To restrict access to a FTP site to a specific IP address, Click on “Start > Administrative Tools > Internet Information Services (IIS) Manager”
Expand “SERVERNAME“, and then expand “FTP Sites“.
Right Click on “Default FTP Site” and choose “Properties“.
Click on the “Directory Security” tab.
Click “Add“, and then enter the desired IP address you want to Allow FTP access to, and Click “OK“.
Click “OK” to close the window
You must Stop and Start the FTP Site in order for the changes to take effect, by either restarting the FTP Publishing Service or IIS.