Core Technical Skills
Networking Essentials for Hackers
TCP/IP, ports, and what actually happens when you connect to a server.
You can't attack what you don't understand. Every remote attack rides on top of networking, so a working mental model of TCP/IP is non-negotiable.
Ports & services
A server has 65535 TCP ports. A service 'listens' on a port. Finding which ports are open tells you what you can attack.
| Port | Service | Why it matters |
|---|---|---|
| 22 | SSH | Remote shell — brute force / key attacks |
| 80 / 443 | HTTP / HTTPS | Web apps — the biggest attack surface |
| 3306 | MySQL | Database — often misconfigured |
| 445 | SMB | Windows file sharing — classic exploits |
| 3389 | RDP | Windows remote desktop |
The TCP handshake
TCP opens a connection with a 3-way handshake: SYN → SYN/ACK → ACK. Port scanners abuse this: send a SYN, and the response tells you if the port is open, closed, or filtered.