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OpenBSD that runs exclusively off CD-ROM for router purposes


Has anyone experimented with making a OpenBSD system that can run off only a

On Linux this has been done with Floppy disks and CD-ROMs to allow for
router/firewall systems that are noise-free.  Basically there are four major
technical issues:

  1) Creating a RAM Disk (typically of small size such as 8MB) so that log
files and temp files can be created.
  2) Getting the system to boot from CD-ROM in an operational mode...
configured so it uses the ramdisk for anything that requires write.
  3) Having some way to configure the system from files other than what is
on the CD-ROM;  For system-specific information.  Given the nature of
read-only media -- some place must be available to read information such as
ipf.rules and the adapter configurations.  It is best to avoid having to
burn a new CD-ROM just to do something like add 1 rule.  Although CD-RW
media may make this acceptable...
  4) Run without swapping/paging.

The advantages of doing this are that a system with as little as 24MB of RAM
could be configured to act as a diskless BIOS.  Set the system to boot from
cd-rom, once booted a cd-rom will quit spinning and shut down; with the lack
of hard drive, you can often eliminate all systems fans and have a
noise-free router/firewall.  Furthermore, backing up your firewall is
nothing more than just the configuration files... and getting another box
installed as a firewall is as simple as inserting the CD-ROM.

Another advantage is that you can run the firewall/router on the system
without impacting any of what is on the hard drive.  Great for new users
wanting to test out OpenBSD capabilities without having to touch their hard

Has anyone done work along this line?  If not, any ideas on the hurdles and
ease of adaptation from stock (forthcoming) 2.8?  I'm assuming the bootable
installation cd-rom does something similar?


  Stephen Gutknecht
  Renton, Washington