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At the May 6th general meeting, DACS President Jim Scheef gave members the whole scoop on what's going on behind the scenes on the Internet. Jim's presentation was so absorbing that it was difficult to take notes, so what follows is a brief summary of his remarks.

Jim's ultimate goal was to make us understand what can get through open ports when we are
innocently or naively surfing the web or checking e-mail using modems connected through DSL
or cable modems. He prepared us to set up Internet security on our computers, especially to users on a network.

Before starting on setting up Network security Jim mentioned some rules. If he used any acronym
not understood, we could interrupt him but otherwise keep questions to the end. On his slides was a drawing of a computer, a cloud and another connected computer and that he was going to elaborate on the content of the cloud. We started with the history of the Internet, where it came from (probably a military project but no certainty on this), who invented it (J.C.R. Licklider according to Jim's research), but many others collaborated. Jim talked about the beginning of the Arpanet in 1969 and continued with packet switching, where only a small amount of data is routed. Packets take different routes when being sent and when received. The Internet was switched to TCP/IP (invented by Vinton Cerf but not exclusively on January 1st, 1983 from NCP or Network Control program).

Jim defined the "plumbing" of the Internet as a "network of network." He explained some terminology such as repeaters, that send signals, bridges, routers and switchers--all devices used in connection with the drawn bubble of his slides used in connecting computers. He also mentioned MAC address, a definition that I was anxious to find out about. A few weeks earlier I had gotten a couple of e-mails from Charter Cable, my ISP supplier, requesting the MAC address of my cable modem. I had ignored the first request, and upon the second I asked acquaintances because I wondered whether that was a legitimate e-mail or someone who had "borrowed" an e-mailing list from Charter. Earlier Jim suggested that I contact Charter to find out what the reason was. A 15 minutes phone call with a Charter customer representative did not bring much, except being put on hold for 14 minutes. The customer rep told me that if my connection was ok not to bother to answer to the e-mail which I was confirmed was legitimate. If my connection was not good I was advised to reply to the e-mail. So much for that and the request was duly ignored. I wonder why Charter would not keep a log or list of the modem that they supply.

Jim defined the MAC address under the subject of switches which has two definitions, the older being a device similar to a bridge that works at the data link (MAC address) layer but begin to forward the packet immediately and newer switches that include some router like functions to decide which port should received the packet.

Downloads:

How the Internet Works.pdf - 1,224KB

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