Yosemite as ftp server
Have you checked that it listening on the correct network interface? If connecting to localhost:21 works, but connecting to your LAN IP does not, it's likely just a misconfiguration. You can confirm with something like this:

$ netstat -an | grep LISTEN
tcp4       0      0  *.21                *.*                    LISTEN


You want to see *.21 or 0.0.0.0.21 or 192.168.0.x.21.

If you see ::1.21 or 127.0.0.1.21 then it's only listening on the localhost interface and won't be reachable from other systems.

I couldn't reproduce your problem on my Yosemite system; when I ran ftpd with the arguments you provided, it correctly listened on all interfaces (*.21).