6Security

• 6.1Filtering traffic with a firewall

  Covers the role of a firewall that screens traffic at a network boundary, the permit and deny rules that decide what passes or is stopped, the default-deny posture of blocking by default and opening only what is needed, and the stateful mechanism that remembers a connection to let the return traffic back automatically—as the basis for telling "is this traffic failing because of the filter."

• 6.2Fundamental security concepts

  Covers the three security pillars CIA (confidentiality/integrity/availability), AAA (authentication/authorization/accounting) that verifies, controls, and records users, MFA that strengthens identity checks with multiple factors, the identity foundations of encryption, certificates, password complexity, and Active Directory, plus threats such as phishing, malware, and DoS—as the basis for telling "what a control is meant to protect."

• 6.3Wireless security settings on a home router

  Covers the generational differences of the wireless encryption standards WPA/WPA2/WPA3 that protect home and SOHO Wi-Fi, how to choose between Personal (PSK) using a pre-shared key and Enterprise (802.1X/RADIUS) using per-user authentication, and why the still-seen WEP and WPA (TKIP) are deprecated—as the basic judgment of "which method to choose for this environment."