This article describes how to enable ICMP traffic from protected SecureNet clients to external hosts in Microsoft Internet Security and Acceleration (ISA) Server 2006 and in Microsoft ISA Server 2004.

ISA Server does not pass ICMP traffic from protected SecureNet clients without a firewall policy that is configured to let ICMP traffic to pass through the ISA Server. ISA Server cannot pass ICMP traffic from non-SecureNet clients.

You must have a firewall policy that permits the ISA Server computer to send and receive Internet Control Message Protocol (ICMP) packets. Additionally, you must enable Internet Protocol (IP) routing on the ISA Sever computer.

To enable IP routing in ISA Server 2004, follow these steps:

1.	Click Start, point to Programs, point to Microsoft ISA Server, and then click ISA Server Management.
2.	In the ISA Server Management console tree, expand Server_Name, where Server_Name is the name of the ISA Server that you want to configure. Note For ISA Server 2004, Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2004, expand Arrays, and then expand Array_Name.
3.	Expand Configuration, and then click General.
4.	In the details pane, click Define IP Preferences under Additional Security Policy.
5.	In IP Preferences, click the IP Routing tab.
6.	Make sure that the Enable IP routing check box is selected, and then click OK. Note By default, the Enable IP routing check box is selected.

To enable IP routing in ISA Server 2006, follow these steps:

1.	Click Start, point to All Programs, point to Microsoft ISA Server, and then click ISA Server Management.
2.	Expand Microsoft Internet Security and Acceleration Server 2006, expand Server _Name, expand Configuration, and then expand General. Note For ISA Server 2006 Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2006, expand Arrays, expand Array_Name, and then expand Configuration.
3.	In the details pane, click Configure IP Protection.
4.	Click the IP Routing tab, click to select the Enable IP routing check box, and then click OK.