README.md

gday

Command line tool to securely send files (without a relay or port forwarding).

peer_1: gday send file.mp4 folder
Tell your mate to run "gday get 1.n5xn8.wvqsf".

peer_2: gday get 1.n5xn8.wvqsf
Transfer complete.

Installation

To run the executable directly:

1. Download an executable from releases.
2. Extract it (on Linux: tar xf <file>).
3. Run it: ./gday

To install with cargo:

cargo install gday

To install with brew:

brew install manforowicz/tap/gday

Features

• No limit on the size of files and folders sent.

• Files are sent directly, without relay servers. A server is only used to exchange socket addresses at the beginning.

• Automatically resumes interrupted transfers. Just gday send the same files, and partial downloads will be detected and resumed.

• Doesn't require port forwarding. Instead, uses TCP Hole Punching to traverse NATs. This may not work on very restrictive NATs. If that happens, enable IPv6 or move to a different network.

• If a contact exchange server is down, just uses a different one from the default list. Or specify your own with --server.

• Server connection encrypted with TLS and file transfer is over TCP that's end-to-end encrypted with ChaCha20Poly1305.

• Automatically tries both IPv4 and IPv6.

• Resistant to malicious servers impersonating your peer. Uses SPAKE2 to derive an encryption key from a shared secret.

• No unsafe Rust in this repository.

Usage

Usage: gday [OPTIONS] <COMMAND>

Commands:
  send  Send files and/or directories
  get   Receive files
  help  Print this message or the help of the given subcommand(s)

Options:
  -s, --server <SERVER>        Use a custom gday server with this domain name
  -p, --port <PORT>            Connect to a custom server port
  -u, --unencrypted            Connect to server with TCP instead of TLS
  -v, --verbosity <VERBOSITY>  Verbosity. (trace, debug, info, warn, error) [default: warn]
  -h, --help                   Print help
  -V, --version                Print version

Similar Projects

	No relays	Works beyond LAN	Works through very strict NATs	No port forwarding	Encrypted	Can resume interrupted transfers
gday	✅	✅	❌	✅	✅	✅
magic-wormhole	❌	✅	✅	✅	✅	✅
croc	❌	✅	✅	✅	✅	✅
p2pcopy	✅	✅	❌	✅	❌	❌
qft	✅	❌	❌	✅	❌	❌
iwant	✅	❌	❌	✅	❌	❌
zget	✅	❌	❌	✅	❌	❌
sharedrop	❌	✅	✅	✅	✅	❌
filepizza	❌	✅	✅	✅	✅	❌
Personal SSH or HTTPS	✅	✅	✅	❌	✅	❌
Personal FTP	✅	✅	✅	❌	❌	❌
Dropbox, Google Drive, etc.	❌	✅	✅	✅	✅	❌
Delivering a USB drive	✅	✅	✅	✅	✅	❌

Open an issue to add more projects to this list.

Technical Overview

1. Peer A randomly generates a "room code" and a "shared secret".

2. Peer A randomly selects a gday server ID and connects to it over TLS.

3. Peer A sends its room code and its local IP address and port number to the gday server.

4. Peer A combines the server's ID, room code, and shared secret into a code of form "1.n5xn8.wvqsf".

5. Peer A tells this code to Peer B, possibly via phone call or text message.

6. Peer B also sends this room code and its local IP address and port number to the gday server.

7. The gday server sends both peers the public and local IP addresses and ports of the other peer.

8. From the same local port that they used to connect to the server, each peer tries a few times to connect over TCP to both the local and public socket addresses of the other peer.

9. Once any of the connection attempts succeeds, they use password-authenticated key exchange to derive a strong shared key from their shared secret, and use it to encrypt their TCP connection with chacha20poly1305.

10. Peer A sends Peer B a list of offered files and their sizes.

11. Peer B checks for files left over from any previous interrupted downloads, and replies with the file portions it would like to receive.

12. Peer A sends all the accepted files to Peer B, back-to-back.

In this repository

• gday - Command line tool for sending files.
• gday_server - Server that lets two peers share their socket addresses.
• gday_hole_punch - Library for establishing peer-to-peer TCP connection.
• gday_file_transfer - Library for transferring files over a connection.
• gday_encryption - Library for encrypting an IO stream.
• gday_contact_exchange_protocol - Library with protocol for two peers to share their socket addresses via a server.

See CONTRIBUTING.md if you'd like to contribute to this project.