When configuring a Microsoft ISA Server 2006 array you have two options for authentication and communication between the Microsoft ISA 2006 Configuration Storage Server and the array members.
I normally configure the array members within a DMZ environment en install the CSS server on the internal network.
To maximize the security the array members aren’t part of the Active Directory. So communication between the CSS and the array members is workgroup based and the authentication type used is Authentication over SSL encrypted channel. This option needs the configuration of SSL certificates to authenticate and secure the connection. The certificates have a certain validity period, after which the certificate needs to be renewed.
Normally I always ran the repair option from the installation and specified the new certificate. I discovered a new and simpler method by using the ISACertTool. This tool provides an easy way to renew the certificate on the Configuration Storage Server and the root CA certificate on the array members.
You just need to create a web server certificate in pfx format from a Windows CA server of any other CA server. If the CA server isn’t trusted by the array members, you need to install the CA certificate on the array members. If you use trusted CA server certificate, you can skip this step.
The syntax for the ISACertTool is very straightforward. On the Configuration Storage Server you need to run the following command:
ISACertTool.exe /st <pfx file> /pswd <password> /keepcerts
On the array member you run the following command to install the root CA certificate.
ISACertTool.exe /fw <root ca file>
IMPORTANT: for a correct usage of the tool you need to extract the tool to the Microsoft ISA Server install directory, which is by default C:\Program Files\Microsoft ISA Server.