File Tunnel

Tunnel TCP connections through a file.

Download

Portable executables for Windows, Linux and Mac can be found over in the releases section.

Example 1 - Bypassing a firewall

You'd like to connect from Host A to Host B, but a firewall is in the way. But both hosts have access to a shared folder.

Host A

ft.exe -L 5000:127.0.0.1:3389 --write "\\server\share\1.dat" --read "\\server\share\2.dat"

This command listens for connections on port 5000. When one is received, it is forwarded through the file tunnel and then onto 127.0.0.1:3389.

Host B

ft.exe --read "\\server\share\1.dat" --write "\\server\share\2.dat"

Now on Host A, connect the client to 127.0.0.1:5000 and it will be forwarded to the remote server.

This is what the File Tunnel looks like when operating:

Example 2 - Tunnel TCP through RDP (similar to SSH tunnel)

You'd like to connect to a remote service (eg. 192.168.1.50:8888), but only have access to Host B using RDP.

Host A

ft.exe -L 5000:192.168.1.50:8888 --write "C:\Temp\1.dat" --read "C:\Temp\2.dat"

Run an RDP client and ensure local drives are shared as shown here.

RDP to Host B.

Host B

ft.exe --read "\\tsclient\c\Temp\1.dat" --write "\\tsclient\c\Temp\2.dat"

Now on Host A, you can connect to 127.0.0.1:5000 and it will be forwarded to 192.168.1.50:8888

Other interesting features

• -L can be used multiple times, to forward numerous ports through the one tunnel.

• To enable other computers to use the tunnel, specify a binding address of 0.0.0.0. For example: -L 0.0.0.0:5000:192.168.1.50:3389 allows any computer on the network to connect to the tunnel and onto 192.168.1.50:3389

• Use -R for remote forwarding. For example: -R 5000:10.0.0.50:6000 instructs the remote side to listen on port 5000, and when a connection is received forward it through the tunnel and onto 10.0.0.50:6000 via the local machine. This allows you to share a server running on your local machine, with other computers.

• The read and write files don't have to be in the same folder or even server.

How does it work?

The program starts a TCP listener, and when a connection is received it writes the TCP data into a file. This same file is read by the counterpart program, which establishes a TCP connection and onforwards the TCP data. To avoid the shared file growing indefinitely it is purged whenever it gets larger than 10 MB.