Did you know that your ISA firewall has a System Policy? You might not know this if you haven’t read about it, since the System Policy is hidden from view by default. The ISA Firewall System Policy is a collection of pre-defined rules that are evaluated before any other firewall rules that you create. System Policy rules are unique in the their main function is to control traffic direct to or from the ISA firewall itself. System Policy rules do not control traffic moving though the ISA Firewall.

System Policy rules may be the reason things don’t work the way you think they should. If you haven’t learned about System Policy Rules, then you should check them out. Here’s a great article to get you started:

http://technet.microsoft.com/en-us/library/bb794729.aspx

Keep in mind that TMG firewalls also using System Policy. So if you’re running the EBS version of the TMG, you should check out that System Policy as well, although the EBS team has pre-configured it for you so that everything should work right out of the box.

HTH,

Tom

Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer
Prowess Consulting www.prowessconsulting.com
PROWESS CONSULTING documentation | integration | virtualization
Email: tshinder@isaserver.org
MVP — Forefront Edge Security (ISA/TMG/IAG)