Network Security Essentials
Threats and Controls
Security goals
Networking security aims to protect confidentiality, integrity, and availability. Controls are applied at the device, protocol, and policy levels.
Defense in depth
No single control is enough. Combine segmentation, authentication, encryption, patching, monitoring, and least privilege.
Common threats
Typical network threats include sniffing, spoofing, man-in-the-middle attacks, denial of service, and unauthorized lateral movement.
Security Controls
| Control | Purpose |
|---|---|
| Firewall | Filter traffic by policy |
| VPN | Encrypt traffic over untrusted networks |
| TLS | Protect application sessions |
| 802.1X | Authenticate network access |
Which control primarily protects data in transit for web sessions?
TLS encrypts and authenticates application traffic such as HTTPS.
Correct answer: TLS
What is the difference between encryption and authentication?
Both are important, but they solve different security problems.
Correct answer: Encryption hides data, while authentication verifies identity or message origin
What is the most likely purpose of a firewall rule denying inbound traffic on unused ports?
Blocking unnecessary exposure reduces opportunities for unauthorized access.
Correct answer: Reduce attack surface
Secure network design checklist
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1
Step 1: Segment sensitive systems from general user traffic.
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2
Step 2: Enforce authentication for network access.
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3
Step 3: Encrypt traffic where confidentiality matters.
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4
Step 4: Log and monitor unusual access patterns.
Why is segmentation useful in security?
Smaller trust zones contain damage and improve policy enforcement.
Correct answer: It limits how far an attacker can move laterally if one segment is compromised