Network Security
Network Security Fundamentals
Understand what network security actually protects: confidentiality, integrity and availability.
Read →Defense in Depth
Learn why security is built in layers instead of relying on one control.
Read →Common Network Threats — A Defender's Overview
Recognise the common threat categories a network engineer is expected to defend against.
Read →Security Zones and Trust Boundaries
Learn how networks are split into trust zones like Inside, Outside and DMZ.
Read →Network Segmentation as a Security Control
Learn how VLANs and ACLs are combined for security, not just for traffic separation.
Read →AAA: Authentication, Authorization and Accounting
Understand the three-part model every access control system is built on.
Read →Firewall Fundamentals: Stateless vs Stateful
Understand how firewalls decide what traffic to allow, and why state matters.
Read →Firewall Policies and Rule Base Design
Learn how firewall rules are ordered and why 'least privilege' and 'implicit deny' matter.
Read →Zone-Based Firewall (Cisco ZBFW)
See how Cisco IOS implements zones and policies with Zone-Based Firewall.
Read →NAT and Security Policy: How They Work Together
See why NAT is treated as a security boundary, not just an addressing trick.
Read →IDS vs IPS: Detection vs Prevention
Understand the difference between detecting and actively blocking malicious traffic.
Read →VPN Fundamentals: Site-to-Site vs Remote Access
Understand the two main VPN types and when each is used.
Read →Remote Access VPN and SSL VPN
Understand how remote users securely connect in, and why SSL VPN is so common today.
Read →IPsec Fundamentals: AH, ESP and the Two Phases
Understand how IPsec actually builds and protects a VPN tunnel.
Read →Security Logging and Monitoring
Learn why 'blocking' isn't enough — logs are what let you actually detect and investigate.
Read →A Troubleshooting Mindset for Network Security
Tie the whole section together: how to methodically work through a security-related outage.
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