Firewall and Security Overview

ISA Server can be deployed as a dedicated firewall that acts as the secure gateway to the Internet for internal clients. ISA Server protects all communication between internal computers and the Internet. In a simple firewall scenario, the ISA Server computer has two network interface cards, one connected to the local network and one connected to the Internet.

You can use ISA Server to configure the firewall, configuring policies and creating rules to implement your business guidelines. By setting the security access policies, you prevent unauthorized access and malicious content from entering the network. You can also restrict what traffic is allowed for each user and group, application, destination, content type, and schedule.

ISA Server includes the following firewall and security features:

• Outgoing access policy. You can use ISA Server to configure access rules that control how your internal clients access the Internet. Access rules specify which sites and content can be accessed, and which protocols can be used for access.
• Intrusion detection. Integrated intrusion detection mechanisms can alert you when a specific attack is launched against your network. For example, you can configure the ISA Server to alert you if a port scanning attempt is detected. For more information, see Intrusions and Alerts.
• Application filters. ISA Server controls application-specific traffic with data-aware filters. ISA Server uses the filters to determine if packets should be accepted, rejected, redirected, or modified. For more information, see Application Filters.
• Authentication. ISA Server supports the following user authentication methods: Integrated Windows authentication, client certificates, digest, and basic. ISA Server also supports third-party authentication schemes, registered with Web filters. For more information, see About Authentication in ISA Server.