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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.
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
- The CDs contains binaries (and source) for the most popular supported
- 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 and preserves bandwidth.
- OpenBSD CDs always come with very nice artwork and stickers.
Your system isn't fully complete without these.
You can only get these stickers by buying a CD set.
- 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 an official
3.2 - Buying OpenBSD shirts
Yes, OpenBSD has T-shirts for your wearing enjoyment!
You can view them here.
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 that can be used to create bootable OpenBSD install CD-ROMs.
Both "full install" (all files needed for a full OpenBSD install, named
installXX.iso) and "boot only" (for installing from a network file
source, named cdXX.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
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 instead can use the
installXX.fs (bootable, plus install sets) or minirootXX.fs
(just bootable, file sets are pulled down via network) files, which can be
imaged onto a USB flash disk or other storage device with the
3.4 - Downloading via HTTP, rsync or AFS
There are numerous international mirror sites offering HTTP access to
OpenBSD releases and snapshots.
Some mirrors also provide rsync and AFS access.
You should always use the site nearest to you.
Before you begin fetching a release or snapshot, you may wish to use
traceroute(8) 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.
3.5 - Verifying your download
In the same directory as the installation sets, each mirror includes a file
named SHA256 that contains checksums of the various installation
You can confirm that none of the downloaded files were mangled in transit
Note that this only checks for accidental corruption.
You can use
signify(1) to cryptographically verify the downloaded files.
$ sha256 -c SHA256
This will verify the installXX.iso file, for example.
Replace "XX" with the version of OpenBSD that you're verifying.
Note that you will need the public key files for OpenBSD's base system
(and the signify program!) in order to do this.
$ signify -Cp /etc/signify/openbsd-XX-base.pub -x SHA256.sig install*.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 a project.
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
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 more expensive machine is a better quality machine.
Other times it is not.
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 disks 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
- 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, then 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.
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
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 such a 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, "the more, the better" to a point.
While OpenBSD's requirements are very modest, 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
or amd64 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.
You would be hard-pressed to find a new CPU that isn't adequate.
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.
- 128M RAM or better:
If you wish to run X, 256M would be a better starting point.
- Hard disk:
2GB of disk space 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 at
least 8GB available.
If you have a very large hard drive, don't feel obligated to allocate all
of it initially -- there is nothing wrong with leaving part of your disk
unallocated if you only need a small amount.
- Network adapter:
Use a PCI or PCIe 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 on.
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 installation.
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 recommended.
Do your research beforehand.
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[To Section 4 - Installation Guide]