networking fundamentals

RFC 1918 Address Allocation For Private Internets

If your IP address starts with 169.254.x.x then that means that you were not given an IP address by your DHCP server.

WAN

Wide Area Network

The network on the outside

LAN

Local Area Network

The network that you control

NAT

Network Address Translation

Think of it like a mail sorting machine. An envelope slides down a single chute and when it comes to the fork a device knows which path to route the envelope (left, right, or middle).

private IP addresses

IP addresses that are reserved for use on LANs and not the Internet

• 192.168.0.0 - 192.168.255.255
• 172.16.0.0 - 172.31.255.255
• 10.0.0.0 - 10.255.255.255

IPv4 address blocks

/8 = 255.0.0.0

/16 = 255.255.0.0.

/24 = 255.255.255.0

/32 = 255.255.255.255

example: 192.168.1.0/24 = 192.168.1.0-192.168.1.255

example: 192.168.1.1/16 = 192.168.1.0-192.168.2.255

how your home network works

If you have several computers in your home then you'll be using some type of router. Here's a quick rundown of how it all works

1. The modem makes a request to your Internet provider for an IP address.
2. The Internet provider acknowledges that the modem is part of their network and gives the OK to supply an IP address.
3. The modem receives the IP address supplied.
4. Your router is looking for an IP address as well. It sends out a request that is answered by the modem.
5. The modem tells the router "Here's the number I got from the Internet provider. You use it."
6. The router now knows how to get to the outside world or the WAN.
7. The router then creates a private network so it can share this one IP address amongst several computers attached to it.
8. The router makes use of NAT so it can figure out which computer to send the data to.