Windows XP Services

Application Layer Gateway Service - Windows XP Service

Provides support for 3rd party protocol plug-ins for Internet Connection Sharing and the Windows Firewall.

This service also exists in Windows 10, 7, 8 and Vista.

Startup Type

Windows XP edition without SP SP1 SP2 SP3
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Default Properties

Display name:Application Layer Gateway Service
Service name:ALG
Error control:normal
Object:NT AUTHORITY\LocalService

Default Behavior

The Application Layer Gateway Service runs as NT AUTHORITY\LocalService in its own process. It does not share the executable file with other services. If the Application Layer Gateway Service fails to load or initialize, the error is recorded into the Event Log. Windows XP startup should proceed, but a message box is displayed informing you that the ALG service has failed to start.


If the Application Layer Gateway Service is stopped, the Internet Connection Firewall (ICF) / Internet Connection Sharing (ICS) fails to start and initialize.

Restore Default Startup Type of Application Layer Gateway Service

Automated Restore

1. Select your Windows XP edition and Service Pack, and then click on the Download button below.

2. Save the RestoreApplicationLayerGatewayServiceWindowsXP.bat file to any folder on your hard drive.

3. Run the downloaded batch file.

4. Restart the computer to save changes.

Note. Make sure that the alg.exe file exists in the %WinDir%\System32 folder. If this file is missing you can try to restore it from your Windows XP installation media.

Yea, though I walk through the valley of the shadow of death, I will fear no evil: for thou art with me; thy rod and thy staff they comfort me.