Ethical Hacking for Beginners (Chapter-8)
IP ADDRESS OVERVIEW
Classification of IP:-
IP addresses are generally divided into 3 classes.
Class A: 0.0.0.0 - 127.255.255.255
Class B: 128.0.0.0 - 191.255.255.255
Class C: 192.0.0.0 - 223.255.255.255
Public vs Private IP address:-
A public IP address is an IP address that can be accessed directly over the internet and is assigned to your network router by your internet service provider (ISP). Your personal device also has a private IP that remains hidden when you connect to the internet through your router's public IP.
A private IP address is an address your network router assigns to your device. Each device within the same network is assigned a unique private IP address, this is how devices on the same internal network talk to each other. When you type ipconfig or ifconfig then your computer shows you the private IP of your device eg:- 192.168.xxx.xxx
Structure of an IP Packet and Classification of IP addresses:-
An IP packet consists of mainly 6 parts:-
Header:- It contains the header and version information of an IP address.
Checksum:- This field is used to keep the checksum value of the entire header which is then used to check if the packet is received error-free.
Source address:- 32-bit address of the Sender (or source) of the packet.
Destination Address:- 32-bit address of the Receiver (or destination) of the packet.
Options:- This is an optional field, which is used if the value of IHL is greater than 5. These options may contain values for options such as Security, Record Route, Time Stamp, etc.
Data:- It contains the actual information which that data packet contains
An IP packet can max 64Kb in length.
IP address Classification:-
IP addresses are classified into 3 categories mainly Class A, B, C. Except this D and E also exist but they are used for another purpose. D used for multicast purpose and E for experimental purpose.
