NAT Benefits for New Users

The Olden Days

Back in ancient history (really just two years ago), your organization could request and be issued a network address of your own that could be used on the Internet. Those days are gone, largely due to the surprise explosion of interest in the Internet. The problem that appeared relates to the size of the Internet routing tables that control the direction each message takes as it runs through the Internet to its destination. The tables are simply too large to allow discrete routes to small isolated networks like that. Now, instead of being assigned your own network to keep forever, you are "loaned" a network by your Internet Service Provider. That's fine until you have to switch providers.

Independence from Your ISP

Sometimes our needs or preferences change, or we simply must switch our provider for reasons beyond our control. When that happens, and you are using loaned IP Addresses within your organization, you will need to reconfigure each and every computer to the new addresses that your new provider loans you. Do you have the time and staff to do this? Do you want to hire someone to do it? With our NAT products, you don't have to do it at all!

Our NAT Products

With one of our NAT products, you use "private" IP Addresses from the list defined in Internet Standard RFC 1597, rather than addresses loaned to you by your provider. The "other side" of the NAT, the side that your provider connects to, uses a single IP Address from the provider's assigned addresses. All messages that leave your site and go out through your provider use the outside address. None of your inside addresses are visible to anyone. If you change providers, only the outside address needs to be changed. Your inside addresses never need to be touched. How does it work? Read on for the short answer, or follow the link to the complete techie details?

Network Address Translation
The Short Answer

Each of our NAT products acts like an IP router. The Internet Service Provider assigns an IP Address from his assigned numbers to the ISP's side of the NAT. On "the other side" of the NAT (your private Intranet), almost any IP Addresses may be used. If none are in use yet, we recommend the "private" addresses from RFC 1597. These are free to use forever, but for internal use only.

When a user computer on the "inside" sends a message to the outside world via the NAT, the NAT keeps track of the actual "inside" address of that computer, but substitutes the assigned "outside" address into the message before it is sent into the Internet. When a reply comes back from the outside, the NAT restores the actual address before sending the reply to the user computer.

There are cases that get more complicated than this, and if you are interested, you should read the complete techie details.

Internet Security

We're all concerned about security, and our NAT helps you here. Only messages that exactly match a connection are permitted in from the Internet. This means that only messages that are in response to your requests may enter your Intranet, unless you explicitly allow them through configuration. Competing NATs that provide a simple mapping of IP Addresses may unintentionally give the hacker a window into your Intranet.

This page was last modified on April 19, 1996.