Each month follows this structure:
| Section | Focus |
|---|---|
| ❓ WHY | The real-world motivation for the month |
| 📘 Concepts | What to learn & understand |
| 🧪 Labs | Visuals, experiments, and tools |
| 💻 Code | Hands-on programming |
| 📚 Resources | Only curated, non-boring content |
Why can I Google anything instantly from my phone? How does my laptop even know where Google's server is?
- What is a network? Why do computers need to talk?
- The Internet is not just a website: it’s a system of rules + layers
- MAC address vs IP address (street name vs phone number analogy)
- Layers: Like a courier system (You → Post office → Truck → Delivery)
- Run:
ping,traceroute,ipconfig/ifconfig - Draw your home network + devices
- Wireshark: capture and examine a single ping packet
- C++ program to list available network interfaces
- Log your own IP and MAC address via system calls
- 🎥 How the Internet Works in 5 mins
- 🎥 Ben Eater – TCP/IP Explained
- 📘 CS144 Textbook – Intro
- 🧾 PacketLife Cheat Sheets
When I visit a website, how does the request reach the right server? Why do some devices have 192.168.x.x addresses?
- IP addressing (v4, v6), Public vs Private IP
- Subnets and CIDR (helps break big networks into pieces)
- Routing: How routers act like traffic cops
- ARP, DNS, DHCP explained through daily device usage
- Subnetting drills by hand + subnettingpractice.com
- Wireshark: capture ARP, DNS, DHCP traffic
- Set up a 3-device network in Cisco Packet Tracer
- C++ ARP request + parse response (via raw sockets)
- Write a subnet calculator CLI
- 🎥 Computerphile – IP Packets
- 📘 [TCP/IP Illustrated Vol 1 – Ch. 5-6]
- 🧪 Subnetting Practice
- 🛠 Cisco Packet Tracer or GNS3 Setup
How does Zoom or WhatsApp call work in real-time? What makes downloads reliable even with network issues?
- Ports, multiplexing, and socket lifecycle
- TCP: Handshake, reliable streams
- UDP: Fire-and-forget, used in games/calls
- NAT and Port forwarding (home router behavior)
- Simulate connection using
telnet,netcat - Wireshark: trace a TCP 3-way handshake + UDP DNS query
- TCP echo server + client in C++
- UDP chat app in C++
- Log dropped/retransmitted packets using socket options
- 📘 Beej's Guide to Network Programming
- 🎥 CS144 Lab 1 – TCP Socket
- 📘 Linux Socket Programming – GeeksForGeeks
What’s really inside a packet? Can I make my own? What if I want to build a ping tool from scratch?
- Ethernet, IP, TCP, UDP headers (bit by bit)
- Checksums, fragmentation, TTL
- ICMP (used in ping, traceroute)
- Packet crafting: building your own packets
- Wireshark: decode full packet (Ethernet → IP → TCP → HTTP)
- Simulate packet loss using
tcon Linux - Craft TCP SYN packets using
scapy
- Send an ICMP echo using raw sockets
- Craft and send UDP packet by manually setting headers
- Parse incoming packet headers
- 📘 [TCP/IP Illustrated Vol 1 – Ch. 17–23]
- 🧠 Scapy Docs
- 🛠️ Raw Sockets C Guide
Can I create a computer that talks to others without relying on the OS's network stack?
- Userspace networking
- Mini-stack structure: Ethernet → ARP → IP → UDP → handler
- Buffering, routing, local IP tables
-
Create:
- Ethernet + ARP decoder
- IP + UDP parsing
- Routing table + port handler
-
Build a small CLI that listens on a UDP port using your own stack
What makes HTTPS secure? How do VPNs or BGP work in big-scale internet routing?
- TLS, HTTPS basics
- NAT traversal (P2P, STUN)
- BGP and Internet-scale routing
- Performance: RTT, jitter, congestion
- 🌐 Your Own DNS Resolver
- 📡 UDP Chat with Your Stack
- 📊 Custom Packet Sniffer with libpcap
- 🧾 Minimal HTTP Client using raw TCP
| Tool | Purpose |
|---|---|
| Wireshark | Inspect traffic deeply |
| Scapy | Craft & send packets |
| tcpdump | CLI packet sniffer |
| iptables, tc | Simulate network conditions |
| libpcap | Build sniffing tools |