Microsoft Internet Security and
Acceleration Server 2000
About ISA Server
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
All the services work with dynamic IP packet filtering, to
provide a complete security model.