Networking Fundamentals: IP Addresses, DNS, Ports and Packets
YOUR LEARNING PATH
Learn why knowing an address is not enough to establish a connection. Separate the roles of IP, MAC, DNS and ports, follow a request across the network, then use tools and packet observations to explain what happened.
Who is this path for?
Beginners learning IP and DNS, and programmers or security learners who need a practical networking foundation
Before you begin
Start with basic terminal skills. Early lessons inspect your own computer and network; later exercises use the environment specified in the individual lesson.
What you will practice
- Distinguish public and private IP addresses, gateways and DNS.
- Explain ports and TCP or UDP connections using observed results.
- Narrow down a connection problem using packet and service information.
STEP BY STEP
Your suggested lesson order
Separate addresses from names
- 031 Understanding IP Addresses Completely — Neighborhood Name and House NumberExplain that an IPv4 address is actually a 32-bit number
- 032 MAC Addresses and ARP — The Real Address on the WireExplain the difference between IP and MAC addresses from three perspectives (who assigns it, does it change, w…
- 033 DNS — The Internet's Phone BookExplain that DNS is a hierarchical system that converts "name → IP"
- 034 Ports and Services — Room Numbers Inside the BuildingExplain what a port is and how it differs from an IP (building and room number)
Understand how connections travel
- 035 TCP Deep Dive — The Art of the HandshakeExplain what it means that TCP is "connection-oriented"
- 036 UDP and ICMP — The Courier Who Throws and the Status HotlineExplain the difference between TCP and UDP by the criterion "is it meaningful to receive the missing piece aga…
- 037 Routing and Gateways — Follow the Letter's JourneyExplain what a router and a hop are
- 038 NAT and Home Routers — The Secret of the Disguise-Managing DoorstepRecite the three private IP ranges and tell whether a given address is private or public
- 039 The OSI 7 Layers — A Map for Placing Nine PiecesRecite the OSI 7 layers in order and describe each layer’s role in one line
- 040 Level 0 Comprehensive Test — Examining YourselfPinpoint what you know and what you don’t across all of Level 0
Build tools and observe packets
- 077 Socket Communication 1 — A TCP Echo Server and ClientExplain in code that a socket is "a communication endpoint between program and program"
- 078 Socket Communication 2 — A Multi-Client Chat ServerExplain that a thread is "a flow of execution sharing memory inside the same process"
- 079 The Port Scanner — A Scout That Finds Open DoorsExplain, with a tool you built yourself, that the principle of port scanning is "attempting a connection (conn…
- 080 Introduction to Scapy — The Handmade Packet WorkshopAssemble IP/TCP/data and distinguish uncalculated fields from serialized values.
- 081 Mastering nmap — The Standard Tool of ReconnaissanceChoose the right nmap option (-sT/-sS/-sV/-O/--script) for the situation
- 082 Project — Network Map and Risk AssessmentDefine assets, attack surface, and risk.
- 083 Wireshark 1 — Capture and Filters, the Microscope of NetworksPick a network interface and start and stop a capture
- 084 Wireshark 2 — Dissecting Protocols and Detecting AnomaliesFind the TCP 3-way handshake as three packets in a real capture
- 085 Project — HTTP vs HTTPS Comparison ReportOpen a plaintext web server locally and prove with a capture that requests/responses ride in packets letter fo…
- 158 Packet Sniffing Advanced — The Two Faces of Filters and Reassembling ConversationsExplain the difference between capture filters (BPF syntax) and display filters (Wireshark syntax), and use ea…
- 160 SSL/TLS and HSTS — The ID-Card System That Stops the Man in the MiddleExplain the TLS handshake's stages (Client Hello → certificate → key agreement → encrypted communication)
- 161 Firewalls and iptables — Designing the Gatekeeper's RulesExplain the meaning of chains (INPUT/OUTPUT/FORWARD) and targets (ACCEPT/DROP/REJECT)
- 163 SSH Tunneling and Port Forwarding — Loading Other Roads onto an Encrypted PassageExplain the directional differences of local (-L), remote (-R), and dynamic (-D) forwarding with diagrams
Before you move on
Break a connection problem into name resolution, destination address, port and connection stages. Link each conclusion to command output or a packet observation instead of relying on a guess.
Check each lesson’s setup and completion criteria. If you already know a section, start with the lessons you need.