croc is a tool that allows any two computers to simply and securely transfer files and folders. AFAIK, croc is the only CLI file-transfer tool does all of the following:

• allows any two computers to transfer data (using a relay)
• provides end-to-end encryption (using PAKE)
• enables easy cross-platform transfers (Windows, Linux, Mac)
• allows multiple file transfers
• allows resuming transfers that are interrupted
• local server or port-forwarding not needed
• faster than wormhole, rsync, scp through compression and multiplexing (speedups 1.5x to 4x)
• supports ipv6

For more information about croc, see my blog post.

Install

Download the latest release for your system, or install a release from the command-line:

$ curl https://getcroc.schollz.com | bash

On macOS you can install the latest release with Homebrew:

$ brew install schollz/tap/croc

On Windows you can install the latest release with Scoop:

$ scoop install croc

On Unix you can install the latest release with Nix:

$ nix-env -i croc

On Arch Linux you can install the latest release with pacman:

$ pacman -S croc

On Ubuntu you can install with snap:

$ snap install croc

Or, you can install Go and build from source (requires Go 1.12+):

$ GO111MODULE=on go get -v github.com/schollz/croc/v8

Usage

To send a file, simply do:

$ croc send [file(s)-or-folder]
Sending 'file-or-folder' (X MB)
Code is: code-phrase

Then to receive the file (or folder) on another computer, you can just do

$ croc code-phrase

The code phrase is used to establish password-authenticated key agreement (PAKE) which generates a secret key for the sender and recipient to use for end-to-end encryption.

There are a number of configurable options (see --help). A set of options (like custom relay, ports, and code phrase) can be set using --remember.

Custom code phrase

You can send with your own code phrase (must be more than 4 characters).

$ croc send --code [code-phrase] [file(s)-or-folder]

Use pipes - stdin and stdout

You can pipe to croc:

$ cat [filename] | croc send

In this case croc will automatically use the stdin data and send and assign a filename like "croc-stdin-123456789". To receive to stdout at you can always just use the --yes will automatically approve the transfer and pipe it out to stdout.

$ croc --yes [code-phrase] > out

All of the other text printed to the console is going to stderr so it will not interfere with the message going to stdout.

Self-host relay

The relay is needed to staple the parallel incoming and outgoing connections. By default, croc uses a public relay but you can also run your own relay:

$ croc relay

By default it uses TCP ports 9009-9013. Make sure to open those up. You can customized the ports (e.g. croc relay --ports 1111,1112), but you must have a minimum of 2 ports for the relay. The first port is for communication and the subsequent ports are used for the multiplexed data transfer.

You can send files using your relay by entering --relay to change the relay that you are using if you want to custom host your own.

$ croc --relay "myrelay.example.com:9009" send [filename]

Note, when sending, you only need to include the first port (the communication port). The subsequent ports for data transfer will be transmitted back to the user from the relay.

Self-host relay (docker)

If it's easier you can also run a relay with Docker:

$ docker run -d -p 9009:9009 -p 9010:9010 -p 9011:9011 -p 9012:9012 -p 9013:9013 -e CROC_PASS='YOURPASSWORD' schollz/croc

Be sure to include the password for the relay otherwise any requests will be rejected.

$ croc --pass YOURPASSWORD --relay "myreal.example.com:9009" send [filename]

License

MIT

Acknowledgements

croc has gone through many iterations, and I am awed by all the great contributions! If you feel like contributing, in any way, by all means you can send an Issue, a PR, ask a question, or tweet me (@yakczar).

Thanks @warner for the idea, @tscholl2 for the encryption gists, @skorokithakis for code on proxying two connections. Finally thanks for making pull requests @maximbaz, @meyermarcel, @Girbons, @techtide, @heymatthew, @Lunsford94, @lummie, @jesuiscamille, @threefjord, @marcossegovia, @csleong98, @afotescu, @callmefever, @El-JojA, @anatolyyyyyy, @goggle, @smileboywtu, @nicolashardy, @fbartels, @rkuprov, @xenrox and Ipar!