Sentinel: Network Firewall
See and block app traffic
Only for Mac
Free
Mac
See what your Mac is doing online, understand each decision, and choose what connects. Sentinel keeps your rules and history local.
Sentinel is a private network firewall for macOS. Home explains what is happening on your Mac in plain language, while the map and connection history let you explore where apps connect and what Sentinel did about it.
After you choose to enable its system filter, Sentinel can monitor or control network activity through Apple's Network Extension system. Monitor records unknown connections, Ask lets you decide when an app connects, and Lockdown blocks unknown traffic until you allow it. Rules can match an app and destination, and imported Little Snitch or LuLu rules can help you get started.
Review recent activity, replay map history, search and edit rules, and use temporary modes from the menu bar. A first-run learning period can help you review the apps you use before making rules.
Rules and connection history are stored locally on your Mac. Sentinel has no account, advertising, tracking SDK, analytics SDK, or automatic upload of your connection history. You control retention and can delete local history.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Sentinel 2.0 is a ground-up rebuild. A new Home view explains what needs attention, and a smaller Ask panel lets you decide without losing your place. The night map shows recent routes and marks blocked connections beside your Mac. Rules now have clearer matching and precedence, with Little Snitch and LuLu import. Review apps after a learning period, and switch to temporary modes from the menu bar. The new Beacon design supports light and dark appearances.
The developer, Guangyu Song, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Guangyu Song
- Size
- 16.1 MB
- Category
- Utilities
- Compatibility
Requires macOS 26.0 or later.
- Mac
Requires macOS 26.0 or later.
- Mac
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Guangyu Song