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NETWORK SECURITY AND BACKUP SYSTEMS

Prevention is the key when it comes to network security. Identifying and stopping intrusion—in all its forms—is what security is all about. But identifying a potential intrusion is not always obvious, or likely. The usual security suspects — CIA agents, and industrial espionage—make great headlines, but they don't pose real risks to the average company. However, just because you're not building the next secret weapon doesn't mean that you're not at risk from security breaches. Far more often, security risks come from acts committed out of human error, greed, malcontent, or machine error.

Physical theft, electronic tampering, and unauthorized access are just three of the more obvious threats to network equipment and data. Physical theft includes people stealing computers, taking floppies with data, and tapping into the cable to siphon off information. Electronic tampering covers computer viruses and other malicious reprogramming. Unauthorized access, the most common threat to security, usually occurs when people see information they shouldn't.

Networks seriously increase access to your information, and with access comes the responsibility of restriction and control. In addition to the usual sources of security breaches—people taping passwords to their monitors and using scanners to electronically eavesdrop—networks invite a whole host of other vulnerabilities. It's easy enough to drop another workstation or server on the network or add another application. Add the ability to dial into the network system, and you pose an even greater risk.

There is no simple formula for calculating your security needs. The amount of security depends upon the threat you perceive. In some cases, the need for security is clear: banks, airlines, credit card companies, and insurance companies. In other cases, the risks may be less obvious. Allowing any worker to examine the payroll file makes for disgruntled employees. Your personal calendar indicates when you are out of town. The following are some of the more common risks to network security.

Your network can be a danger to itself. Being made of mechanical components, a network can do itself damage when disk heads crash, servers fail, and power supplies blow. Tape and disk platters get old and go bad. Bugs, such as in an out-of-control operating system process or one with a faulty memory mapping, destroy data. Monitor mechanical equipment for wear. For critical components, keep spares onsite or, if warranted, online.

Your network is physically vulnerable. Thieves and other intruders can physically break into your building, wiring closet, or server room and steal or vandalize equipment and data. When a file is erased, very often it physically remains on disk or tape—only the entry to the directory structure is removed. Sensitive documents may be printed out and left lying around the office, waiting for prying eyes or thieving hands.

Your first line of defense is the simplest: Use locks, guards, and alarms to protect against these physical vulnerabilities. Lock servers in a room and lock wiring closets, permitting access to only those with a key. Sensitive data must be completely wiped off the media when deleted. Shred all sensitive printouts. Bolt expensive equipment to the floor or to a desk. A slew of products exist to prevent intruders from physically taking equipment. Most involve locking equipment with metal bars, in steel cabinets, or with large chains. Others sound loud alarms to deter the thief. These products can help to keep your equipment from being physically stolen (it also makes them difficult to move from one station to another). If your security needs are extreme, you might employ biometric devices. Biometric devices use a physical aspect of people, such as their fingerprints, to verify their identity.



The next step is to secure the cable. Copper cable gives off electromagnetic radiation, which can be picked up with listening devices, with or without tapping into the cable. One solution is to fiber-optic cable, which does not emit electromagnetic signals and is more difficult to tap without detection.

Diskless PCs are a popular security measure. A diskless PC lacks floppy and fixed drives. Users must boot the computers off the file server. With no drives, no way to remove data physically exists. However, be aware that diskless PCs with serial and parallel ports and expansion slots are insecure. A user can insert a removable disk into an expansion slot and remove data. Or the user can attach a printer.

Another step is to physically limit access to data sources. Use the keyboard lock on PCs and file servers. Lock file servers in closets or computer rooms, thus preventing direct access and forcing intruders to circumvent network security. Rooms with doors and locks are good places for printers and other output devices since printed data may be as sensitive as electronic data.

Viruses are potentially one of the most dangerous and costly types of intrusion. Although they are relatively rare to a well-kept network, the penalties inflicted by a virus can be severe. Your network is vulnerable at any point it contacts the outside world, from floppy drives to bridges to modem servers. At these external contacts, your network's messages can be intercepted or misrouted. Workers take notebooks on the road and may come into contact with a virus-infected computer. Users may take work home, where their home computers are infected. Demonstration programs, bulletin boards, and even shrink-wrapped software may have viruses.

Protecting your network against a computer virus is much the same as protecting it from unauthorized access. If intruders can't access the network, they can't unleash a virus. However, many viruses are introduced by unwitting authorized users. Any new software should be suspected of having viruses. Although programs from bulletin boards may sometimes be infected, several software companies have shipped shrink-wrapped software that was infected with a virus. While specialized programs can look out for viruses and limit the havoc they wreak, no program can prevent a virus. It can only deal with the symptoms.

Intentional threats are also potentially damaging. Employees and outsiders pose intentional threats. Outsiders—terrorists, criminals, industrial spies, and crackers—pose the more newsworthy threats, but insiders have the decided advantage of being familiar with the network. Disgruntled employees may try to steal information, but they may also seek revenge by discrediting an employee or sabotaging a project. Employees may sell proprietary information or illegally transfer funds. Employees and outsiders may team up to penetrate the system's security and gain access to sensitive information.

Workstation file systems present a threat to the network. DOS is easy to circumvent. Intruders can use the many available programs to get at a hard disk and remove data, even if security programs are at work. For this reason, high security installations may want to use a different operating system, one with a different file system. Unix has sophisticated file security, and additional programs are available for even more protection.

Your network radiates electromagnetic signals. With an inexpensive scanner, experienced electronic eavesdroppers can listen in on your network traffic and decode it. Shielded cable, such as coax and shielded twisted pair, radiates less energy than unshielded cable, such as telephone wire. Fiber-optic cable radiates no electromagnetic energy at all—since it uses light instead of electrical signals to transmit—and it's relatively easy to detect taps into a fiber cable, since these decrease the light level of the cable. If your installation demands maximum security, Tempest-certified equipment shields electromagnetic emissions.

By far the most common network intrusion is unauthorized access to data, which can take many forms. The first line of defense against unauthorized access should be the workstation interface. Login passwords are a must. Nearly all network operating systems will not give workstation users access to network resources without the correct password. To make passwords more effective, the administrator should assign them and change them at random intervals. Don't let users post their passwords on their monitors or desk blotters. Use mnemonic passwords to help users remember.

Software is available to blank a user's screen or lock the keyboard after a certain definable period of inactivity. Other software will automatically log a user out of the network. In either case, a password is required to renew activity. This prevents the casual snooper, but not a determined one.

A more secure method to stop unauthorized access is an add-in card for each workstation. This card forces the workstation to boot up from a particular drive every time. It can also enforce some kind of user validation, like a password. If the card is removed, the workstation is automatically disabled.

· Your network administrators present yet another risk. If you give them free rein over the applications and data, you're exposing your network to unnecessary risks. Your network administrators manage the network, not the data on it. Administrators should not have access to payroll information, for example. Similarly, don't fall victim to the fallacy that the department heads should have complete access to the network and its information just because they are in charge.

Finally, your network is subject to the whims of nature. Earthquakes, fires, floods, lightning, and power outages can wreak havoc on your servers and other network devices. While the effects of lightning and power outages can be minimized by using uninterruptible power supplies, you'll need to store backups of important data (and perhaps even equipment) offsite to deal with large-scale disasters.

 

4. How to Buy a Personal Computer

Buying a personal computer, like buying a car, often re­quires making a tradeoff between power and expense.

Power Many computer experts try to look for a personal computer system with as much power as possible. The word power has different meanings when describing soft­ware and hardware:

• Powerful software: Applied to software, "powerful" means that the program is flexible. That is, it can do many different things. For example, a word processing program that can print in different typestyles (fonts) is more powerful than one that prints in only one style.

• Powerful hardware: Applied to hardware, "powerful" means that the equipment (1) is fast and (2) has great capacity.

A fast computer will process data more quickly than a slow one. With an older computer, for example, it may take several seconds to save, or store on a disk, a 50-page term paper. On a newer machine, it might take less than a second.

A computer with great capacity can run complex soft­ware and process voluminous files. This is an especially important matter if you want to be able to run the latest releases of software.

Will computer use make up on essential part of your ma­jor, as it might if you ore going into engineering, business, or graphic arts? If so, you may want to try to acquire pow­erful hardware and software. People who really want (and can afford) their own desktop publishing system might buy a new Macintosh Quadra with LaserWriter printer, scan­ner, and PageMaker software. This might we I cost $7000. Most students, of course, cannot afford anything close to this.

Expense If your major does not require a special com­puter system, a microcomputer can be acquired for rela­tively title. You can probably buy a used computer, with software thrown in, for under $500 and a printer for un­der $200.

What's the minimum you should get? Probably an IBM-compatible or Macintosh system, with 4 megabytes of memory and two diskette drives or one diskette and one hard-disk drive. However, up to 16 megabytes of memory is preferable if you're going to run many of to­day's programs. Dot-matrix printers are still in use on many campuses [24-pin printers are preferable to 9-pin). To be sure, the more expensive laser and inkjet printers produce a better image. However, you can always use the dot-matrix for drafts and print out the final version on a cam­pus student-use printer.

Where to Buy New

Fierce price wars among micro­computer manufacturers and retailers have made hard­ware more affordable. One reason IBM-compatibles have become so widespread is that non-IBM manufacturers early on were able to copy, or "clone," IBM machines and offer them at cut-rate prices. For a long time, Apple Macintoshes were considerably more expensive. In part this was be­cause other manufacturers were unable to offer inexpen­sive clones. In recent times, however, Apple has felt the pinch of competition and has dropped its prices. It also has licensed parts of its technology to others so that we are now seeing Macintosh "clones."

When buying hardware, look to see if software, such as word processing or spreadsheet programs, comes "bun­dled" with it. In this case, bundled means that software is included in the selling price of the hardware. This arrange­ment can be a real advantage, saving you several hundred dollars.

Because computers are somewhat fragile, it's not unusual for them to break down, some even when newly pur­chased. Indeed, nearly 25% of 45,000 PC users surveyed by one computer magazine reported some kind of problem with new computers. (The failure rates were: hard drive—21%, motherboard—20%, monitor—12%, diskette drive—11%, and power supply—10%.) The PCs (Apple was not included) that had the fewest problems included those from AST Research, Compaq, Epson, Hewlett-Packard, IBM, and NCR (AT&T). Most troublesome were low-cost PCs.

There are several sources for inexpensive new comput­ers, such as student-discount sources, computer super­stores, and mail-order houses.

Where to Buy Used Buying a used computer can save you a minimum of 50%, depending on its age. If you don't need the latest software, this can often be the way to go. The most important thing is to buy recognizable brand names, examples being Apple and IBM or well-known IBM-compatibles: Compaq, Hewlett-Packard, NCR, Packard Bell, Tandy, Toshiba, Zenith. Obscure or discontinued brands may not be repairable.

Among the sources for used computers are the follow­ing:

• Retail sources: A look in the telephone-book Yellow Pages under "Computers, Used" will produce several leads. Authorized dealers (of IBM, Apple, Compaq, and so on) may shave prices on demonstration (demo) or training equipment.

• Used-computer brokers: There are a number of used-computer brokers, such as American Computer Ex­change, Boston Computer Exchange, Damark, and Na­tional Computer Exchange.

• Individuals: Classified ads in local newspapers, shop­per throwaways, and (in some localities) free computer newspapers/magazines provide listings of used com­puter equipment. Similar listings may also appear on electronic bulletin board systems (BBSs).

One problem with buying from individuals is that they may not feel obligated to take the equipment back if something goes wrong. Thus, you should inspect the equipment carefully.

For a small fee, a computer-repair shop can check out the hardware for damage before you buy it.

How much should you pay for a used computer? This can be tricky. Some sellers may not be aware of the rapid depreciation of their equipment and price it too high. The best bet is to look through back issues of the classified ads for a couple of newspapers in your area until you have a sense of what equipment may be worth.

Checklist Here are some decisions you should make be­fore buying a computer:

• What software will I need? Although it may sound back­ward, you should select the software before the hard­ware. This is because you want to choose software that will perform the kind of work you want to do. First find the kind of programs you want—word processing, spreadsheets, communications, graphics, or whatever. Check out the memory and other hardware require­ments for those programs. Then make sure you get a sys­tem to fit them.

The advice to start with software before hardware has always been standard for computer buyers. How­ever, it is becoming increasingly important as programs with extensive graphics come on the market. Graphics tend to require a lot of memory, hard-disk storage, and screen display area.

• Do I want a desktop or a portable? Look for a computer that fits your work style. For instance, you may want a portable if you spend a lot of time at the library. Some students even use portables to take notes in class. If you do most of your work in your room, you may find it more comfortable to have a desktop PC. Though not portable, the monitors of desktop computers are usually easier to read.

It's possible to have both portability and a readable display screen. Buy a laptop, but also buy a monitor that you can plug the portable into. Computers are also available with "docking" systems that permit a portable to fit inside a desktop computer or monitor.

Also keep in mind that portable computers are more expensive to maintain than desktop computers, and portable keyboards are smaller.

• Is upgradability important? The newest software being released is so powerful (meaning flexible) that it re­quires increasingly more powerful hardware. That is, the software requires hardware that is faster and has greater main memory and storage capacity. If you buy an outdated used computer, you probably will not be able to upgrade it. That is, you will be unable to buy in­ternal parts, such as additional memory, that can run newer software. This imitation may be fine if you expect to be able to afford an all-new system in a couple of years, if, however, you are buying new equipment right now, be sure to ask the salesperson how the hardware can be upgraded.

• Do I want on IBM-style or a Macintosh? Although the sit­uation is changing, until recently the division between IBM and IBM-compatibles on the one hand and Apple Macintoshes on the other was fundamental. Neither could run the other's software or exchange files of data without special equipment and software. We mentioned that some campuses and some academic majors tend to favor one type of microcomputer over the other. Outside of college, however, the business world tends to be dominated by IBM and IBM-compatible machines. In a handful of areas—graphic arts and desktop publishing, for example—Macintosh is preferred.

If you think there's a chance you will need to become familiar with both IBMs and Macs, you might consider buying a high-end Macintosh PowerMac. This microcom­puter can handle disks and programs for both systems.


Date: 2015-04-20; view: 930


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