The exit-node host rules existed only for Linux (iptables + policy routing);
macOS reported "only supported on Linux yet".
Offering: a pf anchor com.apple/tsunagi-exit-<if> (evaluated by the stock
pf.conf) holds a nat rule per offered range and a pass-in rule. pf is enabled
if needed and the pfctl -E reference is released when the rules are removed.
net.inet.ip.forwarding is only read, never written, as on Linux.
Using: macOS has no uidrange policy routing and the agent is root, so the
overlay gets 0.0.0.0/1 and 128.0.0.0/1 routes and a pf route-to rule (matched
by the agent's uid) sends the agent's own QUIC/relay traffic back out the
physical interface, translated to its address. The rules are loaded before the
routes, so a failed load never sends traffic into a tunnel it cannot exempt
the agent from. IPv6 is blocked with rejecting ::/1 and 8000::/1 routes.
ExitHostPlan gains `overlay` (every network range) for the route-to exemption;
Linux ignores it.
Known limits: the egress is the default route's interface at apply time; other
root processes also bypass the tunnel. Forwarding hints in the CLI and tray
name the macOS sysctl. The rule text and command order are unit-tested with a
scripted host; nothing was run against a live pf/route (needs root), so the
route-to + nat second-pass behaviour is unverified.
Checks: cargo fmt --check, cargo clippy --locked --workspace --all-targets
-D warnings and cargo test --locked --workspace --all-targets, run on macOS
only.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
UltradesuandClaude Sonnet 5.5
47c5d38d0c