48 changed files with 580 additions and 114220 deletions
--- a/.drone.yml
+++ b/.drone.yml
@ -1,89 +0,0 @@
 kind: pipeline
 name: default
 workspace:
  base: /go
  path: src/deadbeef.codes/steven/hyp
 steps:
 - name: create build environment
  image: plugins/docker
  settings:
    repo: registry.deadbeef.codes/hyp-build
  when:
    target:
      include:
      - environment
 - name: build hyp (client) linux-amd64
  image: registry.deadbeef.codes/hyp-build:latest
  pull: always
  volumes:
  - name: publicrelease
    path: /dist
  environment:
    GOOS: linux
    GOARCH: amd64
    CGO_ENABLED: 0
  commands:
  - . /root/.profile
  - cd hyp
  - go build -o /dist/hyp-linux-amd64 .
 - name: build hypd (server) linux-amd64
  image: registry.deadbeef.codes/hyp-build:latest
  pull: always
  volumes:
  - name: publicrelease
    path: /dist
  environment:
    GOOS: linux
    GOARCH: amd64
    CGO_ENABLED: 0
  commands:
  - . /root/.profile
  - cd hypd/server
  - go generate
  - cd ..
  - go build -o /dist/hypd-linux-amd64 .
 - name: build hyp (client) windows-amd64
  image: registry.deadbeef.codes/hyp-build:latest
  pull: always
  volumes:
  - name: publicrelease
    path: /dist
  environment:
    GOOS: windows
    GOARCH: amd64
    CGO_ENABLED: 0
  commands:
  - . /root/.profile
  - cd hyp
  - go build -o /dist/hyp-windows-amd64.exe .
 - name: release
  image: plugins/gitea-release
  pull: always
  volumes:
  - name: publicrelease
    path: /dist
  settings:
    api_key: 
      from_secret: drone_token
    base_url: https://deadbeef.codes
    files: /dist/*
  when:
    event:
    - tag
 volumes:
 - name: publicrelease
  host:
    path: /data/public/build/hyp
--- a/.gitignore
+++ b/.gitignore
@ -1,8 +1,4 @@
 hyp.secret
 *.exe
-hypd/hypd
+hypd
-hyp/hyp
+hyp
 hypd/hypdconfig.json
 hypd/secrets/
 hypd/server/*.o
 env.sh
--- a/20
+++ b/20
@ -1,20 +0,0 @@
 # Build environment container
 # THIS CONTAINER IS NOT FOR RUNNING HYP, IT IS FOR BUILDING IT FROM SOURCE
 FROM debian:stable
 LABEL maintainer="himself@stevenpolley.net"
 # Install build
 RUN apt update -y && \
    apt upgrade -y && \
    apt install -y wget git clang linux-headers-amd64 libbpf-dev
 # Create a few symlinks
 RUN ln -s /usr/bin/llvm-strip-14 /usr/bin/llvm-strip && \
    ln -s /usr/include/x86_64-linux-gnu/asm /usr/include/asm
 # Install golang - Latest at: https://go.dev/dl/
 RUN wget https://go.dev/dl/go1.22.2.linux-amd64.tar.gz && \
    rm -rf /usr/local/go && tar -C /usr/local -xzf go1.22.2.linux-amd64.tar.gz && \
    rm -rf *.tar.gz && \
    echo "export PATH=$PATH:/usr/local/go/bin" >> /root/.profile && . /root/.profile
--- a/253
+++ b/253
@ -1,29 +1,232 @@
-Copyright (c) 2024 Steven Polley 
+GNU GENERAL PUBLIC LICENSE
 Version 3, 29 June 2007
-All rights reserved.
+Copyright © 2007 Free Software Foundation, Inc. <https://fsf.org/>
-Redistribution and use in source and binary forms, with or without
+Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
 modification, are permitted provided that the following conditions are
 met:
-   * Redistributions of source code must retain the above copyright
+Preamble
 notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
 copyright notice, this list of conditions and the following disclaimer
 in the documentation and/or other materials provided with the
 distribution.
   * Neither the name of Steven Polley, hyp, nor the names of its
 contributors may be used to endorse or promote products derived from
 this software without specific prior written permission.
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+The GNU General Public License is a free, copyleft license for software and other kinds of works.
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.
 For the developers' and authors' protection, the GPL clearly explains that there is no warranty for this free software. For both users' and authors' sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.
 Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users' freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.
 Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.
 The precise terms and conditions for copying, distribution and modification follow.
 TERMS AND CONDITIONS
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 END OF TERMS AND CONDITIONS
 How to Apply These Terms to Your New Programs
 If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
 To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
     hyp
     Copyright (C) 2024  steven
     This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
     This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
     You should have received a copy of the GNU General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
 Also add information on how to contact you by electronic and paper mail.
 If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
     hyp  Copyright (C) 2024  steven
     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
     This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
 The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
 You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see <https://www.gnu.org/licenses/>.
 The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read <https://www.gnu.org/philosophy/why-not-lgpl.html>.
--- a/README.md
+++ b/README.md
@ -1,51 +1,36 @@
 # hyp | Hide Your Ports
-[![Build Status](https://drone.stevenpolley.net/api/badges/steven/hyp/status.svg)](https://drone.deadbeef.codes/steven/hyp)
+hyp is a [port knocking](https://www.youtube.com/watch?v=a7VJZEJVhD0) implementation written in Go, using spread-spectrum UDP as an authentication mechanism.  It enables trusted devices to access services over the internet, wherever they are, and without the service being publicly accessible.  The benefit is that the ports are not open publicly on the internet, they won't show in a port scan and are therefore less likely to be attacked by a threat actor. 
-hyp is a [port knocking](https://www.youtube.com/watch?v=a7VJZEJVhD0) implementation written in Go and C.  hyp uses spread-spectrum UDP as an authentication mechanism and enables trusted agents to access services over the internet, wherever they are, and without the service being accessible by others. Your TCP and UDP ports are closed. They will not show in a port scan.  Nobody else can connect to them.  This is particularly useful as [there](https://nvd.nist.gov/vuln/detail/CVE-2024-21888) [have](https://nvd.nist.gov/vuln/detail/CVE-2023-20269) [been](https://nvd.nist.gov/vuln/detail/CVE-2021-26109) [a](https://nvd.nist.gov/vuln/detail/CVE-2024-22394) [few](https://nvd.nist.gov/vuln/detail/CVE-2024-21894) [VPN](https://nvd.nist.gov/vuln/detail/CVE-2024-3400) [gateway](https://nvd.nist.gov/vuln/detail/CVE-2023-27997) [vulnerabilities](https://nvd.nist.gov/vuln/detail/CVE-2024-21762) [over](https://nvd.nist.gov/vuln/detail/CVE-2022-3236) [the](https://nvd.nist.gov/vuln/detail/CVE-2024-21893) [years](https://nvd.nist.gov/vuln/detail/CVE-2022-42475).  I often wonder what's out there and hasn't been discovered.  Why take the chance of leaving your VPN open to the whole internet?  With hyp, you don't have to.  
+hyp provides security through obscurity.  Security through obscurity tends to have a negative connotation, at least in the IT world.  I don't agree with this, but it's prescribed as being bad.  My belief is security through obscurity is a "further step" one can take to eliminate a certain class of threats.  It by no means should be the only mechanism of protection, but instead should be incorporated only as part of a layered defense.  
-Compared to most port knocking daemons, hyp is extremely fast, lightweight and has no dependency on libpcap.  Instead of libpcap, hyp uses eBPF technology which runs in the kernel and only sends data to userspace that's absolutely required.  hyp also provides additional protection against replay and sweep attacks. Each authentic knock sequence is a one time use, and new knock sequences are generated every 30 seconds.  hyp makes use of pre-shared keys and time to calculate an authentic knock sequence on both the client and server. The following process describes how hyp works:
+### Physical World Analogy
-1. The pre-shared key is generated and distributed between both the hyp client and the hyp server. 
+*Scenario:* You drive to the grocery store and you happen to have your laptop computer with you in the car.  You're worried someone may break into your car and steal your laptop, but luckily you have some options to consider before you leave the car to go into the store:
 2. The pre-shared key is run through a sha1-hmac algorithm along with the current system time, this produces the same 160 bits of output on both sides.
 3. The 160 bits is reduced down to 64 bits. This helps protect the key by not revealing the entire output of the hmac... we assume you are transmitting over an untrusted network.
 4. The 64 bits are divided into four 16-bit structures which are typecast to 16-bit unsigned integers. A 16-bit integer can have a value from 0-65535, the same as UDP port numbers. We have four of them now.
 5. Transmit one empty datagram to the knock daemon at a time, one after another using the four integers from the previous calculation as the destination port numbers.
 6. The knock daemon on the firewall verifies the sequence and performs the action of opening the firewall port configured for the client to let them in while remaining closed to everyone else. 
 7. The client connects to their application which has its own authentication, authorization, and auditing. 
-![Authentic Knock Sequence](https://code.stevenpolley.net/steven/hyp/raw/branch/main/docs/authentic-knock-sequence-calculation.png)
+1. You could leave your laptop sitting where it is, on the passenger seat
 2. You could conceal the laptop from outside view
-### Runtime Requirements
+Option 1 is the default option and is analogous to having your services internet-accessible.  Option 2 is similar to what port knocking is trying to achieve.  In either case, there still exists some risk that your laptop will be stolen in a random bip, which is why port knocking should not be your sole focus when it comes to your security strategy and should instead be something you can use to reduce the risk of drive-by attacks.
-Port knocking clients have minimal requirements and can run on x86, ARM, MIPS, PowerPC, IBM390, or RISC-V. Currently only supported OS's are Linux and Windows, with support for Android planned to be added in the future.
+### Brute Force Simple Overview
-The port knocking daemon has more strict requirements and is only available for Linux. It requires the kernel be built with CONFIG_DEBUG_INFO_BTF, which most major distributions have out of the box.  Additionally, hypd has some network requirements.  hypd is only expected to work on ethernet networks with IPv4.
+To put it in simple terms, hyp requires an adversary to guess a number between 1 and 18,446,744,073,709,551,615 within 90 seconds.  Each guess attempt requires four ordered UDP datagrams to be transmitted.  The requirement for correct order on arrival, multiple network paths, and network latency means the datagrams have to be spaced out and transmitted one at a time with time spent waiting before the next datagram is sent.  An odd but perhaps useful implication of this is that the further away you are (higher latency), the less reliable guess attempts you can make before the number changes.  With 20ms of latency, you can perform a maximum of 4,500 reliable guesses.  With 100ms of latency, you can only perform a maximum of 900 reliable guesses.
-Once you get the runtime requirements sorted, be sure to check out the hyp and hypd directories of the repository for README information for how to use hyp.    
+### Protection Against Replay Attacks
-### Build Requirements
+Most port-knocking implementations are susceptible to replay attacks, a network operator could intercept your authentic knock sequence and then replay the sequence.  hyp works around this by using 64-bit time-based one-time tokens.  The 64 bits of the token are then divided into 4x16-bit unsigned integers representing a port number.  
-Pre-built binaries for configurations I've tested are available on the [releases page](https://deadbeef.codes/steven/hyp/releases). This will likely run in many CPU architectures I haven't tested yet though. 
+hyp supports a clock skew of up to 30 seconds between client and server.  
-To build this yourself, you will need Linux with packages for: git, clang, linux-headers-<architecture> libbpf-dev and golang. Check out the [Dockerfile](https://deadbeef.codes/steven/hyp/src/branch/main/Dockerfile) as a reference for how the build environment for official releases is configured. Once the environment is ready, you can clone the repo and build.
+### TBD: Protection Against Sweeping Attacks
-```sh
+~~hyp protects against sweeping attacks where an adversary modulates over the entire port range multiple times by ensuring the authentic knock sequence is strict and ordered correctly.  If the first port is guessed, but the next pack arrives and is the incorrect second port in the sequence, the progress gets reset.~~
 # Clone repository
 git clone https://deadbeef.codes/steven/hyp.git
-# Build eBPF program
+### Known Weaknesses
 cd hyp/hypd/server
 go generate
-# Build knock daemon
+* Lossy networks can result in the knock sequence failing
-cd ..
+* Networks with latency > 500ms can result in the knock sequence failing if packets arrive out of order
 go build -o hypd .
 chmod +x hypd
 # Run knock daemon and show help
 ./hypd -h
 ```
 ### References
--- a/client/README.md
+++ b/client/README.md
@ -0,0 +1,9 @@
 # hyp-client
 The client expects there to be a file named hyp.secret in the same directory.  This file is generated by the hypd server using ./hypd generatesecret.  
 ```bash
 # Example Usage
 # ./hyp-client <server>
 ./hyp-client 192.168.50.5
 ```
--- a/client/go.mod
+++ b/client/go.mod
@ -0,0 +1,5 @@
 module deadbeef.codes/steven/hyp-client
 go 1.22.0
 require deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee
--- a/client/go.sum
+++ b/client/go.sum
@ -0,0 +1,2 @@
 deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee h1:r9xdoIGPhc/tXzyOj+lCDb+ReYa/zkysqK3ZRCqpyIU=
 deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee/go.mod h1:NANpGD/K+nDkW+bkomchwaXMrsXWza58+8AR7Sau3fs=
--- a/client/main.go
+++ b/client/main.go
@ -0,0 +1,51 @@
 package main
 import (
 	"fmt"
 	"log"
 	"net"
 	"os"
 	"time"
 	"deadbeef.codes/steven/hyp/otphyp"
 )
 // MaxNetworkLatency specifies the number of milliseconds
 // A packet-switched network... more like "race condition factory"
 const MaxNetworkLatency = 500
 func main() {
 	// validate number of input arguments
 	if len(os.Args) < 2 {
 		usage()
 		os.Exit(1)
 	}
 	// load secret and generate ports using secret and current time
 	secretBytes, err := os.ReadFile("hyp.secret")
 	if err != nil {
 		log.Fatalf("failed to read file 'hyp.secret': %v", err)
 	}
 	sharedSecret := string(secretBytes)
 	ports, err := otphyp.GeneratePorts(sharedSecret, time.Now())
 	if err != nil {
 		log.Fatalf("failed to generate ports from shared secret: %v", err)
 	}
 	// Transmit
 	fmt.Println("Transmitting knock sequence:", ports)
 	for _, port := range ports {
 		conn, _ := net.Dial("udp", fmt.Sprintf("%s:%d", os.Args[1], port))
 		conn.Write([]byte{0})
 		conn.Close()
 		time.Sleep(time.Millisecond * MaxNetworkLatency)
 	}
 }
 func usage() {
 	fmt.Println(os.Args[0], "usage")
 	fmt.Println("Supply an ordered list of ports to knock")
 	fmt.Println(os.Args[0], "server")
 }
--- a/docs/authentic-knock-sequence-calculation.png
+++ b/docs/authentic-knock-sequence-calculation.png
--- a/go.mod
+++ b/go.mod
@ -1,15 +0,0 @@
 module deadbeef.codes/steven/hyp
 go 1.22.0
 require (
 	github.com/cilium/ebpf v0.14.0
 	github.com/spf13/cobra v1.8.0
 )
 require (
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	golang.org/x/exp v0.0.0-20240416160154-fe59bbe5cc7f // indirect
 	golang.org/x/sys v0.19.0 // indirect
 )
--- a/go.sum
+++ b/go.sum
@ -1,26 +0,0 @@
 github.com/cilium/ebpf v0.14.0 h1:0PsxAjO6EjI1rcT+rkp6WcCnE0ZvfkXBYiMedJtrSUs=
 github.com/cilium/ebpf v0.14.0/go.mod h1:DHp1WyrLeiBh19Cf/tfiSMhqheEiK8fXFZ4No0P1Hso=
 github.com/cpuguy83/go-md2man/v2 v2.0.3/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
 github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/spf13/cobra v1.8.0 h1:7aJaZx1B85qltLMc546zn58BxxfZdR/W22ej9CFoEf0=
 github.com/spf13/cobra v1.8.0/go.mod h1:WXLWApfZ71AjXPya3WOlMsY9yMs7YeiHhFVlvLyhcho=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 golang.org/x/exp v0.0.0-20240416160154-fe59bbe5cc7f h1:99ci1mjWVBWwJiEKYY6jWa4d2nTQVIEhZIptnrVb1XY=
 golang.org/x/exp v0.0.0-20240416160154-fe59bbe5cc7f/go.mod h1:/lliqkxwWAhPjf5oSOIJup2XcqJaw8RGS6k3TGEc7GI=
 golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
 golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/go.work
+++ b/go.work
@ -0,0 +1,7 @@
 go 1.22.0
 use (
 	./client
 	./otphyp
 	./server
 )
--- a/hyp/README.md
+++ b/hyp/README.md
@ -1,34 +0,0 @@
 # hyp | Hide Your Ports Client
 The hyp client is used on machines to perform an authentic knock sequence.  
 ### Usage
 You can use -h to get help for hyp and all its commands.  When figuring out how to do something, -h is your friend.
 ```bash
 # Get general hyp help
 ./hyp -h
 # Get help specific to the hyp knock command
 ./hyp knock -h
 ```
 In order to use the hyp client, it must have the secret.  Secrets are generated by hypd, the knock daemon.  See the hypd README.md file for more information about generating secrets.
 Once you have the secret, you can then perform an authentic knock sequence to a server.
 ```bash
 # Assumes secret is in file named my-first-secret in same directory
 ./hyp knock 8.69.4.20 --secret my-first-secret
 # If you omit --secret, hyp will look for a file named hyp.secret
 ./hyp knock 8.69.4.20
 ```
 This will perform a single one-shot knock sequence and then hyp will exit.  You can also run hyp in a persistent mode where it will perform an authentic knock sequence at a specified interval.
 ```bash
 # Performs an authentic knock sequence every 45 minutes
 ./hyp knock 8.69.4.20 --refreshtime=45
 ```
--- a/hyp/cmd/knock.go
+++ b/hyp/cmd/knock.go
@ -1,98 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"encoding/base32"
 	"fmt"
 	"log"
 	"net"
 	"os"
 	"time"
 	"deadbeef.codes/steven/hyp/otphyp"
 	"github.com/spf13/cobra"
 )
 // knockCmd represents the knock command
 var knockCmd = &cobra.Command{
 	Use:   "knock <hypServer>",
 	Short: "Sends an authenticated knock sequence to the server specified",
 	Long: `Runs the hyp client and performs an authentic knock sequence
 against the server provided.  
 Example usage:
 	hyp knock <hypServer>
 	hyp knock hyp.deadbeef.codes
 	hyp knock 10.69.4.20
 	`,
 	Args: cobra.ExactArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
 		// load secret and generate ports using secret and current time
 		secretFilePath, err := cmd.Flags().GetString("secret")
 		if err != nil {
 			panic(fmt.Errorf("failed to parse command flag 'secret': %w", err))
 		}
 		maxJitter, err := cmd.Flags().GetInt("maxjitter")
 		if err != nil {
 			panic(fmt.Errorf("failed to parse command flag 'maxjitter': %w", err))
 		}
 		if maxJitter < 1 || maxJitter > 1500 {
 			panic(fmt.Errorf("maxjitter must be value between 1 and 1500"))
 		}
 		refreshTime, err := cmd.Flags().GetInt("refreshtime")
 		if err != nil {
 			panic(fmt.Errorf("failed to parse command flag 'refreshtime': %w", err))
 		}
 		secretBytes, err := os.ReadFile(secretFilePath)
 		if err != nil {
 			log.Fatalf("failed to read file 'hyp.secret': %v", err)
 		}
 		decodedSecret, err := base32.StdEncoding.DecodeString(string(secretBytes))
 		if err != nil {
 			log.Fatalf("failed to base32 decode secret '%s': %v", secretFilePath, err)
 		}
 		for {
 			ports, err := otphyp.GeneratePorts(decodedSecret, time.Now())
 			if err != nil {
 				log.Fatalf("failed to generate ports from shared secret: %v", err)
 			}
 			// Transmit
 			for _, port := range ports {
 				fmt.Printf("knock | %s:%d\n", args[0], port)
 				conn, _ := net.Dial("udp", fmt.Sprintf("%s:%d", args[0], port))
 				conn.Write([]byte{0})
 				conn.Close()
 				time.Sleep(time.Millisecond * time.Duration(maxJitter)) // TBD: Make this configurable with flag (maxJitter)
 			}
 			if refreshTime < 1 {
 				break
 			}
 			sleepDuration := time.Minute * time.Duration(refreshTime)
 			fmt.Printf("waiting until: %s...\n", time.Now().Add(sleepDuration).Format("15:04:05"))
 			time.Sleep(sleepDuration)
 		}
 	},
 }
 func init() {
 	rootCmd.AddCommand(knockCmd)
 	knockCmd.PersistentFlags().String("secret", "hyp.secret", "Path to the file containing the hyp secret")
 	knockCmd.PersistentFlags().Int("maxjitter", 200, "Specifies the time in milliseconds between transmissions while performing the knock sequence")
 	knockCmd.PersistentFlags().Int("refreshtime", 0, "If specified, the hyp client will run persistently and send a full knock sequence at this interval in minutes")
 }
--- a/hyp/cmd/root.go
+++ b/hyp/cmd/root.go
@ -1,33 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"os"
 	"github.com/spf13/cobra"
 )
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
 	Use:   "hyp",
 	Short: "Hide Your Ports Client",
 	Long: `Hide Your Ports (hyp) is a combination of Port Knocking and One Time Passwords:
 hyp uses a pre-shared key distributed between the server and client, as well as the time
 to calculate a unique authentic knock sequence which is only valid for 90 seconds.`,
 }
 // Execute adds all child commands to the root command and sets flags appropriately.
 // This is called by main.main(). It only needs to happen once to the rootCmd.
 func Execute() {
 	err := rootCmd.Execute()
 	if err != nil {
 		os.Exit(1)
 	}
 }
 func init() {
 }
--- a/hyp/main.go
+++ b/hyp/main.go
@ -1,10 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package main
 import "deadbeef.codes/steven/hyp/hyp/cmd"
 func main() {
 	cmd.Execute()
 }
--- a/hypd/README.md
+++ b/hypd/README.md
@ -1,47 +0,0 @@
 # hypd | Hide Your Ports Daemon
 hypd is the pork knocking daemon which listens for incoming authentic knock sequences.  When it sees an authentic knock sequence, it then performs an action.
 ### Usage
 You can use -h to get help for hypd and all its commands.  When figuring out how to do something, -h is your friend.
 ```bash
 # Get general hypd help
 ./hypd -h
 # Get help specific to the hypd generate command
 ./hypd generate -h
 ```
 Running hypd requires generating secrets which are then shared with hyp clients.  hypd is used to generate these secrets, and it's recommended you create a directory just for hyp secrets.
 ```bash
 # Example: create a directory named secrets
 mkdir -p secrets
 # Then generate a secret file in this directory
 ./hypd generate secret > secrets/my-first-secret
 ```
 It's recommended you generate a secret for each trusted agent so you can granularly control revocation just by removing a secret file from the secrets directory.
 Running hypd requires specifying a configuration file.  It's recommended you generate the default configuration file and then edit it afterwards.
 ```bash
 # Create a default configuration file
 ./hypd generate defaultconfig > hypd.conf
 ```
 Make sure you take the time to review the hypd.conf file and edit it to your liking, this is the most important step.  Make sure the network interface is correct, hypd will make an educated guess based on the interfaces your system has.
 If you have complex requirements, you can make the successAction/timeoutAction an external shell script.  If you want to disable the timeoutAction, you can set timeoutSeconds to 0.
 Once you have set your config file, you can finally run hypd.
 ```bash
 # As root or sudo, specify the configuration file
 sudo ./hypd server hypd.conf
 ```
 If you encounter any errors while trying to run, address those.  If not, then you're now listening for incoming authentic knock sequences.  Make sure you distribute the secret to the client.  
--- a/hypd/cmd/defaultconfig.go
+++ b/hypd/cmd/defaultconfig.go
@ -1,34 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"encoding/json"
 	"fmt"
 	"deadbeef.codes/steven/hyp/hypd/configuration"
 	"github.com/spf13/cobra"
 )
 // defaultconfigCmd represents the defaultconfig command
 var defaultconfigCmd = &cobra.Command{
 	Use:   "defaultconfig",
 	Short: "Prints the default configuration to stdout",
 	Long: `The default configuration is used if one is not set.  The default configuration
 can be used as a reference to build your own. 
 hypd generate defaultconfig | tee hypdconfig.json`,
 	Run: func(cmd *cobra.Command, args []string) {
 		config := configuration.DefaultConfig()
 		b, err := json.MarshalIndent(config, "", "    ")
 		if err != nil {
 			panic(fmt.Errorf("failed to marshal default configuration to json (this should never happen): %v", err))
 		}
 		fmt.Println(string(b))
 	},
 }
 func init() {
 	generateCmd.AddCommand(defaultconfigCmd)
 }
--- a/hypd/cmd/generate.go
+++ b/hypd/cmd/generate.go
@ -1,18 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"github.com/spf13/cobra"
 )
 // generateCmd represents the generate command
 var generateCmd = &cobra.Command{
 	Use:   "generate",
 	Short: "Generates configuration for Hide Your Ports",
 }
 func init() {
 	rootCmd.AddCommand(generateCmd)
 }
--- a/hypd/cmd/root.go
+++ b/hypd/cmd/root.go
@ -1,33 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"os"
 	"github.com/spf13/cobra"
 )
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
 	Use:   "hypd",
 	Short: "Hide Your Ports Daemon",
 	Long: `Hide Your Ports (hyp) is a combination of Port Knocking and One Time Passwords:
 hyp uses a pre-shared key distributed between the server and client, as well as the time
 to calculate a unique authentic knock sequence which is only valid for 90 seconds.`,
 }
 // Execute adds all child commands to the root command and sets flags appropriately.
 // This is called by main.main(). It only needs to happen once to the rootCmd.
 func Execute() {
 	err := rootCmd.Execute()
 	if err != nil {
 		os.Exit(1)
 	}
 }
 func init() {
 }
--- a/hypd/cmd/secret.go
+++ b/hypd/cmd/secret.go
@ -1,34 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"fmt"
 	"deadbeef.codes/steven/hyp/otphyp"
 	"github.com/spf13/cobra"
 )
 // secretCmd represents the secret command
 var secretCmd = &cobra.Command{
 	Use:   "secret",
 	Short: "Generates a secret key for hyp",
 	Long: `Generates a secret for hyp which should be distributed to both the
 server and to clients.  
 Example:
 hypd generate secret > hyp.secret`,
 	Run: func(cmd *cobra.Command, args []string) {
 		sharedSecret, err := otphyp.GenerateSecret()
 		if err != nil {
 			panic(fmt.Errorf("failed to generate shared secret: %w", err))
 		}
 		fmt.Println(sharedSecret)
 	},
 }
 func init() {
 	generateCmd.AddCommand(secretCmd)
 }
--- a/hypd/cmd/server.go
+++ b/hypd/cmd/server.go
@ -1,67 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package cmd
 import (
 	"fmt"
 	"os/user"
 	"deadbeef.codes/steven/hyp/hypd/configuration"
 	"deadbeef.codes/steven/hyp/hypd/server"
 	"github.com/spf13/cobra"
 )
 // serverCmd represents the server command
 var serverCmd = &cobra.Command{
 	Use:   "server <configFilePath>",
 	Args:  cobra.ExactArgs(1),
 	Short: "Runs hyp in server mode",
 	Long: `Runs the hyp server and begins watching for authentic knock sequences.
 Before running this command, you must first have a configuration file.  You can
 generate a configuration file with:  hypd generate defaultconfig > hypdconfig.json
 You should then edit the config file to meet your needs.  
 In addition to a config file you will need to generate pre-shared keys: 
 mkdir -p ./secrets
 hypd generate secret > secrets/mykey.secret
 Example Usage:
 	# Use config file in local directory
 	hypd server hypdconfig.json
 	# Use config file in /etc/hyp/
 	hypd server /etc/hyp/hypdconfig.json
 	`,
 	Run: func(cmd *cobra.Command, args []string) {
 		currentUser, err := user.Current()
 		if err != nil {
 			panic(fmt.Errorf("could not determine current user: %w", err))
 		}
 		if currentUser.Username != "root" {
 			fmt.Println("WARNING: It's recommended you run this as root, but will proceed anyways...")
 		}
 		hypdConfiguration, err := configuration.LoadConfiguration(args[0])
 		if err != nil {
 			panic(fmt.Errorf("failed to load configuration file '%s': %w", args[0], err))
 		}
 		secrets, err := configuration.LoadSecrets(hypdConfiguration.PreSharedKeyDirectory)
 		if err != nil {
 			panic(fmt.Errorf("failed to load secrets from directory '%s': %w", hypdConfiguration.PreSharedKeyDirectory, err))
 		}
 		err = server.PacketServer(hypdConfiguration, secrets)
 		if err != nil {
 			panic(fmt.Errorf("failed to start packet server: %w", err))
 		}
 	},
 }
 func init() {
 	rootCmd.AddCommand(serverCmd)
 }
--- a/hypd/configuration/configuration.go
+++ b/hypd/configuration/configuration.go
@ -1,75 +0,0 @@
 package configuration
 import (
 	"encoding/json"
 	"fmt"
 	"os"
 )
 type HypdConfiguration struct {
 	NetworkInterface      string `json:"networkInterface"`      // The network interface that the eBPF program attaches to
 	PreSharedKeyDirectory string `json:"preSharedKeyDirectory"` // hypd will load all *.secret files from this directory
 	SuccessAction         string `json:"successAction"`         // The action to take for a successful knock, each argument is a separate string
 	TimeoutSeconds        int    `json:"timeoutSeconds"`        // If > 0, once a knock sequence has been successful this value will count down and when it reaches 0, it will perform the TimeoutAction on the client
 	TimeoutAction         string `json:"timeoutAction"`         // The action to take after TimeoutSeconds has elapsed.  only applicable if TimeoutSeconds is > 0, each argument is a separate string
 }
 // LoadConfiguration opens and parses the configuration file into a HypdConfiguration struct
 // If a configFilePath is not specified, it will search in common locations
 func LoadConfiguration(configFilePath string) (*HypdConfiguration, error) {
 	if configFilePath == "" {
 		commonLocations := []string{"hypdconfig.json",
 			"~/.hypdconfig.json",
 			"~/.config/hyp/hypdConfig.json",
 			"/etc/hyp/hypdConfig.json",
 			"/usr/local/etc/hyp/hypdConfig.json",
 		}
 		for _, loc := range commonLocations {
 			if _, err := os.Stat(loc); err == nil {
 				configFilePath = loc
 				break
 			}
 		}
 	}
 	// if it's still not found after checking common locations, load default config
 	if configFilePath == "" {
 		fmt.Println("no configuration file found.  You can generate one with ./hypd generate defaultconfig | tee hypdconfig.json")
 		return DefaultConfig(), nil
 	}
 	// Otherwise if a config is specified, try to load it and error if it fails.
 	// I think it's better to error here if a config was intended and failed
 	// rather than failing back to default
 	b, err := os.ReadFile(configFilePath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read config file '%s': %w", configFilePath, err)
 	}
 	hypdConfiguration := &HypdConfiguration{}
 	err = json.Unmarshal(b, hypdConfiguration)
 	if err != nil {
 		return nil, fmt.Errorf("failed to unmarshal config file json to HypdConfiguration (is the config file malformed?): %w", err)
 	}
 	return hypdConfiguration, nil
 }
 func DefaultConfig() *HypdConfiguration {
 	var ifaceString string
 	iface, err := getDefaultNIC()
 	if err == nil {
 		ifaceString = iface.Name
 	} else {
 		ifaceString = "enp0s3" // fallback to fixed value
 	}
 	return &HypdConfiguration{
 		NetworkInterface:      ifaceString,
 		PreSharedKeyDirectory: "./secrets/",
 		SuccessAction:         "iptables -A INPUT -p tcp -s %s --dport 22 -j ACCEPT",
 		TimeoutSeconds:        1440,
 		TimeoutAction:         "iptables -D INPUT -p tcp -s %s --dport 22 -j ACCEPT",
 	}
 }
--- a/hypd/configuration/defaultNIC.go
+++ b/hypd/configuration/defaultNIC.go
@ -1,81 +0,0 @@
 package configuration
 import (
 	"fmt"
 	"net"
 )
 // QoL feature to try and detect the best NIC for hyp
 func getDefaultNIC() (*net.Interface, error) {
 	ifaces, err := net.Interfaces()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get network interfaces on this system: %v", err)
 	}
 	if len(ifaces) < 1 {
 		return nil, fmt.Errorf("this system has no network interfaces: %v", err)
 	}
 	// Just pick one to start
 	selectedIface := ifaces[0]
 	filteredIfaces := make([]net.Interface, 0)
 	// Check for ethernet addresses
 	for _, iface := range ifaces {
 		if len(iface.HardwareAddr) == 6 {
 			selectedIface = iface
 			filteredIfaces = append(filteredIfaces, iface)
 		}
 	}
 	ifaces = filteredIfaces
 	filteredIfaces = make([]net.Interface, 0)
 	// Check for interfaces that are up and not loopbacks
 	for _, iface := range ifaces {
 		if iface.Flags&net.FlagUp != 0 && iface.Flags&net.FlagRunning != 0 && iface.Flags&net.FlagLoopback == 0 {
 			selectedIface = iface
 			filteredIfaces = append(filteredIfaces, iface)
 		}
 	}
 	ifaces = filteredIfaces
 	filteredIfaces = make([]net.Interface, 0)
 	// Check for interfaces that have IPv4 addresses assigned
 	for _, iface := range ifaces {
 		addresses, err := iface.Addrs()
 		if err != nil {
 			continue
 		}
 		for _, address := range addresses {
 			ip, _, err := net.ParseCIDR(address.String())
 			if err != nil {
 				continue
 			}
 			if ip.To4() != nil {
 				selectedIface = iface
 				filteredIfaces = append(filteredIfaces, iface)
 			}
 		}
 	}
 	ifaces = filteredIfaces
 	filteredIfaces = nil
 	// Check for interfaces that have non RFC1918 addresses assigned
 	for _, iface := range ifaces {
 		addresses, err := iface.Addrs()
 		if err != nil {
 			continue
 		}
 		for _, address := range addresses {
 			ip, _, err := net.ParseCIDR(address.String())
 			if err != nil {
 				continue
 			}
 			if !ip.IsPrivate() {
 				selectedIface = iface
 			}
 		}
 	}
 	return &selectedIface, nil // TBD
 }
--- a/hypd/configuration/secrets.go
+++ b/hypd/configuration/secrets.go
@ -1,49 +0,0 @@
 package configuration
 import (
 	"encoding/base32"
 	"fmt"
 	"io/fs"
 	"os"
 	"path/filepath"
 )
 var secrets [][]byte
 // LoadSecrets processes all files within the specified directory and attempts to
 // convert the file contents to secrets to by used by hypd
 func LoadSecrets(preSharedKeyDirectory string) ([][]byte, error) {
 	secrets = make([][]byte, 0)
 	err := filepath.Walk(preSharedKeyDirectory, processSecretFile)
 	if err != nil {
 		return nil, fmt.Errorf("failed to walk directory '%s': %w", preSharedKeyDirectory, err)
 	}
 	return secrets, nil
 }
 // processSecretFile is called against each file in the preSharedKeyDirectory
 // It reads each file and attemts to base32 decode their contents
 func processSecretFile(path string, info fs.FileInfo, err error) error {
 	if err != nil {
 		return fmt.Errorf("failed to process file '%s': %w", path, err)
 	}
 	if info.IsDir() {
 		return nil
 	}
 	secretBytes, err := os.ReadFile(path)
 	if err != nil {
 		return fmt.Errorf("failed to read file '%s': %w", path, err)
 	}
 	decodedSecret, err := base32.StdEncoding.DecodeString(string(secretBytes))
 	if err != nil {
 		return fmt.Errorf("failed to base32 decode secret '%s': %w", path, err)
 	}
 	secrets = append(secrets, decodedSecret)
 	return nil
 }
--- a/hypd/examples/fortigate/hypdconfig.json
+++ b/hypd/examples/fortigate/hypdconfig.json
@ -1,7 +0,0 @@
 {
    "networkInterface": "enp0s3",
    "preSharedKeyDirectory": "./secrets/",
    "successAction": "./examples/fortigate/openfortigate.sh %s",
    "timeoutSeconds": 0,
    "timeoutAction": ""
 }
--- a/hypd/examples/fortigate/openfortigate.sh
+++ b/hypd/examples/fortigate/openfortigate.sh
@ -1,33 +0,0 @@
 #!/bin/bash
 # Make sure you have environment variables set for FORTIGATE_MGMT_URL, FORTIGATE_API_TOKEN and FORTIGATE_ADDRESS_OBJECT_GROUP
 # Examples:
 export FORTIGATE_MGMT_URL="https://69.4.20.10:8443" 
 export FORTIGATE_API_KEY="5fkwkkzgQ4s31bdH60qsxxfN093zgt"
 export FORTIGATE_ADDRESS_OBJECT_GROUP="hyp-allowed-clients"
 if [ $# -lt 1 ]; then
    echo "Usage: $0 <srcip>"
    exit 1
 fi
 echo $FORTIGATE_MGMT_URL
 echo $1
 # Create the address object
 curl "$FORTIGATE_MGMT_URL/api/v2/cmdb/firewall/address?datasource=1" \
    -X "POST" \
    -H "Authorization: Bearer $FORTIGATE_API_KEY" \
    -H "Content-Type: application/json" \
    --data-raw "{\"name\":\"hyp_$1\",\"subnet\":\"$1/32\",\"color\":\"0\"}" \
    --insecure # LOL - remove this if you want, but I want this to be easy for noobs
 # Add to address object group
 curl "$FORTIGATE_MGMT_URL/api/v2/cmdb/firewall/addrgrp/$FORTIGATE_ADDRESS_OBJECT_GROUP/member" \
    -X "POST" \
    -H "Authorization: Bearer $FORTIGATE_API_KEY" \
    -H "Content-Type: application/json" \
    --data-raw "{\"name\":\"hyp_$1\"}" \
    --insecure # And here too
--- a/hypd/examples/openwrt-wireguard/README.md
+++ b/hypd/examples/openwrt-wireguard/README.md
@ -1,12 +0,0 @@
 # Using hyp with OpenWrt Wireguard
 This example case is to deploy hypd on OpenWrt to open up access to the WireGuard VPN service.
 hyp utilizes eBPF technology to ensure runtime overhead is extremely small (in a way, but in a way not).  Most Linux distributions have support for this out of the box, however OpenWrt does not.  OpenWrt has a very stripped down, purpose-configured kernel and does not have the requirements built in to run hyp.  
 The good news is, you can build OpenWrt yourself and configure it with the requirements.  Follow the directions at this page: https://openwrt.org/docs/guide-developer/toolchain/use-buildsystem
 When you run *make menuconfig*, make sure you check off *Enable additional BTF type information* which is also known as CONFIG_KERNEL_DEBUG_INFO_BTF.  This is required to support eBPF CO:RE. 
 ![Kernel Config](https://deadbeef.codes/steven/hyp/raw/branch/main/hypd/examples/openwrt-wireguard/kernel_config.png)
--- a/hypd/examples/openwrt-wireguard/closewireguard.sh
+++ b/hypd/examples/openwrt-wireguard/closewireguard.sh
@ -1,14 +0,0 @@
 #!/bin/sh
 if [ $# -lt 1 ]; then
    echo "Usage: $0 <srcip>"
    exit 1
 fi
 # Can't use dots in rule name, so swap for underscores
 rulename="hypd_${1//./_}_wireguard"
 # Configure the rule in OpenWRT's uci interface
 uci delete firewall.$rulename
 uci commit firewall
 service firewall restart
--- a/hypd/examples/openwrt-wireguard/hypdconfig.json
+++ b/hypd/examples/openwrt-wireguard/hypdconfig.json
@ -1,7 +0,0 @@
 {
    "networkInterface": "enp0s3",
    "preSharedKeyDirectory": "./secrets/",
    "successAction": "./examples/openwrt-wireguard/openwireguard.sh %s",
    "timeoutSeconds": 1440,
    "timeoutAction": "./examples/openwrt-wireguard/closewireguard.sh %s"
 }
--- a/hypd/examples/openwrt-wireguard/kernel_config.png
+++ b/hypd/examples/openwrt-wireguard/kernel_config.png
--- a/hypd/examples/openwrt-wireguard/openwireguard.sh
+++ b/hypd/examples/openwrt-wireguard/openwireguard.sh
@ -1,24 +0,0 @@
 #!/bin/sh
 if [ $# -lt 1 ]; then
    echo "Usage: $0 <srcip>"
    exit 1
 fi
 # Can't use dots in rule name, so swap for underscores
 # example: 10.69.69.100 changes to hypd_10_69_69_100_wireguard
 rulename="hypd_${1//./_}_wireguard"
 # Configure the rule in OpenWRT's uci interface
 uci set firewall.$rulename=redirect
 uci set firewall.$rulename.dest=lan
 uci set firewall.$rulename.target=DNAT
 uci set firewall.$rulename.name=$rulename
 uci set firewall.$rulename.src=wan
 uci set firewall.$rulename.src_dport=51820
 uci set firewall.$rulename.dest_ip=10.0.100.1
 uci set firewall.$rulename.dest_port=51820
 uci set firewall.$rulename.src_ip=$1
 uci add_list firewall.$rulename.proto=udp
 uci commit firewall
 service firewall restart
--- a/hypd/main.go
+++ b/hypd/main.go
@ -1,10 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package main
 import "deadbeef.codes/steven/hyp/hypd/cmd"
 func main() {
 	cmd.Execute()
 }
--- a/hypd/server/README.md
+++ b/hypd/server/README.md
@ -1,30 +0,0 @@
 # hypd server
 hypd is the port knocking daemon which runs on an edge device connecting to an untrusted network.  Leveraging eBPF's XDP hook point, it extracts header information directly and sends to userspace the specific information required.  This method is faster than alternative methods such as using libpcap.  
 ### eBPF
 The hyp_bpf.c program can be recompiled using go generate.
 ```bash
 # Debian: sudo apt install git clang linux-headers-amd64 libbpf-dev
 go generate .
 ```
 ### Generating vmlinux.h
 vmlinux.h is included in hyp_bpf.c and can be regenerated with bpftool.
 ```bash
 # Debian: sudo apt install bpftool
 sudo bpftool btf dump file /sys/kernel/btf/vmlinux format c > ../headers/vmlinux.h
 ```
 ### Building hypd
 hypd has no CGO dependencies and so can run on musl systems as well.  
 ```bash
 # To ensure it can run on  systems don't use CGO
 CGO_ENABLED=0 go build .
 ```
--- a/hypd/server/bpf_endian.h
+++ b/hypd/server/bpf_endian.h
@ -1,100 +0,0 @@
 // Code lifted from the folks at Cilium from ebpf-go repo
 #ifndef __BPF_ENDIAN__
 #define __BPF_ENDIAN__
 /*
 * Isolate byte #n and put it into byte #m, for __u##b type.
 * E.g., moving byte #6 (nnnnnnnn) into byte #1 (mmmmmmmm) for __u64:
 * 1) xxxxxxxx nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx
 * 2) nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx 00000000
 * 3) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn
 * 4) 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn 00000000
 */
 #define ___bpf_mvb(x, b, n, m) ((__u##b)(x) << (b-(n+1)*8) >> (b-8) << (m*8))
 #define ___bpf_swab16(x) ((__u16)(			\
 			  ___bpf_mvb(x, 16, 0, 1) |	\
 			  ___bpf_mvb(x, 16, 1, 0)))
 #define ___bpf_swab32(x) ((__u32)(			\
 			  ___bpf_mvb(x, 32, 0, 3) |	\
 			  ___bpf_mvb(x, 32, 1, 2) |	\
 			  ___bpf_mvb(x, 32, 2, 1) |	\
 			  ___bpf_mvb(x, 32, 3, 0)))
 #define ___bpf_swab64(x) ((__u64)(			\
 			  ___bpf_mvb(x, 64, 0, 7) |	\
 			  ___bpf_mvb(x, 64, 1, 6) |	\
 			  ___bpf_mvb(x, 64, 2, 5) |	\
 			  ___bpf_mvb(x, 64, 3, 4) |	\
 			  ___bpf_mvb(x, 64, 4, 3) |	\
 			  ___bpf_mvb(x, 64, 5, 2) |	\
 			  ___bpf_mvb(x, 64, 6, 1) |	\
 			  ___bpf_mvb(x, 64, 7, 0)))
 /* LLVM's BPF target selects the endianness of the CPU
 * it compiles on, or the user specifies (bpfel/bpfeb),
 * respectively. The used __BYTE_ORDER__ is defined by
 * the compiler, we cannot rely on __BYTE_ORDER from
 * libc headers, since it doesn't reflect the actual
 * requested byte order.
 *
 * Note, LLVM's BPF target has different __builtin_bswapX()
 * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
 * in bpfel and bpfeb case, which means below, that we map
 * to cpu_to_be16(). We could use it unconditionally in BPF
 * case, but better not rely on it, so that this header here
 * can be used from application and BPF program side, which
 * use different targets.
 */
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 # define __bpf_ntohs(x)			__builtin_bswap16(x)
 # define __bpf_htons(x)			__builtin_bswap16(x)
 # define __bpf_constant_ntohs(x)	___bpf_swab16(x)
 # define __bpf_constant_htons(x)	___bpf_swab16(x)
 # define __bpf_ntohl(x)			__builtin_bswap32(x)
 # define __bpf_htonl(x)			__builtin_bswap32(x)
 # define __bpf_constant_ntohl(x)	___bpf_swab32(x)
 # define __bpf_constant_htonl(x)	___bpf_swab32(x)
 # define __bpf_be64_to_cpu(x)		__builtin_bswap64(x)
 # define __bpf_cpu_to_be64(x)		__builtin_bswap64(x)
 # define __bpf_constant_be64_to_cpu(x)	___bpf_swab64(x)
 # define __bpf_constant_cpu_to_be64(x)	___bpf_swab64(x)
 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 # define __bpf_ntohs(x)			(x)
 # define __bpf_htons(x)			(x)
 # define __bpf_constant_ntohs(x)	(x)
 # define __bpf_constant_htons(x)	(x)
 # define __bpf_ntohl(x)			(x)
 # define __bpf_htonl(x)			(x)
 # define __bpf_constant_ntohl(x)	(x)
 # define __bpf_constant_htonl(x)	(x)
 # define __bpf_be64_to_cpu(x)		(x)
 # define __bpf_cpu_to_be64(x)		(x)
 # define __bpf_constant_be64_to_cpu(x)  (x)
 # define __bpf_constant_cpu_to_be64(x)  (x)
 #else
 # error "Fix your compiler's __BYTE_ORDER__?!"
 #endif
 #define bpf_htons(x)				\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_htons(x) : __bpf_htons(x))
 #define bpf_ntohs(x)				\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_ntohs(x) : __bpf_ntohs(x))
 #define bpf_htonl(x)				\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_htonl(x) : __bpf_htonl(x))
 #define bpf_ntohl(x)				\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_ntohl(x) : __bpf_ntohl(x))
 #define bpf_cpu_to_be64(x)			\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_cpu_to_be64(x) : __bpf_cpu_to_be64(x))
 #define bpf_be64_to_cpu(x)			\
 	(__builtin_constant_p(x) ?		\
 	 __bpf_constant_be64_to_cpu(x) : __bpf_be64_to_cpu(x))
 #endif /* __BPF_ENDIAN__ */
--- a/hypd/server/hyp_bpf.c
+++ b/hypd/server/hyp_bpf.c
@ -1,74 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 //go:build ignore
 #include "vmlinux.h"
 #include "bpf_endian.h"
 #include <bpf/bpf_helpers.h>
 char __license[] SEC("license") = "BSD";
 // representation of knock data that gets sent to userspace
 struct knock_data {
 	__u32 srcip; // 4 bytes
 	__u16 dstport; // 2 bytes
 	__u16 pad; // required padding - struct must be multiple of 4 bytes
 };
 // ring buffer used to send data to userspace
 struct {
 	__uint(type, BPF_MAP_TYPE_RINGBUF);
 	__uint(max_entries, 1 << 24);
 } rb SEC(".maps");
 // force emitting struct event into the ELF
 const struct knock_data *unused __attribute__((unused));
 // hook into xpress data path attach point
 SEC("xdp")
 int xdp_prog_func(struct xdp_md *ctx) {
 	// xdp gives us the raw frame with no structures, it must be parsed
 	void *data = (void *)(long)ctx->data;
 	void *data_end = (void *)(long)ctx->data_end;
 	// A knock should not contain any data
 	if (data_end - data > 60) { 
 		return XDP_PASS;
 	}
 	// parse ethernet header
 	struct ethhdr *eth = data;
 	if ((void *)eth + sizeof(*eth) > data_end) {
 		return XDP_PASS;
 	}
 	// parse IP header
 	struct iphdr *ip = data + sizeof(*eth);
 	if ((void *)ip + sizeof(*ip) > data_end) {
 		return XDP_PASS;
 	}
 	// Ensure IP header protocol field is UDP (protocol 17)
 	if (ip->protocol != IPPROTO_UDP) {
 		return XDP_PASS;
 	}
 	// parse UDP header
 	struct udphdr *udp = (void *)ip + sizeof(*ip);
 	if ((void *)udp + sizeof(*udp) > data_end) {
 		return XDP_PASS;
 	}
 	// pack into knock structure and send to userspace
 	struct knock_data knock = {
 		.srcip = bpf_ntohl(ip->saddr),
 		.dstport = bpf_htons(udp->dest),
 		.pad = 0
 	};				
 	bpf_ringbuf_output(&rb, &knock, sizeof(knock), BPF_RB_FORCE_WAKEUP);
 	// We send everything to XDP_PASS
 	return XDP_PASS;
 }
--- a/hypd/server/hyp_bpf_bpfeb.go
+++ b/hypd/server/hyp_bpf_bpfeb.go
@ -1,125 +0,0 @@
 // Code generated by bpf2go; DO NOT EDIT.
 //go:build mips || mips64 || ppc64 || s390x
 package server
 import (
 	"bytes"
 	_ "embed"
 	"fmt"
 	"io"
 	"github.com/cilium/ebpf"
 )
 type hyp_bpfKnockData struct {
 	Srcip   uint32
 	Dstport uint16
 	Pad     uint16
 }
 // loadHyp_bpf returns the embedded CollectionSpec for hyp_bpf.
 func loadHyp_bpf() (*ebpf.CollectionSpec, error) {
 	reader := bytes.NewReader(_Hyp_bpfBytes)
 	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
 	if err != nil {
 		return nil, fmt.Errorf("can't load hyp_bpf: %w", err)
 	}
 	return spec, err
 }
 // loadHyp_bpfObjects loads hyp_bpf and converts it into a struct.
 //
 // The following types are suitable as obj argument:
 //
 //	*hyp_bpfObjects
 //	*hyp_bpfPrograms
 //	*hyp_bpfMaps
 //
 // See ebpf.CollectionSpec.LoadAndAssign documentation for details.
 func loadHyp_bpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
 	spec, err := loadHyp_bpf()
 	if err != nil {
 		return err
 	}
 	return spec.LoadAndAssign(obj, opts)
 }
 // hyp_bpfSpecs contains maps and programs before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfSpecs struct {
 	hyp_bpfProgramSpecs
 	hyp_bpfMapSpecs
 }
 // hyp_bpfSpecs contains programs before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfProgramSpecs struct {
 	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
 }
 // hyp_bpfMapSpecs contains maps before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfMapSpecs struct {
 	Rb *ebpf.MapSpec `ebpf:"rb"`
 }
 // hyp_bpfObjects contains all objects after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfObjects struct {
 	hyp_bpfPrograms
 	hyp_bpfMaps
 }
 func (o *hyp_bpfObjects) Close() error {
 	return _Hyp_bpfClose(
 		&o.hyp_bpfPrograms,
 		&o.hyp_bpfMaps,
 	)
 }
 // hyp_bpfMaps contains all maps after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfMaps struct {
 	Rb *ebpf.Map `ebpf:"rb"`
 }
 func (m *hyp_bpfMaps) Close() error {
 	return _Hyp_bpfClose(
 		m.Rb,
 	)
 }
 // hyp_bpfPrograms contains all programs after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfPrograms struct {
 	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
 }
 func (p *hyp_bpfPrograms) Close() error {
 	return _Hyp_bpfClose(
 		p.XdpProgFunc,
 	)
 }
 func _Hyp_bpfClose(closers ...io.Closer) error {
 	for _, closer := range closers {
 		if err := closer.Close(); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 // Do not access this directly.
 //
 //go:embed hyp_bpf_bpfeb.o
 var _Hyp_bpfBytes []byte
--- a/hypd/server/hyp_bpf_bpfel.go
+++ b/hypd/server/hyp_bpf_bpfel.go
@ -1,125 +0,0 @@
 // Code generated by bpf2go; DO NOT EDIT.
 //go:build 386 || amd64 || arm || arm64 || loong64 || mips64le || mipsle || ppc64le || riscv64
 package server
 import (
 	"bytes"
 	_ "embed"
 	"fmt"
 	"io"
 	"github.com/cilium/ebpf"
 )
 type hyp_bpfKnockData struct {
 	Srcip   uint32
 	Dstport uint16
 	Pad     uint16
 }
 // loadHyp_bpf returns the embedded CollectionSpec for hyp_bpf.
 func loadHyp_bpf() (*ebpf.CollectionSpec, error) {
 	reader := bytes.NewReader(_Hyp_bpfBytes)
 	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
 	if err != nil {
 		return nil, fmt.Errorf("can't load hyp_bpf: %w", err)
 	}
 	return spec, err
 }
 // loadHyp_bpfObjects loads hyp_bpf and converts it into a struct.
 //
 // The following types are suitable as obj argument:
 //
 //	*hyp_bpfObjects
 //	*hyp_bpfPrograms
 //	*hyp_bpfMaps
 //
 // See ebpf.CollectionSpec.LoadAndAssign documentation for details.
 func loadHyp_bpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
 	spec, err := loadHyp_bpf()
 	if err != nil {
 		return err
 	}
 	return spec.LoadAndAssign(obj, opts)
 }
 // hyp_bpfSpecs contains maps and programs before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfSpecs struct {
 	hyp_bpfProgramSpecs
 	hyp_bpfMapSpecs
 }
 // hyp_bpfSpecs contains programs before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfProgramSpecs struct {
 	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
 }
 // hyp_bpfMapSpecs contains maps before they are loaded into the kernel.
 //
 // It can be passed ebpf.CollectionSpec.Assign.
 type hyp_bpfMapSpecs struct {
 	Rb *ebpf.MapSpec `ebpf:"rb"`
 }
 // hyp_bpfObjects contains all objects after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfObjects struct {
 	hyp_bpfPrograms
 	hyp_bpfMaps
 }
 func (o *hyp_bpfObjects) Close() error {
 	return _Hyp_bpfClose(
 		&o.hyp_bpfPrograms,
 		&o.hyp_bpfMaps,
 	)
 }
 // hyp_bpfMaps contains all maps after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfMaps struct {
 	Rb *ebpf.Map `ebpf:"rb"`
 }
 func (m *hyp_bpfMaps) Close() error {
 	return _Hyp_bpfClose(
 		m.Rb,
 	)
 }
 // hyp_bpfPrograms contains all programs after they have been loaded into the kernel.
 //
 // It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
 type hyp_bpfPrograms struct {
 	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
 }
 func (p *hyp_bpfPrograms) Close() error {
 	return _Hyp_bpfClose(
 		p.XdpProgFunc,
 	)
 }
 func _Hyp_bpfClose(closers ...io.Closer) error {
 	for _, closer := range closers {
 		if err := closer.Close(); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 // Do not access this directly.
 //
 //go:embed hyp_bpf_bpfel.o
 var _Hyp_bpfBytes []byte
--- a/hypd/server/packet.go
+++ b/hypd/server/packet.go
@ -1,254 +0,0 @@
 /*
 Copyright © 2024 Steven Polley <himself@stevenpolley.net>
 */
 package server
 import (
 	"bytes"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"log"
 	"net"
 	"os/exec"
 	"time"
 	"deadbeef.codes/steven/hyp/hypd/configuration"
 	"deadbeef.codes/steven/hyp/otphyp"
 	"github.com/cilium/ebpf/link"
 	"github.com/cilium/ebpf/ringbuf"
 	"github.com/cilium/ebpf/rlimit"
 )
 //go:generate go run github.com/cilium/ebpf/cmd/bpf2go --type knock_data hyp_bpf hyp_bpf.c
 // Client is used to keep track of a client attempting to perform an authentic knock sequence
 type Client struct {
 	Progress    int       // index of current progress in sequence.   Value of 1 means first port has been matched
 	Sequence    [4]uint16 // stores the knock sequence the current client is attempting.  It's set and tracked here to prevent race conditions during a knock sequence being received and key rotations
 	LastSuccess time.Time
 }
 // KnockSequence is used keep track of an ordered knock sequence and whether it's been marked for use (to prevent replay attacks)
 type KnockSequence struct {
 	Used         bool      // If true, that means this knock sequence has already been used once.  It may still be within the valid time window, but it can't be used again
 	PortSequence [4]uint16 // Each knock sequence is four ports long
 }
 const (
 	KnockSequenceTimeout = 3 // TBD: Make this a configurable value
 )
 var (
 	clients        map[uint32]*Client // Contains a map of clients, key is IPv4 address
 	knockSequences []KnockSequence    // We have 3 valid knock sequences at any time to account for clock skew
 	serverConfig   *configuration.HypdConfiguration
 	sharedSecrets  [][]byte // A slice of byte slices, each being a secret key
 )
 // PacketServer is the main function when operating in server mode
 // it sets up the pcap on the capture device and starts a goroutine
 // to rotate the knock sequence
 func PacketServer(config *configuration.HypdConfiguration, secrets [][]byte) error {
 	serverConfig = config
 	sharedSecrets = secrets
 	iface, err := net.InterfaceByName(serverConfig.NetworkInterface)
 	if err != nil {
 		log.Fatalf("lookup network iface %q: %v", serverConfig.NetworkInterface, err)
 	}
 	clients = make(map[uint32]*Client, 0)
 	knockSequences = []KnockSequence{}
 	// Setup a goroutine to periodically rotate the authentic knock sequence
 	go rotateSequence()
 	////////////////////////////////////
 	// Allow the current process to lock memory for eBPF resources.
 	if err := rlimit.RemoveMemlock(); err != nil {
 		log.Fatal(err)
 	}
 	// Load pre-compiled programs into the kernel.
 	objs := hyp_bpfObjects{}
 	if err := loadHyp_bpfObjects(&objs, nil); err != nil {
 		log.Fatalf("loading objects: %v", err)
 	}
 	defer objs.Close()
 	// Attach the program.
 	l, err := link.AttachXDP(link.XDPOptions{
 		Program:   objs.XdpProgFunc,
 		Interface: iface.Index,
 	})
 	if err != nil {
 		log.Fatalf("could not attach XDP program: %v", err)
 	}
 	defer l.Close()
 	log.Printf("Attached XDP program to iface %q (index %d)", iface.Name, iface.Index)
 	log.Printf("Press Ctrl-C to exit and remove the program")
 	rd, err := ringbuf.NewReader(objs.Rb)
 	if err != nil {
 		log.Fatalf("could not open ring buffer reader: %v", err)
 	}
 	defer rd.Close()
 	var event hyp_bpfKnockData
 	for {
 		record, err := rd.Read()
 		if err != nil {
 			if errors.Is(err, ringbuf.ErrClosed) {
 				log.Println("eBPF ring buffer closed, exiting...")
 				return nil
 			}
 			log.Printf("error reading from ring buffer reader: %v", err)
 			continue
 		}
 		if err := binary.Read(bytes.NewBuffer(record.RawSample), binary.LittleEndian, &event); err != nil {
 			log.Printf("error parsing ringbuf event: %v", err)
 			continue
 		}
 		go handleKnock(event)
 	}
 }
 // intToIP converts IPv4 number to net.IP
 func intToIP(ipNum uint32) net.IP {
 	ip := make(net.IP, 4)
 	binary.BigEndian.PutUint32(ip, ipNum)
 	return ip
 }
 // packets that match the BPF filter get passed to handlePacket
 func handleKnock(knockEvent hyp_bpfKnockData) {
 	client, ok := clients[knockEvent.Srcip]
 	if !ok { // client doesn't exist yet
 		client = &Client{}
 		clients[knockEvent.Srcip] = client
 	}
 	if client.Progress == 0 {
 		for i, knockSequence := range knockSequences { // identify which of the authentic knock sequences is matched
 			if knockSequence.Used { // skip over sequences that are already used to prevent replay attack
 				continue
 			}
 			if knockEvent.Dstport == knockSequence.PortSequence[0] {
 				knockSequences[i].Used = true // TBD: This is vulnerable to a DoS just by doing a full UDP port scan
 				client.Progress = 1
 				client.Sequence = knockSequence.PortSequence
 				go timeoutKnockSequence(knockEvent.Srcip)
 			}
 		}
 		return
 	}
 	// if it's wrong, reset progress
 	if knockEvent.Dstport != client.Sequence[client.Progress] {
 		delete(clients, knockEvent.Srcip)
 		fmt.Printf("port '%d' is in sequence, but came at unexpected order - resetting progress", knockEvent.Dstport)
 		return
 	}
 	// Client increases progress through sequence and checks if sequence is completed
 	client.Progress++
 	if client.Progress >= len(client.Sequence) {
 		client.Progress = 0
 		client.LastSuccess = time.Now()
 		handleSuccess(knockEvent.Srcip) // The magic function, the knock is completed
 		return
 	}
 }
 // Remove the client after the timeout value has elapsed.  This prevents a client from
 // being indefinitely stuck part way through an old knock sequence.  It's also helpful
 // in preventing sweep attacks as the authentic knock sequence must be correctly entered
 // within the timeout value from start to finish.
 // Note: This is not related to handling the timeout / clsoe ports action after a client
 // has successfully completed an authentic knock sequence
 func timeoutKnockSequence(srcip uint32) {
 	time.Sleep(time.Second * KnockSequenceTimeout)
 	client, ok := clients[srcip]
 	if ok {
 		if client.LastSuccess.IsZero() { // If they've never succeeded, just drop them from the map
 			delete(clients, srcip)
 		} else { // If they have succeeded, just reset their progress to 0 but keep them in map.  They will be cleaned in handleSuccess
 			client.Progress = 0
 		}
 	}
 }
 // Used to rotate the authentic port knock sequence
 func rotateSequence() {
 	for {
 		// Generate new knock sequences with time skew support
 		t := time.Now().Add(time.Second * -30)
 		for i := len(knockSequences) / len(sharedSecrets); i < 3; i++ {
 			for _, secret := range sharedSecrets {
 				portSequence, err := otphyp.GeneratePorts(secret, t.Add((time.Second * 30 * time.Duration(i))))
 				if err != nil {
 					log.Fatalf("failed to generate port knock sequence: %v", err)
 				}
 				knockSequence := KnockSequence{PortSequence: portSequence}
 				knockSequences = append(knockSequences, knockSequence)
 			}
 		}
 		// Sleep until next 30 second offset
 		time.Sleep(time.Until(time.Now().Truncate(time.Second * 30).Add(time.Second * 30)))
 		// pop first value, next iteration pushes new value
 		knockSequences = knockSequences[len(sharedSecrets):]
 	}
 }
 // handleSuccess is ran when a source IP successfully enters the authentic knock sequence
 // the configured success action is ran
 func handleSuccess(srcip uint32) {
 	srcipf := intToIP(srcip) // formatted as net.IP
 	log.Printf("Successful knock from: %s", srcipf)
 	client, ok := clients[srcip]
 	if !ok {
 		log.Printf("failed to lookup %s in clients", srcipf)
 		return
 	}
 	// Don't care about command injection, the configuration file providing the command literally NEEDS to be trusted
 	// TBD: Use template / substitution instead of string formatting directive - allows for srcip token to be used multiple times
 	cmd := exec.Command("sh", "-c", fmt.Sprintf(serverConfig.SuccessAction, srcipf))
 	err := cmd.Run()
 	if err != nil {
 		log.Printf("failed to execute success action command for '%s': %v", srcipf, err)
 	}
 	// Handle timeout action
 	if serverConfig.TimeoutSeconds < 1 { // Timeout action is disabled
 		delete(clients, srcip)
 		return
 	}
 	// Handle checks for client timeout
 	// TBD: Persistence / journaling state to disk?  How to handle case if knock daemon is restarted - ports would remain open
 	lastSuccess := client.LastSuccess
 	time.Sleep(time.Until(client.LastSuccess.Add(time.Duration(serverConfig.TimeoutSeconds * int(time.Second)))))
 	if client.LastSuccess.After(lastSuccess) { // The client has refreshed
 		return
 	}
 	// Don't care about command injection, the configuration file providing the command literally NEEDS to be trusted
 	// TBD: Use template / substitution instead of string formatting directive - allows for srcip token to be used multiple times
 	log.Printf("Performing timeout action on: %s", srcipf)
 	cmd = exec.Command("sh", "-c", fmt.Sprintf(serverConfig.TimeoutAction, srcipf))
 	err = cmd.Run()
 	if err != nil {
 		log.Printf("failed to execute timeout action command for '%s': %v", srcipf, err)
 	}
 	delete(clients, srcip)
 }
--- a/hypd/server/vmlinux.h
+++ b/hypd/server/vmlinux.h
--- a/otphyp/go.mod
+++ b/otphyp/go.mod
@ -0,0 +1,3 @@
 module deadbeef.codes/steven/hyp/otphyp
 go 1.22.0
--- a/otphyp/otphyp.go
+++ b/otphyp/otphyp.go
@ -15,7 +15,12 @@ import (
 // A loose implementation of hotp meant for our specific purposes of generating four random port numbers
 // Accepts a base32 encoded shared secret and a time
-func GeneratePorts(sharedSecret []byte, t time.Time) (ports [4]uint16, err error) {
+func GeneratePorts(sharedSecret string, t time.Time) (ports [4]uint16, err error) {
 	sharedSecretBytes, err := base32.StdEncoding.DecodeString(sharedSecret)
 	if err != nil {
 		return [4]uint16{0, 0, 0, 0}, fmt.Errorf("failed to base32 decode shared secret string to bytes: %v", err)
 	}
 	// 30 second key rotation
 	movingFactor := uint64(math.Floor(float64(t.Unix()) / float64(30)))
@ -23,7 +28,7 @@ func GeneratePorts(sharedSecret []byte, t time.Time) (ports [4]uint16, err error
 	binary.BigEndian.PutUint64(buf, movingFactor)
 	// calculate hmac and offset
-	mac := hmac.New(sha1.New, sharedSecret)
+	mac := hmac.New(sha1.New, sharedSecretBytes)
 	mac.Write(buf)
 	sum := mac.Sum(nil)
 	offset := sum[len(sum)-1] & 0xf
@ -47,7 +52,7 @@ func GeneratePorts(sharedSecret []byte, t time.Time) (ports [4]uint16, err error
 // 2. Save the secret to a file
 // 3. Distribute the secret to a client
 func GenerateSecret() (sharedSecret string, err error) {
-	sharedSecretBytes := make([]byte, 500)
+	sharedSecretBytes := make([]byte, 20)
 	r := rand.Reader
 	_, err = r.Read([]byte(sharedSecretBytes))
 	if err != nil {
--- a/server/README.md
+++ b/server/README.md
@ -0,0 +1,25 @@
 # hypd
 hypd is the hyp (Hide Your Ports) server.  
 ### Requirements
 On the server, libpcap-dev needs to be installed on linux or pcap from nmap.org on Windows.
 ### Usage
 ##### Generating a new shared key
 ```bash
 # As user that can write to current directory
 ./hypd generatesecret
 ```
 Then copy the file to a client
 ##### Starting the server
 ```bash
 # As root - or user that can capture packets and modify IPTables
 ./hypd server eth0
 ```
--- a/server/go.mod
+++ b/server/go.mod
@ -0,0 +1,10 @@
 module deadbeef.codes/steven/hypd
 go 1.22.0
 require (
 	deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee
 	github.com/google/gopacket v1.1.19
 )
 require golang.org/x/sys v0.19.0 // indirect
--- a/server/go.sum
+++ b/server/go.sum
@ -0,0 +1,19 @@
 deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee h1:r9xdoIGPhc/tXzyOj+lCDb+ReYa/zkysqK3ZRCqpyIU=
 deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee/go.mod h1:NANpGD/K+nDkW+bkomchwaXMrsXWza58+8AR7Sau3fs=
 github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
 github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
 golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
--- a/server/main.go
+++ b/server/main.go
@ -0,0 +1,74 @@
 package main
 import (
 	"fmt"
 	"log"
 	"os"
 	"os/exec"
 	"deadbeef.codes/steven/hyp/otphyp"
 )
 func main() {
 	if len(os.Args) < 2 {
 		usage()
 	}
 	switch os.Args[1] {
 	case "generatesecret":
 		sharedSecret, err := otphyp.GenerateSecret()
 		if err != nil {
 			log.Fatalf("failed to generate shared secret: %v", err)
 		}
 		f, err := os.Create("hyp.secret")
 		if err != nil {
 			log.Fatalf("failed to create file 'hyp.secret': %v", err)
 		}
 		_, err = f.WriteString(sharedSecret)
 		if err != nil {
 			log.Fatalf("failed to write to file 'hyp.secret': %v", err)
 		}
 		f.Close()
 		fmt.Println("Created file hyp.secret")
 	case "server":
 		secretBytes, err := os.ReadFile("hyp.secret")
 		if err != nil {
 			log.Fatalf("failed to read file 'hyp.secret': %v", err)
 		}
 		sharedSecret = string(secretBytes)
 		if len(os.Args) < 3 {
 			usage()
 		}
 		packetServer(os.Args[2])
 	}
 }
 func usage() {
 	fmt.Print(`hyp <command>
 	Commands:
 	generatesecret - creates a pre shared key file named hyp.secret which can be distributed to a trusted client
 	server <device> - TBD
 	Example Usage:
 	# Linux
 	hyp server "/dev/eth0"
 	# Windows - get-netadapter | where {$_.Name -eq “Ethernet”} | Select-Object -Property DeviceName
 	hyp server "\\Device\\NPF_{A066F7DE-CC2D-4E4B-97C4-BF0EC4C03649}"
 `)
 	os.Exit(1)
 }
 // TBD: Implement
 func handleSuccess(srcip string) {
 	fmt.Println("Success for ", srcip)
 	cmd := exec.Command("iptables", "-A", "INPUT", "-p", "tcp", "-s", srcip, "--dport", "22", "-j", "ACCEPT")
 	err := cmd.Run()
 	if err != nil {
 		log.Printf("failed to execute iptables command for '%s': %v", srcip, err)
 	}
 }
--- a/server/packet.go
+++ b/server/packet.go
@ -0,0 +1,120 @@
 package main
 import (
 	"encoding/binary"
 	"fmt"
 	"log"
 	"time"
 	"deadbeef.codes/steven/hyp/otphyp"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/pcap"
 )
 // type client is used to keept track of a client attempting to perform an authentic knock sequence
 type Client struct {
 	Progress int       // index of current progress in sequence.   Value of 1 means first port has been matched
 	Sequence [4]uint16 // stores the knock sequence the current client is attempting.  It's set and tracked here to prevent race conditions during a knock sequence being received and key rotations
 }
 var (
 	clients       map[string]*Client // Contains a map of clients
 	portSequences [][4]uint16
 	sharedSecret  string // base32 encoded shared secret used for totp
 )
 func packetServer(captureDevice string) {
 	clients = make(map[string]*Client, 0) // key is flow, value is the current progress through the sequence. i.e. value of 1 means that the first port in the sequence was successful
 	portSequences = [][4]uint16{}         // Slice of accepted port sequences, there have to be several to account for clock skew between client and server
 	handle, err := pcap.OpenLive(captureDevice, 1600, true, pcap.BlockForever)
 	if err != nil {
 		log.Fatalf("failed to open adapter")
 	}
 	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
 	go rotateSequence(handle)
 	for packet := range packetSource.Packets() {
 		handlePacket(packet) // Do something with a packet here.
 	}
 }
 // packets that match the BPF filter get passed to handlePacket
 func handlePacket(packet gopacket.Packet) {
 	port := binary.BigEndian.Uint16(packet.TransportLayer().TransportFlow().Dst().Raw())
 	srcip := packet.NetworkLayer().NetworkFlow().Src().String()
 	client, ok := clients[srcip]
 	if !ok { // create the client, identify which authentic knock sequence is matched
 		for _, sequence := range portSequences {
 			if port == sequence[0] {
 				clients[srcip] = &Client{Progress: 1, Sequence: sequence}
 			}
 		}
 		return
 	}
 	// if it's wrong, reset progress
 	// TBD: vulnerable to sweep attack - this won't be triggered if a wrong packet doesn't match BPF filter
 	if port != client.Sequence[client.Progress] {
 		delete(clients, srcip)
 		fmt.Printf("port '%d' is in sequence, but came at unexpected order - resetting progress", port)
 		return
 	}
 	// Client increases progress through sequence and checks if sequence is completed
 	client.Progress++
 	if client.Progress >= len(client.Sequence) {
 		delete(clients, srcip)
 		handleSuccess(srcip)
 		return
 	}
 }
 // Used to rotate the authentic port knock sequence
 func rotateSequence(handle *pcap.Handle) {
 	for {
 		if len(portSequences) < 3 {
 			t := time.Now().Add(time.Second * -30)
 			for i := 0; i < 3; i++ {
 				portSequence, err := otphyp.GeneratePorts(sharedSecret, t.Add((time.Second * 30 * time.Duration(i))))
 				if err != nil {
 					log.Fatalf("failed to generate port knock sequence: %v", err)
 				}
 				portSequences = append(portSequences, portSequence)
 			}
 		}
 		fmt.Println("New sequences:", portSequences)
 		err := setPacketFilter(handle)
 		if err != nil {
 			log.Printf("failed to change packet filter: %v", err)
 		}
 		// Sleep until next 30 second offset
 		time.Sleep(time.Until(time.Now().Truncate(time.Second * 30).Add(time.Second * 30)))
 		// TBD: pop first value and only generate latest (time.Now().Add(time.Second*30)) value instead of re-initializing completely
 		portSequences = [][4]uint16{}
 	}
 }
 // Given a pcap handle and list of authentic port knock sequences, configures a BPF filter
 func setPacketFilter(handle *pcap.Handle) error {
 	filter := "udp && ("
 	for i, portSequence := range portSequences {
 		for j, port := range portSequence {
 			if i == 0 && j == 0 {
 				filter += fmt.Sprint("port ", port)
 			} else {
 				filter += fmt.Sprint(" || port ", port)
 			}
 		}
 	}
 	filter += ")"
 	err := handle.SetBPFFilter(filter)
 	if err != nil {
 		return fmt.Errorf("failed to set BPF filter '%s': %v", filter, err)
 	}
 	return nil
 }
		`@ -0,0 +1,2 @@`
							`deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee h1:r9xdoIGPhc/tXzyOj+lCDb+ReYa/zkysqK3ZRCqpyIU=`
							`deadbeef.codes/steven/hyp/otphyp v0.0.0-20240407035202-7ccdf4d89fee/go.mod h1:NANpGD/K+nDkW+bkomchwaXMrsXWza58+8AR7Sau3fs=`
		`@ -0,0 +1,3 @@`
							`module deadbeef.codes/steven/hyp/otphyp`

							`go 1.22.0`