IP Addressing
IP Addressing
IP (Internet Protocol) addresses are numerical labels used to identify devices on a network. Without them, no device would know where to send or receive data.
What is an IP Address?
An IP address is a unique identifier for a device on a network. It works like a digital address so data knows where to go.
IPv4 Format
Most commonly, IP addresses appear in IPv4 format: four numbers (0–255) separated by dots.
Example:
- `192.168.1.10`
Each number is called an octet, representing 8 bits of data:
- `192 = 11000000`
- `168 = 10101000`
- `1 = 00000001`
- `10 = 00001010`
Together: 32 bits total.
Private vs Public IP Addresses
There are two main types of IP addresses based on visibility:
| Type | Description | Assigned By | Example |
|---|---|---|---|
| Private IP | Only used inside local networks (not visible on the internet) | Your router (via DHCP) | `192.168.1.10` |
| Public IP | Used to identify your network online (visible to the internet) | Your Internet Service Provider (ISP) | `86.157.52.21` |
Devices on the same local network get unique private IPs from the router, which acts as a gateway. However, all devices appear to the internet under a single public IP, which is assigned by your ISP.
This is why your laptop, phone, and PC at home may all show the same public IP when browsing the web, but still communicate separately using their private IPs inside your network.
Example Setup
| Device | Private IP | Public IP |
|---|---|---|
| Laptop | 192.168.1.5 | 86.157.52.21 |
| Desktop | 192.168.1.10 | 86.157.52.21 |
These devices can talk to each other using their private IPs. Any connection they make to the internet will appear as coming from the public IP.
Dynamic vs Static IPs
IP addresses can change or stay the same, depending on how they’re assigned.
| Type | Description |
|---|---|
| Dynamic IP | Assigned automatically by a router using DHCP. Changes over time. |
| Static IP | Manually assigned to a device. Remains fixed unless changed manually. |
Most home networks use dynamic IPs, but in hacking or server setups, static IPs are often required for consistency.
IPv6 Overview
Due to the limited number of IPv4 addresses, a newer format was introduced: IPv6.
- IPv6 uses 128-bit addresses (compared to 32-bit in IPv4)
- Allows over 2128 unique addresses
- Supports direct device-to-device communication
- Helps eliminate the need for NAT
Example IPv6 address:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
Relevance for Hacking
Understanding IP addresses is key to:
- Scanning and identifying targets
- Avoiding detection and filtering
- Navigating local vs. external access
- Recognizing how routing and NAT affect visibility