Excellent Utilities: croc – securely transfer files and folders

Last Updated on May 13, 2023

In Operation

croc is a command-line app. Almost all the functionality of the tool uses its send command. Let’s say we want to send a folder to another machine securely. At the command line we issue the command:

$ croc send folder-name

The tool reports how many files and the total size of the files together with the command to issue on the receiving computer.

The short video below shows us transferring a folder called Remixing which contains 13 files. We issue the command:

sde@ganges:~$ croc send Remixing

As you can see, we’re instructed to enter the command croc 2714-liter-compass.pogo on the other computer.

The image below shows that we’ve entered the command on the other computer and received the folder containing the 13 files. It’s that simple.


As you may realize, this transfer was performed between two machines on a local network. But croc allows any two computers to transfer data.

What else does croc offer?

  • Provides end-to-end encryption (using PAKE). In cryptography, a password-authenticated key agreement method is an interactive method for two or more parties to establish cryptographic keys based on one or more party’s knowledge of a password.An important property is that an eavesdropper or man-in-the-middle cannot obtain enough information to be able to brute-force guess a password without further interactions with the parties for each (few) guesses.
  • Enables easy cross-platform transfers (Linux, Android, macOS, and Windows).
  • Allows multiple file transfers.
  • Allows resuming transfers that are interrupted.
  • Uses transmission and therefore does not need a server or port forwarding.

The software also can use a proxy, it defaults to IPv6 (IPv4 as a fallback), define parameters like the sender IP, address of the relay, and password for the relay. We can throttle the upload speed if necessary, disable compression, and even use a built-in DNS stub resolver.

Next page: Page 3 – Summary

Pages in this article:
Page 1 – Introduction / Installation
Page 2 – In Operation
Page 3 – Summary

Complete list of articles in this series:

Excellent Utilities
AES CryptEncrypt files using the Advanced Encryption Standard
AnanicyShell daemon created to manage processes’ IO and CPU priorities
brootNext gen tree explorer and customizable launcher
CerebroFast application launcher
cheat.shCommunity driven unified cheat sheet
CopyQAdvanced clipboard manager
crocSecurely transfer files and folders from the command-line
DeskreenLive streaming your desktop to a web browser
dufDisk usage utility with more polished presentation than the classic df
ezaA turbo-charged alternative to the venerable ls command
Extension ManagerBrowse, install and manage GNOME Shell Extensions
fdWonderful alternative to the venerable find
fkillKill processes quick and easy
fontpreviewQuickly search and preview fonts
horcruxFile splitter with encryption and redundancy
KoohaSimple screen recorder
KOReaderDocument viewer for a wide variety of file formats
ImagineA simple yet effective image optimization tool
LanguageToolStyle and grammar checker for 30+ languages
Liquid PromptAdaptive prompt for Bash & Zsh
lnavAdvanced log file viewer for the small-scale; great for troubleshooting
lsdLike exa, lsd is a turbo-charged alternative to ls
Mark TextSimple and elegant Markdown editor
McFlyNavigate through your bash shell history
mdlessFormatted and highlighted view of Markdown files
notiMonitors a command or process and triggers a notification
NushellFlexible cross-platform shell with a modern feel
nvitopGPU process management for NVIDIA graphics cards
OCRmyPDFAdd OCR text layer to scanned PDFs
Oh My ZshFramework to manage your Zsh configuration
PaperworkDesigned to simplify the management of your paperwork
pastelGenerate, analyze, convert and manipulate colors
PDF Mix ToolPerform common editing operations on PDF files
pecoSimple interactive filtering tool that's remarkably useful
ripgrepRecursively search directories for a regex pattern
RnoteSketch and take handwritten notes
scrcpyDisplay and control Android devices
StickySimulates the traditional “sticky note” style stationery on your desktop
tldrSimplified and community-driven man pages
tmuxA terminal multiplexer that offers a massive boost to your workflow
TuskAn unofficial Evernote client with bags of potential
UlauncherSublime application launcher
WatsonTrack the time spent on projects
Whoogle SearchSelf-hosted and privacy-focused metasearch engine
ZellijTerminal workspace with batteries included
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