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Lesson 2: Network Fundamentals

IP addressing, subnets, ports, and protocols - build your foundation

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IP Addressing Fundamentals

Understanding IP addresses is crucial for NMAP scanning. Every device on a network needs a unique identifier to communicate.

IPv4 Address Structure

Basic Format:
IP Address: 192.168.1.100
Format: XXX.XXX.XXX.XXX
Range: Each octet can be 0-255 (8 bits each)
Total: 32 bits = 4,294,967,296 possible addresses
Address Classes:
Class A
1.0.0.0 - 126.255.255.255
Large networks
Class B
128.0.0.0 - 191.255.255.255
Medium networks
Class C
192.0.0.0 - 223.255.255.255
Small networks
Private IP Ranges:
10.0.0.0/8
16.7M addresses
172.16.0.0/12
1M addresses
192.168.0.0/16
65K addresses
NMAP Example: Scanning IP addresses
nmap 192.168.1.100
Scan a single IP address
nmap 192.168.1.1-100
Scan a range of IP addresses