The Book of PF, 4th Edition: It's Here, It's Real

© 2026 Peter N. M. Hansteen

The long wait is over. Fresh copies of The Book of PF, 4th Edition arrived here today. Which means: I'll bring some to upcoming conferences!

When the email message with package tracking information turned up, I thought at first that this was yet another dirty, scammy, spammy phishing thing.

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It had been years since the last time I had had a UPS delivery, and since then I had only seen obvious scammy phishing things pretending to delivery messages that all in fact looked very much like the crummy fakes they turned out to be.

But this one looked subtly different, in that it had both my address and my somewhat unusual name correctly spelled.

In addition, the URLs were on close inspection all for actual UPS.com resources.

And finally, the shipment had a total weight of 10.4 kg, which sounded about right for the stack of The Book of PF, 4th Edition author copies I was expecting to receive soon after the print run was ready to ship.

Now, a few days later, I have just taken delivery of package, this time delivered to my door by a delivery man who was very excited to be delivering a box of books to their author. The box was slightly heavier than my regular backpack:

and after taking the box inside, I was able to extract the 15 copies, as expected.

This is me, holding my first physical copy of the fourth edition to come out of the box:

This means that the process that started almost two and a half years ago is finally, tangibly complete. I have the shipment of author copies of The Book of PF, 4th Edition in hand.

Regular readers of this column as well people on relevant mailing lists will be aware, as will my followers on various social media, that people who ordered the book early have already started receiving their copies of the refreshed The Book of PF. And some have posted their (so far only positive as far as I am aware) reactions to their media of choice.

But for one reason or the other, my expected stack of author copies were not among the very early deliveries.

Among the likely reasons are the fact that I am located in Bergen, Norway, which, at roughly 62 degrees North and in The Other West Coast fjords country, is somewhat off the beaten track for high speed deliveries.

And as any good business would do, No Starch Press will put a priority on delivering the product to customers who put in preorders or were on the spot once the thing had been declared ready.

Now I can tell you all yet again, the thing exists, and I am delighted to see the actual physical copies.

I know some readers were expecting there to be an auction for the first signed copy like there was for the third edition.

I have to disappoint you there. Unfortunately, side effects of decisions made by politicians on the other side of the Atlantic have made it impractical to set up an equivalent auction this time around.

Instead, I would encourage readers who can afford to do so to make a direct a donation to the OpenBSD Foundation or to the OpenBSD Project directly, in order to support the OpenBSD project and the immensely valuable work they do for free software.

If you're more of a FreeBSD person, the FreeBSD Foundation will be happy to hear from you as well.

Once you have done the rounds of your favorite free operating system supporting foundation and have your (or your bosses') credit card back in its regular location, you can think forward to one or more of the upcoming regional BSD conferences.

The main ones this year are,

• AsiaBSDCon, March timeframe, alternates between Tokyo (JP) and Taipei (TW). AsiaBSDCon 2026 will be March 19-22, 2026 in Taipei, Taiwan.

  This will include the first scheduled Network Management with the OpenBSD Packet Filter Toolset session of the year, on March 19th, 2026.

• BSDCan, Mid May to mid June, Ottawa (CA). BSDCan 2026 will be June 17-20 in Ottawa, Canada.

  This, too, will have a Network Management with the OpenBSD Packet Filter Toolset session, on June 18th. Details to follow closer to the date of the conference.

• EuroBSDcon, September timeframe, each year in a new European city. EuroBSDCon 2026 will be September 10-13 in Brussels, Belgium. The call for papers is open from March 1st, 2026 and runs until June 20th.

All three conferences will welcome submissions during their Call for Papers period for talks, tutorials and other types of sessions as well as general participation by people regardless of geographic or other origin.

And unless truly unexpected events take place, I will be at all three this year, bringing copies of The Book of PF, 4th edition.

I look forward to seeing you at these events.

If you are interested in coming to a regional BSD conference as a speaker, volunteer or other participant, see What is BSD? Come to a conference to find out! (also here) for some information.

Through all of those events, our resident philosopher took it all with her usual calm:

If you want to get the book, and using the link to buy from No Starch Press is not practical, I would encourage you to support your local bookstore and see if they can order it in.

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The Book of PF, 4th Edition: It's Here, It's Real is © 2026 Peter N. M. Hansteen (published 2026-03-06)

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You might also be interested in reading selected pieces via That Grumpy BSD Guy: A Short Reading List (also here).

Yes, The Book of PF, 4th Edition Is Coming Soon

© 2025 Peter N. M. Hansteen

Long rumored and eagerly anticipated by some, the fourth edition of The Book of PF is now available for preorder

This week it was finally time to announce, to the fediverse and to mailing lists, that there is a new edition of The Book of PF in the works, and preordering is now enabled.

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A few questions immediately pop into readers' minds on hearing this news. The ones I get most often are,

Why now? What took you so long?

which quite frequently combines with

What changed? Are previous editions now useless?

I'll address both after repeating what I said in the email announcements:

The fourth edition was written to bring the text into sync with the realities of the modern Internet, seen from the perspective of someone working with OpenBSD 7.8 or FreeBSD 14-STABLE.

The structure and chapter titles will be recognizable to readers of the previous edition, with the content updated to reflect the realities of the modern Internet.

What happened was, for quite some time after the third edition was finished, there were essentially no user visible changes such as syntax changes in the configuration for OpenBSD PF.

The code was definitely being worked on, developers fixed bugs, introduced optimizations such as network stack wide improvements in multicore support. But user-visible changes other than likely performance improvements did not appear, so I saw no urgent need to make updates to the book.

During the years following the late 2014 publication of third edition, I went on giving talks and tutorials, and at some point I welcomed input and help from my present co-presenters of the Network Management with the OpenBSD Packet Filter Toolset tutorials, Max Stucchi and Tom Smyth.

Over a few revisions, the tutorial sessions became ever more OpenBSD centered, possibly because we were all focusing more on that system than the others. And of course, over time we made tweaks to the material we present at the tutorials in response to our own real world experiences and feedback from attendees and others.

This went on for some years, with the still moderately popular conference sessions each yielding incremental changes to the material. Then, COVID-19 put all physical conference activities on hold for the years 2020 and 2021. EuroBSDCon 2022 in Vienna (originally planned as the 2020 conference), was our first post-lockdown presentation and a well attended one at that.

We went on to do more sessions at BSDCan 2023 and EuroBSDCon 2023. During the post-lockdown period, one question started popping up ever more frequently in email, social media (direct messages, even) and in connection with the sessions themselves,

Are you working on a fourth edition?

more often than not accompanied by

I'd love to get this in a FreeBSD version, can you do that too?

My answers would be roughly, "No tech book writer will ever reveal what their current project is until they have a specific publication date set", and "Sure, I will look into what I can do about that for sometime later"

On my way back from EuroBSDCon 2023 in Coimbra, where these questions had of course come up again, even from the quite small group of attendees at our session, I decided I that after eight years it might be worth at least looking into what, if anything beyond incrementing version numbers, would make sense to do to produce a new edition.

So I set out to assess. The book had seen some light touch updates for its second printing that were not in my pre-production .odt files, so I set out with the freshest .pdf and started making annotations. After a little while the volume of annotations had grown enough that I found it more useful to transfer those annotations to a normal text file. That file was becoming something like an outline of what a fourth edition would look like.

So testing my own 8 year old work against modern OpenBSD and FreeBSD, and poking around for PF material in general, I noticed several things.

Since the third edition was written, NetBSD, prominently featured in that edition, had developed their own NPF packet filter subsystem and deprecated their PF port. While DragonFly BSD still had PF in their tree, it looked like their version was seriously out of date (as far as I could tell equal to roughly OpenBSD 3.6, released in 2004).

So concentrating on the two free systems I was anyway in daily contact with -- OpenBSD and FreeBSD -- made sense.

My notes of things that needed to be done swelled over the next few weeks. The revision notes work became my main activity on evenings and weekends for a while, and by late November I sent off that file as an attachment to a mail message to Bill at No Starch that started with,

Dear Bill,
I think a fourth edition of The Book of PF might have a reason to exist soonish.

I went on to explain that while we had not had major announcements in the packet filtering space during the past few years, quite a few incremental and larger changes had indeed happened. A lot more had happened in user visible PF matters on the FreeBSD side than on the OpenBSD side, but incremental changes had happened there too.

And as you could reasonably expect, the world around us had changed enough that in addition to introducing some new features, existing examples and the way we present the issues to the reader needed a refresh in order to be relevant to anyone working in or starting out with modern TCP/IP networks.

It took some weeks before the yes, we're on board for a fourth edition message came back. It is entirely possible that making an important business pitch just before Thanksgiving weekend is not an optimal thing to do, timing-wise.

But when the go-ahead came, I asked Henning Brauer, who had been very much involved with technical editing for the previous versions, and Kristof Provost, who does the major PF things on the FreeBSD side, to be my tech reviewers. Both accepted immediately.

Over the next few months intense editing and revising followed -- yes, I do make mistakes, and Henning and Kristof proved to be very good at catching them.

Now we are very close to having the final result. The fourth edition of The Book of PF focuses on PF on modern versions of OpenBSD and FreeBSD, with only minor mention of other platforms. The ports to Apple systems and Oracle Solaris are mentioned, but I decided early on to focus on the free systems for all examples. The FreeBSD parts have received significantly more attention than in previous versions, to the extent that we jokingly referred to the fourth edition as the be nice to FreeBSD edition.

NEWS FLASH 2025-12-05: Final proofs done 2025-11-30, the thing is now in production,

The editing process has taken longer than I had anticipated, but we are on track now to have copies in readers' hands some time in the second half of 2025. I hope I will be able to bring physical copies of the fourth edition to Unfortunately physical copies will not be ready for us to bring to EuroBSDcon 2025 in Zagreb in September. There will be a revised and updated version of the Network Management with the OpenBSD Packet Filter Toolset session there, a full day tutorial starting at 2025-09-25 10:30 CET. You can register for the conference and tutorial by following the links from the conference Registration and Prices page.

So summing up,

The fourth edition was written to bring the text into sync with the realities of the modern Internet, seen from the perspective of someone working with OpenBSD 7.8 or FreeBSD 14-STABLE.

The structure and chapter titles will be recognizable to readers of the previous edition, with the content updated to reflect the realities of the modern Internet.

If you have actually read this far, there is a good chance you might be interested in the book, the tutorial, or both. I welcome your comments and input.

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If you found this piece to be useful, informative, annoying or would for some other reason like to contact me or comment, please do.

You might also be interested in reading selected pieces via That Grumpy BSD Guy: A Short Reading List (also here).

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