Changing WiFi details

Luckily, there’s a way to put in a new WiFi password without having a screen or keyboard attached to the Pi. Instead you, need an SD card reader.

Mount the SD Card on your dev computer

Take the MicroSD card out of the Pi and put it in the card reader attached to your dev computer.

Then, pop it in your computer and it should automatically “mount”, and appear in your file browser, the same way that you’d expect from an thumb drive. That’s “Files” in Gnome (used by Ubuntu Linux), Finder in MacOS, Windows Explorer etc.

When you do this, it should mount two folders for you, system-boot and writable.

Editing network config

Inside the system-boot folder, you’ll find a file called network-config. Edit this in the text editor of your choice. It’s contents should look a bit like this:

network:
  version: 2
  wifis:
    wlan0:
      dhcp4: true
      regulatory-domain: "AU"
      access-points:
        "My Awesome WiFi":
          password: "8FFA2C40DF18020B75496602F7D10A7E7AF4C00C059E7CB811C16B7ED3B09C44"
      optional: true

In this file we can see nested config. The format of this file is YAML, where each section that has been further indented (in this case by two spaces) is considered to be nested inside the previous section.

Give this, for our network config, we have a wifi interface called wlan0 and that inside it there’s a section called access-points. Inside that, you probably see details for one wireless network, that you configured when initially flashing the SD card. The example above has that called “My Awesome WiFi”, and it has a password which has been encrypted into a hexadecimal string so we can’t read it.

You can add another wifi network and password to this. It’s a bit hard to encrypt the password yourself, but it still works to put it in plain text.

Adding your own network

So, let’s add another network to that.

network:
  version: 2
  wifis:
    wlan0:
      dhcp4: true
      regulatory-domain: "AU"
      access-points:
        "My Awesome WiFi":
          password: "8FFA2C40DF18020B75496602F7D10A7E7AF4C00C059E7CB811C16B7ED3B09C44"
        "My new house":
          password: "topsecret"
      optional: true

You’ll see above that I added the wifi network for My new house with the password top secret.

With that done, save the file. Then un-mount the two mounts for the SD card in your file manager, pull the card out, pop it back in the Pi and boot it up. It should automatically connect to your new network.