Administrators who are new to Linux, especially those who are used to the Windows NT/2000 GUI, often don’t know where to go to administer key programs and services in Linux. In this article, we will take a look at Webmin, a Web-based GUI that is useful and efficient for administering a Linux server. We will cover the basics of installing and using Webmin and highlight some of its handiest features.
Webmin is now included by default on a number of Linux distributions. To find out if Webmin is installed on your Linux system, simply open a browser window on your Linux machine—from Xwindows—and go to http://127.0.0.1:10000 (or https://127.0.0.1:10000 to see if you have the 128-bit encrypted version). If you see something similar to the login screen in Figure A, you already have Webmin.
If you don't receive the login screen, simply download the appropriate rpm or tar file and install it on your Linux system. If you are going to remotely administer the Linux server with Webmin, you should also plan on setting up Webmin with 128-bit encryption via SSL.
Once you have Webmin installed, open up your browser again and go to http://127.0.0.1:10000. (You can replace 127.0.0.1 with localhost or the host name of your Linux server.) At the login prompt, enter root for the username and the root password. This will bring you to the main Webmin page (Figure B), where you can access all of Webmin's configuration parameters and gain quick access to all of the included utilities.
The Webmin Configuration button will take you to several useful options, among which you can automatically update your Webmin utility to the latest version by simply clicking the Upgrade Webmin button and then selecting Latest Version From www.webmin.com.
In the Webmin Configuration section, you can control access to the Webmin server with the IP Access Control module, and you can customize the settings and the appearance of Webmin itself. There are numerous options, so my best advice is to play around with them and read their summaries to see which ones will be useful to you.
The Webmin utility has a good wizard-like interface that offers help and explanations for many of the configurations you can set up with the tool. However, if you happen to get stuck, check out this Webmin guide. It's an outstanding reference for both the new and advanced Webmin user.
Digging into configuration
After you explore the Webmin Configuration section, you are ready to move on to the other major sections of Webmin, which are dedicated to managing the Linux server itself. These sections are:
Note that some Webmin versions for different Linux and UNIX distributions have additional tabs, such as Networking and Clusters. The System tab and the Servers tab are the most comprehensive and are the ones you will probably spend the most time working with.
The System tab (Figure C) contains a number of useful system administration utilities for working with disk quotas, running processes, managing users and groups, scheduling cron jobs, monitoring system logs, and much more.
The Servers tab (Figure D) provides access to server administration modules such as Apache, Samba, Squid, BIND, Sendmail, and DHCP, to name a few. Keep in mind that to use these modules, the related software must already be installed.
The Hardware tab is for administering printers, setting up a Linux RAID, configuring Lilo, setting up and tweaking your hard drives and disk partitions, configuring network devices, and setting the system time. Be careful using the hard disk utility since it is possible to cause data loss if you don't follow the advice contained within this section.
As you adjust the hard drive settings, make sure that when you are in the Edit IDE Parameters tab, you select each setting’s hyperlink and read the advice given. This will prevent mistakes and offer you some great ways to improve IDE performance. As an example, I tested my Western Digital drive at stock settings and found it to be at 185.51 MB/sec buffer cache with 24.15 MB/sec buffered; with a little tweaking, I am now at 191.04 MB/sec buffer cache with 24.24 MB/sec buffered. This is no earthshaking increase but, as it is a little extra performance with minimal effort, I will gladly take it.
In the Others tab, you will find some other miscellaneous configuration utilities that may prove quite helpful. Again, this will vary depending on your version of Webmin and your Linux/UNIX distribution. However, you should find the File Manager, which is a Windows Explorer-type browser to view, edit, add, or delete any of your server files, a command shell for executing single commands, and a server status link, which is customizable and offers a nice way to monitor server software.
Thus far, we have covered some of the capabilities of the default Webmin installation that can make the life of a Linux administrator easier and more productive. In fact, these capabilities can easily be extended. Webmin lets you add third-party modules with very little effort—and there are many to choose from, with the list growing each day.
There are modules to aid in firewall configuration, modules for Apple file and print services (for those who support Mac users), and a module to monitor your APC UPS battery backup, among many others.
To add a module, first download it to your Linux system. Next, log in to Webmin, click the Webmin Configuration tab, and click the Webmin Modules icon (Figure E). Then, choose to install From Local File and click Browse (the small box with three periods in it). This will bring up a small Explorer-type utility for you to browse to the Webmin module you want to install. (Note: Webmin modules all end with the .Wbm extension.) Finally, click the Install Module From File button. You should soon be greeted with a message stating that the module was installed successfully.
Webmin enables you, as a Linux administrator, to handle your tasks more quickly and efficiently than ever before. For those that need to administer their Linux machine(s) from another computer on their LAN/WAN or who need to access the machine across the Internet, Webmin can combine with SSL to provide a secure and effective administration option.
How does Webmin help you be a better Linux admin?
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