ton - Transfer Over Network

ton is an answer to the problem "I have a file on computer A, and I want to copy it to computer B sitting right next to it on the same network, but I now realise this is nowhere near as easy as it should be in 2022".

ton copies the file or files securely from one machine to the other, provided you have access to both machines, ton is installed on both, and they can see each other on the same network.

This aims to be easier than messing about with USB sticks, or looking up and typing IP addresses, or emailing the file to yourself. No configuration is required other than entering a one-time passphrase on the receiving end.

Usage example

Say you want to transfer myfile.tar.gz from computer A to computer B. Both machines are on the same local network.

1. Run ton push myfile.tar.gz on computer A. ton will generate and print a random four-word passphrase.

2. Run ton pull on computer B. It will prompt for a passphrase. Enter the same passphrase as generated above.

3. The two machines find each other on the network, authenticate to each other using the passphrase, and transfer the file over an encrypted channel. The file lands in the current working directory on computer B.

How it works

The receiving or "pulling" side sends UDP multicast packets to the whole network announcing that it's ready to receive a file, inviting the sending side to connect to it on a TCP port. These announcement packets are sent on every available IPv4 and IPv6 network interface in the hope that at least one of them allows two-way communication. The announcement packets are encrypted with the passphrase.

The sending or "pushing" side listens for these announcement packets, and tries to decrypt them with its passphrase. In the event of a successful decryption, the pushing side makes a TCP connection to the port indicated in the announcement packet.

Both sides authenticate with each other over the TCP connection using the passphrase as a pre-shared key. If this succeeds, the channel is encrypted with this key, and the file is transferred.

Building ton for Linux on Linux

Prerequisites

Install the following packages, if they are not already installed:

• gcc
• libssl-dev
• libcunit1 (only if you want to run the unit tests)
• libcunit1-dev (only if you want to run the unit tests)

Build

Clone the ton git repository to a local directory of your choice, cd to that directory and build ton:

make ton

This produces a binary called ton.

Install

sudo make install

This installs ton in /usr/local/bin/ and the man pages in /usr/local/share/man/.

Use

For help, use ton push -h or ton pull -h as appropriate.

To transfer a file:

• On the sending machine:
  • ton push /path/to/file/or/dir
  • A random passphrase is displayed.
• On the receiving machine:
  • ton pull [/optional/path/to/destination/dir]
  • Enter the passphrase displayed on the pushing side.

Both machines must be on the same network and the passphrases must match. If there's a problem, they'll sit there not being able to find each other. If this happens, you can enable additional verbosity by using the -v option on both sides.

Testing

To build ton with the unit tests:

TON_CUNIT=1 make ton

To run the unit tests:

ton test

Building ton for Windows using MinGW

Building ton on Linux for Windows is possible with MinGW, but there are additional prerequisites. First you need to install mingw64, download the OpenSSL source (and CUnit if required) and build custom MinGW versions of them.

Building a custom MinGW OpenSSL

To configure and build OpenSSL with MinGW:

• Download and unpack the OpenSSL source into a directory of your choice. You want the latest openssl-1-*.tar.gz package.
• Navigate to the unpacked directory.
• ./Configure --cross-compile-prefix=x86_64-w64-mingw32- mingw64
• make

You should now have libssl.a and libcrypto.a, built with MinGW.

Building ton for Windows

ton's Makefile then requires the following environment variables to be set:

• MINGW_OPENSSL_ROOT: the path containing the libssl.a and libcrypto.a files you built with MinGW.
• MINGW_CUNIT_ROOT: the path to the top-level directory containing install/lib/libcunit.a. (This is only required if you're building ton.exe with the unit tests using TON_CUNIT=1.)

Finally, build ton.exe. This is a Windows console application.

make ton.exe

Licensing

ton is released under the 3-Clause BSD License. Run ton licence for more information.

If you build the Windows version using the instructions above, you get a statically-compiled binary which includes the required OpenSSL libraries inside it. Run ton notices for the relevant acknowledgements.