bootstrap_mk5

This repo contains some tools and scripts to bootstrap a Cohda MK5 for 802.11p operation.

Context

• Cohda MK5
  • A V2X hardware platform developed by Cohda Wireless
• 802.11p
  • An 802.11a-based standard that provides fast peering by doing away with BSSes (everyone is always on 00:00:00:00:00:00)
• eth0
  • The wired interface on a Cohda MK5
• wave-data
  • The wireless interface on a Cohda MK5

Goal

The code in this repo seeks to set up a Cohda MK5 in 802.11p mode, operating as part of a /24 network (on the wireless side) and tying in a /24 network (on the wired side).

So, if we look at a network of 3 radios:

• cohda-mk5-1
  • eth0 = 192.168.1.1/24
  • wave-data = 172.16.137.1/24
  • routes
    • 192.168.2.0/24 via 172.16.137.2
    • 192.168.3.0/24 via 172.16.137.3
• cohda-mk5-2
  • eth0 = 192.168.2.1/24
  • wave-data = 172.16.137.2/24
  • routes
    • 192.168.1.0/24 via 172.16.137.1
    • 192.168.3.0/24 via 172.16.137.3
• cohda-mk5-3
  • eth0 = 192.168.3.1/24
  • wave-data = 172.16.137.3/24
  • routes
    • 192.168.1.0/24 via 172.16.137.1
    • 192.168.2.0/24 via 172.16.137.2

As you can see, there'll be a lot of static routes, so this is handled by some Go command line tools (that get cross-compiled for ARM, i.e. the Cohda MK5) and some scripting.

The problem is probably not a bad argument for a dynamic routing protocol, but then you're at the mercy of that routing protocol's discovery intervals.

Prerequisites

• Linux or MacOS
• go1.12 (or newer, probably)
• ping6
• sshpass
  • see https://gist.github.com/arunoda/7790979
• ansible

What does it do?

• With rc.local as the entrypoint
  • Call bootstrap.sh
    • Using the Cohda chconfig tool
      • Set the radio interface to operate in 802.11p
    • Using the generate_mac tool and the last octet of the eth0 MAC
      • Set the wave-data MAC
    • Using the generate_ip tool and the last octet of the eth0 MAC
      • Set the wave-data IP
      • Set the eth0 IP
    • Using the add_routes tool
      • Create routes for all 253 other possible nodes
    • Using the castinator tool
      • Provide a bidirectional relay between UDP broadcasts on port 13337 on eth0 and UDP broadcasts on port 13338 on wave-data
    • Using the locator tool
      • Forward TPV packets from gpsd as UDP broadcasts port 13339 on eth0

What are the components?

This project is laid out largely in the Standard Go Project Layout format; here is an breakdown of the folders:

• cmd (Go code that gets built to a command line executable)
  • add_routes
    • Tool to add routes (within some guidelines)
  • castinator
    • Tool to relay UDP packets from one address to another
  • find_mk5s
    • Tool used to discover MK5s plugged in locally via Ethernet
  • generate_ip
    • Tool to generate an IP address (from a MAC address, within some guidelines)
  • generate_mac
    • Tool to generate a MAC address (from a MAC address, within some guidelines)
  • locator
    • Tool to receive TPV packets from gpsd and send them a UDP address
• deploy (Files and executables that relate to deployment)
  • ansible.cfg
    • Ansible config
  • deploy-no-reboot.yml
    • Ansible Playbook
  • hosts-base
    • Base template for Ansible hosts file
• dist (Where artifacts to-be-deployed are built to)
• internal (Go code used only by this repo)
• pkg (Go code that can be used externally)
  • generate
    • Functions used to generate MACs and IPs
  • route
    • Functions used to add routes
• scripts
  • bootstrap.sh
    • The script that pulls everything together
  • rc.local
    • The entrypoint script

What gets deployed?

./dist/generate_mac -> /home/user/bootstrap_mk5/generate_mac
./dist/castinator -> /home/user/bootstrap_mk5/castinator
./dist/add_routes -> /home/user/bootstrap_mk5/add_routes
./dist/generate_ip -> /home/user/bootstrap_mk5/generate_ip

./scripts/bootstrap.sh -> /home/user/bootstrap_mk5/bootstrap.sh

./dist/build_hash.txt -> /home/user/bootstrap_mk5/build_hash.txt
./dist/build_date.txt -> /home/user/bootstrap_mk5/build_date.txt

./scripts/rc.local -> /mnt/ubi/rc.local

./deploy/deploy_date.txt -> /home/user/bootstrap_mk5/deploy_date.txt

How do I build it?

For your native platform:

./build.sh

For a Linux, ARM-based platform:

GOOS=linux GOARCH=arm ./build.sh

How do I test it?

Heh, TBD.

How do I deploy it?

Ensure you've built for the ARM-based platform:

GOOS=linux GOARCH=arm ./build.sh

Then run the deploy script

./deploy.sh

NOTE: You may pass the optional reboot flag to deploy.sh; e.g.: ./deploy.sh reboot

What might I want to change?

• The Cohda IPv6 link local address prefix for discovery (e.g. if the hardware revision changes)
  • cmd/find_mk5s/main.go
    • CohdaIPv6AddrPrefix = "fe80::6e5:"
• The Cohda MK5 credentials for deployment
  • deploy/hosts-base
    • ansible_ssh_user=user
    • ansible_ssh_pass=user
• The IP and MAC address specifics in scripts/bootstrap.sh
  • ETH_INTERFACE=eth0
  • ETH_BASE_IP=192.168.x.1
  • ETH_NETMASK=255.255.255.0
  • ETH_PREFIX=24
  • WAVE_DATA_INTERFACE=wave-data
  • WAVE_DATA_BASE_IP=172.16.137.x
  • WAVE_DATA_NETMASK=255.255.255.0
• The rate and channel specifics in scripts/bootstrap.sh
  • DEFAULT_MCS=MK2MCS_R34QAM64 # 54 Mbps
  • DEFAULT_TX_POWER=5 # 2.5 dBm (5 * 0.5 dBm)
  • CHANNEL_NUMBER=174 # ETSI = 23 dBm, SCH; IEEE = 33 dBm, SCH
• The multicast-to-broadcast relay specifics in scripts/bootstrap.sh
  • ETH_PORT=13337
  • WAVE_DATA_PORT=13338
• The GPS forwarder specifics in scripts/bootstrap.sh
  • GPS_PORT=13339