Downloading FAQ

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This FAQ is comprised of both downloading & burning questions.

Return to Knoppix FAQ

Tip: Use CD-RWs instead of CD-Rs every time you can - save your budget and our environment!

Q: How do I get the CD/current beta?

A: Several possibilities:

Q: Can you download Knoppix in parts if you have a low bandwith (28.8 Kbps) such a pausing the download and continue it another day?

A: Yes, Bittorrent supports resume, and so does many ftp clients such as wget ( use wget -c ) or ncftp. You can use other download managers too.

Q: What are these strange MD5 files that accompany the ISO CD images?

A: The files with the .md5 extension contain checksums for the actual CD ISO images. A MD5 checksum is a way of fingerprinting files. Just like a real fingerprint identifies a single person, a MD5 checksum is unique and matches exactly one file. It is used to verify that the file downloaded matches the original all the way down to the smallest details. In the case of downloading a Knoppix ISO image, the MD5 checksum is used in order to verify that the file downloaded is perfect and not corrupt.

When you download both the ISO image for the CD, you also must download it's corresponding .md5 file. The .md5 file is a plain-text file and can be viewed in a text editor or web browser. You can verify that your download was perfect and that the ISO's contents are unchanged by typing "md5sum -c filename.md5" under Linux/Unix.

Further information about MD5 and programs for various OS's can be found at and The MD5 Protocol Documentation. Here is a small list of MD5 checksum calculators for Windows™ but note that the methods to verify the checksum & make sure you have a perfect ISO file vary between programs.

Q: What are these strange ASC files that accompany the ISO CD images?

A: Most users can ignore the .asc files. If there is ever an uncertainty as whether or not the ISO image file and it's accompanying MD5 file are originals & untampered, then the .asc files are important. The .asc files are digital signature messages. Digital signatures are a method of authenticating digital information similar to ordinary physical signatures on paper, but implemented using techniques from the field of cryptography. With this you can be sure the ISO image and accompanying MD5 file are genuine, because the .asc file containing the MD5 is signed with Klaus Knopper's PGP key. To verify the file, you need to import PGP key ID 0xBA8F038D from your favorite keyserver, then in Linux you can type "gpg --verify KNOPPIX_Vxxxxxxxxxxxxxxxxx.iso.md5.asc". Then you must check that the MD5 checksum in the .asc file is the same that the MD5 checksum in the .md5 file.

To download the keys, type:

gpg --keyserver --recv-keys BA8F038D

If you want to verify the signed md5 file and the ISO file in one step, you can type:

gpg --decrypt  KNOPPIX_Vxxxxxxxxxxxx.iso.md5.asc | md5sum -c -

Q: I have downloaded the ISO file. How do I burn the ISO? How is the ISO supposed to be burned?

A: First check to see if the ISO that was downloaded is perfect & not corrupt. See the above FAQ labeled #Q:_What_are_these_strange_MD5_files_that_accompany_the_ISO_CD_images.3F. If it passes the MD5 checksum then you must burn the ISO as an image.

  • Linux
    • You can use the command cdrecord or the CD burning program K3b.
  • Windows
    • Quick answer: You will need one 700MB/80min blank CDR. Use a program such as Nero Burning Rom or Roxio CD Creator. You can get a free trial of Nero from their site. In most cases you will want to skip the burning wizard and choose File -> Burn Image or File -> Open. Select the KNOPPIX_Vxxxxxxxxxxxxxxxxx.iso file, then -> Burn.
    • Long answer: Of course the answer depends on the individual program you are using to burn CDs, but all common CD-Writing programs should support the option of burning the ISO as an image, you probably just have to find the right menu option. In the burning program, do not drag & drop the ISO into the burning screen. In the windows explorer, do not attempt to decompress the ISO with something like WinRAR or WinZip. You must CHOOSE to burn it as an image. Do not burn it at a fast speed greater than 16X. You must burn it at a very slow speed preferably 4X or 8X. Burn your CDR as a "Single Session CD" or select finalize. The Mode "Disk at once" or "Track at once" should not matter (have a look at the Online-Help of your burning software).

A common mistake made when burning ISOs: "I downloaded & burned the ISO to CDR as a bootable data disc. Now it boots to a A:\ Caldera DR-DOS prompt." You are probably seeing something like:

Caldera DR-DOS 7.03
Copyright (c) 1976, 1998 Caldera, Inc. All rights reserved.
[DR-DOS] A:\]

This means that the ISO was burned as a bootable CD or bootable data disc. A Knoppix ISO already includes the boot instructions so it is not necessary to burn it as as a bootable data CD. Burning the ISO file as an image will automatically take care of the bootable details.

Q: My computer won't boot from CD. What should I do?

A: Look in your computer's BIOS (on many computers you need to push the "delete" or F1 key during the POST) to see whether it is set to boot from CD. If this is already set, your computer may not be able to read the CD (some notebooks have problems with black-coated CD's, for example). Some computers will only use the new BIOS settings after a hard reset. Other resources are this page which explains the PC BIOS and this page explains the boot order.

A: If your computer doesn't support booting from CD, you can create a bootfloppy using the "rawrite" or better yet the mkfloppy.bat file program in the "KNOPPIX" directory on the CD.

A: Get the Smart Boot Manager, and install to floppy, this should let you boot from any bootable CD. Download Smart Boot Manager. If you want to install from windows, download the sbminst.exe and run it from the Command Prompt like : sbminst.exe -d 0 to install to floppy drive.

Q: My PC will boot off of the burned disc. It is strange since it loads but then stalls or it loads but is giving me I/O errors. What's going on?

A: You possibly only got a partial download or the download was complete, but corrupt. If this is the case, then the ISO image is defective and the CDR burn of Knoppix is also defective. This is because the data in the missing/changed parts cannot be accessed (sometimes one can even "hear" this because of the sound the CD-ROM drive makes due to repeated read attempts). It appears to work because the directory tree is written at the beginning of the CD and can be correctly read. However, reading the actual contents of the missing/changed parts is impossible, or in other words, accessing the contents fails. If the ISO image was checked & found to be unchanged and not corrupt, then it is possible that the CDR has been improperly burned or a bad piece of CDR media was used. To rule out the possibility of a bad download or a bad burn, some solutions can be found in the section #Q:_What_are_these_strange_MD5_files_that_accompany_the_ISO_CD_images.3F and #Q:_I_have_downloaded_the_ISO_file._How_do_I_burn_the_ISO.3F_How_is_the_ISO_supposed_to_be_burned.3F.

Q: After I've used KNOPPIX, my "other" OS suddenly shows a blue screen with the message "File kernel.exe not found or defective" and "reinstall..." shortly after boot.

A: Simply take the KNOPPIX CD out of the CD-Rom drive and restart the computer.

Q: I have a fast access to a Knoppix-mirror. How can I burn with GNU/Linux this ISO file directly to CD-RW?

- mkfifo KNOPPIX.fifo # mkfifo create a fifo file
- screen ftp mirror ....# screen creates multiple shells in one terminal (handy!) ftp connect to your mirror...
get KNOPPIX-3.10-EN.iso KNOPPIX.fifo #command to copy inside your ftp-session
- C-a C-c # screen will make a new shell
- cdrecord dev=(your burner) speed=4 KNOPPIX.fifo # ftp starts to get data when cdrecord starts to read from fifo
wait; exit; rm KNOPPIX.fifo; exit

(Attention, use "cdrecord -scanbus" before cdrecord to find the correct device of your cd-writer. If you own SCSI hds, you could lose all data of one hd when you use cdrecord with a wrong dev=(controller,id,partiton) !)


This works well and is much simpler: wget -O - URL_OF_IMAGE | cdrecord -v speed=4 -eject -

Q: Must I burn Knoppix on CD-RW to be able to test it?

A: When you run another GNU/Linux system, you can copy the content of the Iso-file to your hd and boot it directly from hd. See Hd Based HowTo.

Q: How do I burn an image on to a CD using B's Recorder Gold from BHA?

A: Close the Wizard dialog if it pops up when you start the application. Drag the KNOPPIX-*.iso file to the lower RIGHT region of the app window. It is shaded in yellow and has the title "Track Type"(The icon with a musical note and a folder will be seen in the middle panel). Right click the left region where it says ")1 DATA -mode1 and from the popup menu choose properties. Choose "ISO compatible" and "create from standard bootable disk image" in the two selection boxes. Then press the record button (Upper left), pick your options, and Voila - one KNOPPIX bootable CD is yours.

Q:Why do 750 MB fit onto an audio CD but only 650 MB onto a data CD?

A: A sector of a CD consists of 2352 bytes. With an audio CD, these are used completely for audio information. With data CDs, an additional fault correction is inserted, and the usable capacity shrinks to 2048 bytes. A 74 minute CD consists of 74x60x75 = 333000 sectors. With 2048 bytes per sector, this gives a usable capacity of around 650.1 MB, with 2352 bytes per sector it gives around 746.6 MB. This therefore also produces a difference in data rates for reading/writing: 172 kbps with audio and 150 kbps for data.

Q: Why does my writer/software not accept to write to my 80 minute CD-R?

A:Some older writers or older versions of writer software cannot recognise the new playing lengths, because the groove is laid more narrowly. Check with your hardware and software manufacturer to see if these newer media are supported. In most cases, updating the writer software's current firmware (check out the web site of the software manufacturer) will solve these problems.

Q: What to do if I haven't got enough space in the CD to burn Knoppix on it?

A: You can overburn it ( ).