Security Fundamentals

Learn how networks are protected using ACLs, AAA, encryption, and device security features.

Network Security Overview

Network security protects data, devices, and communication from unauthorized access and attacks.

CIA Triad

Confidentiality, Integrity, and Availability are the core principles of security.

Common Threats

Malware, phishing, MITM attacks, and unauthorized access.

AAA Security Model

Authentication, Authorization, and Accounting framework.

Authentication

Verifies user identity.

Authorization

Defines user permissions and access levels.

Accounting

Tracks user activity and logs actions.

Secure Device Access

Methods used to securely access network devices.

SSH

Encrypted remote access protocol (replaces Telnet).

Telnet (Legacy)

Unencrypted remote access (not secure, deprecated).

Password Security

Strong passwords and encryption for device access.

Access Control Lists (ACLs)

Rules that filter traffic entering or leaving a network.

Standard ACL

Filters traffic based only on source IP address.

Extended ACL

Filters based on source, destination, protocol, and ports.

ACL Placement Rule

Standard ACL near destination, extended ACL near source.

Device Security Features

Protecting switches and routers from unauthorized access.

Port Security

Limits MAC addresses allowed on a switch port.

DHCP Snooping

Prevents rogue DHCP servers.

Dynamic ARP Inspection

Protects against ARP spoofing attacks.