Allow homelab users to send webhooks to internal services while maintaining security defaults.
Changes:
- Add webhookAllowedPrivateCIDRs field to SystemSettings (persistent config)
- Implement CIDR parsing and validation in NotificationManager
- Convert ValidateWebhookURL to instance method to access allowlist
- Add UI controls in System Settings for configuring trusted CIDR ranges
- Maintain strict security by default (block all private IPs)
- Keep localhost, link-local, and cloud metadata services blocked regardless of allowlist
- Re-validate on both config save and webhook delivery (DNS rebinding protection)
- Add comprehensive tests for CIDR parsing and IP matching
Backend:
- UpdateAllowedPrivateCIDRs() parses comma-separated CIDRs with validation
- Support for bare IPs (auto-converts to /32 or /128)
- Thread-safe allowlist updates with RWMutex
- Logging when allowlist is updated or used
- Validation errors prevent invalid CIDRs from being saved
Frontend:
- New "Webhook Security" section in System Settings
- Input field with examples and helpful placeholder text
- Real-time unsaved changes tracking
- Loads and saves allowlist via system settings API
Security:
- Default behavior unchanged (all private IPs blocked)
- Explicit opt-in required via configuration
- Localhost (127/8) always blocked
- Link-local (169.254/16) always blocked
- Cloud metadata services always blocked
- DNS resolution checked at both save and send time
Testing:
- Tests for CIDR parsing (valid/invalid inputs)
- Tests for IP allowlist matching
- Tests for bare IP address handling
- Tests for security boundaries (localhost, link-local remain blocked)
Related to #673🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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