GoKawiilEvery time an application on your computer opens a network connection, it does so quietly, without asking. Little Snitch for Linux makes that activity visible and gives you the option to do something about it. You can see exactly which applications are talking to which servers, block the ones you didn't invite, and keep an eye on traffic history and data volumes over time.
Getting started
Once installed, open the user interface by running littlesnitch in a terminal, or go straight to http://localhost:3031/ . You can bookmark that URL, or install it as a Progressive Web App. Any Chromium-based browser supports this natively, and Firefox users can do the same with the Progressive Web Apps extension.
Watching your connections
The connections view is where most of the action is. It lists current and past network activity by application, shows you what's being blocked by your rules and blocklists, and tracks data volumes and traffic history. Sorting by last activity, data volume, or name, and filtering the list to what's relevant, makes it easy to spot anything unexpected. Blocking a connection takes a single click.
The traffic diagram at the bottom shows data volume over time. You can drag to select a time range, which zooms in and filters the connection list to show only activity from that period.
Keeping blocklists
Blocklists let you cut off whole categories of unwanted traffic at once. Little Snitch downloads them from remote sources and keeps them current automatically. It accepts lists in several common formats: one domain per line, one hostname per line, /etc/hosts style (IP address followed by hostname), and CIDR network ranges. Wildcard formats, regex or glob patterns, and URL-based formats are not supported. When you have a choice, prefer domain-based lists over host-based ones, they're handled more efficiently. Well known brands are Hagezi, Peter Lowe, Steven Black and oisd.nl, just to give you a starting point.
One thing to be aware of: the .lsrules format from Little Snitch on macOS is not compatible with the Linux version.
Writing your own rules
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