types of NAT

mohsin.khan · ‎03-02-2010

Hi,

Need to know the difference between, Source NAT and Destination NAT... My understanding is the Source NAT is No-NAT and destination NAT is the actual NAT.

Also, there are two type of natting, one method is to map a group of IP addresses coming on ingress interface to another group of IP addresses on egress interface. Other method is to NAT the ingress interface to egress interface. Which is one suitable for what scenario? what if there are 2 egress interfaces part of the same security zone?

regards,

Mohsin

Panos Kampanakis · ‎03-03-2010

Source nat is when you translate the source of the packet, destination is for the destination.

Let's sat x is going to y. When you translate x to x; you are doing source nat, and when y is translated to y' you are doing destination natting.

Usually people translate hosts behind their internal high security interfaces that use local ip addresses to the outside worlds to a global ip address.

Very rarely do people translate the outside people coming in to your internal network so they look to a different ip than they have.

In other words most people do outbound source nat.

I hope it helps.

PK

mohsin.khan · ‎03-03-2010

Very rarely do people translate the outside people coming in to your internal network so they look to a different ip than they have.

Will this be called inbound source nat?

Let's sat x is going to y. When you translate x to x; you are doing source nat, and when y is translated to y' you are doing destination natting.

When you say x, is it source interface or source IP/ip pool?

KARUPPUCHAMY MALAIYANDI · ‎03-03-2010

Hi,

//Very rarely do people translate the outside people coming in to your internal network so they look to a different ip than they have.

Will this be called inbound source nat? //

There is nothing like inbound source NAT.

// Let's sat x is going to y. When you translate x to x; you are doing source nat, and when y is translated to y' you are doing destination natting.

When you say x, is it source interface or source IP/ip pool? //

It should be your source network either it might be a single IP or multiple IPs.

Souce NAT : Inside source IP will be NAT into outside IP. The best example is your internet proxy server want to communicate to internet.But if your proxy server has private IP then you have to do source NAT with public IP,then only it can be reached to internet.

Destination NAT : You have hosted one WEB server in your network.if the peoples from internet want to access your server, then we have to to destination NAT.

Regards

Karuppu