All tooled up
A reader recently wrote to ask us what software we use to manage our systems and network. She’s the sole network admin/systems admin/IT guru for a company with about 30 employees and a handful of servers, and her question was hedged with the condition “but I don’t have any budget to buy new software” – a common complaint, especially for smaller companies whose managers seem to believe that technology should “just work”. So with her question in mind, here are a handful of the open-source packages we use daily, or have been recommended to us for managing systems, servers and software inventories. All are, of course, free to download and deploy and, although we’ve covered a few of them before, we felt it would be worthwhile to gather them all together here in a sort of essential network/system admin toolkit.
We’ve talked about Nagios in this column before; to be more exact, last summer in issue 127. However, it’s well worth mentioning again, because it’s really saved our bacon on more than one occasion. Nagios is a systems-monitoring suite that will keep an eye on all your various servers and all the services running on those servers. It can display real-time fault reports and even send that information to your mobile phone or pager to ruin your evening in the pub. Nagios comes with a wide range of plug-in modules that enable you to monitor large numbers of services and different types of server and, if you find there’s something you need to monitor that isn’t currently covered, you can always write your own plug-in to do just that (and, of course, offer it back to the community).
This software is very scalable and will work happily whether you have a couple of servers or a couple of hundred servers – it’s in constant use here at Wide Area, alerting us immediately to any problems with our own servers or with the public-facing machines on our clients’ networks. (It’s amazing how often we are called and told that one of our machines has failed – a mailserver, for example – when in fact it’s the client’s router that’s died.) For anyone who’s running more than a couple of machines, a program like Nagios is essential and, although there are plenty of commercial packages available that do a similar job, Nagios is completely free and rivals pretty much anything else out there. If you do need commercial support, the people who wrote the program can provide that too, for a charge.
Ethereal is a network protocol analyser, which, like Nagios, rivals just about any of the commercial offerings that are available. You use the program to analyse the packets flying around your network, which it can record for later analysis or allow you to view on-the-fly. Not only can it read back its own data dumps, but it will also handle capture files from many other packages such as Sniffer PRO, EtherPeek and Microsoft’s Network Monitor. Ethereal understands around 750 different network protocols, so it should be capable of analysing just about any data that passes across your network – simply place your computer at the required point in the network and start capturing data.
Once your data has been captured, Ethereal will allow you to view the raw information, but it will also “decode” the packet for you. This can be incredibly useful, since it enables you to see exactly what data is being transmitted and received. For instance, if you’re having problems with your DNS you can view, in a very easy-to-read format, exactly what queries are being sent to the domain name server and what values it’s returning.