Andrew Hudson - Fedora™ Unleashed, 2008 edition

Several conversion rules may be specified in wu-ftpd's default ftpconversionsfile. Additional examples of conversion rules, such as for Sun's Solaris operating system, might be available in the wu-ftpddocumentation.

The purpose of the ftphostsfile is to allow or deny specific users or addresses from connecting to the FTP server. The format of the file is the word allowor deny, optionally followed by a username, followed by an IP or a DNS address.

allow username address

deny username address

Listing 20.3 shows a sample configuration of this file.

# Example host access file

#

# Everything after a '#' is treated as comment,

# empty lines are ignored

allow tdc 128.0.0.1

allow tdc 192.168.101.*

allow tdc insanepenguin.net

allow tdc *.exodous.net

deny anonymous 201.*

deny anonymous *.pilot.net

The *is a wildcard that matches any combination of that address. For example, allow tdc *.exodous.netallows the user tdcto log in to the FTP server from any address that contains the domain name exodous.net. Similarly, the anonymous user is not allowed to access the FTP if he is coming from a 201 public class C IP address.

Changes made to your system's FTP server configuration files become active only after you restart xinetdbecause configuration files are parsed only at startup. To restart xinetdas root, issue the command /etc/rc.d/init.d/xinetd restart . This makes a call to the same shell script that is called at system startup and shutdown for any runlevel to start or stop the xinetdaemon. xinetdshould report its status as:

# /etc/rc.d/init.d/xinetd restart

Stopping xinetd: [ OK ]

Starting xinetd: [ OK ]

When the FTP server restarts, it is accessible to all incoming requests.

wu-ftp provides a few commands to aid in server administration. Those commands are:

► ftpwho — Displays information about current FTP server users

► ftpcount — Displays information about current server users by class

► ftpshut — Provides automated server shutdown and user notification

► ftprestart — Provides automated server restart and shutdown message removal

Each of these commands must be executed with superuser privileges because they reference the ftpaccessconfiguration file to obtain information about the FTP server.

The ftpwho command provides information about the users currently connected to the FTP server. Here's the command line:

/usr/bin/ftpwho

Table 20.3 shows the format of the output ftpwhodisplays.

TABLE 20.3 ftpwhoFields

Listing 20.4 shows typical output from this command. It lists the process ID for the ftpdaemon handling requests, the class to which the particular user belongs, the total time connected, the connected username, and the status of the session.

In addition to the information given about each connected user, ftpwhoalso displays the total number of users connected out of any maximum that has been set in the ftpaccessfile. This information can be used to monitor the use of your FTP server.

You can pass one parameter to ftpwho. (You can find the parameter by using the ftpwho --helpcommand.) The single parameter you can pass to ftpwhois -V. This parameter prints out version and licensing information for wu-ftp, as shown here:

# ftpwho

Service class all:

10447 ? SN 0:00 ftpd: localhost: anonymous/winky@disney.com: IDLE

1 users (no maximum)

The output of ftpwho, using the -Voption, which shows version information, is shown in Listing 20.4.

Copyright © 1999,2000,2001 WU-FTPD Development Group.

All rights reserved.

Portions Copyright © 1980, 1985, 1988, 1989, 1990, 1991, 1993, 1994

The Regents of the University of California.

Portions Copyright © 1993, 1994 Washington University in Saint Louis.

Portions Copyright © 1996, 1998 Berkeley Software Design, Inc.

Portions Copyright © 1989 Massachusetts Institute of Technology.

Portions Copyright © 1998 Sendmail, Inc.

Portions Copyright © 1983, 1995, 1996, 1997 Eric P. Allman.

Portions Copyright © 1997 by Stan Barber.

Portions Copyright © 1997 by Kent Landfield.

Portions Copyright © 1991, 1992, 1993, 1994, 1995, 1996, 1997

Free Software Foundation, Inc.

Use and distribution of this software and its source code are governed by

the terms and conditions of the WU-FTPD Software License ("LICENSE").

If you did not receive a copy of the license, it may be obtained online

at http://www.wu-ftpd.org/license.html.

Version wu-2.6.2-8

/usr/bin/ftpcountcounts the number of connected users to the FTP server and the maximum number of users allowed. This same information is found at the end of the output for the ftpwhocommand. This command takes only one parameter, -V, which displays the same output as the previous ftpwhoexample.

# ftpcount

Service class all - 4 users (no maximum)

As with any public server administration, it is always good practice to let users of the FTP server know about upcoming outages, when the server will be updated, and other relevant site information. The ftpshutcommand allows the administrator to let the FTP server do much of this automatically.

The ftpshutcommand enables the administrator to take down the FTP server at a specific time, based on some parameters passed to it. The format of the command is as follows and is documented in the ftpshutman page: