Networking Learning Guide¶

Introduction¶

This folder contains materials for systematically learning computer networking. You can understand the principles of network communication from the OSI 7-layer model to TCP/IP, routing, and security.

Target Audience: Developers, system administrators, anyone learning networking fundamentals

Learning Roadmap¶

[Basics]                  [Intermediate]            [Advanced]
  │                         │                         │
  ▼                         ▼                         ▼
Network Overview ───▶ IP Addressing ──────▶ Routing Protocols
  │                         │                         │
  ▼                         ▼                         ▼
OSI/TCP-IP ─────────▶ TCP/UDP ────────────▶ Network Security
  │                         │                         │
  ▼                         ▼                         ▼
Physical/Data Link ──▶ Application Layer ──▶ Practical Tools

Prerequisites¶

Computer fundamentals (operating system concepts)
Understanding of binary and hexadecimal numbers
Basic command-line usage

File List¶

Network Fundamentals (01-04)¶

File	Difficulty	Key Topics
01_Network_Fundamentals.md	⭐	Network definition, LAN/WAN, topology
02_OSI_7_Layer_Model.md	⭐⭐	Layer roles, protocols, PDU
03_TCP_IP_Model.md	⭐⭐	TCP/IP 4-layer, comparison with OSI
04_Physical_Layer.md	⭐	Transmission media, signals, Ethernet cables

Data Link and Network Layer (05-09)¶

File	Difficulty	Key Topics
05_Data_Link_Layer.md	⭐⭐	MAC address, frames, switches, ARP
06_IP_Address_Subnetting.md	⭐⭐	IPv4, subnet masks, CIDR
07_Subnetting_Practice.md	⭐⭐⭐	Subnet calculations, VLSM
08_Routing_Basics.md	⭐⭐⭐	Routing tables, static/dynamic routing
09_Routing_Protocols.md	⭐⭐⭐	RIP, OSPF, BGP

Transport Layer (10-11)¶

File	Difficulty	Key Topics
10_TCP_Protocol.md	⭐⭐⭐	3-way handshake, flow/congestion control
11_UDP_and_Ports.md	⭐⭐	UDP characteristics, port numbers, TCP vs UDP

Application Layer (12-14)¶

File	Difficulty	Key Topics
12_DNS.md	⭐⭐	Domain structure, DNS lookup, records
13_HTTP_and_HTTPS.md	⭐⭐⭐	HTTP methods, status codes, TLS
14_Other_Application_Protocols.md	⭐⭐	DHCP, FTP, SMTP, SSH

Network Security and Practice (15-17)¶

File	Difficulty	Key Topics
15_Network_Security_Basics.md	⭐⭐⭐	Firewalls, NAT, VPN
16_Security_Threats_Response.md	⭐⭐⭐⭐	Sniffing, spoofing, DDoS
17_Practical_Network_Tools.md	⭐⭐⭐	ping, netstat, tcpdump, Wireshark

Modern Networking (18-19)¶

File	Difficulty	Key Topics
18_IPv6.md	⭐⭐⭐	IPv6 addressing, SLAAC, DHCPv6, transition mechanisms
19_Container_Networking.md	⭐⭐⭐⭐	Docker CNM, K8s networking, CNI plugins, service mesh

Recommended Learning Path¶

Phase 1: Network Fundamentals (1 week)¶

01_Network_Fundamentals → 02_OSI_7_Layer_Model → 03_TCP_IP_Model

Phase 2: Lower Layers (1 week)¶

04_Physical_Layer → 05_Data_Link_Layer

Phase 3: IP and Routing (1-2 weeks)¶

06_IP_Address_Subnetting → 07_Subnetting_Practice → 08_Routing_Basics → 09_Routing_Protocols

Phase 4: Transport Layer (1 week)¶

10_TCP_Protocol → 11_UDP_and_Ports

Phase 5: Application Layer (1 week)¶

12_DNS → 13_HTTP_and_HTTPS → 14_Other_Application_Protocols

Phase 6: Security and Practice (1-2 weeks)¶

15_Network_Security_Basics → 16_Security_Threats_Response → 17_Practical_Network_Tools

Phase 7: Modern Networking (1-2 weeks)¶

18_IPv6 → 19_Container_Networking

Practice Environment¶

Command-Line Tools¶

# Test network connectivity
ping google.com
traceroute google.com

# Check network information
ip addr                    # Linux
ifconfig                   # macOS
ipconfig                   # Windows

# Check connection status
netstat -an
ss -tuln                   # Linux

# DNS lookup
nslookup google.com
dig google.com

Packet Capture¶

# tcpdump (Linux/macOS)
sudo tcpdump -i eth0 -n

# Wireshark (GUI)
# https://www.wireshark.org/

# tshark (CLI)
tshark -i eth0

Simulators¶

Cisco Packet Tracer: Network simulation
GNS3: Advanced network emulation
EVE-NG: Virtual network lab

Common Port Numbers¶

Port	Protocol	Description
20, 21	FTP	File transfer
22	SSH	Secure shell
23	Telnet	Remote access (unencrypted)
25	SMTP	Email transmission
53	DNS	Domain name service
67, 68	DHCP	Automatic IP assignment
80	HTTP	Web
443	HTTPS	Secure web
3306	MySQL	Database
5432	PostgreSQL	Database

Links to Other Folders¶

Folder	Related Content
Linux/	Network configuration, firewalls
Docker/	Container networking
Web_Development/	HTTP, REST API

External Resources¶

Learning Tips¶

Layer-by-Layer Understanding: Thoroughly understand OSI/TCP-IP layers
Practice-Oriented: Directly verify with ping, traceroute, Wireshark
Packet Analysis: Learn actual packet structures with Wireshark
Subnetting Practice: Solve many subnet calculation problems
Protocol Headers: Memorize header structures of each protocol