Windows Firewall behaviour during clean installation of Windows Server 2003 SP 1
Unlike Windows XP Service Pack 2, the Windows Firewall is off by default on Server 2003 Service Pack 1, and must be turned on to begin protecting systems. The Windows Firewall is enabled for a brief time during Service Pack 1 clean installs for the duration of the new Post-Setup Security Updates (PSSU) portion of setup.
Servers are vulnerable in the time between initial installation and having the latest security updates applied. To counter this, Windows Server 2003 with Service Pack 1 uses Windows Firewall to block all inbound connections to the server after installation until Windows Update delivers the latest security updates to the new computer. After updating, Windows Firewall is turned off until it is configured for server roles. PSSU also guides users through immediate configuration of Automatic Updates.








