Start with networking

Every attack and every defence travels over a network, so security starts here. Before you can secure traffic, you need to understand how data moves.

Key ideas to learn:

• IP addresses and ports: how machines are found and how services are reached
• TCP vs UDP: reliable delivery versus fast delivery
• The OSI model: the layered way we describe network communication
• DNS and HTTP/HTTPS: how names become addresses, and how the web talks
• Firewalls and NAT: the first line of network defence

Aim for roughly the CompTIA Network+ level of understanding. It is the foundation everything else builds on.

Resources

• Professor Messer Network+ (N10-009) full course

Practice

Find your own device's IP address. Then look up the difference between a private IP and a public IP, and write one sentence on each.