Support for whitelisting SIP trunks and providers by hostname or SRV
record with automatic IP resolution and periodic refresh.
Features:
- Hostname resolution via A/AAAA records
- SRV record resolution (e.g., _sip._udp.provider.com)
- Configurable refresh interval (default 5m)
- Stale entry handling when DNS fails
- Admin API endpoints for DNS whitelist management
- Caddyfile directives: whitelist_hosts, whitelist_srv, dns_refresh
This allows whitelisting by provider name rather than tracking
constantly-changing IP addresses.
Documents all new features:
- Extension enumeration detection with config examples
- SIP message validation rules and modes
- Topology hiding (B2BUA-lite) with request/response flow diagrams
- Complete Caddyfile configuration reference
- Prometheus metrics reference
- Admin API endpoints
- Integration examples for FreePBX, Kamailio, and HA setups
- Security considerations
Architecture diagram updated to show full processing pipeline.
