Practical TCP/IP and Ethernet Networking- P47

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Practical TCP/IP and Ethernet Networking- P47: The transmitter encodes the information into a suitable form to be transmitted over the communications channel. The communications channel moves this signal as electromagnetic energy from the source to one or more destination receivers. The channel may convert this energy from one form to another, such as electrical to optical signals, whilst maintaining the integrity of the information so the recipient can understand the message sent by the transmitter....

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212 Practical TCP/IP and Ethernet with whom they are working. It is possible to live action color video and voice with shared workspace on the PC screen over the Internet. VidCall uses anyone of over 25 video capture boards digital plug and play cameras) to transmit still and motion video. on the speed of the computer modem, VGA display and LAN/WAN, virtual motion of up to 10 frames per second is video and document is available over LAN/WAN up to 10 who can be located across the globe. VidCall also supplies freeware for VidCall users on the Internet. enables to setup their own user groups and to be informed as soon as members of their group are logging in to the video 13.10.2 Video Another company providing video and video software is BitField claims to be the first company to have provided a complete H320 video codec on a single PC video adapter board. Their video products turn PCs into video full motion video between standard PCs via ISDN, LANs, and other networks. Since the products utilize existing PC and they can be applied in many areas where video equipment is too expensive and flexible. 13.11 News 13.11.1 News push The original approach to news via the Internet has been to search the World Wide Web and ‘pull down’ relevant news items. This is not only time consuming but also costly for an who has to connect through an ISP. On the other hand, products such as aggregate news from more than 700 sources, process this in a central broadcast facility and then broadcast it via the Internet. Only the news selected by the user is PUSHED down for every morning. delivers national, business, industry and company news, stock quotes, sports scores, weather reports, news and more. it acquires from sources such as CNN, CNNfn, NY Times, Wall Street Journal, Reuters, Business Wire, PR News Wire, Standard and Poor’s ComStock, Sports Ticker and network will work with a dial-up as long as the dial-up assigns a valid IP Address. The PointCast network offers support for viewers using Shiva, FTP and Windows 95 Internet dialers. As for the on-line it depends on how they implement the Internet access. PointCast will work with America On-line and MicroSoft Network. From an point of view, PointCast allows to news to all employees using the existing network keeping in mind that PointCast is free thanks to To help the system customize the PointCast Network, PointCast offers a suite of free tools, the so-called Intranet Broadcast Solution which allows the • It ensures that important company news is widely seen and read by it directly to employees desktops via a private Intranet channel on PointCast The Internet for 213 • It allows the to time sensitive messages through special windows on desktops • It empowers workers’ by supplying all the news they need to be including news from and industry 13.11.2 News pull The pull services are still widely available with many private their own webster. A case in point is the South African based East London Daily Dispatch, which is widely read by South African living in news IBM Internet Services offers a news service to available in 10 languages and utilizing a news search engine that pulls stories from over 250 news sources from over the globe. Topics include top stories in politics, culture news, CAN world news, TechWeb and USA today. It is also possible to select world news on a regional basis. 13.11.3 News groups: USENET While web (www) sites have received most of the attention from software and the press, the news and service, USENET, another major Internet resource. USENET is based on news groups, such as or that contain articles similar to e-mail messages. News groups exist for virtually every and personal interest. Some news groups serve as problem solving forums and as the ‘help desks’ of the Internet. Most news groups are public and can be viewed anywhere the Internet reaches. Anyone with a news client and an Internet can submit an article. Some news group’s subject articles to a screening prior to others all World wide, over 300 000 articles are posted each day to over 50 000 news groups. Because of the massive storage articles begin to disappear within a few days of news client software is available from several sources. News clients are also built into Netscape Navigator and Microsoft Internet Explorer. As users of these web browsers become more they are able to to the world of USENET news. There are several packages available for dealing with USENET and many of them are as freeware. We will now deal with some of them: 13.11.4 Search agents The question may well be asked: Why on earth would a company care about USENET Here are a few reasons: • Find out who is your products • Find out who is using or misusing your • Discover people and companies looking for solutions that your can provide 214 Practical TCP/IP and Ethernet • Find out what people are saying about your products and services • Detect imposters forging messages that appear to originate from your A good example of a USENET search agent is by TechSmith the search query for you, or allows you to create the query yourself. It searches public USENET groups for each of your active queries using Digital’s Alta Vista engine. It removes duplicate articles and new It then notifies you via e-mail when articles matching your criteria are A similar product is OUI (off-line user which has the ability to locate, download and post to and from news groups. Upload utilities AutoPost is a program, which is capable files, and uploading them to a new server, i.e. it automates the process of posting large volumes of files to news services. programs There are several programs for USENET, available as either shareware or Programs worth noting are: • Agent • Free Agent • News XPress • Pluckit 3 • SBNews; NewsRobot of these packages include news reading, e-mail viewers for graphics files, and the ability to launch URLs, firewall spam and automatic to protect sensitive images. The user will have to peruse the and make a decision as to the most suitable package for a 13.12 details about products mentioned in this chapter can be obtained from the web sites. 13.12.1 Internet telephony PGPfone (Pretty Good Privacy Phone): FreeTel: Internet Phone Release 5: Internet Phone Call Waiting: Aplio (Voice over IP): NetPhone IPBX: The Internet for 215 13.12.2 Video VidCall has a running’ demo system with IP Address First download and register the demo program, then ping the demo system to make sure it is running, then follow the steps supplied on the screen. 13.12.3 Paging SMS (Small Message 13.12.4 Fax VocalTec PASSaFAX: 13.12.5 Voice via web page link Mini WebPhone: 13.12.6 Voice mail Voice Mail: BitWare: 13.12.7 News services News Services on the Internet (listing) : WebGate: CNN UseNet News Readers: East London Daily Dispatch: 13.12.8 PPP servers Foray PPP Remote Access Server: 13.12.9 E-mail Eudora Webmail: Eudora Lite: Voice e-mail: 14 When you have completed study of this chapter you should be able to: • Explain the security problem • Define the ways of access to a network �� �� people tend to refer to the as one global entity, there are in fact three clearly defined subsets of this global network. Four, in fact, if one wishes to include the network’. It just depends on where the are drawn. • In the center is the in-house corporate primarily for the benefit of the people within the • The intranet is by the exterior to the yet to access by business partners, customers and preferred suppliers • Third, and this is optional, there can be a layer around the This space is shared with a community of interest, e.g. industry • Finally, these three layers are by the global Internet as we know it, which is shared by and the rest of the world This expansion of the Internet into in fact right down to the factory floor, has opened the door to it has also opened the door to pirates and hackers. as the use of the Internet, and extranets has grown, so has the need for security. The TCP/IP protocols and network are designed to be open in order to allow unless proper are taken, data can readily be and altered – often without either the sending or the receiving party being aware of the security breach. Because dedicated