Only a few steps are needed to activate FTPS :

1. First you must generate an appropriate ssl certificate:
   openssl req -new -x509 -nodes -out vsftpd.pem -keyout vsftpd.pem
2. Copy the cert to your vsftpd directory:
   cp vsftpd.pem /etc/vsftpd
3. Add the following to vsftpd.conf:
   ssl_enable=YES
   rsa_cert_file=/etc/vsftpd/vsftpd.pem
   force_local_data_ssl=NO

Once the above configuration is active, system (and “virtual”) users will be required to use a client that supports FTPS. If your server allows Anonymous users, they will only be able to login with plain old FTP. With vsftpd, FTPS is only for authenticated users.