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Operation - Networking

✎

Modified 2021-03-13 by duckietown

This page is for the DB18 configuration used in classes in 2018. For last year’s instructions see here.

A Duckiebot that is initialized according to Unit C-4 - Setup - Duckiebot SD Card.

Patience (channel your inner Yoda).

A Duckiebot that you can connect to and that is connected to the internet.

The instructions here are ordered in terms of preference, the first being the most preferable and best.

By default on boot your robot will look for a network with a “duckietown” SSID, unless you changed it in the SD card flashing procedure. You can connect to your robot wirelessly by connecting to that network.

This page describes how to get your robot connected to the wide-area network (internet).

Add WiFi Networks without reinitializing the SD card

✎

Modified 2021-03-21 by Andrea F. Daniele

To add networks at a later stage or modify existing settings, edit the file wpa_supplicant.conf in the main partition of the SD card.

For robots based on Raspberry Pi, (e.g., DB17, DB18, DB19), this file is located at /etc/wpa_supplicant/wpa_supplicant.conf in the root partition; For robots based on Nvidia Jetson Nano, (e.g., DB21M), this file is located at /etc/wpa_supplicant.conf in the APP partition;

New networks can be created by adding a new network= paragraph, and then entering the network information. An example network configuration is shown below:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=CH

network={
    id_str="network_1"
    ssid="comnet23243"
    psk="MSNDJWKE32"
    key_mgmt=WPA-PSK
}

network={
    id_str="network_2"
    ssid="TPlink23432"
    psk="ksnbn4wn3"
    key_mgmt=WPA-PSK
}

Testing if your Duckiebot is Connected to the Internet

✎

Modified 2020-09-02 by frank-qcd-qk

Some networks block pings from passing through, so a better way is to execute on your duckiebot:

duckiebot $ sudo curl google.com

which will try to download the Google homepage. If it is successful, you should see an output like:

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>

Option 1: Connect your Duckiebot to the internet through a WiFi router that you control

✎

Modified 2021-02-17 by tanij

If you are working from your home, for example, you simply need to make the Duckiebot connect to your home network. You may have input the proper SSID and password when you initialized the SD card, in which case, your Duckiebot should be connected to the internet already.

If you didn’t enter the right SSID and password for your network or you want to change you need to connect to your robot somehow (e.g. with Ethernet) and then edit the file /etc/wpa_supplicant/wpa_supplicant.conf as explained in the Duckiebot initialization procedure.

This is the best option.

Option 2: Bridge the internet connection through your laptop with Ethernet

✎

Modified 2021-02-17 by tanij

This method assumes that you can connect your laptop to a network but it is one that you don’t control or is not open. For example, on campus many networks are more protected, e.g., with PEAP. In that case, it can be difficult to get your configurations right on the Duckiebot. An alternative is bridge the connection between your laptop and your Duckiebot whenever you need internet access on the robot.

Ubuntu

✎

Modified 2021-02-17 by tanij

Connect your laptop to a wireless network.
Connect the Duckiebot to your laptop via an Ethernet cable.
Make a new Ethernet connection:
Network Settings… (or run the command nm-connection-editor)
Click “Add”
Type -> Ethernet
Connection Name: “Shared to Duckiebot”
Select “IPV4” tab
Select Method
Select “Shared to other computers”
Click apply.

Now, you should be able to SSH to your Duckiebot:

laptop $ ssh hostname

Check whether you can access the internet from your Duckiebot:

duckiebot $ sudo curl google.com

Now, try to pull a Docker image:

duckiebot $ sudo docker pull duckietown/rpi-simple-server # This should complete successfully

If the previous command does not work, you may need to change the system date. To do so, run the following command:

duckiebot $ sudo date -s "2018-09-18 15:00:00" # Where this is the current date in YYYY-MM-DD HH-mm-ss

Mac

✎

Modified 2018-09-22 by liampaull

Untested instructions here

Option 3: Push Docker Images from Laptop

✎

Modified 2020-09-02 by frank-qcd-qk

Since we are primarily using the internet to pull Docker images, we can simply connect the laptop and the Duckiebot then push Docker images from the laptop over SSH like so:

laptop $ docker save duckietown/image-name | ssh -C hostname docker load

Then the image will be available on your Duckiebot.

If you can connect to your laptop (e.g. through a router) but do not have internet access then you can proceed for now, but everytime you see a command starting with:

duckiebot $ docker run ...

note that you will need to pull onto your laptop and push to your Duckiebot in order to load the latest version of the image.

Troubleshooting

✎

Modified 2021-02-17 by tanij

I cannot ping the Duckiebot

✎

Modified 2020-09-10 by frank-qcd-qk

ping robot_name does not work.

Check if your laptop and Duckiebot are connected to the same network.

Additional debugging steps:

Step 1: Check that your Raspberry Pi is responsive by observing the blinking LED on the Raspberry Pi.
Step 2: Connect your Duckiebot with the laptop using the ethernet cable. Check if you are able to ping the Duckiebot. This will provide you an hint if there is an issue with the robot or network.
Step 3: Check that this file: /etc/wpa_supplicant/wpa_supplicant.conf contains all the wifi networks in the correct syntax that you want to connect.
Step 4: If it’s your private access point, then you can access your router, typically connecting to 192.168.0.1, where you can see all the devices connected. Make sure that both your Duckiebot and your laptop are in the list.
Step 5: Check the file ~/.ssh/config has the correct name hostname with hostname.local defined.

I cannot access my Duckiebot via SSH

✎

Modified 2020-09-02 by frank-qcd-qk

When I run ssh robot_name.local I get the error ssh: Could not resolve hostname robot_name.local.

Make sure that your Duckiebot is ON. Connect it to a monitor, a USB mouse and a keyboard. Run the command:

duckiebot $ sudo service avahi-daemon status

You should get something like the following:

● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
   Active: active (running) since Sun 2017-10-22 00:07:53 CEST; 1 day 3h ago
 Main PID: 699 (avahi-daemon)
   Status: "avahi-daemon 0.6.32-rc starting up."
   CGroup: /system.slice/avahi-daemon.service
           ├─699 avahi-daemon: running [robot_name_in_avahi.local
           └─727 avahi-daemon: chroot helpe

Avahi is the module that in Ubuntu implements the mDNS responder. The mDNS responder is responsible for advertising the hostname of the Duckiebot on the network so that everybody else within the same network can run the command ping robot_name.local and reach your Duckiebot. Focus on the line containing the hostname published by the avahi-daemon on the network (i.e., the line that contains robot_name_in_avahi.local). If robot_name_in_avahi matches the robot_name, go to the next Resolution point. If robot_name_in_avahi has the form robot_name-XX, where XX can be any number, modify the file /etc/avahi/avahi-daemon.conf as shown below.

Identify the line

use-ipv6=yes

and change it to

use-ipv6=no

Identify the line

#publish-aaaa-on-ipv4=yes

and change it to

publish-aaaa-on-ipv4=no

Restart Avahi by running the command

duckiebot $ sudo service avahi-daemon restart

I can SSH to the Duckiebot but not without a password

✎

Modified 2020-09-02 by frank-qcd-qk

Check the file ~.ssh/config and make sure you add your ssh key there, in case it doesn’t exists.

The init_sd_card procedure should generate a paragraph in the above file in the following format:

# --- init_sd_card generated ---
Host duckiebot
    User duckie
    Hostname duckiebot.local
    IdentityFile /home/user/.ssh/DT18_key_00
    StrictHostKeyChecking no
# ------------------------------

Do:

$ ssh-keygen -f "/home/user/.ssh/known_hosts" -R hostname.local

It will generate a key for you, if it doesn’t exists.

Unable to communicate with Docker

✎

Modified 2020-09-10 by frank-qcd-qk

Error message appears saying I cannot communicate with docker. Also a warning \"DOCKER_HOST\" is set to hostname.local is present.

Unset the DOCKER_HOST, running:

laptop $ unset DOCKER_HOST

Can ping but the robot doesn’t move with the virtual joystick

✎

Modified 2020-09-10 by frank-qcd-qk

You can ping the robot, ssh into it, start the demos, but the commands from the virtual joystick do not seem to reach the robot.

A possible cause is that your computer’s firewall is blocking the incoming traffic from the robot.

Check the settings for the firewall on your computer and make sure that any incoming traffic from the IP address of the robot is allowed on all ports. Keep in mind that if your robot’s IP address changes, you might need to update the rule.