I need to test FTP client codes, so I need to find an FTP server for testing my codes. After searching for a while I find out that OS X already equipped FTP server. I am currently using OS X El Capitan 10.11.*.

Let’s now test the FTP server on Mac OS X with the following steps:

• Launch the Terminal.app
• Type the following command to start the FTP server.

sudo -s launchctl load -w /System/Library/LaunchDaemons/ftp.plist

• Connect to the FTP server by running ftp localhost command.
• We’ll be asked to enter the username and password.

$ ftp localhost
Trying ::1...
Connected to localhost.
220 ::1 FTP server (tnftpd 20100324+GSSAPI) ready.
Name (localhost:wsaryada): wsaryada
331 User wsaryada accepted, provide password.
Password: 
230 User wsaryada logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>

• If we see the messages above and the ftp> prompt means that the FTP server works and ready to accept our command.
• We can also try to access the FTP server using a browser. In the URL box type `ftp://localhost` to connect. We need to supply username and password to login.
• To exit or close the connection to FTP server we can run the exit command.
• Finally, to shut down the FTP server we run:

sudo -s launchctl unload -w /System/Library/LaunchDaemons/ftp.plist

After the FTP server ready, I can now continue to create some test program to access the FTP server. There are already some examples you can find in the Apache Commons Net category that use the FTPClient library to access FTP server.