Flynn

A local-first network monitor and firewall. Flynn logs every connection a device makes, lets you investigate them in an explorer, and blocks or allows by app, domain, IP or port. Nothing leaves the device by default.

Status: early development. iOS and iPadOS come first, then Android on the same core, then desktop. See docs/Flynn-plan.md for the product plan and docs/development-plan.md for the build order.

What Flynn can and cannot see

Flynn aims to log everything, but no app can see everything, and Flynn says so rather than implying otherwise.

Layer	What Flynn sees	What Flynn can do
App traffic through the tunnel	App (on supervised iOS devices and Android), domain, IP, port, bytes, timing	Allow, block
App traffic that goes around the tunnel	That it happened and how much, not where it went	Flag it; force traffic through the tunnel
Traffic the OS never gives any app (DHCP, captive portal sign-in, VoLTE, calls, SMS, paired-watch traffic)	Not the traffic, only the event and the reason	Record it in the gap log
Bluetooth, NFC, Wi-Fi Direct	Connection events where the platform exposes them	Log and alert; point to the system setting that stops it

Whatever Flynn cannot block, it logs. Where it cannot log the traffic, it logs the gap.

Layout

core/      Rust workspace: parsers, rules, data plane, store, enrichment, FFI, host harness
apple/     iOS and iPadOS app and Network Extensions (Xcode project generated by XcodeGen)
android/   reserved for Phase 2
scripts/   build and check scripts
data/      source lists compiled into bundled lookup tables
docs/      plans, spike results, device checklists

Building

Requirements: Xcode 26 or newer, rustup, XcodeGen (brew install xcodegen).

scripts/bootstrap.sh

That installs the Rust targets, builds the core as an XCFramework, generates the Swift and Kotlin bindings and generates apple/Flynn.xcodeproj. To run every check:

scripts/check.sh

Network Extensions do not run in the iOS Simulator. The app runs there against a mock capture source; capture itself needs a real device and an Apple Developer Program team.

Licence

MPL-2.0.