
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