Andrew Hudson - Fedora™ Unleashed, 2008 edition

Using messages is a good way to give information about where things are on your site as well as information that is system dependent, such as alternative sites, general policies regarding available data, server availability times, and so on.

You can use magic cookies to breathe life into your displayed messages. Magic cookies are symbolic constants that are replaced by system information. Table 20.1 lists the messagecommand's valid magic cookies and their representations.

TABLE 20.1 Magic Cookies and Their Descriptions

To understand how this command works, imagine that you want to display a welcome message to everyone who logs in to the FTP server. An entry of:

message /home/ftp/welcome.msg login

message /welcome.msg login

shows the contents of the welcome.msgfile to all authenticated users who log in to the server. The second entry shows the same message to the anonymous user.

The welcome.msgfile is not created with the installation of the RPM, but you can create it using a text editor. Type the following:

Welcome to the anonymous ftp service on %L!

There are %N out of %M users logged in.

Current system time is %T

Please send email to %E if there are any problems with this service.

Your current working directory is %C

Save this file as /var/ftp/welcome.msg. Verify that it works by connecting to the FTP server:

220 FTP server ready.

504 AUTH GSSAPI not supported.

504 AUTH KERBEROS_V4 not supported.

KERBEROS_V4 rejected as an authentication type

Name (shuttle:phudson): anonymous

331 Guest login ok, send your complete e-mail address as password.

Password:

230-Welcome to the anonymous ftp service on shuttle.home.org!

230-

230-There are 1 out of unlimited users logged in.

230-

230-Current system time is Mon Nov 3 10:57:06 2003

230-

230-Please send email to root@localhost if there are

230-any problems with this service.

230-Your current working directory is /

This line sets the email address for the FTP administrator:

email

This string is printed whenever the %Emagic cookie is specified. This magic cookie is used in the message line or in the shutdown file. You should display this string to users in the login banner message so that they know how to contact you (the administrator) in case of problems with the FTP server.

Do not use your live email address in the display banner; you want others to be able to access user emails as necessary. Instead, use an alias address that routes the messages to the appropriate IT department or other address.

The readmeline tells the server whether a notification should be displayed to the user when a specific file was last modified. Here's the command:

readme {}}

The path parameter is any valid path for the user. The optional when parameter is exactly as seen in the message line. classcan be one or more classes as defined in the class file. The pathis absolute for real users. For the anonymous user, the pathis relative to the anonymous home directory, which is /var/ftpby default.

Part of system administration involves reviewing log files for what the server is doing, who accessed it, what files were transferred, and other pieces of important information. You can use a number of commands within /etc/ftpacessto control your FTP server's logging actions.

This line allows the administrator to redirect where logging information from the FTP server is recorded:

log {+}

By default, the information for commands is stored in /var/log/messages, although the man pages packaged in some RPMs state that this information is written to /var/log/xferlog. Check your server's settings for information regarding the location of your file transfer logs.

This line enables logging for all commands issued by the user:

log commands []

typelistis a comma-separated list of anonymous, guest, and real. If no typelistis given, commands are logged for all users. Some wu-ftpdRPMs set the logging of all file transfers to /var/log/xferlog(see the next section). However, you can add the logcommand to ftpaccesswith the commandskeyword to capture user actions. Logging is then turned on and user actions are captured in /var/log/messages. Here is a sample log file:

Oct 6 12:21:42 shuttle2 ftpd[5229]: USER anonymous

Oct 6 12:21:51 shuttle2 ftpd[5229]: PASS phudson@widget.com

Oct 6 12:21:51 shuttle2 ftpd[5229]: ANONYMOUS FTP LOGIN FROM 192.168.2.31 [192.168.2.31], phudson@widget.com

Oct 6 12:21:51 shuttle2 ftpd[5229]: SYST

Oct 6 12:21:54 shuttle2 ftpd[5229]: CWD pub

Oct 6 12:21:57 shuttle2 ftpd[5229]: PASV

Oct 6 12:21:57 shuttle2 ftpd[5229]: LIST