Files
pf-linux-port/README.md
T
lgcosta dff2185b20 Docs: bring the documentation in line with the code
- Demo docs replaced by the screencast docs (single source of truth): the
  legacy demo-session.sh/demo-record.py and the v0.9 renderer were removed
  instead of being kept as a second convention.
- feature-matrix: stale 'M2-in-progress' vocabulary gone; the rows the 15
  gates prove now say VERIFIED-in-VM and name the gate; af-to is now an
  explicit non-goal row (INET6 0 in this build).
- guide: the queues/divert/pflog sections described a state that no longer
  exists (priq-only, divert dropping packets, pflog logging nothing); they
  now describe the shipped behaviour.
- vm-lab: the 15 real gates with what each proves, 15/15 green, and the
  pf0 -> cli/srv/gw2 ssh setup the screencasts rely on.
- install/build: pdivert and pflogd are built and ported (docs said
  otherwise); module object list now includes hfsc.c, fq_codel.c, pfk_pflog.c;
  the screencast pipeline is an optional build stage.
- pf-guide: the 'M2 scope only' framing is gone; honest gaps listed.
- caveats: three new sections about the screencast pipeline (MiniMax video
  generation blocked by the account tier, narration as a separate track, a
  video frame is not a verdict).
- porting-notes: what the recording taught us.
- README/README.pt-BR: status, milestones, layout and video section updated.

All internal doc links verified.
2026-11-12 11:51:25 -03:00

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PF on Linux

Port of the OpenBSD PF (packet filter) to Linux 7.3.4 as an out-of-tree kernel module — the real PF engine (pf.c, pf_norm.c, pf_table.c, pf_lb.c, hfsc.c, … ported from OpenBSD 8.0 sources) driven by the real OpenBSD pfctl over the /dev/pf ioctl ABI.

Status: the filter core, stateful filtering, tables, anchors, NAT (nat-to/rdr-to/binat-to), forced routing (route-to/dup-to/reply-to), pools, divert, pflog and the OpenBSD 8.0 queues (HFSC) are verified in a real libvirt lab — 15/15 gates green. What is still pending is stated per feature in docs/en/feature-matrix.md.

Screencasts (EN + PT, narrated): docs/en/screencast.md. Design: docs/superpowers/specs/2026-11-11-pf-linux-port-design.md · plan: docs/superpowers/plans/2026-11-11-pf-linux-port.md.

Milestones

Milestone Scope Status
M0 repo, scripts, kernel build, VM boots the custom kernel done
M1 compat layer, pf.ko loads, /dev/pf, pfctl -f / -s info done
M2 filter core: rules/states/tables/anchors, VM gates 01–04 done — gates 01/02/03/04 green
M3 NAT (nat-to/rdr-to/binat-to), scrub done — gates 05/06/07/09 (incl. 2 MB integrity through a redirect, min-ttl/max-mss measured)
M4 route-to/dup-to/reply-to, pools, divert e2e, pflog done — divert (11), pflog (12), route-to/dup-to (08), pools (10), reply-to (13) verified
M5 queues: HFSC back end in the data path done (mechanical) — gate 15: queues load, hfsc attaches, pfctl -s queue -v reports class stats, a 2 MB queued flow is counted by the class. bandwidth = HFSC linkshare (guarantee, not cap; 8.0 has no upperlimit syntax)
M6 docs complete, patchset tidy, full suite green, tagged release done — docs EN+PT-BR, 15/15 suite green, tagged (v1.0.0)

What you get

Area Feature
Filtering rules, anchors, quick, match/block(drop/return/return-rst)/pass, keep state, syncookies
State/Tables stateful firewall engine, pfr tables (radix + hash, pfctl -t)
NAT nat-to (port pools, sticky-port, static-port), rdr-to, binat-to
Scrub fragment reassembly, overlap drop, min-ttl/max-mss/df/no-df, set reassemble
QoS (ALTQ successor) queue/queue on with OpenBSD 8.0 ifq schedulers: HFSC verified in the data path (gate 15), priq default, FQ-CoDel compiled; pfctl -s queue -v works
Divert divert-to / divert tag + pdivert relay over an in-module PF_DIVERT socket family (verified: packet to userspace and back)
Route route-to/dup-to/reply-to + pools (round-robin, source-hash) verified (fail-to no longer exists in OpenBSD 8.0)
Logging pflogd via /dev/pflog (DLT_PFLOG pcap, OpenBSD record layout) — verified
Control /dev/pf (0600), OpenBSD 8.0 ioctl ABI, Linux build of pfctl (single binary)

Not in scope: pfsync/CARP failover, IPsec/pfkey, ftp-proxy, per-netns PF instances, classic-ALTQ-only schedulers (cbq/wfq/red — removed upstream before OpenBSD 8.0).

Screencasts

Seven narrated screencasts per language (English and Portuguese), 1080p30 with burned-in subtitles, the lab's network diagram drawn over the terminal, and a continuous film that crossfades the phases together. Every video is a real shell session against the Alpine VMs — commands typed key by key, the kernel answering live — with a MiniMax female voice narrating:

./scripts/screencast/build-all.sh       # -> out/screencast/{en,pt}/*.mp4

Details, per-phase breakdown and the YouTube description text: docs/en/screencast.md · docs/pt-BR/screencast.md

Quick start

Full recipe: docs/en/install.md. Short version (commands are read from the scripts):

./scripts/fetch-sources.sh          # OpenBSD 8.0 sources (C3SL mirror, sha256-pinned)
./scripts/vendorize.sh              # stage the pristine files we port
./scripts/build-kernel.sh           # kernel 7.3.4: bzImage + modules_prepare (export patch: none needed)
./scripts/build-module.sh           # -> module/pf.ko
make -C tools                       # -> tools/out/{pfctl,pdivert,pflogd,abitest}
sudo insmod module/pf.ko            # /dev/pf (0600) + netfilter hooks
sudo pfctl -f /etc/pf.conf && sudo pfctl -e

Every feature listed above is exercised by the lab suite before you need it; docs/en/feature-matrix.md says which gate proves what, and docs/en/pf-guide.md lists the deviations you should know before putting PF on a path that matters.

VM validation lab (Alpine on libvirt): docs/en/vm-lab.md. Documentação em português: README.pt-BR.md e docs/pt-BR/.

Layout

  • module/ — kernel sources: ported PF engine (module/pfsrc) + Linux compat layer (module/compat)
  • tools/ — pfctl (static Linux build), pdivert relay, pflogd, ABI harness (make -C tools abi)
  • patches/kernel/ — Linux core patch set (currently empty; evidence in p1-needs.txt, see docs/en/patches.md)
  • scripts/ — fetch/build/patch/VM automation, plus scripts/screencast/ for the videos
  • tests/vm/ — VM suite: 15 gates (tests/vm/NN-*.sh) + lib.sh
  • docs/en/ + docs/pt-BR/ — full bilingual documentation
  • docs/superpowers/ — design spec + implementation plan

License

Ported OpenBSD code retains its original ISC license and copyright notices. New Linux-side code: ISC.