Neville Richter, Lynda Thater & Mark Huth
© CQU 2006
Faculty of Business and Informatics,
Central Queensland University,
n.richter@cqu.edu.au, l.thater@bris.cqu.edu.au,
m.huth@bris.cqu.edu.au
Abstract. This paper presents an overview of the ADIOS Boot CD project. Many boot CDs are currently available for use, so a
short discussion and comparison of these related works is presented. Background information on how the boot CD was built
and why particular decisions were made in choosing the software that was placed on the CD
is discussed. The primary benefit of having
virtual machines with trusted operating system available on virtual networks allows users
to experiment with security and network management. Finally
this paper investigates the latest design issues and techniques used to build boot CDs. An objective of this paper is to motivate as well
as enable Linux developers to build their own boot CDs.
A boot CD or live CD loads an operating system from
the CD during the PC boot process. A Linux
boot CD allows new users to Linux the ability to run Linux without having to modify their
existing OS image. Boot CDs have developed to
the point where users do not need to install Linux as the software can now read and write
to most existing filesystems. This means that
the next time the PC is rebooted the same configuration and user files will be available. Live CDs effectively let users try Linux before
they have to decide to install it or not.
The boot
CD is just one part of a larger project which was looking at ways to provide each student access to a Linux enironment. The
Automated Download and Installation of Operating Systems (ADIOS) project began in
1997 [26]. It
was initiated to develop a teaching environment for network management students. To be able to teach networking skills, students
typically need administrator privileges on the operating systems they are using so they
can install software and configure settings.
In 2001, education at university was moving towards providing instruction
at off-campus venues, the on-campus laboratories were overloaded and students were seeking
alternatives to accessing the on-campus laboratory environment. A bootable CD was developed for students so they
could use it anytime or anywhere and still have the same user interface found in on-campus
laboratories.
The ADIOS
live CD is a bootable ISO image which allows the user to run Linux on a standard PC and to
run multiple virtual machines. It is based on Fedora Core 3 [2]
and contains many additional security and management packages, which are all Open Source
distributions. The full specification for the ADIOS boot CD is located at the
project home web site http://os.cqu.edu.au/adios [26].
Other
educational institutions have used ADIOS live CD in Brazil, Austria, Australia and USA. Some crime detection groups in the police and
forensic departments have used it in preference to the Knoppix forensic CD [3]. Home users and researchers looking for an easy way
to build a boot CD, have built their own boot CDs using the ADIOS development kit, even in
different languages, for example Exton [20] has created a Swedish version of ADIOS. Also a fully Chinese version has been built. There is a review of ADIOS at Newsforge, the Online
Newspaper for Linux and Opensource. [17].
1.1 ADIOS
Objectives
The primary objectives for the ADIOS Linux boot
CD were:
1.2 The ADIOS boot CD
Users have
access to up-to-date software, the ADIOS boot CD was built using Fedora Core 3.0 [2],
with Linux kernel 2.6.12 with support for squashfs, [23] this allows the CD to
contain more than 2GBs of files. There are
many additional software tools such as snort, openswan, webmin and nessus,
a full list is available at the ADIOS home site [26]. The online web
tools allow the user to find information and to monitor and control services. The boot CD detects the hardware configuration and
starts X Windows with the KDE desktop environment, or it can be started with XFCE or ICE
window managers.
Users have
access to the documentation of the process of developing a boot CD. A description of the booting process used to start
Linux from a CD image. A discussion of the
issues involved in building a bootable CD such as which compressed filesystem to use, what
copy-on-write filesystems are available and how to use RAM efficiently. The file layout for the CD was such that all
read-only files were grouped together and all read-write files could be placed in RAM, see
http://os.cqu.edu.au/adios [26].
Users have multiple
options in which to run the CD and install the CD image.
The user is able to select alternative ways to save and restore their files to
floppy, USB, disk and network drives. Optional software components can be
automatically loaded from the users hard drive providing even more software. The user can decide to turn on or off features such
as read-write access to the hard disk and decide how to install software on the hard disk. There is an option to install the boot CD onto
disk, which resides on a FAT or EXT3 filesystem or NTFS. This is almost as good as
installing Linux on its own partition. The read-only files reside on the ISO image and the read-write
files all reside in the directory /var. Using copy-on-write technology
with the unionfs kernel module [9], files can be written to the whole filesystem allowing software
to be installed and deleted to the system.
Users can run User Mode Linux (UML) virtual machines [10], which are automatically networked via virtual Ethernet switches and hubs. ADIOS introduces the automation of UML virtual machines by developing scripts to simplify how to configure and run UML virtual machines. The umlconfigurator and uml scripts allows the user to specify the number of virtual machines, to specify how much RAM to use, to start with or without X Windows, to pre-configure the networks and to start selected services on each virtual machine.
Users can
experiment with trusted operating systems. To
support Security Enhanced Linux (SELinux) [7] a separate boot CD was created using an EXT3 filesystem, which
was contained within the squashfs filesystem. The
UML virtual machines can also be started with the Linux Intrusion Detection System (LIDS) [4] or the SELinux trusted
operating system (OS). Users can change
configuration and policy documents to test these trusted OSs.
Users can utilise
the ADIOS development kit (ADK) to build their own boot CDs.
The development kit provided on the CD allows the user to unpack all of the
software on the CD and to rebuild a customised boot CD. If the user wants to rebuild
the kernel or the initial RAM disk then these can be downloaded from the home site via a
second CD image. The development kit “Makefile” automates the
procedure and only requires the user to make sure that their PC configuration is entered
correctly. The original ADIOS project goal was to download operating systems for
laboratory environments. This software is
included as part of the development kit environment. A
recent improvement is the Yet Another ADIOS (YETAA)
boot CD toolkit [25]. YETAA enables users
to take an existing Fedora Core working partition of less than 2.5Gbytes and copy it onto
a bootable CD or install the full Fedora Core 4 system on one partition and build a
bootable DVD.
In the
next section there is a brief overview of other boot CDs. This is followed by a
discussion of the ADIOS boot CD development. This leads on to a discussion on
Virtual Machine technologies that can be used such as UML and Xen [12]. Finally the paper
looks at the future direction of bootable CDs.
There are
a relatively large number of boot CDs available today [18]. Boot CD/DVDs vary in size from small to very large. Small boot CDs can be designed to fit within a
bootable 64MB USB memory drive such as Puppy Linux [1]
and DamnSmall Linux (DSL) [11]. Boot CDs have been also built for
Microsoft Windows XP, such as the work done on Bart's Preinstalled Environment (BartPE)
bootable live Windows CD/DVD [22].
The larger
fully packed boot CDs typically use a compressed filesystems, which contain a sample of
what a full Linux system has to offer. There
are many Linux and FreeBSD boot CDs, which have been designed with a special purpose in
mind such as the Multiple Operating System Linux MOSIX [16], which is built to
demonstrate all of the cluster technologies available on Linux. Other boot CDs focus on security, or games, or
education, etc. A significantly large number
of these CDs are based on the Knoppix boot CD [3]. Many boot CDs such
as ADIOS and XenDemo [12] are built from scratch.
Several
live CDs such as Knoppix and PCLinux claim to be operating system replacements in that
they can perform all the functions required of a fully installed system, that is they have
a complete office suite of software tools. Other
live
CDs such as Puppy and DamnSmall Linux (DSL) are designed to run from USB or from RAM and
can run with limited memory or even with older 386 processors. Several live CDs such as MOPIX and ClusterKnoppix
have been designed to provide a set of cluster software programs so that users can
experiment with cluster technologies. Others
such as ADIOS and now XenDemo have been built to allow end users to use virtual machines
and virtual networks. Virtual networks are
particularly useful in educational environments as this provides users with a simple way
to experiment with routing, firewalls, security and network management utilities. A more
comprehensive list of live CDs can be found at http://www.frozentech.com/content/livecd.php [18].
3 Development of the ADIOS boot CD
In this section
the design issues involved in developing the ADIOS Boot CD will be investigated. This will include an explanation of the overall
approach taken towards the Boot CD, and then specifics on the booting process, memory
issues, file system choice, virtual machine inclusion, the development kit and then
deciding on applications and services to be included on the CD.
3.1 Overall Approach
When
creating a new CD, the first decision is whether to start from scratch or base a CD on the
work of others. Most developers have taken the
approach of using an existing image rather than create their own. This is because many CD
builders encourage others to use their bootable CDs as starting platforms. But if
developers decide to start from scratch there are at least two choices. Firstly the developers can write their own boot
process software (CD developers working on the Knoppix boot CD wrote their own start up
software). Secondly they could use the work
done by the major CD developers who use busybox toolbox [13].
Busybox is
a replacement set of Linux commands, which can be used on small or embedded systems. This is by far the simplest way to create a small
Linux environment. First the software must be downloaded and the development
environment used, which is similar to making a Linux kernel and then installing the files
into a newly created initial RAM disk. Then
devices can be added as well as a few more utilities to customise the start up
environment. To be able to create embedded
Linux systems a small C library called uClibc [14] is required. To
build additional utilities the source code must be recompiled (using the uClibc
library). The ADIOS initial RAM disk uses the busybox
and uClibc library. There is
even an alternative to uClibc called dietlibc [27].
A boot
loader typically isolinux [15] and a utility to create the ISO usually mkisofs [5] is also needed. The
boot CD typically requires a customised Linux kernel, a Linux start up script and an
initial RAM disk so that the OS can start. The advantage of using busybox
is that it contains most of the Linux commands in one small program and by using a RAM
disk Linux can be started in RAM, the full filesystem can then be mounted and the
directory can be changed with a command such as pivotroot (this will allow
access to the full system). Most of the major Linux distributions such as Debian,
RedHat, Slackware, Gentoo and Mandravia all have used busybox as part of
their installer process [13].
Recently, copy-on-write
(COW) technologies have become popular for boot CDs. An
example is to use the kernel module unionfs [9] to apparently allow the
ability to write to the read-only filesystem, by storing the difference in a small
RAM filesystem. Also the inclusion of new
kernel modules to perform specific tasks such Captive NTFS [21] which allows the
writing of files using Windows DLLs.
3.2 Booting Process
Since Linux
was not designed to boot from a CDROM, the boot process and filesystem must be modified. The mkisofs utility is used
to create the bootable CDROM image. The most used software for creating a boot loader for
Linux on CDs is isolinux, which is part
of the syslinux package.
The
following is a description of the sequence of events that occur when the computer boots
from the ADIOS live CD. It uses the isolinux
boot loader, which is similar in principle to other boot loaders such as Grub
[24] and Lilo
[19].
The linux
kernel image vmlinuz is loaded into memory.
This first requires building the latest stable kernel with patches to support the
CD environment.
Next the
initial RAM disk called initrd.gz is uncompressed into RAM and then mounted
as the root filesystem. The size of this
initial RAM filesystem varies from 4MBs to 16MBs depending on how many applications are
supported in this pre-real / (root) filesystem environment. The initial RAM disk is built typically into a loopback
filesystem and includes binaries and libraries to at least allow the OS to mount the
CDROM. A loopback filesystem is a file
in which an EXT3 filesystem has been created.
Next the
startup script linuxrc is used to mount the real filesystem, which is on
CDROM and uncompresses the read-write files into a RAM drive. CD developers can choose from various RAM drive
types: such as tmpfs, which is read-write and can share memory with process
memory space; or cramfs, which creates a read-only compressed initial RAM
drive. The majority of the root filesystem is read-only
and is stored using a compressed filesystem such as cloop, squashfs or ziosfs. Many CD developers are now using unionfs,
which provides a copy-on-write filesystem. This
has lead to developers creating a single large root filesystem, which is then mounted
against a RAM drive to provide a copy-on-write filesystem. The ADIOS boot CD uses two squashfs
files one contains all of /usr directory tree and the other /adios contains
the other read-only directories /bin, /sbin and /lib. The read-write files are written to /var,
which can be placed in a tmpfs RAM drive. The
unionfs run option is available for those who need to write to the read-only
space.
The system
configuration files for the real root fileystem can then be modified to suit the hardware
and users requirements. The system then performs what is commonly known as pivotroot
to swap the current root filesystem with the newly mounted real filesystem. All that is left is to start the init
process. The init process is
effectively the parent process to all others and starts the OS at the specified run-level
to start services as required.
The isolinux configuration file that
starts the boot CD uses a set of labelled sequences to load the kernel and the initial RAM
disk and select options on how the image should start.
See the isolinux.cfg configuration file to
see how ADIOS starts.
Before the init process starts the linuxrc script is used to mount
the Boot CD and configure the startup scripts. For
example the hardware detection can be performed so that X Windows can be configured.
3.3 Memory and disk usage
issues
Allocating too much memory
to RAM disk means that there may not be enough RAM for large memory processes. There are several solutions for this problem:
One technique is for the
RAM disk to be compressed this usually requires the filesystem to be read-only, as
with cramfs. Read-only initial RAM disks require the boot
process to create an additional RAM drive to enable writing of files.
Another solution is to use
real disk space this requires users or software to modify the disk partition and allocate
space for the operating system files. Alternatively
USB devices, that appear as disk drives, can be used instead of storing files in RAM.
Lastly either request
users to have more real memory in their PC or rebuild all applications to use less memory.
The initial RAM disk can
be kept small or memory can be reused. If the
boot CD is run entirely in RAM then the usage of the tmpfs RAM drive can be setup to
share RAM with memory allocated for processes.
3.4 File System Choices
Since
most PCs already have Windows installed and are using the NTFS filesystem. The file systems issues are summarised below:
To fit more on the CD a compressed filesystem is required;
The OS may require extended attributes to support NFS shares and to use SELinux;
Linux
currently only supports read-only
for the NTFS filesystem, performance is greatly improved by running the ISO image and
optional components from NTFS;
Read-write
files can be placed in a loopback
file on FAT or use Captive NTFS,
Creating a separate FAT filesystem using ntfsresize [6] allows the ISO image and the read-write files to be on disk;
Creating separate EXT3 or Resierfs partition using ntfsresize allows the read-write files to use a partition for themselves;
If
there is FAT or EXT3 partition then a swap
file can be created or alternatively a swap
partition can be created;
Using
copy-on-write
technology provides the user with the most flexible boot CD environment.
The
ADIOS boot CD provides solutions to the file system issues by providing run options to
repartition and reformat partitions as well as implement copy-on-write
technology.
3.5 File Compression
The
Knoppix boot CD uses cloop a compressed ISO image within the CD ISO image. The ADIOS boot CD uses multiple squashfs
files on the boot CD ISO image. Other
developers have used zisofs to compress the whole ISO image. Developers can either write their own compressed
filesystem, or select another one that is available.
Effectiveness
of the compression algorithm can be measured by the speed to access the files within the
compressed filesystem. Other considerations
include the flexibility of using more than one compressed filesystem, the inclusion of
extended attributes to support trusted operating systems and the efficiency of sharing of
compressed files over a network. In
summary the main compression techniques used today are as follows:
ziosfs was built to create compressed ISO images. The command mkisofs –z creates a
compressed ISO image.
cloop developed for the knoppix CD and uses zlib
and is built using an ISO type filesystem.
squashfs supports multiple squashed filesystems,
has slightly better compression, fast access of files, but is not ext3 compatible, that is
cannot share filesystem using NFS, and does not have extended attributes.
loopback file within a compressed filesystem, this
is the technique used to build the SELinux version of the ADIOS boot CD. Although the double mount marginally slows down the
access to files and increases the overall size of the filesystem the benefit of having a
filesystem with extended attributes means that trusted operating system security can be
made functional on the boot CD.
The
Ubuntolinux distribution [8]
has analysed the compressed filesystems available in terms of the effectiveness of
compression and performance, the results shows that squashfs creates the smallest
compressed files and it has the fastest to random access time. In summary cloop was nearly 3 times faster
than zisofs while squashfs is nearly 5 times faster than zisofs.
3.6 File Layout
The number one issue for
booting from a CDROM is that the vast majority of files are read-only. There are at least two solutions:
·
redesign the file layout
and place all read-write files in RAM or
·
use copy-on-write
technology so that the differences are stored in RAM.
Using the first approach
of redesigning the file layout into read-only and read-write files means
that the read-only filesystem has the advantage of making the OS more secure. A “Makefile” or simple shell script can
automate the process of relocating files into directory trees that are either read-only
or read-write. The second approach of
using the copy-on-write technology is useful for adding, modifying or removing
binary software from the image. The overhead
of copy-on-write is in the order of a 10% reduction in performance.
The ADIOS filesystem
places /bin, /sbin and /lib into a single squashfs file called adios.sqfs. The /usr files are placed in file usr.sqfs and all of the read-write
files have been moved to /var, this includes /etc, /home, /usr/local, /usr/src, /tmp and /root. An alternative approach used in the YETAA boot CD
toolkit is to place all of the files in a single squashfs file and then copy the read-write
files into a RAM drive on startup. Special
directories are created in the root directory such as /dev, /proc, /media, /mnt and /opt. To make ADIOS work plenty of soft links have been
added so that both absolute and relative references to files are not broken.
The development filesystem
is placed in its own partition so that packages using RPMs can be added and erased. This also allows the development environment to be
booted into live mode to allow the developer to refine the image and then rebooted back
into the development mode to build the boot CD image.
In summary the first method is to
redesign the filesystem layout for the CD:
The second
method is to use a single loopback root filesystems with a Copy-On-Write to
RAM drive file. This technique of creating a
single loopback filesystem is used with CoLinux and XenDemo. This method makes the implementation of virtual
machines identical to the parent system straightforward.
3.7 Virtual Machines
The use of virtual
machines is becoming more common as users want to test software to the limit without
modifying the OS on their PC. Another use of
virtual machines has been to setup secure services that run on their own virtual machine
via a real network interface connection.
When discussing Virtual
Machines, most people immediately think of VMWare or Virtual PC. However, if a developer wants to provide a free
virtual machine environment then the choices are limited. The main contenders for
selecting virtual machines are User Mode Linux (UML), XEN or Virtual Iron.
At the time of building
the first ADIOS boot CDs only UML was available and that is why it was chosen. The XEN virtualisation environment may be according
to the literature from the XEN site to be the better alternative. However the ADIOS environment requires that the UML
virtual machines to be able to run X Windows. The Virtual Iron virtualisation from IBM is
according to literature on the Internet to be the best solution for multiprocessor
machines.
Automating
the process of generating networks and how networks are built is one feature that the
ADIOS image has been using for some time. Basically
each virtual machine is connected to multiple virtual Ethernet switches. Each virtual machine is built connected to all of
the virtual Ethernet switches and hubs. Any
network layout can then be built by only activating the network interfaces required for
the topology. The default layout for each
virtual machine is to connect to the next virtual machine via next virtual Ethernet
switch, this means that a network connecting each virtual machine to the next one is
generated automatically. Other network
topologies can be configured before the UML virtual machines are started.
Users can then build their
own networks for testing routing and firewalls designs.
Screened subnet firewall design can be configured and tested. Improvements to firewall design such as using
multiple perimeter networks can be investigated. To
allow each virtual machine access to X Windows the connection to the parent system is left
up but not used in the routing of packets. X
client applications require TCP connections to the X server on the parent machine using Xnest. An alternative would be to use the VNCviewer software on the parent
machine and VNCserver on the virtual machine.
3.8
ADIOS Development Kit (ADK)
One
of the primary tasks of developing the “Makefile” was to automate the procedure
of rebuilding the boot CD from scratch each time it is necessary to start with a new
version of Redhat, Fedora Core, or other Linux OS. Also
each time a new version of the kernel is built it is necessary to rebuild the initial RAM
disk and update the kernel modules on the CD version of the filesystem. The “Makefile” is also used to unpack the
CDROM onto a partition so that it can be used to build customised boot CDs.
To
help developers test the image they are creating without burning a CD, a "live"
mode was added to the “Makefile”. This
adds an entry in the boot loader that will allow the new CD image to boot from the
development partition. The make
“live-stuff” currently only updates the databases for whatis, locate
and swish databases while in live mode.
Upon rebooting back to a non-live environment the user will need to enter
"make normal" to clean up log files and reset configuration files. Just in case the user forgets, the
“Makefile” will check which mode is currently active when the make command is
issued.
This
distribution is based on RedHat Fedora Core, which uses RPMs for package distribution but
could be easily extended to use Debian’s package manager. To simplify the update of packages, a set of
“yum” commands was added to “Makefile”, this has significantly reduced
to time it takes for the developer to update packages on the boot CD image. Entering the command "make yum-update"
without specifying which package will update all RPMs, just sit back and wait. There are separate entries to
“yum-install” and “yum-remove” packages.
To
build the current CD image the read-write files are placed in the directory /mnt/devel/var
and the read-only files in the directory /mnt/devel/adios and /mnt/devel/usr. The adios directory contains the directories
/bin, /sbin and /lib and the usr directory contains all of the
/usr files for the boot CD image. The
following modifications are required to files in /usr that are read-write. Files that are read-write are linked into /var
such as /usr/src to /var/src and /usr/local to /var/local. Where as large read-only files in the /var
tree are linked back to the /usr/var tree. This
reduces the size of /var which is important if RAM size is small.
Now
to build the CD image enter "make files". This
builds the read-write files into the /adios/var directory tree, which is
copied to read-write space on startup (alternatively creates a compressed archive var.tgz),
and builds the read-only files into the compressed files adios.sqfs, usr.sqfs
plus the optional component files uml.sqfs, www.sqfs, and openoffice.sqfs. Additional optional component files for example
java (jdk + tomcat), wine (windows emulator), mono (C#), plt (Dr Scheme) and ns (Network
Simulator + Nino) can also be built and the list expanded upon.
The
“Makefile” includes a section on creating the ISO for CDROM image. Here the developer can erase/blank read-write
CDs and then burn the image onto the CD. The
command "make cdrw" builds the ISO, blanks the CD and then records the image. Some additional commands to use DVDs have been add. Provision is made at the top of the
“Makefile” to change the VERSION, DATE, AUTHORS, etc. Creation of a CD label can
be performed using any graphics package such as "gimp" and saving the file in a
suitable format such as png.
Configuring, building and installing the kernel, modules and building the
initial RAM disk and all included files is documented in the “Makefile”. Before starting, check that the correct version
numbers are set and that the kernel sources are located in /usr/src. For example,
the sequence of commands to rebuild the Linux kernel and then rebuild the initial RAM disk
are as follows:
make menuconfig; make kernel; make build-dir; make extra-modules;
make
initrd-modules; make initrd
Build the Linux kernel and library modules to support squashfs, unionfs and other requirements
Build the initial RAM drive including the Linux rc script using busybox tools
Build the Fedora Core Partition with tools required and making it less than 2.5 Gbytes
Build the squashfs root filesystem from an existing Fedora Core Partition – changes between the disc image and CDROM image are part of this task
Build
the CD environment includes autorun, isolinux and Windows grub
4 Analysis and Discussion
The
limitations and advantages of ADIOS boot CD compared to other live CDs is now described. The primary limitation for most Linux boot CD
systems has been the ability to write to NTFS filesystems.
The use of Captive NTFS has partially resolved this, but the performance of
Captive NTFS has not helped Live CD builders to perform a large number of writes to the
NTFS fileystem. The ADIOS live CD when asked
to write to NTFS minimises these writes by using a “savestate” file (such as var-4.14.tgz). The “savestate” file is written when the
system is shutdown and it only saves changes for the system configuration and users files. Using Windows to copy the ISO image and the Windows
version of grub allows ADIOS live CD to improve performance and useability. An alternative to using NTFS is to repartition the
disk so that a FAT or EXT3 filesystem can be used. Several
live CDs have included software to repartition the disk as well as ADIOS. The primary advantage is that all files can be
saved between sessions and performance is equivalent if not faster than install Linux on
its own disk partition.
The
number and type of applications found on Live CDs varies depending on the theme of the
distribution. ADIOS was developed as an
educational tool for learning about networking, security, web development and network
management. Hence the inclusion of the virtual
machines and virtual networks using trusted operating systems. To provide an operating system replacement
capability OpenOffice was included. The
distribution also has support for many compilers and development libraries. As most network management software has moved to
use a web front end, the web server is setup to help users customise their own
environment. Recently it has become popular to
support content management systems, which require LAMP (Linux + Apache + Mysql + Php) so
phpMyAdmin has also been included.
5 Conclusion
The development of a live
CD has been useful in the educational environment as it allows material to be added to the
CD image that meets the requirements of the subjects being taught. It is useful to the students as the image is the
same as the one in the laboratory environment. The
use of networked virtual machines has helped students experiment with networks and routing
at home without the cost of the hardware. The
inclusion of trusted operating systems has let users experiment with these environments. The development kit has provided a simple way for
users to tailor their own live CDs.
The boot
sequence allows end users to choose different methods of using and installing the Linux
image. The start up of the live CD is
automated to help users to learn how to use Linux. Extra
components can be downloaded or developed in house to extend the usefulness of the live
CD. These components can be included on the
DVD version. The separation of the booting
processes from the filesystem provides a mechanism whereby the filesystem can be replaced
with a new version and the CD repackaged with little overhead in redesigning the software.
Here is a short list of changes and
improvements that may be useful
The future
of boot CD/DVDs for home use, teaching, marketing and kiosk systems will continue to
increase. What is required now are tools to
allow end user to build customised bootable CDs as easily as possible. Development of GUI interfaces to allow end users to
customise the ISO image. Projects such as Colinux implemented on bootable CDs allow
end users to experience multiple operating systems simultaneously and make it easier for
users to migrate to Linux. Boot CDs require
integrated and flexible authenticated resource connections for use in school and
university environments.
6 References
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last accessed 2 May 2005.
[2] Fedora Project. http://fedora.redhat.com/
last accessed 1 May 2005.
[3] Knoppix Live CD. http://www.knoppix.org/
last accessed 1 May 2005.
[4] Linux Intrusion Detection System. http://www.lids.org/ last accessed 2 May 2005.
[5] mkisofs Utility. http://www.andante.org/mkisofs.html last
accessed 1 May 2005.
[6] NTFS Resize Frequently Asked Questions. http://mlf.linux.rulez.org/mlf/ezaz/ntfsresize.html
last accessed 1 August 2005.
[7] SELinux for Distributions. http://selinux.sourceforge.net/ last accessed 1
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