There is logging but it is not enabled by default. You need to enable it. The process I've used is as follows:
1: You must edit the following file:
/Applications/Server.app/Contents/ServerRoot/System/Library/LaunchDaemons/com.ap ple.ftpserver.plist
Change the ProgramArguments section to look like the following:
<key>ProgramArguments</key>
<array>
<string>ftpd</string>
<string>-ll</string>
<string>-r</string>
<string>-n</string>
<string>-d</string>
<string>-c</string>
<string>/Library/Server/FTP/Config</string>
<string>-L</string>
<string>/var/log/ftpd.log</string>
</array>
2: Edit the logging system to capture debug information by editing:
/etc/asl.conf
Add the following line to the end of the file. Make sure the path to the log file is the same as defined above.
? [= Facility ftp] [<= Level debug] file /var/log/ftpd.log
3: Restart the server or restart syslogd to implement the change.
Reid
Apple Consultants Network
Author "El Capitan Server – Foundation Services" :: Exclusively available in Apple's iBooks Store
Author "El Capitan Server – Control & Collaboration" :: Exclusively available in Apple's iBooks Store
Author of Yosemite Server and Mavericks Server books