Number 290 - July 2007

Experimenting With Live CD-ROMs
by Dick Maybach (n2nd@att.net), Brookdale Computer Users Group
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 as 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. Don't 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. Changing boot order    If you think you've 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 deviced 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 okay, 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 what is called an ISO image. This is not a file, and if you write it to a CD-ROM as a file, it won't be bootable. Unfortunately, the free versions of CD-ROM burner programs included with many PCs won't burn ISO images. But a suitable program, ISO Recorder, is available free at . Many live CD-ROMs are 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 .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. DOS lives at freedos.org    If you long for the simpler days of DOS, see 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 aren't ready yet to install it on your hard disk, look at Ubuntu www.ubuntu.com/, which provides a Windows-like interface, or Knoppix 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 www.inside-security.de/insert_en.html. This is worth a complete article, and I'll discuss it in next month's column. Your Knoppix secret decoder CD    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 anaIyzing and breaking passwords, for analyzing network traffic, and for assessing computer vulnerability.    You can see a long list of available live CD-ROMs at www.frozentech.com/content/livecd.php. Most of these are versions of Linux, because its source code is available and free, and because it's modular. Windows, by comparison, is proprietary and monolithic. At one point, Microsoft claimed that you couldn't remove even its Internet browser without disabling the operating system.    Happy exploring!
Number 290 - July 2007