10. Feed Filter

1. What Feed Filter does

Feed Filter filters messages before they are propagated to the rest of the system.

2. Main options

1. Enable Feed Filter enables/disables filtering globally.
2. Prohibit MLAT Positions strips MLAT lat/lon/track from BaseStation and drops MLAT Mode-S frames.
3. Block Unfilterable Feeds blocks passthrough/raw feeds that cannot be filtered per message.

3. ICAO filter mode

1. Blocklist (ProhibitIcaos=true): ICAOs in list/ranges are blocked.
2. Allowlist (ProhibitIcaos=false): only ICAOs in list/ranges are allowed.
3. Individual ICAO entries must be exactly 6 hex characters.
4. ICAO ranges are inclusive (start and end included).

4. Apply behavior

1. no service restart required,
2. settings are hot-reloaded,
3. frontend/admin message indicates changes usually become visible within 2-5 minutes.

5. Safe rollout sequence

1. verify raw feed flow first (without filter),
2. enable filter with minimal scope,
3. validate map and list output after each step,
4. only then add additional ICAO rules/ranges.