macOS
Homebrewverified · 100%
brew install fwknoplocal Homebrew formula metadata
MacPortsverified · 94%
sudo port install fwknopMacPorts ports tree · net/fwknop/Portfile · source: api.github.com
brew
Install fwknop with Homebrew, apk, apt, dnf, MacPorts, Nix, pacman, zypper
Single Packet Authorization and Port Knocking. Version 2.6.11 via Homebrew; verified 2026-06-22.
install
Additional install commands
Linux
Alpine Linux apkverified · 92%
sudo apk add fwknopAlpine Linux edge package indexes · fwknop · source: dl-cdn.alpinelinux.org
Debian aptverified · 92%
sudo apt install fwknop-apparmor-profileDebian stable package indexes · fwknop-apparmor-profile · source: deb.debian.org
Fedora dnfverified · 92%
sudo dnf install fwknopFedora Rawhide package metadata · fwknop · source: dl.fedoraproject.org
Nixverified · 92%
nix profile install nixpkgs#fwknopnixpkgs package indexes · pkgs/by-name/fw/fwknop/package.nix · source: api.github.com
Arch Linux pacmanverified · 92%
sudo pacman -S fwknopArch Linux sync databases · fwknop · source: geo.mirror.pkgbuild.com
openSUSE zypperverified · 92%
sudo zypper install fwknopopenSUSE Tumbleweed package metadata · fwknop · source: download.opensuse.org
overview
Package summary
Single Packet Authorization and Port Knocking
Project links
Commands and aliases
- fwknop
- fwknopd
history
Project history and usage
fwknop, the FireWall KNock OPerator, is a security tool for Single Packet Authorization. It conceals services behind a default-drop firewall and temporarily opens access only after a valid encrypted, authenticated, non-replayed packet is observed.
Project history
The official project page says fwknop began in 2004 as a port-knocking implementation and was the first tool to combine traditional encrypted port knocking with passive OS fingerprinting. The project later emphasized Single Packet Authorization as a stronger successor to port knocking.
The current C implementation includes libfko, client and server applications, and support for Linux iptables and firewalld, OpenBSD PF, FreeBSD and macOS ipfw, and custom scripts. The README describes the project state around the 2.5 release in July 2013, when libfko, the client, and fwknopd server formed the core distribution.
The official site continues to publish releases, with the project page listing 2.6.11 as the latest release and the blog showing a 2024 software release post.
Adoption history
fwknop became known in the security community through port-knocking and SPA discussions. The official project page notes two Slashdot appearances in 2004 and 2005, one about combining port knocking with OS fingerprinting and another about going beyond port knocking with single-packet access.
Package metadata shows fwknop in multiple Unix-like package ecosystems, and upstream documentation covers Linux, BSD, macOS, Windows under Cygwin, Android clients, and graphical clients. Its adoption is strongest among administrators who want SSH or internal services invisible to ordinary scans.
How it is used
A typical deployment generates encryption and HMAC keys, stores client settings in `~/.fwknoprc`, places shared authorization material in `/etc/fwknop/access.conf`, starts `fwknopd`, and keeps the protected service blocked by default firewall policy until a valid SPA packet arrives.
The tutorial focuses on SSH concealment, NAT gateway use, cloud environments, replay protection, HMAC authenticated encryption, and the operational tradeoff of needing both a client and a daemon.
Why package nerds care
fwknop is significant because it turns firewall access into a packageable client-server protocol with config files, manpages, libraries, distro packages, and alternate clients. It is not just a security script; it is an ecosystem around SPA packets and firewall rule orchestration.
For maintainers, fwknop is also a reminder that security packages often include sensitive config defaults, key files, init or service integration, firewall backend differences, and compatibility with old protocol modes.
Timeline
- 2004: Project begins as a port-knocking implementation.
- 2004: Project receives Slashdot attention for encrypted port knocking with OS fingerprinting.
- 2005: Single Packet Authorization direction receives further Slashdot attention.
- 2006: Single Packet Authorization with fwknop paper published in USENIX ;login: Magazine.
- 2011: GitHub repository created.
- 2013: README describes the 2.5 release with libfko, client, and server applications.
- 2016: Comprehensive tutorial updated.
- 2024: Official site announces fwknop 2.6.11.
Related projects
- fwknop is closely related to port-knocking tools but positions Single Packet Authorization as a stronger design.
- The official README names fwknop-gui and Android Fwknop2 as related clients.
- Other Cipherdyne projects listed near fwknop include psad, fwsnort, gpgdir, and IPTables parsing or chain-management modules.
Sources
security posture
Risk level: green
narrow executable package without higher-risk signals.
Risk classifier
green risk · low confidence · appliance
Why
- narrow executable package without higher-risk signals
Signals
- metadata:no-higher-risk-signals
Install behavior
- No Homebrew post-install hook is recorded in formula metadata.
- Homebrew bottle metadata is available for 8 platform targets.
- Installs with 3 runtime dependencies.
- Build metadata lists 1 build dependencies.
Recommended review
Before unattended agent use, check whether the tool reads plaintext credentials, writes remote state, publishes artifacts, or shells out to plugins.
local files
Configuration and credential file locations
These source-backed paths show where this package keeps local settings or durable credentials. Automic Vault can use them as review targets for secret scanning, migration, and command approval.
Configuration files
Config paths the tool may read or write during local use.
- Unix
~/.fwknoprc/etc/fwknop/fwknopd.conf/etc/fwknop/access.conf
Credential files
Credential-bearing paths to review before unattended agent runs.
- Unix
~/.fwknoprc/etc/fwknop/access.conf
executables
Installed executables
| Command | Kind | Exposure | Note |
|---|---|---|---|
fwknop | cli | global executable | |
fwknopd | cli | global executable |
freshness
Version and freshness
These signals separate page generation age, package-manager activity, and upstream release comparison. Version lag is warned only when an evidence URL and comparable versions are present.
page generated2026-07-08
manager version2.6.11
manager updated2026-06-22
local dataok
upstreamnot checked
latest detectednot detected
https://www.cipherdyne.org/fwknop/
- infoRelease/tag comparison is only available for GitHub repositories.https://www.cipherdyne.org/fwknop/none confidence
install metadata
Package metadata
| Package key | brew:fwknop |
|---|---|
| Version | 2.6.11 |
| Package manager | Homebrew |
| Package manager page | https://formulae.brew.sh/formula/fwknop |
| Homepage | https://www.cipherdyne.org/fwknop/ |
| Repository | https://github.com/mrash/fwknop |
| Upstream docs | https://www.cipherdyne.org/fwknop |
| License | GPL-2.0-or-later |
| Source archive | https://www.cipherdyne.org/fwknop/download/fwknop-2.6.11.tar.gz |
| Last updated | 2026-06-22T14:03:23-07:00 |
| Pulse | updated |
| Dependencies | gpgme, libassuan, libgpg-error |
| Build dependencies | texinfo |
| Uses from macOS | libpcap |
| Bottle | available (on arm64_linux, arm64_sequoia, arm64_sonoma, arm64_tahoe, arm64_ventura, sonoma, ventura, x86_64_linux) |
| Homebrew post-install | not defined |
| Service | none declared |
registry facts
Source database details
| Source Database | Homebrew formula API |
|---|---|
| Tap | homebrew/core |
| Full Name | fwknop |
| Version Scheme | 0 |
| Revision | 1 |
| Head Version | HEAD |
| Bottle Stable Root URL | https://ghcr.io/v2/homebrew/core |
| Deprecated | no |
| Disabled | no |
| Keg Only | no |
| URL Keys |
|
source database matches
Other package-manager records
Matches are pulled from external package-manager indexes and kept separate from local Automic Vault package links.
Debian apt95%
fwknop-apparmor-profile 2.6.11-2
FireWall KNock OPerator - Apparmor profile
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-apparmor-profile- Section: admin
- Architecture: all
- Source Package: fwknop
- 2 dependencies
- normalized package name match
- Matched by: Fwknop
Debian apt95%
fwknop-client 2.6.11-2+b1
FireWall KNock OPerator client side - C version
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-client- Section: admin
- Architecture: amd64
- Source Package: fwknop
- 2 dependencies
- normalized package name match
- Matched by: Fwknop
Debian apt95%
fwknop-server 2.6.11-2+b1
FireWall KNock OPerator server side - C version
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-server- Section: admin
- Architecture: amd64
- Source Package: fwknop
- 5 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Fwknop
Debian apt95%
libfko-doc 2.6.11-2
FireWall KNock OPerator - documentation
https://www.cipherdyne.com/fwknop/
sudo apt install libfko-doc- Section: doc
- Architecture: all
- Source Package: fwknop
- normalized package name match
- Matched by: Fwknop
Debian apt95%
libfko-perl 2.6.11-2+b1
FireWall KNock OPerator - Perl module
https://www.cipherdyne.com/fwknop/
sudo apt install libfko-perl- Section: perl
- Architecture: amd64
- Source Package: fwknop
- 4 dependencies
- normalized package name match
- Matched by: Fwknop
Debian apt95%
libfko3-dev 2.6.11-2+b1
FireWall KNock OPerator - development library
https://www.cipherdyne.com/fwknop/
sudo apt install libfko3-dev- Section: libdevel
- Architecture: amd64
- Source Package: fwknop
- 1 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Fwknop
Debian apt95%
libfko3t64 2.6.11-2+b1
FireWall KNock OPerator - shared library
https://www.cipherdyne.com/fwknop/
sudo apt install libfko3t64- Section: libs
- Architecture: amd64
- Source Package: fwknop
- 2 dependencies
- 1 provides
- normalized package name match
- Matched by: Fwknop
Nix95%
fwknop
nix profile install nixpkgs#fwknop- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
fwknop-apparmor-profile 2.6.10-20.2build3
FireWall KNock OPerator - Apparmor profile
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-apparmor-profile- Section: universe/admin
- Architecture: all
- Source Package: fwknop
- 2 dependencies
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
fwknop-client 2.6.10-20.2build3
FireWall KNock OPerator client side - C version
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-client- Section: universe/admin
- Architecture: amd64
- Source Package: fwknop
- 2 dependencies
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
fwknop-server 2.6.10-20.2build3
FireWall KNock OPerator server side - C version
https://www.cipherdyne.com/fwknop/
sudo apt install fwknop-server- Section: universe/admin
- Architecture: amd64
- Source Package: fwknop
- 5 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
libfko-doc 2.6.10-20.2build3
FireWall KNock OPerator - documentation
https://www.cipherdyne.com/fwknop/
sudo apt install libfko-doc- Section: universe/doc
- Architecture: all
- Source Package: fwknop
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
libfko-perl 2.6.10-20.2build3
FireWall KNock OPerator - Perl module
https://www.cipherdyne.com/fwknop/
sudo apt install libfko-perl- Section: universe/perl
- Architecture: amd64
- Source Package: fwknop
- 4 dependencies
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
libfko3-dev 2.6.10-20.2build3
FireWall KNock OPerator - development library
https://www.cipherdyne.com/fwknop/
sudo apt install libfko3-dev- Section: universe/libdevel
- Architecture: amd64
- Source Package: fwknop
- 1 dependencies
- 1 optional deps
- normalized package name match
- Matched by: Fwknop
Ubuntu apt95%
libfko3t64 2.6.10-20.2build3
FireWall KNock OPerator - shared library
https://www.cipherdyne.com/fwknop/
sudo apt install libfko3t64- Section: universe/libs
- Architecture: amd64
- Source Package: fwknop
- 2 dependencies
- 1 provides
- normalized package name match
- Matched by: Fwknop
apk95%
fwknop 2.6.11-r2
Single Packet Authorization (SPA) implementation
https://cipherdyne.org/fwknop/
sudo apk add fwknop- License: GPL-2.0-or-later
- Architecture: x86_64
- Source Package: fwknop
- 1 dependencies
- 1 provides
- normalized package name match
- Matched by: Fwknop
source trail
Generated from repository data
This page is generated by av-web from the private package SQLite artifact built by scripts/generate-pkg-sqlite.py.
Combined YAML source
View the package source record on GitHub.
Used sources
- Geiger risk classifier
- Nucleus package database
- av.db category and tag curation
- cross-ecosystem install command graph
- curated configuration and credential file locations
- curated package history
- external package-manager database matches
- package relationship graph
- package version freshness
- package-page enrichment