About ISA Server Services

ISA Server acts as a gateway to the Internet, implementing security in three security layers: IP packet filtering, application layer, and circuit layer. ISA Server's multilayered approach is made possible by the services included with ISA Server:

• ISA control service. This service is responsible for the IP packet filter (enabling, opening static filters, logging), restarting the other services as necessary, generating alerts, running actions and other functions.
• Scheduled cache content download service.
• Web proxy service. The Web proxy service is implemented at the application level, and works only with application protocols.
• Firewall service. The Firewall service is implemented at the circuit level.

All the services work with dynamic IP packet filtering, to provide a complete security model.

This section contains the following sections:

• About the ISA Control Service
• About the Scheduled Cache Content Download Service
• About the Firewall Service
• About the Web Proxy Service