Backing up a web server with FTP is a popular choice. However, it's hazardous to give the web server delete access because unauthorized users could delete the backups. This guide demonstrates how to configure `vsftpd`, a popular FTP server, to deny delete access. The web server and FTP server are physically separate in different datacenter locations. This guide uses WordPress and UpdraftPlus, a popular backup plugin, but you can substitute any server and backup method that uses FTP to upload fil......