Question: how vsftpd run over ssl?
Answer: Prepare a place for the SSL key to live: mkdir /etc/ssl/private. For this example we'll use a self-signed SSL: ...  Next, configure vsftpd to make use of that certificate. ...  Add the below configurations at the bottom of /etc/vsftpd/vstpd. ...  To exit type “:wq” and that will save the file and quit the program.