HTB Intro to Networking – Log 02: Network Structures, Topologies & Proxies

🧱 Network Structures

Before diving into attacks and defenses, you’ve gotta know the battlefield layout.

🧠 Two Ways to Think About Networks:

1. Real-World (Common) Terms

2. Academic (Book) Terms

Let’s break both down.

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🔍 Common Network Terminology

• WAN (Wide Area Network)
  \= The Internet. Just a massive mesh of LANs.
  Often used globally — even governments build their own “private internets” (aka internal WANs).
  WANs use protocols like BGP, and they don’t follow local IP rules (e.g., RFC1918 ranges).

• LAN (Local Area Network)
  \= Your home, office, or internal network — private and self-contained.
  Uses IP ranges like 192.168.0.0/16, 10.0.0.0/8, etc.

• WLAN (Wireless LAN)
  \= Same as LAN, just without the cables. It’s LAN over Wi-Fi.
  Nothing fancy — just a wireless version.

• VPN (Virtual Private Network)
  \= Tunnels connecting distant systems as if they were all in one LAN.
  Three major types:

  1. Site-to-Site VPN

  • Connects networks across locations (e.g., HQ ↔ Branch Office).

  • All devices talk as if they’re on the same network.

2. Remote Access VPN

• Connects an individual user to a distant network.

• You appear as if you’re sitting at another machine.

• Split-tunnel VPNs only route some traffic through the tunnel (e.g., 10.10.10.0/24). Internet goes outside.
  ❌ Not ideal for companies — malware can bypass detection.

3. SSL VPN

• VPN that runs in your browser.

• Quick access, usually login-based. Common in corporate remote portals.

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📚 Book-Style Network Terminology

• GAN (Global Area Network)
  \= Entire internet. Connects countries, continents, galaxies (well, almost).

  • Think undersea fiber and satellites.

  • Big corps (Amazon, Google) build their own GANs for global infrastructure.

• MAN (Metropolitan Area Network)
  \= A network spanning a city.

  • Faster than the internet (uses fiber).

  • Used by governments, large campuses, ISPs.

• PAN/WPAN (Personal Area Network / Wireless PAN)
  \= Super short-range networks.

  • PAN: USB, direct cable.

  • WPAN: Bluetooth, NFC.

  • Example: Your phone paired to your laptop.

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🌐 Network Topologies – The Blueprint

Topology just means: how devices are connected together.

1. Point-to-Point

• Just two devices connected directly.

• Simple, clean, boring.

2. Bus Topology

• Everyone shares one cable.

• One speaks, the rest listen.

• Collisions happen if multiple devices speak at once.

3. Star Topology

• All devices connect to a central hub (usually a switch).

• Most common today (home, office setups).

• Weak point: If the hub dies, everything breaks.

4. Ring Topology

• Devices form a circle.

• Data flows one way using a token to avoid collisions.

5. Mesh Topology

• Each device connects to every other.

• Full mesh = all-to-all.

• Partial mesh = only important paths.

• Very reliable and scalable.

6. Tree Topology

• Like a hierarchy — one main node branches out.

• Think of it as multiple stars connected together.

• Great for large buildings and enterprise setups.

7. Hybrid Topology

• Combo of two or more topologies.

• Most real-world networks = hybrids (e.g., Star + Bus).

8. Daisy Chain

• Devices are linked one after another.

• Common in IoT or automation systems.

• One break = potential cascade failure.

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💡 Network Components 101

1. Connections:

• Wired:

  • Twisted Pair (Ethernet)

  • Coaxial (Old school)

  • Fiber (Fast AF)

• Wireless:

  • Wi-Fi

  • 4G/5G

  • Satellite

2. Devices (Nodes):

• Basic:

  • NICs, Repeaters, Hubs, Bridges

• Smart:

  • Switches, Routers, Firewalls, Gateways

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🧰 Proxies – The Middleman

A proxy sits between you and your destination, controlling or modifying the traffic in-between.

Think of it like a club bouncer — checks who you are, what you want, and either lets you through or stops you.

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🧠 Common Mistake:

People say:

“I’m hiding my IP = I’m using a proxy.”

Reality:

That’s often a VPN.
A true proxy understands and controls traffic. VPNs just tunnel and encrypt it.

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🔍 Where It Works

Proxies usually operate at Layer 7 (Application Layer) — they inspect things like HTTP/S requests.

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⚙️ Types of Proxies

1. 🔁 Forward Proxy

• Sits in front of the client.

• Path: You → Proxy → Internet

• Common Uses:

  • Blocking internet access

  • Burp Suite (for intercepting)

  • Anonymity tools

💡 Fun Fact:
Firefox ignores system proxy settings (safer in corp setups).
Chrome/Edge do not.

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2. ⏪ Reverse Proxy

• Sits in front of the server.

• Path: You → Internet → Proxy → Server

• Common Uses:

  • Hiding origin servers (e.g., Cloudflare)

  • Load balancing

  • Application-layer firewalling (e.g., ModSecurity)

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3. 👻 Transparent vs Non-Transparent

• Transparent Proxy:
  You don’t know it’s there.
  Used in public Wi-Fi, schools, cafes.

• Non-Transparent Proxy:
  You must configure your system to use it.
  Common in locked-down corp environments.

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🎯 TL;DR – Why This Matters

Understanding network structures and proxies isn't just about passing certs — it’s about knowing how attackers move, how defenders block, and how data flows.

When you see a topology diagram or hear “reverse proxy detected,” your brain should go:
“I know exactly what that means and why it matters.”