ftpusers

The ftpusers file is used to specify the users who are denied access to your FTP server. This file is in the /etc directory by default. The /etc/ftpusers file allows you to keep certain users from logging into your machine via FTP. When an incoming FTP connection is received, the /etc/ftpusers file is read by the FTP daemon program (ftpd). The file is a simple list of those users who are not allowed to log on. The content of the file is given here:

root
bin
daemon
adm
lp
sync
shutdown
halt
mail
news
uucp
operator
games
nobody

ftpconversions

The ftpcomversions file contains instructions for compressing files before transfer. The file contains the conversion types and their attributes. The format for entries in the file is given here:

In the preceding format, field1 and field2 specify the prefix and postfix to be removed. field3 and field4 specify the prefix and postfix to be added. field5 is an external command. field6, field7, and field8 are types, options, and descriptions, respectively.

FTP Administrative Tools

Many tools are available to monitor your FTP servers. Here are two such administrative tools:

• ftpwho. This tool displays all the active FTP users and their current processes.
• ftpcount. This tool displays only the number of users currently logged on to the FTP server. In addition, it also displays the maximum number of users who are allowed access.