How does natting work ?

Question

Natting is done to save public IP's

Answer 1

NAT (Network Address Translation)

There are three main types - One-to-One , One-to-Many , Many to One (PAT)

Since private ip address (192.168.x.x , 172.16.x.x , 10.x.x.x) cannot be routed over the internet , we need to "NAT" them into a public ip address. Since it is not practical to have a public ip for each machine with private ip, NAT is used.

A device which is Natting maintains a table where it notes the source ip and port and destination ip and port and changes the ip in the packet header going out. when the packet comes back, the source ip and port is checked from the table again a change in the header takes place.

Answer 2

Natting is NAT (Natural address translation). It maps specific ports on a router to internal IP addresses. For example, map port 80 to your web server's IP and any communication on port 80 will go directly to the web server; map port 23 to your telnet server's IP and all telnet traffic will route there, etc. With NAT, a single "public" IP address can be routed to dozens (or even thousands) of internal private IP addresses on your network.