🎯 Goal
Understand how computers communicate: protocols, addressing, routing, and the essential network services that power the internet. This is the backbone for every cybersecurity task, from scanning networks to detecting intrusions.
🔑 Key Skills to Learn
- OSI & TCP/IP Models: Layers, encapsulation, the role of each layer.
- IP Addressing (IPv4 & IPv6): Subnet masks, CIDR notation, public vs. private IPs, NAT.
- Subnetting: Calculating network and broadcast addresses, host ranges, VLSM.
- Core Protocols: TCP (three-way handshake, flags), UDP, ICMP, ARP.
- Application Layer Protocols: DNS, HTTP/HTTPS, DHCP, FTP, SMTP, SSH.
- Routing & Switching Basics: MAC addresses, switches, routers, default gateways, ARP tables, basic routing concepts.
- Network Devices: Hub, switch, router, firewall, access point – their functions and how they differ.
- DNS Deep Dive: Recursive vs. authoritative servers, record types (A, AAAA, CNAME, MX, NS, PTR), how a DNS query works.
- Wireless Networking: 802.11 standards, basic Wi-Fi security (WPA2, WPA3).
- Ports & Services: Common ports (20, 21, 22, 23, 25, 53, 80, 443, 3389, etc.) and their associated services.
🛠️ Essential Tools & Technologies
| Tool | Purpose |
|---|---|
| Wireshark | Capture and analyze network traffic visually. |
| Tcpdump | Command-line packet capture (Linux). |
| Nmap | Network discovery, port scanning, service enumeration. |
| Ping / Traceroute | Connectivity and path analysis. |
| Netstat / ss | Display active network connections and listening ports. |
| Dig / nslookup | DNS queries and troubleshooting. |
| Cisco Packet Tracer | Free network simulation tool (switches, routers, virtual labs). |
| GNS3 | Advanced network emulator for complex topologies. |
📖 Free Learning Resources
- Professor Messer's Network+ (N10-008) Videos – Complete, exam-focused. Link
- Cisco Networking Academy – Packet Tracer & Intro to Networks – Free introductory course with simulation labs. Link
- Wireshark University – Free SharkFest Videos – Learn to use Wireshark. Link
- Practical Networking – Subnetting Mastery Series – The simplest subnetting guide. YouTube Playlist
- TryHackMe – Networking Modules – Rooms: "Intro to LAN", "OSI Model", "Intro to Networking". Link
- "Computer Networking: A Top-Down Approach" – Companion Website – Interactive animations and quizzes. Link
🔗 Roadmap Placement
- Prerequisite: IT Fundamentals (you know what an IP address is in concept).
- Directly Enables: All cybersecurity domains – you'll use Wireshark for incident response, Nmap for pen-testing, and DNS knowledge for OSINT.
- Next Step: Combined with Linux, you're ready for Core Security Concepts (Level 2) or a deeper dive into specific domains.