[This version of Windows Defender is still in development, so some Help information might be inaccurate or missing.]

Using Windows Defender with a firewall

To join the Microsoft SpyNet community, download software updates, and get the latest definitions for Windows Defender, your computer must be connected to the Internet. To help protect your computer when you go online, make sure that you turn on Windows Firewall.

If you use a different firewall, check the publisher's documentation to see how to allow the program, MSASCui.exe, to access Transmission Control Protocol (TCP) port 80.