How the Internet Works

From “www.google.com” onwardshttp://willbradley.name/how-the-internet-works

@willbradleyCactusCon 2014

Connections and Protocols

“7 Layer OSI Model”

Mostly theoretical.

Note: ARP/MAC, IP, TCP, DNS, HTTP.

Packets (in Wireshark)

DNS Lookups

Recursion!

Root: . TLD: .org. NS: heatsynclabs.org.IP: 72.44.240.228

Subnets and Masks

Binary!

Addresses “in” this network start with “011”:

95: 0101 111196: 0110 000097: 0110 000198: 0110 0010

…100: 0110 0100

…124: 0111 1100125: 0111 1101126: 0111 1110127: 0111 1111

128: 1000 0000

NAT (actually PAT)

Real Routing (BGP!)

Port Forwarding / Firewalls

Ethernet (100 BASE T)

Subnetting Issues

DNS Cache Poisoning

Switching and Broadcast Storms

ARP Spoofing / MITM