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Reference date: Jan 03, 20232 min read

Cyber Security: The Fundamentals

S
Shubham Singla

This is an older essay or practical note. Its reference date is retained from the original entry; use current vendor guidance for product versions and security updates.

Cybersecurity is no longer just for IT geeks. It is a fundamental life skill. Whether you are a CEO or a student, understanding the CIA Triad, the OSI model, and the basics of encryption is mandatory. This is the comprehensive manual for surviving the digital age.

Security Shield

The CIA Triad

Ideally, every security control fits into one of three buckets:

  • Confidentiality: Preventing unauthorized access. (e.g., Encryption, ACLs).
  • Integrity: Preventing unauthorized modification. (e.g., Hashing, Digital Signatures).
  • Availability: Ensuring access when needed. (e.g., Redundancy, DDoS protection).

The Seven Layers of OSI

To defend a network, you must understand how it talks. The Open Systems Interconnection (OSI) model describes 7 layers:

  1. Physical: Cables, Fiber, WiFi radio waves. Attack: Cutting the cable.
  2. Data Link: MAC addresses, Switching. Attack: ARP Spoofing.
  3. Network: IP addresses, Routing. Attack: IP Spoofing.
  4. Transport: TCP/UDP ports. Attack: SYN Flood.
  5. Session: Managing connections. Attack: Session Hijacking.
  6. Presentation: Encryption/Formatting (TLS, JPG). Attack: SSL Stripping.
  7. Application: HTTP, FTP, SMTP. Attack: SQL Injection, Phishing.

Encryption 101

Symmetric vs Asymmetric

Symmetric (AES): Uses the SAME key to lock and unlock. Faster, but how do we share the key safely?

Asymmetric (RSA/ECC): Uses a Public Key (to lock) and a Private Key (to unlock). Slower, but solves the key exchange problem.

The internet uses both (TLS). We use Asymmetric to exchange a Symmetric key, then use the Symmetric key for the rest of the conversation. Clever.

Network Diagram

Common Threat Vectors

Phishing: The number one cause of breaches.
Ransomware: Malware that encrypts files for money.
Man-in-the-Middle (MitM): Intercepting WiFi often.
SQL Injection: Asking the database a question it wasn't expecting.

Personal Hygiene Checklist

  1. Password Manager: Use Bitwarden or 1Password.
  2. MFA: Use an Authenticator App (Google/Microsoft), not SMS.
  3. Updates: Turn on auto-updates for OS and Browser.
  4. Backups: 3-2-1 Rule. 3 copies, 2 media types, 1 offsite.