I’ve been using MRTG for a while to monitor assorted servers, routers, and switches I manage at The Windmill. It’s free, works pretty well, and is quite configurable. The graphs it produces are plain but functional, and they do the job.
Recently, I needed a tool to monitor my home network, primarily because the Cisco 3925 router provided by my Internet supplier, UPC, has had a nasty tendency to lockup every week or so. Now, UPC’s 120 Mb/s Internet service is fantastic value, and performs exceptionally well, but having it randomly interrupted like this is really, really annoying — especially when the router is buried in a small cupboard at the back of our attic, where all the TV wiring is concentrated.
I also have a wireless access point (an old reconditioned Eircom Netopia 2247) which periodically hangs, though on a different schedule to the Cisco. So, I figured it was time to start monitoring both devices to see exactly when they go offline, in the hope that I might be able to correlate it with other network activity.
While MRTG can do this, it’s not the most user friendly of systems to configure. Since I crave nothing more than an easy life, I decided to look around for alternatives.
This brought me to PRTG, a commercial monitoring tool from Paessler that covers some of the same ground. It’s free for up to 10 monitoring points, runs under Windows, and has a nice web-based GUI that makes it easy to configure or review logs from anywhere on my LAN. So, I decided to give it a try.
I’ve been using PRTG for about two months now, and it’s working very well. There are a huge number of built-in sensors: everything from basic PING tests, SNMP polling of routers & switches to Windows system metrics (for any machine on the LAN) to remote website HTTP monitoring. With the 10 free sensors included in the evaluation copy, I was able to add rules for three websites I manage, my Wifi and Internet routers, a separate VPN router I use to access client networks, and also a few of my local machines:
PRTG lets you create sensor dependency trees: for example, I monitor the uptime of this website (www.snoopdos.com) but the monitoring rule says not to try and monitor it if the UPC Cisco router is down, OR if Google’s main DNS server at 188.8.131.52 can’t be reached. This ensures I don’t get an onslaught of website failures in the log just because my Internet connection was interrupted.
PRTG also lets you raise alerts whenever a sensor goes on or offline, or crosses a threshold. For example, if the disk space on C:\ on my main Media Center TV system drops below 1 GB, I can easily have PRTG alert me, either by email or SMS.
I’ve barely scratched the surface of what’s possible so far, but it’s a very capable system. When Paessler emailed me today with an offer to upgrade my free 10-sensor license to 30 sensors in return for some blog coverage, it wasn’t a difficult decision. While I only blog about products I actually like and use, PRTG now falls squarely into that camp. Give it a try and see what you think for yourself.