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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 that doesall of the following:

• allowsany two computers to transfer data (using a relay)
• providesend-to-end encryption (using PAKE)
• enables easycross-platform transfers (Windows, Linux, Mac)
• allowsmultiple file transfers
• allowsresuming transfers that are interrupted
• local server or port-forwardingnot needed
• ipv6-first with ipv4 fallback
• canuse proxy, like tor

For more information aboutcroc, seemy blog post or read arecent interview I did.

Downloadthe 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 withHomebrew:

brew install croc

On macOS you can also install the latest release withMacPorts:

sudo port selfupdatesudo port install croc

On Windows you can install the latest release withScoop,Chocolatey, orWinget:

scoop install croc

choco install croc

winget install schollz.croc

On Unix you can install the latest release withNix:

nix-env -i croc

On Alpine Linux you have to install dependencies first:

apk add bash coreutilswget -qO- https://getcroc.schollz.com | bash

On Arch Linux you can install the latest release withpacman:

pacman -S croc

On Fedora you can install withdnf:

dnf install croc

On Gentoo you can install withportage:

emerge net-misc/croc

On Termux you can install withpkg:

pkg install croc

On FreeBSD you can install withpkg:

pkg install croc

Or, you caninstall Go and build from source (requires Go 1.17+):

go install github.com/schollz/croc/v9@latest

On Android there is a 3rd party F-Droid appavailable to download.

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.

You can send with your own code phrase (must be more than 6 characters).

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

By default, croc will prompt whether to overwrite a file. You can automatically overwrite files by using the--overwrite flag (recipient only). For example, receive a file to automatically overwrite:

croc --yes --overwrite <code>

You can pipe tocroc:

cat [filename] | croc send

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

croc --yes [code-phrase] > out

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

Sometimes you want to send URLs or short text. In addition to piping, you can easily send text withcroc:

croc send --text "hello world"

This will automatically tell the receiver to usestdout when they receive the text so it will be displayed.

You can use a proxy as your connection to the relay by adding a proxy address with--socks5. For example, you can send via a tor relay:

croc --socks5 "127.0.0.1:9050" send SOMEFILE

You can choose from several different elliptic curves to use for encryption by using the--curve flag. Only the recipient can choose the curve. For example, receive a file using the P-521 curve:

croc --curve p521 <codephrase>

Available curves are P-256, P-348, P-521 and SIEC. P-256 is the default curve.

You can choose from several different hash algorithms. The default is thexxhash algorithm which is fast and thorough. If you want to optimize for speed you can use theimohash algorithm which is even faster, but since it samples files (versus reading the whole file) it can mistakenly determine that a file is the same on the two computers transferring - though this is only a problem if you are syncing files versus sending a new file to a computer.

croc send --hash imohash SOMEFILE

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 of2 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.

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

docker run -d -p 9009-9013:9009-9013 -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]

Note: when including--pass YOURPASSWORD you can instead pass a file with the password, e.g.--pass FILEWITHPASSWORD.

MIT

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, or ask a question.

Thanks@warner for theidea,@tscholl2 for theencryption gists,@skorokithakis forcode 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,@hreese,@xenrox andIpar!