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Posted on 23 May 2006 at 12:07

Simon Brock and Ian Wrigley recommend open-source alternatives for Sysadmins who need to manage systems, servers and software

Of course, Ethereal could also be used for less honest purposes too. Remember that it's sniffing every packet that it sees, so if you have unencrypted passwords flying around your network, they're very easily viewable. For many people, using Ethereal will represent overkill, but for those who need to know exactly what's being transmitted over their network it's invaluable.

VNC

We've also covered VNC more than once in past columns, so we won't spend much time talking about it again here. For anyone who needs to remotely control distant machines VNC is the answer to their prayers. It enables any type of machine to be used as the remote controller (even PalmOS-based handhelds) and any type of machine/OS combination can be controlled: Linux, Solaris, Mac OS X, Windows, you name it. For example, we find VNC invaluable for managing the few Windows servers we keep in remote machine racks, as well as for general maintenance work on our Linux and Solaris boxes. One of the key advantages to employing VNC rather than just, say, using SSH to connect to a remote machine is that the session state is preserved after disconnection - in other words, you can be in the middle of editing a file at the office, disconnect from the remote machine, go home, reconnect from home and continue from exactly where you left off.

Windows Inventory

We consider ourselves pretty fortunate in that we don't have large numbers of Windows machines to manage. Not that we're anti-Windows of course, honest (well, okay, perhaps we are a little). It's just that handling large numbers of Windows PCs, making sure they all have the same software versions installed, checking that no-one has downloaded any unauthorised programs is a headache and a half. There are plenty of

system-management packages out there that will inventory the contents of Windows machines, including one from Microsoft itself, but they all tend to be fairly expensive, and thanks to Microsoft's licensing policies they become more expensive the more machines you're managing.

Windows Inventory is a free alternative that's been recommended to us by a number of people. It requires Apache, PHP and MySQL to be installed on the (Windows-based) server, as well as Windows Management Instrumentation and Windows Script (both free Microsoft packages) on all the clients. Once all that's in place, you're ready to go. The software will gather information about the hardware, software and operating system on all your Windows boxes, and display it via a web-based front end, so you can even view machines' configurations while sitting at home with a nice cold beer in your hand. The software is extendible via a range of plug-ins, so if you're in need of a specific type of report it shouldn't be that difficult to write one yourself.

Amanda

We've been using Amanda (officially the Advanced Maryland Automatic Network Disk Archiver) to back up our Solaris and Linux boxes for several years now. It enables you to back up one or a multitude of machines to a tape drive or a tape changer, using a variety of different backup regimens - full, incremental and so on. Amanda isn't the easiest backup system in the world to configure, but once you have the configuration file sorted it's a joy to use, in as much as you can just ignore it and let it get on with its work. It supports a large number of different makes of tape changer, so you don't even need to manually swap the tapes, as your hardware will do all the work for you.

Data recovery is about as simple as it is with more or less any other backup software, which is to say nowhere near as easy as you want it to be when you're asked to find a deleted file just before you were about to leave the office for the night, but it's nowhere near as painful as having to recreate that file from scratch. Its only downside is that there's no Amanda client for Windows: you can use SAMBA to share your Windows disks and back them up that way, but that route is far from foolproof, as SAMBA sometimes raises permissions issues, for example. For that reason, we tend to stick with Retrospect (a commercial package) to back up our Windows servers, but for any flavour of Unix you're dealing with Amanda works like a charm.