Basic in securing a LAN

Date: 05/03/02

Date: Fri, 3 May 2002 12:22:25 +0200

Hello ,

  I have a little problem in securing a network. It's all based on
  public IP's (so basicly each computer may be a server of any
  kind...), and there is a mail server in the LAN too. My problem is,
  that I would like to switch to private IP's and put it all behind a
  firewall. There is no possibility for me to do it during one day, so
  I have to do it slowly, computer after computer. During that time,
  the mail server needs to be accessed both by the "new" IP's and the
  old ones. It's a Windows NT4.0 with Exchange 5.5 on it. How can I do
  that, without any problems? Is there any way I could assign two IP
  numbers to the mailserver (one public IP and one private IP)? If any
  questions, then I'm waiting.

Best regards,