The ftpusers file lists users for whom ftp login privileges are disallowed. Each ftpuser entry is a single line of the form:
where name is the user's login name.
The FTP Server, in.ftpd(1M), reads the ftpusers file. If the login name of the user matches one of the entries listed, it rejects the
The ftpusers file has the following default configuration entries:
These entries match the default instantiated entries from passwd(4). The list of default entries typically contains the superuser root and other administrative and
system application identities.
The root entry is included in the ftpusers file as a security measure since the default policy is to disallow remote logins for this identity. This policy is also set in the the default value of the CONSOLE entry in the /etc/default/login
file. See login(1). If you allow root login privileges by deleting the root entry in ftpusers, you should also modify the security
policy in /etc/default/login to reflect the site security policy for remote login access by root.
Other default entries are administrative identities that are typically assumed by system applications but never used for local or remote login, for example sys and nobody. Since these entries do not have a valid password field instantiated in shadow(4), no login can be performed.
If a site adds similar administrative or system application identities in passwd(4) and shadow(4), for example, majordomo, the site should consider including them in the ftpusers file for a consistent security policy.
Lines that begin with # are treated as comment lines and are ignored.