====== Security Architecture ======

The AI-Homelab implements a comprehensive security model based on defense in depth, zero trust principles, and industry best practices.

===== Security Principles =====

**Defense in Depth:**
  * **Multiple Layers**: Network, application, and data security
  * **Fail-Safe Defaults**: Secure by default, explicit opt-out
  * **Least Privilege**: Minimal required permissions
  * **Continuous Monitoring**: Real-time threat detection

**Zero Trust:**
  * **Never Trust**: Verify every access request
  * **Assume Breach**: Design for compromised systems
  * **Micro-Segmentation**: Isolate services and data
  * **Continuous Verification**: Ongoing authentication

**Compliance:**
  * **Data Protection**: Encryption at rest and in transit
  * **Access Control**: Role-based and attribute-based access
  * **Audit Logging**: Comprehensive activity tracking
  * **Regular Updates**: Security patch management

===== Authentication & Authorization =====

**Authelia SSO System:**

**Architecture:**
  * **Protocol**: OpenID Connect, SAML 2.0
  * **Storage**: File-based user database
  * **Session Management**: Secure JWT tokens
  * **Multi-Factor**: TOTP, WebAuthn, Push notifications

**User Management:**
```yaml
users:
  admin:
    displayname: Administrator
    password: $argon2id$...
    email: admin@yourdomain.duckdns.org
    groups:
      - admins
      - dev
```

**Access Policies:**
```yaml
access_control:
  default_policy: deny
  rules:
    # Admin services require 2FA
    - domain: "*.yourdomain.duckdns.org"
      policy: two_factor
      subject:
        - "group:admins"
    
    # Media services bypass SSO
    - domain: "jellyfin.yourdomain.duckdns.org"
      policy: bypass
    
    # API access with tokens
    - domain: "*.yourdomain.duckdns.org"
      policy: one_factor
      resources:
        - "^/api/.*"
```

**Session Security:**
  * **Expiration**: 8 hour sessions
  * **Inactivity Timeout**: 10 minute timeout
  * **Secure Cookies**: HttpOnly, Secure, SameSite
  * **CSRF Protection**: Token-based validation

===== SSL/TLS Encryption =====

**Certificate Management:**
  * **Authority**: Let's Encrypt (trusted CA)
  * **Type**: Wildcard ECDSA certificate
  * **Domains**: *.yourdomain.duckdns.org
  * **Renewal**: Automatic (30 days before expiry)

**SSL Configuration:**
```yaml
tls:
  certificates:
    - certFile: /ssl/cert.pem
      keyFile: /ssl/private.key
  options:
    default:
      minVersion: VersionTLS12
      cipherSuites:
        - TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
        - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
      sniStrict: true
```

**Security Headers:**
```yaml
headers:
  # Prevent clickjacking
  customResponseHeaders:
    X-Frame-Options: "SAMEORIGIN"
    X-Content-Type-Options: "nosniff"
    Referrer-Policy: "strict-origin-when-cross-origin"
    Permissions-Policy: "geolocation=(), microphone=(), camera=()"
  
  # HSTS (HTTP Strict Transport Security)
  stsSeconds: 31536000
  stsIncludeSubdomains: true
  stsPreload: true
```

===== Network Security =====

**Firewall Configuration:**
  * **UFW**: Uncomplicated Firewall
  * **Default Policy**: Deny all incoming
  * **Allowed Ports**: 22 (SSH), 80 (HTTP), 443 (HTTPS)
  * **Docker Isolation**: Container network segmentation

**Network Segmentation:**
  * **traefik-network**: Web-facing services
  * **homelab-network**: Internal services
  * **media-network**: Media services
  * **isolated-networks**: High-security services

**VPN Protection:**
  * **Gluetun**: VPN client container
  * **Provider**: Surfshark (configurable)
  * **Protocol**: WireGuard (preferred)
  * **Kill Switch**: Prevents IP leaks

===== Container Security =====

**Docker Security Best Practices:**
  * **Non-root Users**: PUID/PGID environment variables
  * **No Privileged Containers**: Minimal capabilities
  * **Read-only Filesystems**: Where possible
  * **Resource Limits**: CPU and memory constraints

**Security Scanning:**
```yaml
# Trivy vulnerability scanning
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  aquasec/trivy image your-image:latest

# Container security audit
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  docker/docker-bench-security
```

**Image Security:**
  * **Official Images**: LinuxServer.io preferred
  * **Version Pinning**: Specific version tags
  * **SBOM**: Software Bill of Materials
  * **Signature Verification**: Image signing

===== Data Protection =====

**Encryption at Rest:**
  * **SSL Certificates**: Encrypted storage
  * **User Data**: Service-specific encryption
  * **Backups**: AES-256 encryption
  * **Secrets**: Environment variable protection

**Encryption in Transit:**
  * **HTTPS**: End-to-end encryption
  * **API Communication**: TLS 1.2+
  * **Database Connections**: SSL/TLS
  * **VPN Tunneling**: WireGuard/OpenVPN

**Data Classification:**
  * **Public**: No encryption required
  * **Internal**: TLS encryption
  * **Sensitive**: Additional encryption layers
  * **Critical**: Multi-layer encryption

===== Access Control =====

**Role-Based Access Control (RBAC):**
```yaml
# Authelia groups
groups:
  admins:
    - admin
  users:
    - user1
    - user2
  media:
    - family
```

**Service-Level Permissions:**
  * **Nextcloud**: User and group permissions
  * **Gitea**: Repository access control
  * **Grafana**: Dashboard permissions
  * **API Keys**: Scoped access tokens

**Network Access Control:**
  * **IP Whitelisting**: Restrict by IP address
  * **Geo-blocking**: Country-based restrictions
  * **Rate Limiting**: Prevent brute force attacks
  * **Fail2Ban**: SSH protection

===== Monitoring & Auditing =====

**Security Monitoring:**
  * **Authentication Logs**: Authelia events
  * **Access Logs**: Traefik requests
  * **System Logs**: Docker and system events
  * **Intrusion Detection**: Pattern matching

**Audit Logging:**
```yaml
# Loki log aggregation
scrape_configs:
  - job_name: 'authelia'
    static_configs:
      - targets: ['authelia:9091']
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: localhost:3100
```

**Alerting:**
  * **Failed Logins**: Brute force detection
  * **Certificate Expiry**: SSL renewal warnings
  * **Service Downtime**: Availability monitoring
  * **Security Events**: Suspicious activity

===== Threat Mitigation =====

**Common Threats:**
  * **Brute Force**: Rate limiting, 2FA
  * **SQL Injection**: Parameterized queries
  * **XSS**: Content Security Policy
  * **CSRF**: Token validation

**Incident Response:**
  1. **Detection**: Monitoring alerts
  2. **Assessment**: Determine impact
  3. **Containment**: Isolate affected systems
  4. **Recovery**: Restore from backups
  5. **Lessons Learned**: Update policies

**Backup Security:**
  * **Encryption**: AES-256-GCM
  * **Integrity**: SHA-256 checksums
  * **Retention**: Configurable policies
  * **Testing**: Regular restoration tests

===== Compliance & Governance =====

**Security Standards:**
  * **OWASP**: Web application security
  * **NIST**: Cybersecurity framework
  * **ISO 27001**: Information security
  * **GDPR**: Data protection

**Regular Assessments:**
  * **Vulnerability Scanning**: Weekly
  * **Penetration Testing**: Monthly
  * **Security Audits**: Quarterly
  * **Compliance Reviews**: Annual

**Documentation:**
  * **Security Policies**: Access and usage rules
  * **Incident Response**: Procedures and contacts
  * **Change Management**: Update procedures
  * **Training**: Security awareness

===== Advanced Security =====

**Zero Trust Network Access (ZTNA):**
  * **Identity-Based**: User and device verification
  * **Context-Aware**: Risk-based access
  * **Micro-Segmentation**: Service isolation
  * **Continuous Monitoring**: Real-time assessment

**Secrets Management:**
  * **Environment Variables**: Runtime secrets
  * **Docker Secrets**: Swarm mode secrets
  * **External Vaults**: HashiCorp Vault integration
  * **Key Rotation**: Automatic secret renewal

**Intrusion Detection:**
  * **Network IDS**: Traffic analysis
  * **Host IDS**: System monitoring
  * **Log Analysis**: Pattern detection
  * **SIEM Integration**: Centralized logging

This security architecture provides comprehensive protection for your homelab while maintaining usability and performance.

**Next:** Learn about [[architecture:storage|Storage Strategy]] or [[architecture:backup|Backup Strategy]].