The installation procedures for installing ISA Server 2004 with a single network adapter are identical to the steps outlined for installing ISA Server 2004 Standard Edition, except for the following steps:
On the Custom Setup page, choose not to install the Firewall Client Share, because a single NIC configuration does not support firewall or SecureNAT clients.
When specifying the internal network addresses during the setup, include all of your address ranges except for 0.0.0.0, 255.255.255.255, and the address range from 127.0.0.0 to 127.255.255.255.
With only a single network adapter, all your address ranges constitute the internal network.
After the installation has completed, open the ISA Management console and apply the Single Network Adapter network template.
For more information about network templates, see Chapter 9, "Configuring Multinetworking."
On the Internal Network page, choose to add only those network addresses that are defined by the Windows Routing Table by selecting the single network adapter. To keep the attack surface smaller, clear the Add The Following Private Ranges check box.
ISA Server 2000 had an installation mode known as Caching-Only Mode, which hearkens back to ISA Server's genesis as a pure proxy server in the Proxy 2.0 product. ISA Server 2004 doesn't have a built-in caching-only mode, but does support a single network adapter configuration. The scenario of a single network adapter is useful when you want to provide only Web caching services, but not if you want to use the firewall and VPN functionality. Although ISA Server 2004 supports this configuration, you should be aware that it limits the product's functionality; the following components are not available when ISA Server is installed with a single network adapter:
All forms of virtual private networking (VPNs)
Firewall or SecureNAT clients
Multinetwork firewall policy
IP packet filtering (it is available only for the ISA Server's Local Host network)
Server publishing (Web publishing is available)
Application-level filtering (excluding application-level filtering for HTTP)
Any protocol except for FTP, HTTP, and HTTPS