Chandigarh, Thursday, May 6, 1999
Chandigarh, Thursday, May 6, 1999 |
Build your own network by T.M.S. Virdi Beware of spammers
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Build your own network
WINDOWS 95/98 offers three hardware methods of connecting computers into a network: modified serial or parallel cable, modem and network interface card (NIC). The fastest solution allowing the greatest network sophistication is using NICS, of which Ethernet cards are the most common. If you want a network of three or more devices simultaneously connected to one another, NICs are your only choice. But if all you’re after is a simple network to share files, a printer and perhaps a CD-ROM or removable disk drive between two computers, Windows 95/98 provides Direct Cable Connection (DCC) and Dial-Up Networking. Direct Cable Connection(DCC) As the name suggests, with Direct Cable Connection you connect two computers using a null modem cable running directly from one machine to the other. The cable differs from a standard serial cable in that the pin assignments on one end are different from those on the other (standard serial cable pins have the same assignments on both ends). More significantly, the Transmit Data wire and Receive Data wire are reversed to allow data to be transmitted from one computer and received by the other (See Figure 1). You can also achieve a faster connection by running a modified parallel cable between the parallel (printer) ports of the two machines. The cable’s pin assignments are modified on one end to allow direct data transfer. If each computer has a bi-directional parallel port (which is now a standard), you can reach up to 120K per second, approximately eight times the speed of a connection through two 16550 UART serial ports. With two Enhanced Parallel Ports (EPPs) or Extended Capabilities Ports (ECPs), speeds can reach a full megabyte per second or better. In all cases, you must have the same type of port on both computers. Once you’ve connected the cable between the serial or parallel ports of the two machines, you must install Windows 95’s DCC software. Open the Add/Remove Programs applet in Control Panel, click on the Windows Setup tab, select Communications, click Details and check Direct Cable Connection (this will also install Dial-Up Networking, if it isn’t already installed). Note : You’ll be asked for your Windows 95 CD. When the installation is complete, including the mandatory restart, choose Start> Programs> Accessories> Direct Cable Connection. This starts the DCC wizard, which begins by asking if you want establish the current machine as host or guest. This relationship is the basis of the DCC network: the guest machine has access to shared resources on the host machine, but the host has no access to the guest. It’s a one-way network. The wizard will then ask you to select a port (parallel or serial) to use as the DCC connection and instruct you to plug in the cable. Figure 2 shows the final dialog of a Guest setup. Network interface cards NICs have dropped in price over the past few months and many are cheaper than modems. They also offer much faster data transfer than modems or null modem cables. Because of these reasons, plus the fact that NIC based connections provide richer networking features than either DCC or Dial-Up Networking, the best Windows 95/98 networking solution-even for networks of two or three computers is using NICs. A NIC based network lets you connect more than two machines. You can also establish true peer to peer networks, with each machine having access to resources on all the others. On a NIC based network, all machines can share a printer from one computer, a removable disk drive from another, files and folders on all and so on. It is by for the most versatile solution. The most common type of NIC is designed for the Ethernet architecture and is thus called an Ethernet adapter (or card). Each computer must have its own Ethernet card. Many different brands are on the market. SMS and 3 COM are two-and they can be mixed and matched across the network. I recommend 3 COM because of its versatility. The first step is to install a network card in each machine, then power up Windows 95/98. Usually and especially with recently released cards Windows 95/98 recognises the hardware and automatically installs the drivers for you. If it doesn’t, you can install the adapter using the Network applet in Control Panel. Click Add, then choose Adapter and select your adapter from the list or install the drivers from the disk you received with the card. Where most first try Ethernet installations fail isn’t in the choice of adapter card, but rather in the choice of cable or in the omission of a hub. The most common connector type is RJ-45, which looks like a slightly enlarged telephone jack. The cable attached to it is referred to as a twisted pair cable. It would seam that all you need to do is buy a twisted pair cable and plug one RJ-45 end into the Ethernet card of the first computer and the other end into the Ethernet card of the second. Right away, however, you run into the two most common problems. First, if you have three or more computers, you can’t just daisy chain twisted pair cables from machine to machine. Second, if you have a two-computer network, the standard twisted pair cable won’t work. Let’s look at the two station network first. Recall that Direct Cable Connection required not a standard serial or parallel cable to connect two computers, but rather a modified cable. The same holds true for two computers connected through Ethernet cards. You need a modified twisted pair cable, called a crosswire(or X-wire) twisted pair cable, to make the two station network function. Plug one end into the first Ethernet card and the other into the second and you’re ready to establish your network. For more than two computers, you need standard (not crosswire) twisted pair cable, plus a network hub (see figure 3). Hubs are hardware devices that contain multiple RJ-45 ports, and they range in price from about Rs 2,000 to Rs 40,000 or more depending upon their configuration and the number of terminals they support. You plug a twisted pair cable into the Ethernet card of each computer, then into the hub. That lets multiple computers on a network talk to each other; the maximum number of computers depends on the size of the hub. You can buy hubs with as few as four RJ-45 ports, and as your needs grow, you can replace the hub with one that will support more computers. You can also use the hub for your two station network. Instead of buying one crosswire twisted pair cable, you’ll need to buy two standard cables and a small hub. This is a useful solution if you plan on expanding or if you have, say, two desktop machines and one notebook. You can buy an Ethernet PCMCIA card for the notebook and plug it into the hub whenever you need to exchange or update files or resources. If your notebook doesn’t have a CD-ROM drive, for example, this will allow it to use the CD-ROM drive on a desktop machine, and the speed will be quite acceptable. Network protocol and client No matter what kind of network you establish, you need a network protocol and a network client. Protocols allow computers to communicate with one another, and all computers on the network must share the same one. It is possible to have multiple protocols on one computer, but all the computers must have at least one in common in order to talk to each other. Network clients determine how your machine will make use of the protocol to initiate and maintain communications. To set your client and protocol, open the Network applet in Control Panel. If you’ve installed a NIC or modem with Dial-Up Networking, Windows 95/98 installs Client for Microsoft Networks by default, and that’s all you need for your small network. If not, click Add from the Network dialog, then select Client in the Select Network Component Type dialog and click Add. In the resulting dialog (called Select Network Client), choose Microsoft in the Manufacturer pane and Client for Microsoft Networks in the Network Clients pane. Next you’ll need a protocol NetBEUI (NetBIOS Extended User Interface) is standard with all Microsoft based networking. Again, click Add from the Network dialog, but this time click Protocol from the resulting dialog and Microsoft,/ NetBEUI from the protocols dialog. This is the good time to install your TCP/IP protocol if you want to access Internet later on. In order for your network to run, you need to bind the client, protocol and adapter together. Windows 95/98 establishes these bindings for you automatically when you install the three components, so you rarely if ever need to do so yourself, if you do need to bind manually,go to the Properties dialog for the NetBEUI protocol and click the Bindings tab to ensure that a binding is in place for the adapters and clients. The primary function of this dialog is to remove selected bindings for the sake of network performance, but that step won’t be necessary for your small network. File and print sharing The primary function of a peer to peer network is to share files and printers. No matter what hardware method you use, you’ll need to set up File and Print Sharing through Windows 95/98s Network applet in Control Panel (see Figure 4). Open the applet, click the File and Print Sharing button and then tell Windows that you want to allow other computers to share your files, your printer, or both by checking the appropriate box(es). The restart Windows. The next step is establishing which resources you with to share. To share a file, a folder or an entire drive, including a CD-ROM or removable disk drive, locate the resource in My Computer or Explorer. Right click on its icon, then select Sharing from the menu. To share a printer, open the Printers folder through My Computer> Control Panel, or Start> Settings then right-click on the appropriate printer icon and again select Sharing from the menu. In this dialog, the resource is Not Shared by default. Click the Shared As radio button and give the resource a name (use some-thing easily remembered, such as "CD-ROM" or "Data Drive"). In the Comment box, type explanatory text that will appear when users connect to the machine and select the resource from Explorer. In the Access Type area of the dialog, you must determine the degree of access to the resource you wish to allow. Read only means exactly what it says: the accessing computer can view the file but can’t modify it in any way, including deleting or renaming. The file can be downloaded to another machine, however and this is the primary use for read only access. Full access is also obvious: the resource is fair game to anyone who accesses it. The other option is Depends on Password. Here you can specify that one password allows read only access to the resource and a different password gives full access. Using this option, you can give the read only password to certain users and the full access password to others. You can also password protect a shared printer, but all printer shares offer full access only. Now who says that
setting up a network is a daunting task. Those days are
long gone by when people used to setup a network using
complex Unix commands. Today,operating systems are more
user friendly, more sophisticated and more reliable. So
why wait, get yourself started and create a network for
yourself-believe me you won’t lose anything. |
Beware of spammers HOTMAIL is no longer in the hands of its originator, Sabeer Bhatia, but it continues to be one of the most popular free e-mail service providers. After Microsoft bought it, it has thrived even more. But its success has also made it a favourite target of spammers. (Spamming means indiscriminately sending large amount of unsolicited e-mail meant to promote a product or service. Spam is in this sense a sort of equivalent of junk mail. There are some companies that offer spamming services and for this they need to collect e-mail addresses, for which they steal from e-mail service providers like Hotmail.) Despite several precautions, it has not been able to protect itself fully and it is alleged that the details of many people who hold an e-mail address with Hotmail get leaked to the hackers rather easily. The plugging of the holes has been more difficult than imagined and many people have found problems in even logging on. It was last year that Hotmail had discovered to its horror that spammers were getting precious private data about their users. The same problem was faced by Excite also. The addresses were exposed when Hotmail and Excite e-mail users received an e-mail message containing a link to a website. When these users clicked on the link, the website’s "referral logs" recorded their e-mail addresses. By itself, this information may not mean much, and a website operator would have to plough through the site’s daily server logs to harvest the e-mail account names. But to a direct marketer — such as the Net’s notorious senders of unsolicited e-mail — this information can be invaluable. The data could help unsolicited bulk e-mailers identify specific users of the free e-mail services, helping spammers fine-tune their one-to-one marketing tactics and track the outcomes of their sales pitches. According to CNET News.com, the Hotmail hole was initially discovered by Jason Catlett, founder of Junkbusters, a site that offers tools to help people eliminate junk e-mail and protect their online privacy. Last year, Hotmail filed a suit in federal court against certain spammers claiming that the companies forged the "hotmail.com" domain name into the return addresses of unsolicited commercial e-mail messages, falsely identifying Hotmail as the spam’s originating service. Three companies were required to pay $ 275,000, $ 55,000 and $ 7,500 to Hotmail as penalty. Permanent injunction prohibited them from using the Hotmail mark. But even that victory has not helped improve the situation much. Spammers are thriving elsewhere as well. The US Forest service was sent scrambling last month to adopt new rules about how taxpayers can send electronic messages to all its employees after it was hit with a virtual forest fire of unsolicited e-mail. The US Congress too is looking at ways to restrict the flow of constituent e-mail. The home page for the House of Representatives offers a "write your representative" tool, but citizens can write only to a single Congressman, not all at once. During the Clinton impeachment debate, e-mails flooded Capitol Hill and strained computer systems. And in 1996, the Federal Communications Commission received 2,00,000 messages in less than a week when consumers mistakenly believed the agency might propose an Internet tax. At present, some of the most methodical spam attacks are being launched from Yugoslavia. E-mail messages attacking the NATO bombing campaign have been bombarded from 25 computers in that country to more than 10,000 Internet users all over the world (including The Tribune). Show a little interest in the region and you become a target. Sending e-mail messages in reply demanding to be taken off the mailing lists does not solve the problem; it rather aggravates it. It seems that copies of the requests are circulated to everyone who received the messages in the first place. That brings you new messages from new sources. Till things settle down,
the golden rule is to be perpetually on guard and
particularly be wary of visiting sites offering free
goodies till you are very very sure about their
credentials. |
Science Quiz 1. Name the institute where Sir C.V. Raman conducted his famous experiment in 1928, which brought him the coveted Nobel Prize in Physics in 1930. Who founded this institute? Can you also name Raman’s collaborator in his experiment who was not awarded the Nobel Prize along with Raman? 2. With the recent announcement of the creation of ultra-heavy element of atomic number 114 by the Russian scientists, all the elements with atomic numbers from 93 to 114 have now been made in the laboratory, with only one exception. Can you state the atomic number of the element missing from this series? 3. Divers inside sea can "see" objects through dirty water using a system employing ultrasound waves. What is such a system called? 4. Improper use of hair dyes can be harmful to skin and eyes. Which chemicals are generally contained in hair dyes which can cause the damage? 5. This earliest known bird had features of both dinosaurs and birds and is also known as "Ancient Wing". What are we talking about? 6. This protected and endangered animal is killed on large scale in India for its hair to make small, fine brushes for painting. Name this animal. 7. What does a "histogram" convey? 8. Parsec is a unit of measuring astronomical distances. From which expression has the term parsec been derived, which gives a partial clue to its definition? 9. CCD cameras are very powerful high resolution cameras used even in most advanced satellites for digital photography. What does CCD stand for? What does it generally comprise? 10. A unique natural event took place recently when two full moons were observed during both the months of January and March. After how many years does such a rare phenomenon normally take place? What is this time period of phases of the moon called? Answers 1. Indian Association for the Cultivation of Science, Calcutta; Dr Mahendra Lal Sircar; K.S. Krishnan. 2. 113 3. Sonic imaging system 4. Para — phenylenediamine and hydrogen peroxide 5. Archaeopteryx 6. Mongoose 7. Frequency distribution of a variable quantity 8 Parallax of one Second 9. Charged coupled device; it is an array of silicon chips on which charge is deposited when light falls on it 10. 19 Years; Metonic Cycle.
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Device to check bombs A new portable machine, being developed by US researchers, will offer a different way to check, what is inside an abandoned package by using reflected, rather than transmitted, X-rays. In conventional method, transmitted X-ray beam creates an image of a package on a film placed behind the object which requires a person to go near the package which could possibly be an explosive. The new machine developed by researchers at Sandia National Laboratories in New Mexico uses a detector, a video camera and a robotic cart to detect the contents of an unknown package, according to a Sandia release. The technique evolved from more powerful machines developed by Sandia to use reflected X-rays for detecting plastic or metal landmines buried in the ground where no possibility exists to place X-ray films. A special electrically heated filament releases electrons with sufficient energies in the X-ray range. Intense X-rays reflected from the object from the image. A computer programme, developed at the University of Florida, distinguishes between degrees of reflection caused by objects in the package. By stripping layer after layer in a series of X-rays — a technique similar to the computer-aided tomography (CAT) scan — the changes in back-scattered X-rays are collected to form a complete picture. Better cleaning plant for industries A new eco-friendly cleaning plant that provides clean surfaces for industrial units to carry out coating, bonding and welding processes, has been developed by German scientists. The water-based cleaning process, which uses minimal amounts of chemicals and generates little waste water, was developed by researchers of the Fraunhofer Institute for Thin Films and Surface Engineering in Brunswick and the Swiss engineering company ABW. In terms of cleaning quality, the new method is superior to those which are based on halogenated hydrocarbons as these methods, though function well, are a burden on the environment, according to a report in Fraunhofer Gesellschaft Research News. Enzymes to make conductive polymers By combining enzymatic synthesis with modern chemistry, a team of US scientists, including an India-born researcher, has come up with a simple and novel approach to develop conductive polymers — plastics that conduct electricity. Conducting polymers are under intense investigation for use in applications such as lightweight batteries, coatings that reduce static-electrical charges in paper products, plastics and textiles, and optical displays. But finding practical
synthetic methods which yield stable materials that can
be readily processed has proven difficult so far. |
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