The text file ftpusers contains a list of users that may not log
in using the File Transfer Protocol (FTP) server daemon. This
file is used not merely for system administration purposes but
also for improving security within a TCP/IP networked
The ftpusers file will typically contain a list of the users that
either have no business using ftp or have too many privileges to
be allowed to log in through the FTP server daemon. Such users
usually include root, daemon, bin, uucp, and news.
If your FTP server daemon doesn't use ftpusers, then it is
suggested that you read its documentation to find out how to
block access for certain users. Washington University FTP server
Daemon (wuftpd) and Professional FTP Daemon (proftpd) are known
to make use of ftpusers.
The format of ftpusers is very simple. There is one account name
(or username) per line. Lines starting with a # are ignored.