If the FTP Server service from Windows NT version 3.51 or earlier is installed and running on your system, it will continue to run without modification under Windows NT 4.0.
However, if you install the Internet Information Server FTP service, the FTP Server service from Windows NT version 3.51 or earlier will be disabled. Both FTP services cannot run simultaneously.
You can upgrade your Windows NT 3.51 or earlier FTP service to Internet Information Server version 2.0. You must change the Internet Information Server FTP service home directory to the previous location. The FTP service continues to operate in the same way as the Windows NT 3.51 or earlier version of the FTP service.
Note
The Windows NT 3.51 or earlier FTP service permitted users to traverse the directory structure above the specified FTP root. Internet Information Server removes this capability.