forwarded port 
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| - | port | Removes a forwarded port 
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| s | port | Returns whether or not the given local port is being forwarded by PortProxy 
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| t | port | Tests a local port for use by PortProxy or another application 
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| x | Closes PortProxy | |
| n | No operation (no-op) |