After following these instructions you will have a bootable microSD card which can be inserted into a Raspberry Pi 3 to load up the Raspbian Lite image, configured to auto-connect to your wifi network, with a server you can SSH into. For good measure, we will also enable the UART serial console.

All the work is being done on a traditional x86-based Linux laptop - the Pi won’t be needed until you actually want to boot the image!

Downloads

There are 2 files we’ll need to download. The first and most obvious is the official Raspbian Lite image available here,

https://www.raspberrypi.org/downloads/raspbian/

I’ve tested against the April 2017 version. The second is Etcher; a cross-platform tool to flash images. You can get it from,

https://etcher.io/

Flashing the image

Etcher makes the process of flashing Raspbian images ridiculously easy! Open the application, select our Raspbian Lite image, target memory device is auto-selected and finally click the ‘Flash!’ button. In about 5 minutes the flashed memory device will be verified and ready to be ejected from the computer!

Activating the SSH server

Re-insert the memory device. It will show up with two partitions - a FAT boot partition and another ext4 partition. Let’s refer to the latter as the system partition.

You want to navigate into the boot partition and within the /boot directory, create a file called ssh. The contents don’t matter - only the existence of the file is checked to enable the SSH server.

Pay attention to the owners and permissions within the /boot directory.

Enable the serial UART console

Within the same /boot folder is a file called config.txt. You need to edit this text file and append the following,

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enable_uart=1

That’s all it takes to enable the UART console. Bear in mind that using Bluetooth after this might come with a few hiccups.

As usual, pay attention to the owners and permissions within the folder.

Configuring Wifi

Now you need to move into the system partition. Navigate to the folder called /etc/wpa_supplicant. You’ll need to append the following to the file named wpa_supplicant.conf,

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network={
    ssid="YOUR_WIFI_SSID"
    psk="YOUR_WIFI_PASSWORD"
}

The quotes are important. These should be enough if the wifi ssid is being broadcast and WPA2 Personal security settings are used. If that’s not the case, you’ll want to refer to these instructions instead,

https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md

Pay special attention to the file permissions and ownership settings here. I think I needed to use sudo to make the edits.

Conclusion

We’re done. You can now eject the microSD card from your computer, insert it into the Raspberry Pi 3 board, power it on, wait for booting to finish and ssh into it from another system on the wifi network!

Assuming that you don’t run into any hardware trouble (like corrupted microSD cards!), you can use the default credentials to login to your Pi -

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Username : pi
Password : raspberry

Remember to give the Pi enough time to boot before you attempt to SSH into it. About 1 - 3 minutes works for me with a Class 10 microSD card. For convenience, you might want to configure the DHCP server on your network to allocate a static IP address to the Pi 3 board.