Networking Tips & Tools: mDNS, Zeroconf, link-local

Owned by Krishtof Korda
Last updated: Aug 28, 2020
2 min read

This article briefly goes over some basic tools available to help discover an Ouster Sensor on your network.

Command Line Tools

Linux

avahi-browse:

  • This is a tool built into Ubuntu to help find mDNS (multicast Domain Name System) services that are on your network.

  • Example usage

    • avahi-browse -lrt _roger._tcp

      • NOTE: Ouster sensors advertise on mDNS with the service type _roger._tcp. So this command tells avahi-browse to resolve all services of type _roger._tcp. Any sensors that you have connected on any interface will report back their hostnames, IPv6 and IPv4 addresses, as well as a text field with sensor information (serial number, part number, etc)

ping6:

  • This is a ping tool for IPv6 addresses

  • Example usage:

    • ping6 fe80::be0f:a7ff:fe00:65%<interface>

      • fe80 is the link-local prefix

      • be0f:a7ff:fe00:65 is a unique value based on the MAC address of the sensor.

      • <interface> is the Linux name of the interface the sensor is on. i.e. eth0

      • Don’t forget that % between the address and the <interface>

curl:

  • curl (client URL) is a tool for accessing data via URLs

  • The Ouster Sensors host a web server that can be queried with curl

  • Example usage for IPv6 link-local:

    • curl -6 "[fe80::be0f:a7ff:fe00:65%eth0]/api/v1/system/network" | jq -S

nmcli:

  • nmcli (Network Manager Command-Line) is a tool to show connections and devices on your machine.

    • nmcli conn show

      • shows connections

    • nmcli conn dev

      • shows devices

macOS/Windows

dns-sd:

  • This tool work similar to avahi-browse on Linux but is for macOS

  • Example usage

    • dns-sd -B _services._dns-sd._udp

      • Browses a list of all services on the network including Ouster sensors

    • dns-sd -B <Service Type>

      • <Service Type> for our sensors is _roger._tcp

      • Browses a list of sensors on your network

    • dns-sd -L "<Instance Name>" <Service Type>

      • Resolves information about a specific sensor name <Instance Name>

Python

Python socket library:

  • Can quickly get the IPv6 and IPv4 addresses of a sensor from its hostname

  • Example terminal usage:

    • python3, starts a Python 3 interpreter

    • In the Python 3 Interpreter use these commands:

      • import socket socket.getaddrinfo( '<hostname>', <port_number>) # set <port_number> to 0 to search all ports

      • Example output below:

python-zeroconf:

  • This is a multicast DNS Service Discovery tool for Python

  • Install command:

    • pip install zeroconf

pyinstaller:

  • PyInstaller freezes (packages) Python applications into stand-alone executables, under Windows, GNU/Linux, Mac OS X, FreeBSD, Solaris and AIX.

  • Install command:

    • pip install pyinstaller

  • Example usage:

    • pyinstaller yourprogram.py