Sysadmin blog It stands to reason that there would be call for a similar utility to Webmin available to users. Webmin’s extension Usermin answers the call.

Webmin is an excellent way of providing systems administrators a way to manage their servers while abstracting away the underlying operating system. Usermin is an interface that offers access to resources to users of a shared server if they have rights to control them. Many of the modules require a power-user level of knowledge, but they are far simpler than trying to administer your slice of a shared server from the command line.

The server’s sysadmin controls which modules are available through the interface. You can allow users to monitor disk quotas and running processes. Users can kill processes that are executing in their user context. Users can upload and download files in one module and manage them through a Java-based file manager in another. They can even tinker with MySQL or Postgres databases, tables or records to which they have rights, manage cron jobs, SSH keys, Apache .htaccess files for their directories, and more.

Usermin’s real strength is that, if you have set up a Linux mail server for your users, it lets users to manage their mail. A systems administrator can grant users the ability to alter mail forwarding and replies. You can grant them control over MIME type programs, Procmail, Spamassassin and Fetchmail. Users can even schedule emails to be sent at a given time, either as a one-off or on a repeating schedule.

The most popular module is Usermin’s webmail. So popular has this become that it is now offered as a separate download for administrators who want to offer webmail, a means to manage their passwords, and nothing more. It requires that you have already configured Dovecot and have an MTA set up for either Maildir or mbox, which you can do using Webmin.

As a user-oriented extension of Webmin, however, it is limited to what are traditionally considered user-centric tasks. Sysadmins often run across the need to delegate areas of server administration to more junior admins, or even selected end users. Fortunately Webmin bridges the gap.

You can assign modules to individual users so that when they log into Webmin they will see only the modules they have been assigned. Similarly, you can assign modules to a Webmin group of users. Sadly you cannot add a Webmin user to more than one group, although you can cascade groups in a way that lets you work around this limitation. Solaris Users can take advantage of more refined controls through Role Based Access Control (RBAC).

The combination of Webmin’s module delegation abilities and the Usermin extension allow administrators to push the boundaries of Webmin beyond system management. An excellent systems management tool is evolving into a tool that simplifies the delivery of user-configurable services. ®

Editor's note: An anagram of "Trevor Pott sysadmin" is "Nerd vomit spat story". Just saying.