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Maybe you have been reading about the release of OpenBSD 6.5 and wonder:

"What are the differences between Linux and OpenBSD?"

(And, to some extent, other BSDs?)

I've also been there at some point and these are my conclusions 👇
Mandatory disclaimer: this list is aimed at people who are used to Linux and are curious about OpenBSD. It is written to highlight the most important changes from *their* perspective, not the *absolute* most important changes from a technical standpoint.

Please bear with me.
The first thing to realize is that, on the surface, the changes are minimal. Both are UNIX-like. You get a terminal, X windows, Firefox, Libreoffice...

Most free software can be recompiled, though some proprietary software isn't on OpenBSD.

Don't expect any visual changes.
Under the hood, there are some BIG differences with relatively little practical impact:

- BSD licensing vs GNU licensing
- "Whole OS" model where some base packages are treated as first-class citizens with the kernel, VS bare Kernel + everything is 3rd party
- Documentation is considered as important as code VS good luck with Stack Overflow and reading mailing lists
- Whenever a decision has to be made, security and correctness is prioritized VS general-purpose and popularity and efficiency
Do these make little sense to you? I know, I was there.

They're philosophical distinctions which ramifications are not immediately visible.

They can't be explained, you need to understand them by usage.

That's why the typical recommendation is "just try OpenBSD and see"
So, what are some of the actual, tangible, practical differences?

Not many, really. Some are "features" and some are "undesired" side effects. With every decision there is a trade-off.

Let's see some of them
- OpenBSD is a simpler system. It's very comfortable for sysadmins. All pieces are glued together following the UNIX philosophy, focusing on simplicity. Not sure what this means? Think rc VS systemd

- OpenBSD has excellent man pages with practical examples. Use `man`. Really.
OpenBSD has different default daemons/servers/defaults than Linux.

apache/nginx: httpd
postfix/sendmail: opensmtpd
ntp: openntpd
bash: ksh

and so on.

These cover 90% of the use cases, while being robust and simpler to admin.
Think: "knowing what we now today about email, how would we write a modern email courier from scratch, without all the old cruft?"

Voilà, OpenSMTPd.

The same goes for the rest, and there are more projects on the way (openssl -> libressl)
Proactive security: W^X, ipsec, ASLR, kernel relinking, RETGUARD, pledge, unveil, etc.

Do these sound familiar? Most were OpenBSD innovations which trickled down to the rest of the unices

More here: openbsd.org/innovations.ht…
"Does this mean that OpenBSD is more secure than Linux?"

I'd say it's different but equivalent, but OpenBSD's security approach is more robust over time.
System administration and package upgrading is a bit different, but equivalent too, at least on x86.

If you use a different arch, you'll need to recompile OpenBSD stuff from time to time.
"But Carlos, you haven't yet told me a single feature which is relevant for my day to day use!"

That's because there is probably none.

There are very few things OpenBSD does that Linux does not.

However, what they do, they do better.

Is that important for you?
Let's jump to some of the not-so-nice ramifications of OpenBSD's philosophy:

- Most closed-source Linux software does not work: skype, slack, etc. If that's important for you, use the equivalent web apps, or try FreeBSD, which has a Linux compatibility layer
Some Linux-kernel-specific software does not work either. Namely, docker.

The same for drivers: OpenBSD has excellent drivers, but a smaller number of them.

This includes compatibility drivers: modern/3rd party filesystems, for example, are not so well supported.
Because of the focus on security and simplicity, and not on speed or optimizations, software runs a bit slower than on Linux. In my experience (and in some benchmarks) about 10%-20% slower.

phoronix.com/scan.php?page=…
Battery life on laptops is also affected. My x230 can run for 5 hours on Linux, 3:30 on OpenBSD.

More modern laptops and bigger batteries are a practical solution for most of the people.
"Are you telling me that the positives are intangible and the negatives mean a slower system and less software overall?"

At the risk of being technically wrong, but with the goal of empathizing with the Linux user, I'll say yes.
In reality: it means that the intangibles are intangible *for you*. For other people, these features are what draws them to OpenBSD.

For me, the system architecture, philosophy, and administration is 10x better than Linux's.
Let me turn the question around: can you live with these drawbacks if it means you will get a more robust, easier to admin, simpler system?
But wait! My goal with this thread was to pique your interest!

Go ahead and spin up a VM or install OpenBSD on an old machine and see for yourself.

Life isn't black or white. Maybe OpenBSD can not be your daily OS, but it can be your "travel-laptop OS"

That is exactly my case
Actually, my daily driver is OSX, not Linux, because I need to use MS Office and other software which is Windows or Mac only for work.

However, I enjoy using OpenBSD much more. The day I retire I will make the full switch 😃
Well, did I catch your eye or what?

What are you waiting for? It's a fantastic Saturday morning, you have the whole weekend in front of you.

Download OpenBSD and learn what all the fuzz's about!
Thanks for reading! Here are more references:

OpenBSD's website: openbsd.org
Project goals: openbsd.org/goals.html
Download instructions: openbsd.org/faq/faq4.html#…
Official FAQ: openbsd.org/faq/index.html
My first OpenBSD impressions from 2015: cfenollosa.com/blog/openbsd-f…
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