IP Addressing

An IP address uniquely identifies a device on a network.

IPv4

IPv4 addresses are 32-bit numbers written as four octets (e.g. 192.168.1.1).

IPv4 Classes (Legacy)

  • Class A: First octet = network ID
  • Class B: First two octets = network ID
  • Class C: First three octets = network ID
  • Class D: Multicast
  • Class E: Experimental

NAT

Network Address Translation allows multiple devices on a private network to share a single public IP address. This is specially useful in IPv4 systems, as the number of addresses is limited:

IPv6

IPv6 addresses are 128-bit, written in hexadecimal, and use colons (e.g. 2001:0db8::1). They vastly increase the number of available addresses and eliminate the need for NAT.

Address Assignment

  • Static (manual): Using ip addr or config files
  • Dynamic: Using DHCP (Dynamic Host Configuration Protocol)

Assigning an IP Address

ip addr add 192.168.1.10/24 dev eth0