CCNA Networking · Quick Reference

Module 16 — Network Security Fundamentals Cheat Sheet

CCNA Networking

In one line: A vulnerability is a weakness in a system that can be exploited. A threat is the potential danger that exploits that weakness. Understanding both is the starting point for any s...

Key Ideas

1Security Threats and Vulnerabilities. A vulnerability is a weakness in a system that can be exploited. A threat is the potential danger that exploits that weakness. Understanding both is the starting point...

2Network Attacks. Network attacks generally fall into a few broad categories, each with a different goal.

3Network Attack Mitigations. No single tool stops every attack. The defense-in-depth approach layers multiple, independent security measures so that if one fails, others still protect the network.

4Device Security. Securing individual network devices (routers, switches) is a practical, hands-on extension of the password and access concepts from Module 10. A few additional steps r...

5Types of Firewalls. Firewalls have evolved significantly, each generation adding more context about the traffic it inspects.

Code Examples

! 1. Set a hostname and domain name (required for SSH key generation)
Router(config)# hostname R1
R1(config)# ip domain-name bitwithbite.local

! 2. Generate the RSA key pair (minimum 1024 bits — 2048 recommended)
R1(config)# crypto key generate rsa
H...