Little Snitch is not available for Linux but there are some alternatives that runs on Linux with similar functionality. The best Linux alternative is OpenSnitch, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Little Snitch and five of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Little Snitch are Portmaster (Free, Open Source), Douane (Free, Open Source), upribox (Free, Open Source) and InJoy Firewall (Paid).
All-Around System Privacy Since the Portmaster sits on your kernel, you can finally protect your whole computer, not just your browser. Do you want to block Ads and Analytics for your whole operating system? The Portmaster has you covered.
Douane is a personal firewall that protects a user's privacy by allowing a user to control which applications can connect to the internet from their GNU/Linux computer. You can allow network traffic for some applications and deny network traffic for others.