Like Men at Work once asked, ‘Who can it be knocking at my door‘? The smashed glass window next to the door probably suggests that when they knocked, they not only missed the door but also knocked a bit harder than was necessary to get someone’s attention. Unfortunately it’s not just an attempt at a witty opening, but a lead in to a story about a physical break in that occurred at a friend’s work place. I likened it to an APT in IT, and used it as an excuse to use IT to help with physical security — cue the ZoneMinder software.
Just a quick post, mainly to serve as an explanation as to why I haven’t posted anything sooner. I shall, however, attempt to offer some useful information in doing so. I had turned my attention to physical security for a bit, as this intruder was striking me as being like the physical security equivalent of an APT. Or a PT at least — they were persistent — I don’t know about the advanced part, given that they left fingerprints behind which the police had on file.
From the sound of it, the break in was more than someone looking for cash or easily sellable items. They stole a whole load of vehicle keys (and left a cash box), and then it is believed that they were disturbed and made a hurried exit. In their haste and attempt to exit over a barbed wire fence, they split the bag which then leaked most of the vehicle keys — they were found on the ground near the fence.
That, however, was not the end of it. The thieves returned two days later, broke the new padlock on the gate, and drove off with one of the vehicles.
Nor was that. Again, two days later, they returned, removed one of the new wheel clamps from one of the vehicles and drove the vehicle out, this time without even bothering to open the gates first. For some reason, they seemed to be after vehicles.
This incident highlighted an issue similar to that encountered in IT security, in that it tends not to be taken seriously until a major incident occurs. The only advantage in the case of physical security is that a smashed window tends to actually suggest that something has happened. It’s not always that obvious that an IT incident has occurred.
This is where ZoneMinder comes in. ZoneMinder is, as they put it, ‘the top Linux video camera security and surveillance solution’, and I must admit, it does seem pretty spiffy.
So spiffy in fact, that I had built a ZoneMinder box for home and had already installed the software, bought a camera, and had a bit of a play with it, so the software wasn’t completely new to me. I hadn’t yet physically installed the camera (and if you’ve ever seen me use a drill, you’d know why) so I wasn’t really putting it all to any real use.
ZoneMinder uses zones that let you define areas of the frame that ZoneMinder should pay attention to or ignore, or to which you would like to apply different sensitivity settings. This is handy if your camera is also capturing a public area, or part of your neighbour’s property, and you wish to ignore motion in those areas. Depending on your camera placement, zones can also be used to ignore motion close to the ground so, for instance, you could detect a person walking around but ignore pets/animals walking around — unless you have a pet giraffe.
ZoneMinder is also aware of the X-10 home automation equipment, and can be configured to turn X-10 devices on and off when entering / leaving alarm mode. I had configured my demo ZoneMinder installation to turn a vacuum cleaner on when it detects motion, to generate some noise and hopefully make the intruders think that there may be someone around and scarper.
One issue I did find, and this isn’t really the fault of ZoneMinder but more a technical issue with using a 2D camera image, was that it wasn’t detecting motion until it was close to the camera, despite the fact that it could see movement in the background.
I read documentation and thought about this for a moment, and believe the problem is caused by ZoneMinder using the number of changed pixels (but then how else could it be done) to determine whether to generate an alarm.
When a person is close to the camera, they cover a larger number of pixels than when they are farther away from the camera. Hence a person close to the camera causes more pixels to change when they move, than if they were farther away from the camera and moving. I suspect that this problem can be overcome by tweaking some settings and/or splitting the frame in to two zones and using different settings for each zone.
As far as cameras go, I haven’t had much experience with that many. I’m thinking I shall probably go for wireless 802.11 ones.
Wireless cameras have the advantage in that an intruder can’t follow the cable and find the ZoneMinder server, and, assuming you use 802.11 wireless network cameras as opposed to cameras that just transmit video, you only need network connectivity for the ZoneMinder box and don’t need a video capture card, hence it is easier to add more cameras.
Wireless (802.11 wireless network) cameras also have the advantage in that they can be accessed from multiple sources simultaneously. So you could have two ZoneMinder installations watching both their own cameras and each other’s. This is handy because unlike in IT security, someone can actually walk off with your ZoneMinder server.
Wireless cameras (either 802.11 or propriety) have the disadvantage in that they can be jammed. An intruder (or anyone for that matter) only needs to transmit in the 2.4 GHz range and you could lose your video feed(s). Also, in the case of non-802.11 wireless cameras, they will probably transmit on the 2.4 GHz range and hence potentially interfere with your 802.11 wireless network, cordless phone, or any other device(s) you have that also use 2.4 GHz.
I’m now planning on purchasing some cameras and getting a proper ZoneMinder installation up and running. I’m tempted to write a blog entry detailing my experiences when I do so, as it looks like useful software and there are a few advantages to having a computer know that there is someone sniffing around/inside your house — not just the X-10 control but I’m also thinking Asterisk PABX software with its ability to script dialling and integrated Festival text-to-speech capability.
… and now I’m running late for a New Years do.