The network often provides the first—and sometimes the only— layer of defense for network-connected devices. This section explains stateful packet filtering, contextual packet filtering, the firewall, source address validation, and defensive layering. Stateful and Contextual Packet Filtering Network security’s “pointy …

As mentioned earlier, three factors are used to authenticate a user: • Something you know • Something you have • Something you are Passwords and passphrases are something you know. Because people often create easy-to-guess passwords or are sometimes compromised, …

Security systems can rely on three things to prove a user is who they say they are: something they know, something they have, and something they are. Passwords and passphrases are something you know. A password is a set of …

Chapter 19 began the authentication discussion with authentication, authorization, and accounting (AAA) tools. This section extends the authentication discussion with important concepts like single sign-on (SSO ) and  zero trust. None of these authentication systems are foolproof, however; they all …

Take the quiz (either here or use the PTP software) if you want to use the score to help you decide how much time to spend on this chapter. Appendix A, “Answers to the ‘Do I Know This Already?’ Quizzes,” …