Network Configuration Overview

Normally the network bridge and port forwarding are configured automatically when using the cpr_indoornav setup script (see Installing Required Software). This appendix explains the network configuration of the robot’s PC in more detail.

Configuring the Network Bridge

The first step to configure your robot for use with IndoorNav is to make sure that the ethernet communication between the robot’s PC and the IndoorNav backpack works. All Clearpath robots are configured to bridge their physical ethernet ports together. This allows all the ports on the motherboard to operate on multiple subnets simultaneously. By default Clearpath robots use the 192.168.131.0/24 subnet for their internal network, with all IP-based sensors and peripherals operating on this subnet.

IndoorNav requires modifying the default bridge to remove a single ethernet port, eno1 by default, from the bridge and assigning it to the 10.252.252.0/24 subnet. This physical port will be dedicated to communicating with the IndoorNav backpack PC.

To configure eno1 to be used to communicate with the backpack PC, modify /etc/netplan/50-clearpath-bridge.yaml as follows. The example below bridges interfaces with the identifiers eth*, enp*, enx* and usb* together on the 192.168.131.0/24 subnet.

network:
  version: 2
  renderer: networkd
  ethernets:
    # dedicated port for communicating with the IndoorNav backpack
    eno1:
      dhcp4: no
      dhcp6: no
      addresses:
        - 10.252.252.100/24

    # bridge all other ports together on the 192.168.131.0/24 subnet
    bridge_eth:
      dhcp4: no
      dhcp6: no
      match:
        name: eth*
    bridge_enp:
      dhcp4: no
      dhcp6: no
      match:
        name: enp*
    bridge_enx:
      dhcp4: no
      dhcp6: no
      match:
        name: enx*
    bridge_usb:
      dhcp4: no
      dhcp6: no
      match:
        name: usb*
  bridges:
    br0:
      dhcp4: yes
      dhcp6: no
      interfaces: [bridge_eth, bridge_enp, bridge_enx, bridge_usb]
      addresses:
        - 192.168.131.1/24

Instead of using eno1 you can use a specific USB to ethernet dongle, for example:

network:
  version: 2
  renderer: networkd
  ethernets:
    # dedicated port for communicating with the IndoorNav backpack
    enx70886b8f17a5:
      dhcp4: no
      dhcp6: no
      addresses:
        - 10.252.252.100/24

    # bridge all other ports together on the 192.168.131.0/24 subnet
    bridge_eth:
      dhcp4: no
      dhcp6: no
      match:
        name: eth*
    bridge_eno:
      dhcp4: no
      dhcp6: no
      match:
        name: eno*
    bridge_enp:
      dhcp4: no
      dhcp6: no
      match:
        name: enp*
  bridges:
    br0:
      dhcp4: yes
      dhcp6: no
      interfaces: [bridge_eth, bridge_eno, bridge_enp]
      addresses:
        - 192.168.131.1/24

If you made any changes to the bridge configuration reboot the robot now. Once the robot and backpack PC are both powered-on, connect them with an ethernet cable connected to eno1 on the backpack and the IndoorNav port you configured above. Run the following command to check that you can communicate with the backpack PC:

ping 10.252.252.1

Once you have configured the network interfaces and confirmed that the communication works, ensure that the dedicated IndoorNav port is set in the cpr_indoornav package’s config/cyclone_dds.xml file:

<?xml version="1.0" encoding="UTF-8" ?>
<CycloneDDS xmlns="https://cdds.io/config" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://cdds.io/config https://raw.githubusercontent.com/eclipse-cyclonedds/cyclonedds/master/etc/cyclonedds.xsd">
  <Domain id="any">
    <General>
      <!--
        This assumes that eno1 is configured to be a static port dedicated to communicating
        with the autonomy backpack. By default this should use the 10.252.252.0/24 subnet
        with the robot's PC at 10.252.252.100 and the autonomy PC at 10.252.252.1
      -->
      <NetworkInterfaceAddress>eno1</NetworkInterfaceAddress>
      <AllowMulticast>true</AllowMulticast>
    </General>
    <Internal>
      <LeaseDuration>5 min</LeaseDuration>
    </Internal>
  </Domain>
</CycloneDDS>

Configuring Apache2 Proxy Server

IndoorNav operates a web-based mapping GUI that you can use to plan routes, mark areas for specific tasks, view/edit the map, and the like. To access this interface you should install the apache2 package and configure it to act as a proxy server for the IndoorNav backpack:

sudo apt-get install apache2
sudo a2enmod proxy
sudo a2enmod proxy_http
sudo a2enmod proxy_wstunnel
sudo a2enmod rewrite

Create (or edit) /etc/apache2/conf-enabled/clearpath.conf to contain the following:

Listen 2000
Listen 2001
Listen 5000
Listen 9091

<VirtualHost *:2000>
  ProxyRequests On
  ProxyVia On

  ProxyPass / http://10.252.252.1:2000/
  ProxyPassReverse / http://10.252.252.1:2000/
</VirtualHost>

<VirtualHost *:2001>
  ServerName HOSTNAME       # replace HOSTNAME with your robot's hostname!!

  RewriteEngine On

  RewriteCond %{HTTP:Upgrade} =websocket [NC]
  RewriteRule /(.*)           ws://10.252.252.1:2001/$1 [P,L]

  RewriteCond %{HTTP:Upgrade} !=websocket [NC]
  RewriteRule /(.*)           ws://10.252.252.1:2001/$1 [P,L]

  ProxyPass / http://10.252.252.1:2001/
  ProxyPassReverse / http://10.252.252.1:2001/
</VirtualHost>

<VirtualHost *:5000>
  ProxyRequests On
  ProxyVia On

  ProxyPass / http://10.252.252.1:5000/
  ProxyPassReverse / http://10.252.252.1:5000/
</VirtualHost>

<VirtualHost *:9091>
  ServerName HOSTNAME       # replace HOSTNAME with your robot's hostname!!

  RewriteEngine On

  RewriteCond %{HTTP:Upgrade} =websocket [NC]
  RewriteRule /(.*)           ws://10.252.252.1:9091/$1 [P,L]

  RewriteCond %{HTTP:Upgrade} !=websocket [NC]
  RewriteRule /(.*)           ws://10.252.252.1:9091/$1 [P,L]

  ProxyPass / http://10.252.252.1:9091/
  ProxyPassReverse / http://10.252.252.1:9091/
</VirtualHost>

Make sure to replace the two instances of HOSTNAME in the file above with your robot’s hostname, e.g. cpr-j100-1234

Once /etc/apache2/conf-enabled/clearpath.conf has been modified, restart the apache2 service:

sudo systemctl restart apache2

Configuring IP Tables

Warning

It has been observed that using iptables to enable port-forwarding may cause errors with the ROS2 daemon. We recommend using the Apache Proxy Server method described above.

Instead of using Apache2 to act as a proxy server, you can instead use the Linux Kernel’s iptables to enable port-forwarding. If you enable iptables you should also disable the apache2 service to prevent the proxy server from also listening on these ports:

sudo systemctl stop apache2
sudo systemctl disable apache2

To configure iptables run the following commands:

sudo sysctl net.ipv4.ip_forward=1
sudo iptables --policy FORWARD ACCEPT
sudo iptables -t nat -A PREROUTING -p tcp --dport 2000 -j DNAT --to-destination 10.252.252.1:2000
sudo iptables -t nat -A PREROUTING -p tcp --dport 2001 -j DNAT --to-destination 10.252.252.1:2001
sudo iptables -t nat -A PREROUTING -p tcp --dport 5000 -j DNAT --to-destination 10.252.252.1:5000
sudo iptables -t nat -A PREROUTING -p tcp --dport 9091 -j DNAT --to-destination 10.252.252.1:9091
sudo iptables -t nat -A POSTROUTING -j MASQUERADE

To make these changes permanent you should edit /etc/sysctl.conf and make sure that IPv4 forwarding is enabled:

net.ipv4.ip_forward=1

and install the iptables-persistent package:

sudo apt-get install iptables-persistent

If this package is already installed you can update the rules by running

sudo dpkg-reconfigure iptables-persistent

Select Yes when asked if you want to save the IPv4 rules and No if you want to save the IPv6 rules.