The technical details (frequently asked questions about the proxy servers)

For those interested in what goes on behind the scenes with respect to the central proxy servers, here are a few details.

Q. Which software does the proxy service use?

A. Squid - see www.squid-cache.org for details.

Q. Is there a preference for using an automatically or manually configured proxy with a Web browser?

A. The preference would be for an automatic configuration. However, some Web-based applications (e.g. the Quicktime player) will work only with a manually set proxy. When manually setting the proxy, use the name proxy.abdn.ac.uk.

Q. How does the automatic proxy configuration work?

A. The automatic configuration setting is a URL (pointing to a PHP script, see www.php.net) which sends to the browser a small Javascript program that determines how the browser will connect to an external web site. Slightly different Javascript programs are delivered depending on where the browser is located, e.g. in a classroom or using an external Internet Service Provider (ISP).

Q. Why do I see some browsers configured with http://www.abdn.ac.uk/local/autoproxy.pac and others with http://www.abdn.ac.uk/local/autoproxy.php?

A. This is for historical reasons. In our earliest documentation, the first URL (autoproxy.pac) was used. This used the standard extension (.pac) for autoproxy configuration URLs. As the demands on the proxy service became more sophisticated, the necessary Javascript program delivered via the autoproxy.pac file became too large to be acceptable to some browsers. In its place came the autoproxy.php version that ran on the Web server and generated the appropriately tailored (and much smaller) Javascript program that was to be delivered to the browser. Both styles of URL will work.

Q. I use several methods of connecting to the Internet (eg. a dial-up connection, a broadband connection at home and a direct connection when on-campus), do I need to set a proxy for each?

A. If you are using Internet Explorer, then the answer is yes, you do need to configure each connection individually. The same applies if you use more than one dial-up providers. Generally, each connection will appear in Internet Explorer's Options | Internet Options | Connections menu as a separate entry (the exception to this is when your broadband connection is via a router rather than a USB modem, such a connection is treated as a LAN connection by Internet Explorer). If you are using another browser such as Mozilla Firefox, then one setting applies to all connections.