NAT or Proxy

1. Proxy is a form of NAT. Either way you are having many stations without routable IP numbers share the use of a single valid routable IP number. The difference is that with NAT, a router is doing translation invisibly, while with proxy, each client is aware of the proxy server, and makes specific requests to the proxy server.

2. From the safety standpoint they are identical.

3. Depending on what you use, you may get other features, and the costs will differ. If you are using a $200 router, you can get NAT, DHCP, DNS and routing. If you set up a linux box, you are paying for a computer (or using a junk old one), and get whatever features are included in the program you are using. If you are using Microsoft Proxy, you are paying for the Proxy software and for NT or W2K Server.

An important difference may be the level of control you get. If you use a program, everyone on your LAN gets out on an equal basis. Using a Proxy, you have software control over who gets out (by login), where they cannot go, etc.

Depending on the proxy you use, it may do caching for you (or to you). It may also do packet editing to PPTP packets to allow multiple inside users to set up vpn (depends on proxy).

Good luck.

Actually:

1. A true application Proxy is definitely safer. There is no connection between the two end hosts. It appears that a Proxy is doing NAT but it's not. It has two seperate processes, one that uses an IP to communicate with the internal device and one that uses an IP (the same or different) to communicate with the external device.

2. NAT on a fast packet filter such as a router is always faster (layer 3 opposed to Proxy layer 7).

3. Depending on what device is doing the NAT there are any number of other differences. I wrote a short whitepaper on firewalls if you're interested and I can dig up others that confirm and also expand upon it.

http://pages.sbcglobal.net/mckenzies/shawn/whitepapers/threatsandthwarts.pdf
HTH

NAT is a Technique to:
1.- Secure: Hide your nic address from the internet
2.- Lower Internet costs. You need only 1 ip public address for ALL your businnes (1000 wks?)
3.- Very easy and low cost

Proxy is an utility to
1.- Improve Bandwoith: Go for a page only one time for many requests
2.- Secure: Validate user access using rules
3.- Secure: Provide "some" service packet
filtering. It only allows you to have the minimun ports open for ftp, http, ssl, dns, etc

Hope it's clear.!!!