🌐 Network Basics
Before learning hacking or Capture The Flag (CTF), you need to understand how computer networks work. Almost every CTF challenge involves communication between computers over a network.
What is a Network?
A computer network is a collection of two or more devices connected together so they can exchange information.
Examples include:
- Your home Wi-Fi
- Your school's computer lab
- The Internet
When you open Google in your browser, your computer sends a request across the network to Google's server, and Google's server sends the website back to you.
Types of Networks
| Type | Description |
|---|---|
| LAN | Local Area Network (Home, School, Office) |
| WAN | Wide Area Network (Internet) |
| MAN | Metropolitan Area Network |
| PAN | Personal Area Network (Bluetooth) |
How Computers Communicate
Every device connected to a network has an IP Address. Think of an IP address as a house address. Without it, other computers would not know where to send data.
- Your Computer → 192.168.1.10
- Router → 192.168.1.1
- Google Server → 142.250.xxx.xxx
What is a Packet?
Information sent across a network is broken into small pieces called packets. Each packet contains:
- Source IP
- Destination IP
- Protocol
- Data
Wireshark is commonly used to inspect packets during CTF competitions.
Common Protocols
| Protocol | Port | Purpose |
|---|---|---|
| HTTP | 80 | Web Traffic |
| HTTPS | 443 | Secure Web |
| SSH | 22 | Remote Login |
| FTP | 21 | File Transfer |
| DNS | 53 | Domain Name Resolution |
Useful Networking Commands
These commands are frequently used during networking and CTF challenges to gather information about systems and troubleshoot connectivity.
Summary
- ✔ A network connects multiple devices.
- ✔ Every device has an IP address.
- ✔ Data travels in packets.
- ✔ Protocols define communication rules.
- ✔ Ports identify services running on a device.