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Layered Service Provider Examples RRS feed

  • Question

  • I am attempting to teach myself layered service providers, but I am having a difficult time getting my head wrapped around this topic. I have downloaded the SPI guide and have, in the past, written basic socket-based client/server applications, so I'm fairly comfortable with network programming at least from a regular application standpoint.

    As a basic "sample" program, what I wanted to do is have a windows form application (probably written in C#) sit and display URLs which are captured over port 80 or port 443. I figured this would be a good way to learn more about this topic.

    However, despite all my research on the topic, at the moment, I'm having difficult groking how exactly I get a C# app to "communicate" at the lower layers.

    From reading examples, it would appear I need to create an LSP as a windows service which would sit and monitor all port 80/443 packets (something I'm not groking how to do, exactly, from the examples I've downloaded, since the code is nicely documented but explaining how it all comes together at a higher level appears to be lacking). Then (somehow, again, I lack knowledge here) my C# app can communicate with this Windows service (or LSP "somewhere") to receive the captured packets, and then within the C# app I can process the packet and extract the URL, as appropriate, and display it in the window.

    A couple of other "features" I want to learn how to include is have the LSP only monitor traffic for a particular IP or group of IPs (for example, I tell the LSP only intercept traffic for a block of IP addresses), and another "goal" is to have my little C# app maintain a list of 'banned' URLs (such as whitehouse.com) and when it detects a 'banned' URL, replace the 'banned' URL with a URL pointing to a local file on my IIS server saying 'sorry you've reached a banned site".

    I would surely appreciate some guidance in this area, because while I've been able to download the SPI API and the examples, they provide little information on how to bring all of this together. If there are any books, documents, other help files, web sites, etc. which might help me put all of this together, I would most definitely appreciate being guided into the right direction. Thusfar the only promising thing I found was a web site online which offered an configurable LSP service, but at $1300, its well beyond my means as a poor college student simply attempting to learn more about underlying network, and besides, the challenge is in trying to do it myself.

    Thanks,

    Vin

    Friday, August 27, 2010 6:31 PM