I'm looking for information on what the most common FTP server software is. This information is readily available for web server software, but I can't find the equivalent for FTP server software. Is this information available anywhere?
The goal of this is for an FTP client being created. Clients have different options available and different responses to errors, so having a list of servers that could be tested against would be helpful. Straight implementation of the FTP spec seems to be only partway to what we need. Knowing common servers to test against would be helpful to make sure all cases are handled correctly.