Webmin is a (currently) a non commercial web based administrative tool. It’s a set of perl scripts with a self contained www server that you access using a www browser, it has modules for most system administration functions, although some are a bit temperamental. One of my favourite features is the fact is that it holds it’s own username and passwords for access to webmin, and you can customize what each user gets access to (i.e. user1 can administer users, user2 can reboot the server, and user3 can fiddle with the apache settings). Webmin is available at: http://www.webmin.com/.
Linuxconf
Linuxconf is a general purpose Linux administration tool that is usable from the command line, from within X, or via it's built in www server. It is my preferred tool for automated system administration (I primarily use it for doing strange network configurations), as it is relatively light from the command line (it is actually split up into several modules). From within X it provides an overall view of everything that can be configured (PPP, users, disks, etc.). To use it via a www browser you must first run Linuxconf on the machine and add the host(s) or network(s) you want to allow to connect (Conf > Misc > Linuxconf network access), save changes and quit, then when you connect to the machine (by default Linuxconf runs on port 98) you must enter a username and password, it only accepts root as the account, and Linuxconf doesn't support any encryption, so I would have to recommend very strongly against using this feature across public networks. Linuxconf ships with RedHat Linux and is available at: http://www.solucorp.qc.ca/linuxconf/. Linuxconf also doesn't seem to ship with any man pages/etc, the help is contained internally which is slightly irritating.
COAS
The COAS project (Caldera Open Administration System) is a very ambitious project to provide an open framework for administering systems, from a command line (with semi graphical interface), from within X (using the qt widget set) to the web. It abstracts the actual configuration data by providing a middle layer, thus making it suitable for use on disparate Linux platforms. Version 1.0 was just released, so it looks like Caldera is finally pushing ahead with it. The COAS site is at: http://www.coas.org/ .
