Webmin: Good for Guru and Newbie Alike

To quote their web site, “Webmin is a web-based interface for system administration for Unix.” I found Webmin a few years ago when I was looking to register the domain webmin.com. I had an idea for a cool control panel to help administer my Linux server farm, and I was annoyed that someone had gotten to the domain first, until I started looking at the software they had for downloading. After that I was hooked.

Webmin's goal of providing a web-based interface is not unique. A number of tools are out there, both open source and commercial, with the same goal. What makes Webmin stand out from the crowd is that it can be useful to both experienced and inexperienced Linux administrators. Before I explain how it fulfills such a difficult task, let's look at how you install the software and what you can do with it.

Before we delve into the feature set of Webmin, I should explain a little about its design. Webmin is basically a large collection of CGIs written in Perl. It runs its own web server on a port that you specify when you install it, allowing you to manage the security of Webmin separately from your real web server. The full list of supported platforms is on the site, and it includes Red Hat, Solaris, Debian, *BSD, HP-UX, IRIX, AIX, DEC, SCO and Mac OS X.

What makes Webmin unique is its modular design. Every service or feature is exposed through a set of modules. This means that if the application you would like to control from Webmin is not supported, you can use the Webmin API to build a new module that will allow Webmin to control it. Webmin ships with 50 standard modules and many more are available, so you have plenty of source code examples to help get you started. Although Webmin itself is distributed under the BSD license, the modules you build can be distributed under any license you choose. This keeps the tool open to submissions from both the Open Source community and commercial vendors.

Installation is a breeze; go to www.webmin.com/webmin and download either the RPM or the tarball. If you use the tarball, you will need to run the setup.sh once you have unpacked it. This program handles the installation for you. One tip if you use the tarball: make sure you unpack it where you want those files to live. After you have installed Webmin, do not delete the Webmin directory you just unpacked or Webmin will not work. If you want to uninstall Webmin later, an uninstall script is included that will remove the initial directory as well as all the other files Webmin puts on your drive.

Now that you have Webmin installed, you need to open a web browser and log in to the IP address/resolvable server name and port (typically 10,000) that you configured Webmin to use when you installed it (see Figure 1). Once you have logged in, you should be greeted by the index page of Webmin, including several category tabs in which the various Webmin modules are grouped (see Figure 2). For example, the “Webmin” tab is where all the configuration settings for general themes, users, modules, etc., are located (the default theme is used in these figures). Other tab groupings include System, Servers, Networking, Hardware and Others.

Figure 1. Logging in to Webmin

Figure 2. Webmin Tab Groupings

The System tab handles tasks that have to do with managing the computer or server itself. This includes setting disk quotas, setting up NIS, altering PAM, looking at the syslog, adding users, managing cron, setting up NFS and even modifying boot-time services or rebooting the server.

The Servers tab groups all the server service configuration modules together. This is where you will find Apache, BIND, DHCP, sendmail, Squid and a number of other related modules (see Figure 3).

Figure 3. Webmin Modules under the Server Tab

The Networking tab is a new addition, and on Linux it offers a good GUI ipchains configuration module, as well as a subcategory of various network utilities such as ping, traceroute, whois and dig.

The Hardware tab, of course, handles things that are directly hardware-related. This is where you will find information about your disk partitions, system time, network interface configurations, LILO and even software RAID.

The last tab is a potpourri category that has a full Java-based ssh/Telnet client, Java-based file manager, special user-definable module called Custom Commands, system log viewer, Perl modules section, and web-based system and server-status monitoring module. The Custom Commands module lets you build a simple interface to Webmin that allows you to run any command you want. This can be very useful if you need Webmin to do something specific that does not require a full module to accomplish. Figure 4 shows some custom examples that were created quickly and easily.

Figure 4. Creating Custom Commands