Mini-Tip: SFTP Server on MacOS X
If you need to transfer files between your Mac and other machines, do not use the Mac's "FTP Access" in the Sharing preferences. FTP transfers passwords in the clear, which is an unacceptable security risk. Instead, turn on "Remote Login." This enables SSH and SFTP access to your Mac. These protocols encrypt your password and also data traveling across the network. Use SFTP for moving files around.
If you must use FTP, consider creating a separate account on your Mac. That way your primary account's password won't be compromised if someone snoops your FTP traffic. Change the FTP account's password frequently, and always consider that account vulnerable.