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3 - Getting started with OpenBSD
Table of Contents
3.1 - Buying an OpenBSD CD set
Purchasing an OpenBSD CD set is generally the best way to get started. Visit the
ordering page to purchase your copy:
OpenBSD ordering page.
There are many good reasons to own an OpenBSD CD set:
- CD sales support ongoing development of OpenBSD.
- Development of a multi-platform operating system requires constant
investment in equipment.
- Your support in the form of a CD set purchase has a real impact on future
- The CDs contains binaries (and source) for the most popular
- The CDs are bootable on several platforms, and can be used to bootstrap
a machine without a pre-existing installed operating system.
- The CDs are useful for bootstrapping even if you choose to install a
- Installing from CD is faster! Installing from CD preserves network
- OpenBSD CDs always come with very nice stickers. Your system isn't fully
complete without these. You can only get these stickers by buying a CD
set or donating hardware.
- The CD set is complete enough to bring up a full
development environment without any network connection at all.
If you're installing a release version of OpenBSD, you should use a
official CD set.
3.2 - Buying OpenBSD T-Shirts
Yes, OpenBSD has T-shirts for your wearing enjoyment. You can view
these at the OpenBSD T-shirts page.
3.3 - Does OpenBSD provide an ISO image for download?
For select platforms, yes!
Most platforms that are able to boot from CD-ROM have ISO images
available for download which can be used to create bootable OpenBSD
Both "full install" (all files needed for a full OpenBSD install, named
install55.iso) and "boot only" (for installing from a network file
source, named cd55.iso) ISOs are provided for these platforms.
Note, these ISO files are not the same as the
official CD set.
These images are for single platforms, and do not include any of the
pre-compiled packages, stickers, or artwork
that the official CD set does.
The OpenBSD project does not make the ISO images used to master
the official CDs available for download. The reason is simply
that we would like you to buy the CD sets to help fund ongoing
OpenBSD development. The official OpenBSD CD-ROM layout is copyright
Theo de Raadt. Theo does not permit people to redistribute images of the
official OpenBSD CDs. As an incentive for people to buy the CD set, some
extras are included in the package as well (artwork, stickers etc).
Note that only the CD layout is copyrighted, OpenBSD itself is free.
Nothing precludes someone else from downloading OpenBSD and making their
Those that need or want a bootable USB drive can use the
install55.fs (bootable, plus install sets) or
miniroot55.fs (just bootable, file sets are pulled down via
network) files, which can be imaged onto a USB flash disk or other
3.4 - Downloading via HTTP, FTP, RSYNC or AFS
There are numerous international mirror sites offering HTTP and FTP access to
OpenBSD releases and snapshots. RSYNC and AFS access are also available. You
should always use the site nearest to you. Before you begin fetching a release
or snapshot, you may wish to use
to determine which mirror site is nearest to you and whether that
mirror is performing adequately. Of course, your OpenBSD release
CD is always closer than any mirror. Access information is here:
OpenBSD Download page.
3.5 - Verifying your download
In the same directory as the installation sets, each mirror includes a file
named SHA256 which contains checksums of the various installation files. You
can confirm that none of the downloaded files were mangled in transit using
the sha256(1) command:
Starting with OpenBSD 5.5, you can also use
to verify your files:
$ sha256 -c SHA256
which will verify the file install55.iso.
Note that you will need the public key files (and the signify program!)
of OpenBSD 5.5 in order to do this.
$ signify -C -p /etc/signify/openbsd-55-base.pub -x SHA256.sig install55.iso
3.6 - Selecting Hardware
Selecting appropriate hardware to run your OpenBSD system on is
important, as it can mean the difference between success and failure of
If you are shopping for a new PC, whether you are buying it
piece by piece or completely pre-built, you want to make sure first
that you are buying reliable parts. In the PC world, this is not easy.
Bad or otherwise unreliable or mismatched parts can
make OpenBSD run poorly and crash often.
The best advice we can give is to be careful, and buy brands and parts
that have been reviewed by an authority you trust.
Sometimes, a higher-price machine is a better quality machine.
Other times, it is simply more expensive.
There are certain things that will help bring out the maximum
performance of your system:
- Let the application choose the hardware:
It is usually better to make an adjustment to the hardware you were
planning on using rather than compromising on your application design
because you have something you "really wanted to use".
- Identify your bottlenecks:
Don't pay extra for the cutting-edge processor if your application is
restricted by disk I/O.
Don't pay for fast disk if your system is restricted by network speed.
Don't pay for much of anything if your bottleneck is a 128kbps DSL line.
- Keep it simple:
Simple hardware usually has simple problems.
Complex hardware that isn't supposed to ever break may take you a long
time to repair when it breaks anyway.
- Use hardware you understand, or learn the new hardware before you
implement a production system:
Regardless of the technical merits of the hardware, committing to use a
particular type of hardware before you have become familiar with it,
both how it works and how it fails, is foolish.
- Use multiple disks:
Instead of buying one large disk, buy multiple smaller disks. While this
may cost more, distributing the load over multiple spindles will decrease
the amount of time necessary to access data on the disks. And, with more
spindles, you can get more reliability and faster data access with RAID.
- Break up large blocks of storage:
Many people make the mistake of designing a system that stores large
amounts of data to have one Big Block of Storage.
This is usually a bad design.
You will usually find it much better to break up your storage into
This has many advantages, two of the biggest being that you can add more
storage later when you need it easily (you weren't going to get the
requirements estimate right, no one ever does), and you can buy a small
amount of storage now, and add much more later when the price will have
most likely dropped and the capacity will have increased.
- Avoid cheap network adapters:
OpenBSD supports a plethora of cheap network adapters.
These adapters work great in home systems, and low or moderate
throughput business and research environments.
But, if you need high throughput and low impact on your server, you are
better off buying a quality network adapter.
Unfortunately, some name-brand adapters are not much better than the
cheap adapters, and some potentially good adapters do not have accurate
documentation available to write good drivers.
Gigabit adapters often perform better than 10Mbps/100Mbps adapters, even
when used on slower speed networks, due to superior buffering.
3.7 - What is an appropriate "first system" to learn OpenBSD on?
While OpenBSD will run on a smaller, older and less powerful computer
than just about any other modern OS, if you are just getting started with
OpenBSD, using too little machine can be frustrating.
The following guidelines are ONLY guidelines; OpenBSD will run very well
on much more modest equipment than is listed here, but it may be more
frustrating than needed for a first-time user.
Obviously, "more the better" to a point.
Some popular applications seemingly use as much processor and
memory as you can throw at the system.
Use a platform you are familiar with already.
When you are learning a new operating system, it is a very bad time to
also be learning a new platform.
We'll assume you are going to be using the i386
platforms here, as they are probably the ones most people are familiar with.
Once you are familiar with OpenBSD, though, it makes a good introduction
to other platforms.
100MHz Pentium or better processor.
Yes, OpenBSD will run on a 25MHz 80486, but you won't want to do
the experimenting and messing up and reloading you need to do to really
get to know the system on a slow machine.
The primary irritation you will first encounter with a processor slower
than this is the time it takes to SSH into the box.
If you wish to run X, you probably want to move up to at least 200MHz.
X actually runs pretty well on a slower machine once loaded, but it
takes a while to load and start.
- 64M RAM or better:
If you wish to run X, 128M would be a better starting point.
- Hard disk:
A 1G hard disk will give you an easy install of a simple system, such as
a firewall, DNS server, or similar.
If you wish to rebuild the system from source, you will probably want a
4G disk, and if you wish to rebuild X as well, you will want 6G or bigger.
IDE is recommended to start with.
If you have a much larger disk, don't feel the obligation to allocate all
the disk initially -- there is nothing wrong with leaving 72G of an 80G
hard disk unallocated if all you need is 8G.
- Network adapter:
Use a PCI adapter.
If you are planning on putting multiple network adapters in the machine,
write the MAC address on the spine of the card before putting the cover
While the urge to use that old ISA adapter you have may be strong, resist.
You probably don't remember how to properly configure it.
For your first OpenBSD installation, don't attempt to multiboot with
Multibooting is a difficult process
to get right, and you must understand all the OSs involved well before
attempting this, which is clearly not the case on your first
It is very possible you could accidently delete all data on the system.
Rather, use a dedicated computer, or at least, a dedicated disk on a machine.
While many laptops work very well with OpenBSD, they are sometimes not the
easiest systems to get running well, so a laptop might not be the best
choice for your first OpenBSD install.
However, once you are comfortable with OpenBSD, a laptop can be a very
- New hardware:
Brand new, cutting-edge hardware is sometimes not yet supported by
OpenBSD, so for your first OpenBSD system, a slightly older machine is
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