If you are attempting to FTP to a server running vsftpd as its FTP daemon you will be refused if this is a default vsftpd installation. It is strongly recommended to not allow root access to FTP because of security concerns which would provide the ftp user access to destroy anything on the server running FTP at will. Regardless it might be necessary for specific tasks and the below information will assist you in configuring vsftpd to allow the root user to login.
Starting vsftpd for vsftpd: 500 OOPS: vsftpd: not configured for standalone, must be started from inetd
Earlier today I was configuring VSFTPD on a new server. After installing via the yum package manager on a CentOS server and copying the configuration from another server to mimic its behavior I attempted to start VSFTD and it failed with the error noted in detail below. After the error details there is information on what caused the problem followed by how I was able to resolve the issue.
I was tasked with configuring VSFTPD to allow SFTP or FTPES (FTP over explicit TLS/SSL) tonight for a client. The configuration already had regular FTP working which I verified using FileZilla as an FTP client. I was able to login and transfer files in both directions to and from the server. Next I verified that SFTP worked without issue and I was able to also transfer files in both directions using SFTP. For FTPES I had to make some changes and once I did make the changes I was still getting an error when attempting to do a directory listing using FileZilla. Below I describe the initial changes I made to vsftpd.conf, the errors I received attempting to connect with FTPES, and the way I resolved the problem.