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Problems FTPing / Slow FTP

If you are running Windows XP or higher and are having problems with FTP please try stopping the ALG (Application Layer Gateway) service * as this can often cause problems, you can stop this service by doing the following...

  • Click "Start" button

  • Click "Run"

  • Type "cmd" and press enter, then a black command windows will open...

  • Now type the following and press enter

  • 	net stop alg

  • If the service was running you will see a message like this..
    	The Application Layer Gateway Service service was stopped successfully.

You should no longer have any FTP issues now!



Application Layer Gateway (ALG) Service

This subcomponent of the Internet Connection Sharing (ICS)/Internet Connection Firewall (ICF) service provides support for plug-ins that allow network protocols to pass through the firewall and work behind ICS. Application Layer Gateway plug-ins have the power to open ports and change data (such as ports and IP addresses) embedded in packets. File Transfer Protocol (FTP) is the only network protocol with a plug-in that is released with Windows Server 2003, Standard Edition, and Windows Server 2003, Enterprise Edition.

The ALG FTP plug—in is designed to support active FTP sessions through the network address translation (NAT) engine used by these components. The ALG FTP plug—in does this by redirecting all traffic passing through the NAT destined for port 21 to a private listening port in the 3000-5000 range on the loopback adapter. The ALG FTP plug-in then monitors and updates FTP control channel traffic so that the FTP plug-in can plumb port mappings through the NAT for the FTP data channels. The FTP plug-in will also update ports in the FTP control channel stream.

System Service Name ALG

Application protocol : FTP control

Protocol : TCP

Port : 21

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