I don't use fedora, so I can't give you a direct way to find out. Here's what I'd do though.
First run "netstat -tlnp" as root, and look for the process which is listening on port 21. If the name of the process doesn't make it obvious then you can either use "lsof -p ####" or grep through the output of ps using the process id from netstat, to figure out the daemon used.