Basics of NAT

Takes one IP address and translates it into another.
NAT is a technology that allows a gateway, usually a router or firewall to rewrite the source IP of an outgoing IP datagram while retaining the original IP in order to rewrite it into the response.

IP masquerading

No one can establish a connection to your computer if they don't know what IP address it has.

One-to-many NAT

To the outside world, the entire address space of network A is protected and invisible.

NAT and the Transport Layer

Port Preservation (Router)

A technique where the source port chosen by a client , is the same port used by the router. (ephemeral port)

Port Forwarding (NAT)

A technique where a specific destination ports can be configured to always be delevered to specific nodes.

NAT, Non-Routable Address Space and the Limits of IPv4

RIR

Regional Internet Registriy.

5 RIRs

• AFRINIC : The continent of Africa

• ARIN : United States, Canada and parts of the Caribbean

• APNIC : Asia, Australia and New Zealand and Pacific Island Nations.

• LACNIC : Central and South America and any parts of the Caribbean not covered by ARIN

• RIPE : Europe, Russia and the Middle East and portions of Central Asia.