Defense Architecture Guide
Comprehensive guide to designing and implementing defense-in-depth security architecture for telecommunications networks
Architecture Principles
Multiple independent security layers ensure that if one layer is compromised, others continue to provide protection
Never trust, always verify - authenticate and authorize every access request regardless of source
Architecture Components
Signaling Firewalls
SS7, Diameter, and GTP firewalls to filter malicious signaling traffic
Encryption Gateways
IPsec, TLS, and protocol-specific encryption for data protection
Intrusion Detection/Prevention
IDS/IPS systems for real-time threat detection and blocking
Security Monitoring
SIEM, log management, and security analytics platforms
Purpose: Protect network boundaries from external threats
Components:
- Border firewalls and routers with ACLs
- DDoS protection and traffic scrubbing
- VPN gateways for secure remote access
- DMZ for public-facing services
Threats Mitigated:
- Unauthorized network access
- DDoS attacks
- Port scanning and reconnaissance
- Malicious traffic from internet
Purpose: Secure internal network communications and segmentation
Components:
- Internal firewalls and security zones
- Network access control (NAC)
- VLAN segmentation
- Intrusion detection/prevention systems
Threats Mitigated:
- Lateral movement after breach
- Internal reconnaissance
- Unauthorized device connections
- Network-based attacks
Purpose: Protect telecommunications signaling protocols
Components:
- SS7 firewall with message filtering
- Diameter firewall and routing agent
- GTP firewall for mobile data
- SIP security gateway
Threats Mitigated:
- SS7 location tracking and interception
- Diameter authentication bypass
- GTP tunneling attacks
- SIP fraud and DoS
Purpose: Secure telecommunications applications and services
Components:
- Web application firewalls (WAF)
- API gateways with rate limiting
- Application-level authentication
- Input validation and sanitization
Threats Mitigated:
- SQL injection and XSS attacks
- API abuse and credential stuffing
- Application-layer DDoS
- Business logic exploitation
Purpose: Protect sensitive subscriber and network data
Components:
- Database encryption (at-rest and in-transit)
- Data loss prevention (DLP)
- Access controls and audit logging
- Backup encryption and secure storage
Threats Mitigated:
- Data breaches and exfiltration
- Unauthorized data access
- Data tampering
- Insider threats
Security Zones
Purpose: Host public-facing services with strict isolation
Components: Web servers, email gateways, DNS servers, VPN endpoints
Security Controls:
- Dual firewall architecture (external and internal)
- Web application firewall (WAF)
- DDoS protection
- Strict egress filtering
Purpose: Protect critical telecommunications infrastructure
Components: HLR/HSS, MSC, SGSN/GGSN, MME, PGW/SGW
Security Controls:
- SS7/Diameter/GTP firewalls
- Strict access control lists
- Network access control (NAC)
- Continuous monitoring and alerting
Purpose: Secure network management and administration
Components: NMS, OSS/BSS, SIEM, jump servers, admin workstations
Security Controls:
- Multi-factor authentication (MFA)
- Privileged access management (PAM)
- Session recording and audit logging
- Out-of-band management network
Purpose: Host business support systems and applications
Components: Billing systems, CRM, provisioning, customer portals
Security Controls:
- Application-level firewalls
- Database activity monitoring
- Data loss prevention (DLP)
- Regular security assessments
Inter-Zone Communication Rules
| From Zone | To Zone | Allowed Traffic | Security Controls |
|---|---|---|---|
| Internet | DMZ | HTTP/HTTPS, DNS | Firewall, WAF, DDoS protection |
| DMZ | Core Network | Specific APIs only | Internal firewall, API gateway |
| Management | All Zones | SSH, SNMP, HTTPS | MFA, PAM, session recording |
| Core Network | Business Apps | Database queries | Database firewall, encryption |
Technical Controls
Administrative Controls
- Information security policy
- Acceptable use policy
- Incident response procedures
- Change management process
- Disaster recovery plan
- Security awareness training (annual)
- Phishing simulation exercises
- Role-specific security training
- Incident response drills
- Security culture development
Phase 1: Assessment & Planning (2-3 months)
- Conduct comprehensive security assessment
- Identify critical assets and data flows
- Define security zones and segmentation strategy
- Design defense architecture and select technologies
- Develop implementation plan and timeline
Phase 2: Perimeter & Network Security (3-4 months)
- Deploy border firewalls and DDoS protection
- Implement network segmentation and VLANs
- Install internal firewalls between security zones
- Deploy IDS/IPS systems
- Establish secure remote access (VPN)
Phase 3: Signaling & Application Security (3-4 months)
- Deploy SS7, Diameter, and GTP firewalls
- Implement SIP security gateway
- Install web application firewalls (WAF)
- Deploy API gateways with security controls
- Implement application-level authentication
Phase 4: Monitoring & Data Security (2-3 months)
- Deploy SIEM and security analytics platform
- Implement log management and correlation
- Enable database encryption and DLP
- Deploy privileged access management (PAM)
- Establish SOC operations
Phase 5: Optimization & Continuous Improvement (Ongoing)
- Fine-tune security controls and reduce false positives
- Conduct regular penetration testing
- Update threat intelligence and detection rules
- Perform security architecture reviews
- Implement lessons learned from incidents
Success Metrics
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