| defense-in-depth authentication-methods security-assessment network-threats |
1. Availability
- Ensuring data is accessible to authorized users at the right time and place
- Main challenges: Cyberattacks and disaster-related outages
- Controls: RAID, backup sites, mirrored drives
2. Internal & External Threats
| Threat Type | Example |
|---|
| Internal | Disgruntled employee leaking sensitive data |
| External | Hackers, script kiddies, state-sponsored APTs |
3. Vulnerabilities
- Weaknesses in hardware, software, or human behavior
- Reference: CVE database maintained by MITRE
- Example: Apache vulnerability used in the Equifax breach
4. Zero-Day Attacks & Exploits
- Zero-Day: Unknown and unpatched vulnerabilities
- Exploit: Active use of a vulnerability for an attack
5. Least Privilege & RBAC
- Users access only resources essential for their tasks
- RBAC: Assigning permissions through predefined roles and groups
6. Zero Trust & Defense in Depth
- Zero Trust: Default access is denied unless explicitly permitted
- Defense in Depth: Multiple security layers such as encryption, ACLs, firewalls
7. Network Segmentation & DMZ
- Layer 1: Physical separation
- Layer 2: VLANs and port security
- Layer 3: ACLs on routers/firewalls
- DMZ: Public servers placed between two firewalls
8. Access Control & Posture Assessment
- NAC: Verifies device compliance before allowing network access
- Posture Assessment: Checks antivirus, OS updates, and registry settings
- Guest Network: Isolates BYOD devices until validated
9. Honeypots & Separation of Duties
- Honeypot: Attracts attackers for monitoring and analysis
- Separation of Duties: Splits sensitive operations among different personnel
10. Authentication Methods
- Multifactor: Password + biometric + smart card
- AAA: Centralized security control (RADIUS, TACACS+)
- SSO, LDAP, Kerberos
- 802.1X & EAP for network authentication
11. Preshared Key (PSK)
Used in wireless networks for encryption; frequent key rotation is vital for security
12. Security Assessments
- Threat Assessment: Uses threat intel feeds (SIEM, ThreatStream)
- Vulnerability Assessment: Tools like Nessus to scan systems
- Penetration Testing: Blind, Double-Blind, and Targeted types
- Process & Vendor Evaluation: Reviews policies and third-party agreements
13. SIEM - Security Information and Event Management
- Log aggregation, event correlation, alerts, compliance reporting
- Example: Detecting multiple failed login attempts from suspicious IPs
14. Key Exam Tips for Network+
- Availability requires fault-tolerance and access controls
- Internal vs External threats → different mitigation approaches
- CVSS and CVE for measuring vulnerabilities
- RBAC, Zero Trust, and DMZ are layered defense strategies
- 802.1X and TACACS+ enable centralized authentication
- SIEM helps real-time monitoring and audit readiness
15. Practice Questions
- What distinguishes a threat from a vulnerability?
- How does DMZ improve network security?
- What are RBAC’s benefits compared to manual permissions?
- Why is SIEM essential in modern security operations?
16. Conclusion
Network security principles form the foundation for designing resilient infrastructures and defending against both internal and external threats. With techniques like least privilege, zero trust, defense in depth, and structured assessments, organizations can build trustworthy and adaptable networks. This knowledge is critical for passing Network+ and advancing your cybersecurity career.
