Network surveillance

You should always watch out for the physical security of your system - after all, you don't want somebody walking off with your hardware. So what can you do that is both affordable and effective? Apart from investing in physical perimeter security such as tougher locks and better doors, there is a place for a hi-tech solution, one that has seen enough products shifting over the counters to become quite affordable - the network-based camera. The idea is a simple one: in addition to your existing security, you have a camera that will record an intruder's movements (and hopefully their face) and save the incriminating evidence off-site so that even if they do pinch all of your hardware, it will still be there.

You can, of course, use a standard USB webcam which will plug into the back of one of your computers. Software on that computer can then detect any movement by comparing successive frames and seeing if the difference is greater than a threshold defined when you set up the camera. However, using a cheap computer USB webcam is not necessarily the best solution as there are a number of vulnerabilities and restrictions.

Which camera?
First of all, as light levels get lower, the noise level on the camera's sensor becomes increasingly significant which can, on its own, trigger movement detection software. Step-changes in light level can do this as well - street lights turning on or off at night or changes in daylight such as clouds blocking out the sun, for example. Secondly, you can only have your USB web camera within five metres of a computer which isn't necessarily convenient. Next, if the intruder cuts the power, you will lose the webcam and although a UPS will keep your computer alive for around 15 minutes, all they have to do is wait until it has died. If you turn up during that time, say to reset your burglar alarm, they just wait until you have gone in the knowledge that a UPS or even a laptop battery will take a lot longer to recharge itself, meaning that they can get in virtually straight away.

A better solution is a web camera that plugs directly into your LAN. With that, the nearest piece of hardware has to be a switch or router at no further than 100 metres. Also, the power consumption is only around 10 Watts so, if it has its own UPS, you are talking literally hours until the battery runs out. In addition to this, there is effectively no limit on the number of them you can use because each has its own IP address, and on a class A internal network (10.*.*.*) you are looking at over 16 million. Even on a class C (192.168.*.*), you are talking about potentially hundreds. As for price, you can pick up an indoor version for as little as 100 and if you want a suitable UPS, you are looking at only another 35 or so. So it is not incredibly expensive to put a camera or two in your office and your corridor.

Being network-based, the camera has no reason to care what your computer itself does, which is an advantage, as you'll never get locked into one particular OS. The configuration is network-based using a web browser (as opposed to being limited to the Command Line Interface via a 9-pin D-series connector) and will work equally well on Linux and Windows, along with pretty much any other OS that has a GUI and a basic browser. The big disadvantage is that motion detection software that is supplied with these products is usually only ever written for Windows, but that's not necessarily a problem.

Configuration
An IP camera merely plugs into your network and a power supply. Some of the more expensive external IP cameras have power supplied along the Ethernet cable so you don't even have to have mains voltage close to your camera. Configuration is performed via a web browser and scripts are not required to do this.

The first problem you are likely to encounter is changing its default IP address to one that is within your network address range but that is fairly straightforward (see this month's HelpDesk - Configuring Network devices boxout for doing so with Windows XP). With an IP address sorted out, you can connect to it again and start configuring parameters, such as user names and passwords, image size and quality, and upload parameters.

The camera used here, a SiteCom LN400 Wired IP camera, will produce either 640x480 or 320x240 pixel images as JPEG files in a variety of qualities. At 320x240, the file size ranged from 8.4Kb to 22.1Kb for highest and lowest compressions respectively for the same shot. At a medium level of compression (11.8Kb), quality was good enough for security purposes. Another tab allows you to configure the ftp upload settings, ie, remote host address, port number (with the default being set to port 21), user name, password, upload directory path and whether you need to use passive mode. Below that is a schedule that allows you to specify file names and time-slots for continual and single uploads.

One feature that this camera has is that you can use its Java applet in your browser to download around 10 frames per second - effectively live video which works on Linux and Windows. If you have a lot of cameras, you should think about the level of network traffic you will be creating with this.

Off-site storage
If your camera is busy taking pictures of an intruder but only storing them locally, they will meet the same fate as your equipment - so you need to store them offsite. With an always-on Internet connection, you can upload to anywhere you have authorised access. ISPs often supply 10 or so MB of webspace for free which can store quite a few pictures although you should make sure that only you can get to them, so you need to talk to your ISP about using a directory with a .htaccess or similar access control file in it to restrict access.

One other alternative is if you use a neighbour's machine. Setting up an ftp server such as vsftpd on a sheep-dip account is fairly easy and, as you wouldn't have access to any other part of his system, there shouldn't be any problems. If more that two of you are doing this with each other's cameras and ftp servers, you should aim to make a ring so as to avoid a situation where two sites were taken out and both had each other's evidence. Although being the Internet, there is no reason why two cooperating sites need to be on the same continent. In addition, you should consider using wireless LAN or securing your cabling.

Other uses
As these cameras are not tied down to any particular computer or use, and you can schedule the automatic ftp upload interval to any number of seconds, you can also use them for time lapse photography. Such things as studying the way that architectural structures are erected, plants grow, traffic flows and so on spring to mind.