wu-ftp provides a few commands to aid in server administration. Those commands are
Each of these commands must be executed with superuser privileges because they reference the ftpaccess configuration file to obtain information about the FTP server. Display Information About Connected UsersThe ftpwho command provides information about the users currently connected to the FTP server. Here's the command line: /usr/bin/ftpwho Table 24.3 shows the format of the output ftpwho displays.
Listing 24.5 shows typical output from this command. It lists the process ID for the ftp daemon handling requests, the class that the particular user belongs to, the total time connected, what username the user is connected as, and the status of his session. In addition to the information given about each connected user, ftpwho also displays the total number of users connected out of any maximum that has been set in the ftpaccess file. 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--help command.) The single parameter you can pass to ftpwho is -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 -V option, which shows version information, is shown in Listing 24.5. Listing 24.5. ftpwho -V Command Output
Count the Number of Connections/usr/bin/ftpcount counts 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 ftpwho command. This command only takes one parameter, -V, which displays the same output as the previous ftpwho example. # ftpcount Service class all - 4 users (no maximum) Use /usr/sbin/ftpshut to Schedule FTP Server DowntimeAs 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 ftpshut command allows the administrator to let the FTP server do much of this automatically. The ftpshut command allows 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 ftpshut man page: ftpshut [ -V ] [ -l min] [ -d min] time [ warning-message ... ] The -V parameter displays the version information of the command. The time parameter is the time when the ftpshut command will stop the FTP servers. This parameter takes either a + number for the number of minutes from the current time, or a specific hour and minute in 24-hour clock format with the syntax of HH:MM. The -l parameter allows the FTP server administrator to specify how long, in minutes, before shutdown the server disallows new connections. The default is 10 minutes. If the time given to shut down the servers is less than 10 minutes, new connections are disallowed immediately. The -d parameter is similar to the -l parameter, but controls when the FTP server terminates the current connections. By default, this occurs five minutes before the server shuts down. If the shutdown time is less than five minutes, the server terminates the current connections immediately. When you execute this command, the FTP server creates a file containing the shutdown information in the location specified under the shutdown section in the ftpaccess file. The default configuration for this file is /etc/shutmsg. If you execute the ftpshut command with warning messages, the messages are displayed when the user logs in to the server. Name (pheniox:tdc): anonymous 331 Guest login ok, send your complete e-mail address as password. Password: 230-system doing down at Mon Sep 3 06:23:00 2001 230-0 users of unlimited on pheniox. 230 Guest login ok, access restrictions apply. Remote system type is UNIX. Using binary mode to transfer files. Here is a sample ftpshut command: ftpshut -l 5 -d 5 +10 "system going down at %s %N users of %M on %R" This command tells the FTP server to disconnect new connections in 5 minutes, drop all current connections in 5 minutes, shut down the server in 10 minutes, and display a warning message to the users at login. The message can be a mixture of text and the magic cookies defined in Table 24.4. It is important to keep in mind that the message can be a maximum of 75 characters in length. Additionally, it is not important to know how many characters the magic cookies take because the system knows this information and truncates the message at 75 characters.
When ftpshut is issued to the system, it creates a file that stores the necessary information. The ftprestart command removes this file for all servers, either canceling the impending shutdown or removing the shutdown file and restarting the FTP server. The ftprestart has only one optional argument, -V, to show version information. Use /var/log/xferlog to View a Log of Server TransactionsThe xferlog file gives a log of what transactions have occurred with the FTP server. Depending on the settings in the /etc/ftpaccess file, the contents of this file can contain the files sent or received, by who, with a date stamp. Table 24.5 lists the fields of this file. The same information can also be found in the corresponding man page included in the wu-ftp RPM.
An example of this file is seen in Listing 24.6. Listing 24.6. Sample /var/log/xferlog File with Inbound and Outbound Logging
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