Initial commit: Caddy SIP Guardian module

Layer 4 SIP protection with:
- SIP traffic matching (REGISTER, INVITE, etc.)
- Rate limiting and automatic IP banning
- Attack pattern detection (sipvicious, friendly-scanner)
- CIDR whitelisting
- Admin API for ban management

Makefile

@@ -0,0 +1,49 @@
+.PHONY: build run stop logs test clean dev
+
+# Build the custom Caddy image
+build:
+	docker compose build --no-cache
+
+# Run the stack
+run:
+	docker compose up -d
+
+# Stop the stack
+stop:
+	docker compose down
+
+# View logs
+logs:
+	docker compose logs -f
+
+# Run with mock asterisk for testing
+test:
+	docker compose --profile testing up -d
+	@echo "Testing SIP Guardian..."
+	@sleep 3
+	@curl -s http://localhost:2019/config/ | jq .
+	@echo "\nSending test SIP packet..."
+	@echo -e "OPTIONS sip:test@localhost SIP/2.0\r\nVia: SIP/2.0/UDP 127.0.0.1:5060\r\n\r\n" | nc -u -w1 localhost 5060
+	@echo "Check logs for SIP Guardian activity"
+
+# Clean up
+clean:
+	docker compose down -v
+	docker rmi caddy-sip-guardian-caddy 2>/dev/null || true
+
+# Development mode - rebuild and run
+dev: build run logs
+
+# Check ban list via admin API
+bans:
+	@curl -s http://localhost:2019/load | jq .
+
+# Add test ban
+test-ban:
+	@curl -X POST http://localhost:2019/api/sip-guardian/ban/192.168.1.100 \
+		-H "Content-Type: application/json" \
+		-d '{"reason": "test_ban"}' | jq .
+
+# View stats
+stats:
+	@curl -s http://localhost:2019/api/sip-guardian/stats | jq .