Wednesday, February 9, 2011

Group Policy: Windows Firewall: Allow inbound file and printer sharing exception

Location: Computer Configuration > Policies > Administrative Templates > Network > Network Connections > Windows Firewall > Domain Profile

Supported on: At least Windows XP Professional with SP2

Allows inbound file and printer sharing. To do this, Windows Firewall opens UDP ports 137 and 138, and TCP ports 139 and 445.

If you enable this policy setting, Windows Firewall opens these ports so that this computer can receive print jobs and requests for access to shared files. You must specify the IP addresses or subnets from which these incoming messages are allowed. In the Windows Firewall component of Control Panel, the "File and Printer Sharing" check box is selected and administrators cannot clear it.

If you disable this policy setting, Windows Firewall blocks these ports, which prevents this computer from sharing files and printers. If an administrator attempts to open any of these ports by adding them to a local port exceptions list, Windows Firewall does not open the port. In the Windows Firewall component of Control Panel, the "File and Printer Sharing" check box is cleared and administrators cannot select it.

If you do not configure this policy setting, Windows Firewall does not open these ports. Therefore, the computer cannot share files or printers unless an administrator uses other policy settings to open the required ports. In the Windows Firewall component of Control Panel, the "File and Printer Sharing" check box is cleared. Administrators can change this check box.

Note: If any policy setting opens TCP port 445, Windows Firewall allows inbound ICMP echo requests (the message sent by the Ping utility), even if the "Windows Firewall: Allow ICMP exceptions" policy setting would block them. Policy settings that can open TCP port 445 include "Windows Firewall: Allow inbound file and printer sharing exception," "Windows Firewall: Allow inbound remote administration exception," and "Windows Firewall: Define inbound port exceptions."

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