 | Level: Introductory Chris Walden (dwinfo@us.ibm.com), e-business Architect, IBM
11 Nov 2003 IBM e-business architect Chris Walden is your guide through a nine-part developerWorks series on moving your operational skills from a Windows® to a Linux® environment. He covers everything from logging to networking, and from the command-line to help systems -- even compiling packages from available source code. In this part, he shows you how to install and use Webmin, a browser-based administration tool for Linux and other platforms that provides a graphical interface to many administrative and operational tasks.
One of the challenges when moving from administering a Windows
environment to administering Linux is learning the new tools at your
disposal. As an administrator, you want to learn the details of the
operating system so that you can get the most out of it. But while you
are learning, you need to get real work done now.
To accelerate your productivity in Linux, we are going to install a
program called Webmin. According to the Webmin.com (see Resources for a link): "Webmin is a Web-based interface for system administration for Unix. Using
any browser that supports tables and forms (and Java for the File Manager
module), you can set up user accounts, Apache, DNS, file sharing, and so on. Webmin consists of a simple Web server, and a number of CGI programs
which directly update system files like /etc/inetd.conf and /etc/passwd. The Web server and all CGI programs are written in Perl version 5, and use
no non-standard Perl modules."
Webmin runs on virtually all Unix-like platforms including Linux, AIX,
HPUX, Solaris, OS X, and others. It provides a Web front end to many
administrative tasks in Linux. It can be run from any graphical browser
either locally or remotely. Webmin can be secured with SSL, to prevent
snooping. As you are learning Linux administration, Webmin is a great
time saver. Webmin is also handy to help with the tedious tasks that you
have not automated.
Webmin is extensible. The author provides a development guide, and there
are several third-party modules available. You can also design your own
modules, so Webmin can always be adapted to fit your needs.
Installing Webmin
The first step to working with Webmin is to install it. Webmin is
included with a few distributions, but it will be just as easy to download
it from the Webmin site (see Resources for a
link).
At the time of this writing, the current version is
1.90. The correct method for installation will vary depending in your
distribution. If you are using Red Hat Linux or one of the UnitedLinux distributions
(SuSE, Turbo, Connectiva, or Caldera), then the RPM will be the simplest
method of installation. If you are using a different distribution, you
will need to check the documentation for your distribution and the
Webmin installation instructions to determine the best method for you.
RPM installation will be assumed.
First check to see if Webmin is installed on your system. From a
text terminal, enter the following:
rpm -q webmin
If Webmin is installed on
your system, you will receive a version number:
Webmin-1.090-1
or an indication that Webmin is not installed:
package webmin is not installed
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Installing software packages
Most packages on Linux install just as easily as the Webmin example in
this article. For more on installing and deleting packages -- and even on
compiling programs from source code -- see Part 9 of this series.
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Even if Webmin is already installed, it will probably
be a version lower than the current one available for download. In this
case, you can do an upgrade or a fresh install with the following command:
rpm -Uvh webmin-1.090-1.noarch.rpm
A verbose upgrade is done with a progress bar printed with #
marks.
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RPM noarch
You will notice that Webmin is listed as a "noarch" package. Since RPMs
are binary files, they are typically compiled for a particular
architecture such as i386 or ppc. Installing the package on the wrong
architecture can have bad results. Since Webmin is written in Perl, which
is architecture independent, the "noarch" designation is used.
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When Webmin is installed, it activates by default. But Webmin
does not install with SSL activated. SSL requires the installation of a
Perl module called Net::SSLeay. Until this is installed,
Webmin will only be secure to run from the local console. Securing Webmin
will be briefly covered at the end of this article.
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Practical Extraction and Reporting Language (Perl)
Perl is a multi-platform interpreted programming language that has been
around since 1987. It is available on a wide variety of platforms,
including Windows, and provides sophisticated scripting capabilities.
Perl excels at text-processing and became very popular for Web CGI
programming. Perl is extensible by adding modules, which are function
libraries, also written in Perl. Most modules, and indeed Perl itself,
are available under a generous free license called The Artistic
License (see Resources for a link).
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Using Webmin
Access Webmin through your favorite Web browser. Two of the tools, a
file explorer and a telnet/ssh client, are applet-based and will require a
Java Runtime Environment to be installed on your browser. These tools are
handy, but not critical. All of the other modules have no special
requirements.
To begin using Webmin, point your browser to port 10000 on the
system. With a browser on the local system, you would use
http://localhost.localdomain:10000/. Webmin will first bring you
to a login screen.
Webmin users are separate from operating system users.
This allows you to set up users for administration through Webmin that
are not in the normal Unix authentication scheme. However, if you have
users that you want to be able to use Webmin, you can enter them
into the Webmin user list and have Webmin authenticate them through Unix
facilities rather than through its internal mechanisms. Access to Webmin modules
can be controlled for each user. Helpdesk staff could have access to just
password functions, while other staff could have access to all modules, for example.
A root user is automatically created with the system's root password upon
installation. Webmin logs activity by login, so in a multi-admin
environment, it would probably be better to create an admin group with the
rights of the root user, and create users for each individual who works on
the system. Your first login must be as root.
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root user
In Linux, the primary administrative user is called root. The
root user has full control over all aspects of the system. The name of
root should never be taken in vain.
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Webmin sections
The first screen you will see is the Webmin Configuration Section. This
is where you configure Webmin users, configure modules, and view activity
logs. The icons at the top switch between the different module
sections in Webmin. All of the modules are configurable, and you can
regroup things to suit your preferences.
Figure 1. Webmin configuration screen
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Webmin is for users, too
There is an icon to configure the optional Usermin package, which
provides a Web-based tool for users to perform functions, such as password
changes, system mail management, and other functions. Usermin does not
provide access to system configuration functions. Usermin and Webmin are
intended to be complimentary products.
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The System section deals with general operating system configuration.
Here, you configure file systems, users, and groups and the general boot
behavior of the system. You can control the services that are running on
the system and whether they start automatically from the Bootup and
Shutdown icon. Configuration of those services, however, is in the
Servers section. The "Software Packages" tool is of
particular interest. It allows easy viewing of packages installed on your
system and interfaces to distribution update repositories and rpmfind.net,
a common RPM repository on the Internet (see Resources for a link).
The Servers section has configuration for various services that you may
be running on the system. The BIND and DHCP tools are very convenient.
Also the Samba tool is simple to use for configuring file and print shares
for Windows and other clients. Sendmail, the SMTP server, is notorious
for having a complex configuration file. The Webmin Sendmail tool keeps
you out of trouble there as well.
Figure 2. Webmin servers screen
The Networking section provides tools for configuring the network
hardware and some of the complex network controls, such as firewalling.
All the tools communicate with the standard configuration files, so
anything you do in Webmin is reflected in the console tools.
The Hardware section is for configuration of physical devices, mostly
printers and storage devices. The Logical Volume Management (LVM) tool is
particularly interesting as it helps you visually manage dynamic volumes
on your Linux system.
The Cluster section contains tools you would use if you were clustering
systems. A cluster, in this context, is a set of related systems that
need to have their configurations synchronized. Systems can synchronize
users, groups, packages, and other things with system failure detection.
These tools will help you set up hot failover systems and other systems
where synchronization is important. Clustering is an advanced topic
and will probably require installation of packages not included with your
Linux distribution.
The Others section contains miscellaneous utilities that you may find
useful. The "SSH/Telnet Login" and "File Manager" tools are
applet-driven, and cannot be run unless your browser has an active JRE.
The "Perl Modules" tool is very useful for keeping up with Perl modules
and will interface directly to CPAN on the Internet. The "File Manager"
tool provides an Explorer-like view of the server's file system,
allowing you to move and copy files around without passing them through
your workstation's memory, if you are working remotely. The "SSH/Telnet
Login" tool is a remote shell console that will allow you console access
through your browser.
Summary
Webmin is a browser-based administration application written in Perl.
Webmin is extensible and available for other Unix-like operating systems
besides Linux. Once installed, Webmin is accessed through a special port,
typically 10000, either locally or from a remote browser. It provides
point-and-click interfaces to a variety of Linux administration tasks,
including user management, network firewalling, and network device
configuration.
Webmin is free to install and use, and is a good way to manage a working
Linux environment while you are making a transition from the graphical
tools of Windows. Webmin tools are a front end to the console-based
tools, so configuration is consistent, and administration can be done from
either set of tools safely.
Resources Learn
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Read the other installments in this Windows-to-Linux roadmap (developerWorks, November 2003).
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Learn about Perl at Perl.org. The CPAN network is the home of many
useful Perl modules and like software.
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Perl is released under the free Artistic
License, which allows you to publish or keep private your changes to the source code.
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Learn more about Perl and keep up with developments in the Perl community
with the Cultured Perl column on developerWorks.
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For additional information, see these developerWorks articles: "Understanding
Linux configuration files", "Using
the xinetd program for system administration", "Automating
UNIX system administration with Perl", and "Administer
Linux on the fly".
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More information on transitioning to Linux awaits you on the developerWorks New to Linux page.
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Find more resources for Linux developers in the developerWorks Linux zone, including our newest how-to tutorials.
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Hone your skills in Linux basics and systems administration with our certification exam study guides. Whether you choose to take the exams or not, our Linux skill-building tutorial series will immerse you in Linux fundamentals as well as advanced topics.
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Learn how to acquire kernel source, configure and boot your new kernel, add a feature, fix a flaw, or just have fun tinkering with operating system source code in our Hacking the Linux kernel tutorial series. Hack and be free.
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IBM developerWorks technical events and Webcasts are a great way to learn more about Linux as well as IBM products that run on Linux.
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The Linux at IBM site offers software, links, end-to-end Linux solutions, and more.
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The Linux Documentation Project is a repository of Linux documentation including documents about individual software, HOWTO documents, FAQs, and more.
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Linux Online! offers non-partisan Linux news and information.
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The O'Reilly Network is an excellent resource for technical books on Linux.
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About the author | | | Chris Walden is an e-business Architect for IBM Developer Relations Technical Consulting in Austin, Texas, providing education, enablement, and consulting to IBM Business Partners. He is the official Linux fanatic on his hallway and does his best to spread the good news to all who will hear it. In addition to his architect duties, he manages the area's all-Linux infrastructure servers, which include file, print, and other application services in a mixed-platform user environment. Chris has ten years of experience in the computer industry ranging from field support to Web application development and consulting. |
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