Article, June 2007
By Dick Maybach.
a Member of the Brookdale Computer User Group, New Jersey
N2nd@att.net (click to email author)
Obtained from APCUG with the author's permission for publication by APCUG member groups.
In the early days of PCs, we did much more experimenting than we do now. The only long-term storage was on diskettes, and when we removed the diskette holding the operating system, we also removed any problems that resulted from our experiments. Now, our hard disks hold large, complex operating systems, and if they are damaged by our errors or by malware such viruses, the recovery process can be long and painful. Those who still like to experiment should consider live CD-ROMs.
A live CD-ROM contains an operating system and applications and can be run without using the hard disk at all. When you remove the CD-ROM, your old operating system (probably Windows) takes over. In fact, since the hard disk was not accessed while the live CD-ROM was running, Windows is no more aware that the PC has been used than if you had never switched on the power.
To use a live CD-ROM, you must set up your PC so that if a CD-ROM is present, it will try to boot from it, rather than the hard disk. Watch carefully as your PC boots, and you should see a message telling you how to start the BIOS set-up program. Often, the procedure is to press the F2 key repeatedly during booting. Donít just hold it down, as the PC will think your keyboard has a stuck key and will refuse to start. Once the set-up program has started, read each screen carefully before changing anything. If you think youíve made a mistake, exit without changing anything (often done by pressing the escape key) and start again. You are looking for the screen that lets you change the boot order, which is the order in which the PC checks devices for an operating system. It always includes the hard disk, diskette, and CD-ROM, and (on newer machines) USB devices. In our case we want the CD-ROM checked before the hard disk. Once you are satisfied that everything is ok, save your changes and exit the program, often done by pressing F10.
You can download live CD-ROM programs free from the Internet. However, you will now have whatís called an ISO image; this is not a file, and if you write it to a CD-ROM as a file, it wonít be bootable. Unfortunately, the free versions of CD-ROM burner programs included with many PCs wonít burn ISO images. However, a suitable program, ISO Recorder, is available, free over the internet from http://isorecorder.alexfeinman.com/isorecorder.htm. Many live CD-ROMs are also available as pre-recorded CD-ROMs; see the referenced Web sites for information.
A good place to start is with the Ultimate Boot CD, available at http://www.ultimatebootcd.com/. This provides four versions of DOS and five of Linux, plus tools for motherboard, hard disk, and file system maintenance, in addition to four virus scanners.
If you long for the simpler days of DOS, see http://www.freedos.org/ to obtain an open-source clone of DOS. This will allow you to get reacquainted with the command line, BAT files, BASIC programming, and run those old programs that no longer work under Windows. The full version contains some extras, FreeGEM (a clone of the old Digital Research graphical user interface), BWBasic (Bywater Basic), and several games.
If you would like to experiment with Linux, but arenít ready yet to install it on your hard disk, look at Ubuntu, http://www.ubuntu.com/, which provides a Windows-like interface, or Knoppix, http://www.knoppix.org/, which is known for being very adaptable to different PC hardware. Several tutorial books are available for each; check your local Barnes & Noble or Borders.
For Linux, Windows, and, to a limited extent, Macintosh maintenance and recovery, my favorite is INSERT, available at http://www.inside-security.de/insert_en.html. This is worth a complete article, and Iíll discuss it next monthís column.
Security Tools Distribution (STD), http://s-t-d.org/, is a variant of Knoppix, customized for those in computer security. It includes tools for encryption and code-breaking, for finding evidence of computer break-ins, for working with firewalls, for building honey pots (traps for ensnaring hackers), for analyzing and breaking passwords, for analyzing network traffic, and for assessing computer vulnerability.
You can see a long list of available live CD-ROMs at http://www.frozentech.com/content/livecd.php. Most of these are versions of Linux, because its source code is available and free, and because itís modular. Windows, by comparison, is proprietary and monolithic; at one point, Microsoft claimed that you couldnít remove even its Internet browser without disabling the operating system.
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