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Randolph J Tata

Talcon Information Systems

v1.40 2002/01/10
Revision History                                                             
Revision v1.40            2002-01-10           Revised by: rjt               
Added description and link to cdtower shell script.                          
Revision v1.30            2002-01-08           Revised by: rjt               
Many additions and changes to markup in DocBook XML source and fix pubdate   
Revision v1.01            2002-01-07           Revised by: rjt               
Updated for 2.4 kernels. Added more References and links. Convert to DocBook 
XML 4.1.2 Change License from LDP boilerplate to GFDL.                       
Revision v1.00            2000-09-23           Revised by: rjt               
Conversion from Linuxdoc SGML to DocBook v3.1 SGML                           
Revision v0.10            2000-09-01           Revised by: rjt               
Conversion to Linuxdoc SGML from text/html, added kerneltweak (addloops)     
Revision v0.01            2000-08-18           Revised by: rjt               
First version released in text and html.                                     

  The CD Server HOWTO describes the steps and commands you can use to setup
your own CD Server using Linux and some built-in Unix commands along with
other freely available software packages. The CD Server can then share the
CD's via the network to Windows and/or other client machines.

Table of Contents
1. Introduction
    1.1. Intended Audience
    1.2. Things You'll Need
    1.3. Suggested Reading and References
    1.4. Copyright and License
    1.5. Disclaimer
    1.6. News
    1.7. Credits
    1.8. Translations
2. Procedure
    2.1. Creating the ISO Images
    2.2. Mounting the ISO Images
    2.3. Mounting the Image upon System Restart
    2.4. Sharing it on a Windows Network using Samba
    2.5. Sharing the Images on a Unix network using NFS
3. Adding Support for More Loop Devices
    3.1. Adding the Loop Module Option
    3.2. Appending to the Boot Prompt
    3.3. Tweaking the Kernel
    3.4. Creating the Loop Devices in /dev
4. More Information
    4.1. Frequently Asked Questions
    4.2. Other Instructions Available on the Web
    4.3. Under Future Consideration
A. GNU Free Documentation License
    How to use this License for your documents

1. Introduction

 With disk space becoming less expensive (100GB Western Digital 7200rpm
available for US $195 in January 2002), it is viable to use an Open Source
software-based CD Server solution, instead of paying $800-$4,000 for a
software, thin-server, or CD Jukebox solution.

 I've setup my CD Server on a Pentium 200 with 64MB RAM, using one of these
large drives.

 Any comments, suggestions, additions, or corrections can be sent to my email
address at []  Talcon Information Systems: <>.

1.1. Intended Audience

 This HOWTO is specifically directed toward System Administrators and uses
Linux for the examples. It should work with other flavors of Unix provided
that they have a loop device or a method of mounting a CD image file within
the directory tree as a block device using the iso9660 file system.

1.2. Things You'll Need

 The commands and utilities needed to setup your own CD Server are already
included in most (if not all) Linux distributions.


��*�  A Linux Distribution (This HOWTO uses   Linux-Mandrake for the
��*�  dd - Converts and copies a file (a standard Unix command)
��*�  mount - Mounts and Unmounts filesystems (a standard Unix command)
��*�  Samba - A Windows SMB/CIFS fileserver for Unix
��*�  NFS (optional for Unix) - Network File System (included in Linux
��*�  Netatalk (optional for Macs) - A package that lets a Unix machine
    supply Appletalk print and file services on a LAN.

     Previous to the 2.4 kernels, the Linux-Mandrake distribution I was using
    only had support for 8 loop devices compiled into the kernel (see Section
    3 to increase this number). At that time, you were only be able to share
    8 CD's on a network with that default value, and to share more than 8,
    the loop block driver source code (loop.c) needed to be modified and a
    new kernel compiled.
    With the 2.4 kernels, that is no longer required. You can now set the
    number of loop devices dynamically via the max_loop module parameter, or
    by passing max_loop=[1-255] to the kernel on boot.

1.3. Suggested Reading and References

  SMB HOWTO by: David Wood, dwood (at) Part of the Linux
Documentation Project. This document describes how to use the Server Message
Block (SMB) protocol, also called the Session Message Block, NetBIOS or
LanManager protocol, with Linux using Samba.

  Using Samba by: Robert Eckstein, David Collier-Brown, Peter Kelly 1st
Edition November 1999, O'Reilly and Associates, Inc. ISBN 1-56592-449-5,

  The Linux CD-ROM HOWTO by: Jeff Tranter, tranter (at) Part of
the Linux Documentation Project. How to install, configure, and use CD-ROM
drives under Linux. It lists the supported hardware and answers a number of
frequently asked questions. This HOWTO also gives some information on using
multi-platter CD-ROM drives with Linux.

  CD-Writing HOWTO by: Winfried Tr�mper, winni (at) Part of the
Linux Documentation Project. This document explains how to write CD-ROMs
under Linux. This HOWTO also includes information on making 1:1 image copies
of CD-ROMs.

1.4. Copyright and License

  CDServer-HOWTO, Copyright � 2000-2002, by []
Randolph J. Tata, All Rights Reserved

  Permission is granted to copy, distribute and/or modify this document under
the terms of the GNU Free Documentation License, Version 1.1 or any later
version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license
is included in Appendix A entitled "GNU Free Documentation License".

1.5. Disclaimer

 Use the information in this document at your own risk. I disavow any
potential liability for the contents of this document. Use of the concepts,
examples, and/or other content of this document is entirely at your own risk.

 All copyrights are owned by their owners, unless specifically noted
otherwise. Use of a term in this document should not be regarded as affecting
the validity of any trademark or service mark.

 Naming of particular products or brands should not be seen as endorsements.

 You are strongly recommended to make a backup of your system before major
installation and should make backups at regular intervals.

1.6. News

 As always, check the revision history at the top of this document.

 []  DocBook
XML source for this document is available. Any additions/changes should be
made to the DocBook XML source, not derivative formats.

 This documents home page is at the []
CDServer-HOWTO site page in case you need the latest version, or there is a
problem with the page format you are viewing.

1.7. Credits

  My thanks go the readers of this HOWTO and those willing to share their
experiences and knowledge with me. I have the pleasure of acknowledging:

Mark F. Komarinski   markk (at)       LDP Author Guide          
Jorge Godoy          godoy (at)    LDP Author Guide          
David C. Merrill     dcmerrill (at) LDP Author Guide          
Stein Gjoen          sgjoen (at)           HOWTO-Template            
Gregory Leblanc      gleblanc (at) HOWTO-Template            
Greg Ferguson        gferg (at)            HOWTO-Template            
Amar Chaouche        achaouche (at)     mount unhide option       
Giblhauser Carl      mike (at)     runoutblock i/o errors    
Monte Milanuk        milanuk (at)        nfs help                  
Paul A. Sand         pas (at)              loop module option        
Tony Melia           Tony.Melia (at)               max_loop kernel boot      
Richard Black        Richard.Black (at) more info and mknod script
Bradley Wendelboe    krakken (at)  cdtower shell script      
James Mumm           dart (at)     cdtower shell script      

1.8. Translations

��*�  [] Korean (html and sgml) at [

 If you have the capacity it would be nice to make the CDServer-HOWTO
available in a number of formats and languages.

  If you've translated this document, please send to me:

��*�  Your name, email address, the language and URL to the translated
    document (preferred).
��*�  Or an email attachment of the work.

 Please send either to my email address at []  Talcon
Information Systems: <>.

2. Procedure

 Summary of Steps

��*� Create a large partition to hold the CD Image Files.
��*� Copy the CD to an image file using the dd command.
��*� Mount the CD image file within the directory tree.
��*�  Share the directory on the network using Samba, NFS, etc.

  Also, make sure you've read Section 1 and Section 1.2.

2.1. Creating the ISO Images

 Choose (or create) a file system with the largest available disk space on
it. Keep in mind that CD-ROM's can hold around 640MB of data, so if you want
to share 8 full CD's on your network, you'll need 5.1GB of space available.

 Login as root or "su" to root.

bash# df -h                                                                  
Filesystem            Size  Used Avail Use% Mounted on                       
/dev/hda5             1.4G   82M  1.3G   6% /                                
/dev/hda1              15M  827k   14M   6% /boot                            
/dev/hda7             2.4G 1008M  1.3G  43% /usr                             
/dev/hda8            23.6G 11.7G 11.7G  50% /home                            

  Here the /home filesystem has the most available space, so it is the most
suitable filesystem to use for dumping the CD images to.

bash# cd /home                                                               
bash# mkdir image                                                            
bash# cd image                                                               

 Now, copy the CD to an ISO image. You must know the device name of your
CD-ROM drive (usually /dev/cdrom, it could be /dev/scd0 for SCSI CD-ROM's)
I'll use the Mandrake distribution CD-ROM as an Example:

bash# dd if=/dev/cdrom of=mndrk81.iso                                        

      The "if=" is the input file, the "of=" is the output file. You should
    see a message stating the number of records in and number of records out.
    If you see i/o errors, they will most likely be due to the lead-in and
    lead-out runoutblocks on the CD. If the number of records in and number
    of records out do not match you may have a problem, otherwise the image
    will most likely be alright, but you can never know if the errors
    happened while reading the ISO part of the CD or not (due to dust or
    scratches on the CD).
    Other utilities to read CD's exist, like readcd or sdd.
    More information about making 1:1 copies of CD's exists in the [
    CD-Writing-HOWTO], see Section 1.3.

 My thanks to Giblhauser Carl Michael for the runoutblock information.

2.2. Mounting the ISO Images

 The next step is to mount the ISO image file. Let's create a directory under
/mnt to place the mounted file.

bash# cd /mnt                                                                
bash# mkdir iso                                                              
bash# cd iso                                                                 
bash# mkdir mndrk81                                                          

 Now mount the ISO image file to this newly created directory

bash# mount -o loop,unhide -t iso9660 -r /home/image/mndrk81.iso /mnt/iso/mndrk81 

      The "-o loop" means use the option that mounts a file as a block
    device. The unhide option shows hidden files. The "-t iso9660" means that
    the file is in the iso9660 CD-ROM format. The "-r" means to mount

  Thanks to Amar Chaouche for pointing out the unhide option for the mount

 Now you can:

bash# cd mndrk81                                                             
bash# ls -al                                                                 

  You should see a listing (ls) of the files and directories that are on the
actual CD (only now they're inside the ISO image file, and that's what you're
currently looking at!)

2.3. Mounting the Image upon System Restart

 Now that we've manually mounted the image, and made sure it works, an entry
needs to made in the /etc/fstab file so that the image is remounted on the
next system startup. It's important to make the entry AFTER the entry for the
parent filesystem, e.g. /home (I use vim, but emacs, joe, pico or jed will
work just as well):

bash# vim /etc/fstab                                                         

 After the line that looks like the following (or whichever filesystem you've
placed your images):

/dev/hda8 /home ext2 defaults 1 2                                            

 Insert the following line with your text editor:

/home/image/mndrk81.iso /mnt/iso/mndrk81 iso9660 ro,loop,auto,unhide 0 0     

2.4. Sharing it on a Windows Network using Samba

 You'll need to have Samba installed and working to perform the next steps
(that's outside the scope of this instruction, see Section 1.3). If it's not
yet installed, consult your Linux distribution's instructions for installing
the Samba package. Or you can visit the Samba website at [http://] for
installation instructions, binaries, and/or the source code.

 To share your mounted CD's on a windows network, simply create a stanza in
the /etc/smb.conf file similar to the following:

  comment = All Shared CD Images                                             
  path = /mnt/iso                                                            
  public = yes                                                               
  writable = no                                                              

  This will share all the subdirectories under the /mnt/iso directory on the
network. To mount the share to a local drive (in this case the I: drive),
bring up an MS-DOS Prompt on the Windows machine and type the following:

C:\> net use I: \\yourlinuxmachine\cdimages                                  

 Each CD image will now appear as a subdirectory on the I: drive of your
Windows machine.

 To mount ONLY the Mandrake CD image to a drive letter (we'll use M:, the
root drive of which, will correspond exactly to the CD as if it was just
inserted in the CD-ROM drive), create the following stanza in the /etc/
smb.conf file.

  comment = Mandrake Linux 8.1                                               
  path = /mnt/iso/mndrk81                                                    
  public = yes                                                               
  writable = no                                                              

 Then, at your MS-DOS Prompt, mount it with the following command:

C:\> net use m: \\yourlinuxmachine\mndrk81                                   

      The Samba smb.conf file stanzas presented here are simplified, and not
    secure. Many more options exist for a Samba share which limit who can
    mount the shares, control how user authentication is performed, and
    whether the share is even browseable through Network Neighborhood on the
    Windows machines.

2.5. Sharing the Images on a Unix network using NFS

 Make sure that NFS is running and configured correctly on your Linux
machine, then add the following to the /etc/exports file using your own
preferred options:

# sample /etc/exports file                                                   
       /mnt/iso            (ro,insecure,nohide,all_squash)                   

     The nohide option will allow you to mount a parent directory, without
    explicitly mounting all exported subdirectories beneath it.

 Now try running:

bash# exportfs -r                                                            

 This should re-export everything in your /etc/exports file.

  Now, when typing "showmount -e yourlinuxmachine" you should see that the /
mnt/iso directory is included in the exports list.

3. Adding Support for More Loop Devices

  Newer Linux kernels (2.4) allow you to add more loop devices easily by
editing /etc/modules.conf or through the use of a boot parameter.

  Older kernels (2.2 ?) only had support for 8 loop devices compiled into the
kernel. In short, you were only able to share 8 CD's on a network with this
default value. In order to support more than that default, you needed to
modify the kernel source and recompile a new kernel.

 Use the following methods to determine which version of the kernel you are

bash# uname -a                                                               


bash# cat /proc/version                                                      

3.1. Adding the Loop Module Option

  Current kernels allow you to set the number of loop devices supported
without recompiling the kernel. One of these methods is to add an options
line to /etc/modules.conf. This method will only work if your loop support
has been configured as a loadable kernel module (which is how most major
Linux distributions come preconfigured now).

  Edit /etc/modules.conf and add the following line.

options loop max_loop=64                                                     

  After making the above change, simply reboot. Or you can try to use rmmod
and insmod to make the change on the fly - but this will not work if you
currently have any loop devices mounted (you'll get an error saying loop:
Device or resource busy).

      If you do not have an /etc/modules.conf file, your module configuration
    file may be called /etc/conf.modules (this name is now deprecated).

  Continue with Section 3.4.

   Thanks to Paul A. Sand for pointing out the /etc/modules.conf option.

3.2. Appending to the Boot Prompt

  If your loop support has been compiled directly into the kernel (in other
words, it is not loaded as a module), you can append the number of loop
devices you would like to support at the linux boot prompt.

boot:  linux max_loop=64                                                     

  Or, if you are using LILO, you can edit your linux boot stanza in /etc/
lilo.conf and add/modify the append= line. Here is an example stanza showing
append= (note: only add or modify the append line, don't change your whole
stanza to look like this one or your system may not boot). For more
information about LILO, consult the [
LILO.html] LILO mini-HOWTO at

        append=" max_loop=64"                                                

  After changing /etc/lilo.conf, you need to run the lilo command for your
changes to take effect.
bash# lilo                                                                   
Added linux *                                                                
Added linux-nonfb                                                            
Added failsafe                                                               
Added windows                                                                
Added floppy                                                                 

  Next restart your system. After your system restarts, you can check your
boot command line by typing the following:

bash# cat /proc/cmdline                                                      

      I am not sure if the loop module (compiled as a module) reads /proc/
    cmdline when the module is loaded, and therefore may not need an options
    line /etc/modules.conf. It's possible that it can (and if it doesn't, it
    should). To summarize: I have not tested this.

  Continue with Section 3.4.

   Thanks to Tony Melia for the boot prompt info.

3.3. Tweaking the Kernel

  If you have an older kernel (v. 2.2) or if you are completely comfortable
recompiling the kernel, you can increase the number of loop devices supported
by editing the /usr/src/linux/drivers/block/loop.c file.

     If you find that the kernel sources are not installed on your machine,
    you'll need to consult your Linux Distribution's documentation on how to
    install them (the Kernel Sources come with all distributions - it's part
    of the GNU GPL licensing).

 Change the number in the following line to however many loop devices you'll

#define MAX_LOOP 16                                                          

 Compile the new kernel or module as the case may be. If you need some help
getting started with this, read /usr/src/linux/README or consult [http://]  The Linux Kernel HOWTO.

  Continue with Section 3.4.

3.4. Creating the Loop Devices in /dev

  You should check how many /dev entries you have for loop devices.

bash# ls -l /dev/loop*                                                       

  The mknod command creates the devices in the /dev directory. The loop
devices have a major number of "7", and the minor numbers begin at "0". If
your MAX_LOOP was defined as "8" in /usr/src/linux/drivers/block/loop.c, you
should have /dev/loop0 through /dev/loop7. To create the /dev/loop8 device,
use the following command (subsitute the appropriate number you need for both
the "8's" in the example below).

bash# mknod -m660 /dev/loop8 b 7 8                                           

  Check Owner/Group & Permissions on the new file (using ls -l). You can
change the owner and group with the following command:

bash# chown root.disk /dev/loop8                                             

 You can change the permissions using the following command:

bash# chmod 666 /dev/loop8                                                   

4. More Information

  Be sure to check the suggested reading in Section 1.3.

4.1. Frequently Asked Questions

 I finally had to create this section - Frequently Asked Questions. Although,
I sometimes think it should be called Frequently Answered Questions (at least
I try to answer them all).

Q: Can I copy CD contents to a directory and share it with SAMBA?
Q: Do any scripts or programs exist that automate this process?
Q: Do any web interfaces exist that automate this process?
Q: Can copy-protected CD's (e.g. laserlok) be shared in this way?

Q: Can I copy CD contents to a directory and share it with SAMBA?

A: In a word - Yes.

      There is nothing to keep you from doing that. However I'm not sure
    which arguments you would have to use with tar and which options to
    include in the SAMBA stanzas. Also, there could be problems with file
    name mangling (case sensitivity, spaces in file names), file attributes
    (read-only), etc. If anyone is doing this successfully, please send me
    examples of the commands you used for copying the contents of the CD, and
    your SAMBA stanzas for the shares.
      Here's some commands you can use to copy the contents:
    bash# cd /home                                                           
    bash# mkdir image                                                        
    bash# cd image                                                           
    bash# mkdir mndrk81                                                      
    bash# mount /mnt/cdrom                                                   
    bash# cd /mnt/cdrom                                                      
    bash# tar cvf - . | (cd /home/image/mndrk81; tar xvf -)                  
      Thanks to Giblhauser Carl Michael for this info
Q: Do any scripts or programs exist that automate this process?

A: Yes:

��*�Bradley Wendelboe and James Mumm wrote a shell script called CDTower -
    see Section 4.2.2 to download it.
    I have no independent test results of this script - use at your own risk.

Q: Do any web interfaces exist that automate this process?

A: Not yet. However there is much interest in this.

��*�Tony Melia [Tony.Melia (at)] has announced that he is
    60% complete with a web interface, i.e. sucking CD's in, creating extra /
    dev/loop entries and seeing what space the CD's are taking up.
��*�I am planning on writing a module for Webmin to automate this process.
    That project is currently hosted on SourceForge at [http://]

Q: Can copy-protected CD's (e.g. laserlok) be shared in this way?

A: To the best of my knowledge, No.

    Others have reported problems to me trying to share ISO images made from
    copy-protected CD's. It seems that even when using the "unhide" option
    with mount that files will remain hidden.
4.2. Other Instructions Available on the Web

  This section is devoted to instructional materials that others have written
or have sent to me.

4.2.1. Saving a CD-ROM to a File and Mounting it

  Richard Black (Compaq) has some good pages about Saving CD-ROM's to files
and mounting them in Red Hat Linux.

��*� [] Saving a CD-ROM to a
    File and Mounting it
��*�  [] Linux Loop Devices -
    This page also includes the script below for creating many loop device
    nodes at once in /dev.

Device nodes are required to access the loop devices. You already have loop0 - loop7.  
You can run the following loop to create the rest of the nodes (loop8 - loop255).      
You can type all of the following lines of code on one single line if you leave off    
the trailing "\" characters.                                                           
C=8; echo; echo "Creating loop device nodes."; \                                       
   while [ $C -lt 256 ]; do mknod /dev/loop$C b 7 $C; \                                
   echo -n .; C=`expr $C + 1`; done; echo;                                             
Note: the quoting around the expr section are called backtick's and they are located   
with the tilde character ("~") in the upper left hand corner of the keyboard. The      
character is not a single quote.                                                       

 Thanks to Richard Black for permission to add this info and for linking back
to this document.

4.2.2. CDTower v.06

 A script to automate the creation of ISO images and share them via Samba

 by Bradley Wendelboe [krakken (at)] and James Mumm [dart

 This software is covered under the GPL See [
gpl.html] for details.

To view/download this script:

    I have no independent test results of this script - use at your own risk.

 Thanks to Bradley Wendelboe for forwarding this script to me.

4.3. Under Future Consideration

  These are things I'm currently looking into, trying to figure out, or
planning to get done.

��*�  Make more scripts available that others have sent to me, either within
    this howto, or by hosting them and linking to them from this document.
��*�  Sharing CD's to Apple and Netware clients (Appletalk and IPX).
��*�  Compressed ISO Images.
��*�  Changing CD Shares on the fly (hopefully transparent to users).
��*�  Adding a module to Webmin to automate the CDServer process.
��*�  Distribution specific instructions.
��*�  I have a volunteer for a German translation, hopefully it will be done

A. GNU Free Documentation License

Version 1.1, March 2000

    Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite
    330, Boston, MA 02111-1307 USA Everyone is permitted to copy and
    distribute verbatim copies of this license document, but changing it is
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document "free" in the sense of freedom: to assure everyone the effective
freedom to copy and redistribute it, with or without modifying it, either
commercially or noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not being
considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative works of
the document must themselves be free in the same sense. It complements the
GNU General Public License, which is a copyleft license designed for free

We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free program
should come with manuals providing the same freedoms that the software does.
But this License is not limited to software manuals; it can be used for any
textual work, regardless of subject matter or whether it is published as a
printed book. We recommend this License principally for works whose purpose
is instruction or reference.


This License applies to any manual or other work that contains a notice
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A "Modified Version" of the Document means any work containing the Document
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