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LOOKING THROUGH THE INTERNET

A Prototype Security System
by Skylar Lei, Jim Haslett, and Mike Smith

Start • Web Server Choice • Interactive GUI • Video System • Remote Camera System • Control RF Link • Solar Power Module • Sources

WEB SERVER CHOICE
The choice of web server played an important role in making a low-cost, Internet-based system possible. The server needed to not only provide web documents but also run CGI (common gateway interface) scripts to make the GUI interactive.

We chose the Apache server. Apache is highly configurable and can be customized by writing "modules" using the Apache module API. The free download comes with full source code and a nonrestrictive license for easy customization. In addition to that, Apache uses password-protected pages to prevent unauthorized users from accessing the remote system.

After installation, some of the configuration files must be modified (see Listing 1). In the file httpd.conf, we had to customize the ServerRoot, ServerAdmin, and ServerName parameters in order to specify directories, host names, and other administrivia. We changed srm.conf to redefine the directories that the web documents will be served out of. In the file access.conf, the directories were reconfigured to allow or disallow various services.

VIDEO STREAMING SOFTWARE

We used the commercial package InetCAM to serve the live video stream on a predefined web page in conjunction with the Apache web server. InetCAM, available for $30, supports a wide variety of frame grabbers, video sources, or other data devices that interface through a media control interface (MCI) driver. Because no special plug-ins are required with InetCAM, any standard Java-compatible web browser can connect for direct viewing of images from the server.

After the standard InetCAM installation procedure, users can access the video stream by pointing their Java-enabled browser to http://hostname/inetcam/ijava.htm. The HTML page ijava.htm embeds the InetCAM Java applet for viewing the video stream (see Listing 2). For our system, a modification was made to the CGI_BASE parameter in ijava.htm to change it from the default /inetcam/CGI to /cgi. As a result, all the CGI scripts are looked up in the new CGI directory established by Apache.

The biggest limitation of InetCAM is the available image size, which we found inconveniently small. Still, it transmits quickly over a slow phone line. Also, InetCAM can only provide moving images at a maximum of 15 frames per second.

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