| 4.3 |  | Cisco Secure ACS |
| 4.3.4 |  | Cisco Secure ACS Solutions Engine |

| The Cisco Secure ACS Solutions Engine is a PC that performs the same functions as the Cisco Secure ACS 3.2 for Windows server product. Additional functionality has been added to manage the appliance itself using both a serial console port interface and a customized Web interface.

Compared to the ACS 3.2 for Windows server version, the ACS Appliance reduces the total cost of ownership by eliminating the need to install and maintain a Microsoft Windows 2000 Server machine.

The Cisco Secure ACS Solutions Engine is built on a rack-mountable (1U) server platform. For security reasons, the second Serial port, Video port, Parallel port, Mouse port, and Keyboard port are not used. Even though the video, mouse, and keyboard ports are active, the appliance does not allow GUI login to the Windows 2000 system.

The appliance uses a standard BIOS with serial console port redirection, and flash ROM. A small portion of the flash ROM is used to store an appliance signature (appliance type). During an appliance upgrade, the upgrade process reads this signature to ensure that the correct device is being upgraded.

The Appliance utilizes a hardened implementation of the Microsoft Windows 2000 Server kernel. This hardened OS is much more secure than a standard Windows 2000 Server machine for the following reasons as shown in Figure . OS services are not accessible remotely due to packet filtering.

Packet filtering blocks traffic on all but necessary IP ports. Only the ports shown in Figure are open: The appliance assigns unique port numbers from this range for each administrative session. The range is defined using the appliance Administration control/Access policy Web page. It is best that the ACS be placed in a protected network segment.

The Appliance runs the same code as the software version of the Cisco Secure ACS 3.2 for Windows. In most cases ACS works the same way on the appliance as the software version. When it is necessary to operate differently, the 3.2 software senses that it is operating on an appliance by checking the platform type (found in the registry). The following ACS components operate differently when running on the Cisco Secure ACS Appliance:

- Backup/Restore - The appliance uses an external FTP server instead of the local file system for ACS data backup and restore.
- Login - The appliance allows only administrator access.

The Appliance ships with a recovery CD that can be used in the following instances:

- Lost administrative password - The recovery CD can be used to reset the password to the factory default. For this reason, it is extremely important that you secure the recovery CD.
- Corrupted hard drive - The recovery CD can be used to re-image the appliance hard drive, returning it to the factory default configuration. This is, of course, another very important reason to secure the recovery CD.