In this post we are going to talk about setting up the device sitting in front of your ISA Server either your Basic Router of choice or in this instance I will be using a Sonic Wall device. What you must decide is the IP Range you are going to use for your space between the SonicWall Lan link and the ISA Servers External NIC. Lets use 10.10.1.1 for your ISA Servers External Nics IP and 10.10.1.2 for your Sonic Wall Lan IP and a Subnet of 255.255.255.0
On your ISA Server on the External Nic properties you would define it’s IP as 10.10.1.1 Subnet of 255.255.255.0 and it’s gateway would be 10.10.1.2 this is your Sonic Walls LAN IP. On the Sonic Wall when you have set this up when you go through the setup Wizard the LAN and the WAN IP’s are defined which makes the whole process pretty darn easy. Once this is completed you would login to your SW and go to the Firewall Rules. I am using a Sonic Wall with the Basic Firmware on it and not the Enhanced OS that is a few more steps but for you that are familiar with the OS this will be a snap. You go to the Firewall Rules and Create the Rules for 443 and set it to allow and then from all on the WAN and point this to 10.10.1.1 on the LAN and do the same for Port 25 and Port 987. That is all you have to do on the Sonic Wall now to the ISA Server but the same logic will hold true for whatever type of device you have setting in front of the ISA Server if that is the choice you make. Or if you have nothing in front of this and you can ignore all of this and now on to setting up the ISA Server.
Til later just Roger