OpenWRT on Raspberry Pi 3B/3B+

Note

OpenWRT 18.06.1 is not working on RPi 3B+ due to a problem with the GPU (which is responsible for the boot process). Support for the RPi 3B+ is available in the snapshot versions, and will probably land in stable at 18.06.2.

Everything works fine on the RPi 3B (non plus).

Update rpi firmware

Before you install OpenWRT on your raspi, it’s a good idea to update the firmwares. With a running install of raspbian, run the following commands:

$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo rpi-update

Get signing keys

Since OpenWRT will probably be used as a firewall, it is essential to verify the authenticity of your downloads. To do that, you’ll need the GPG public keys from OpenWRT.

Figure out which version of OpenWRT you will install, and then download the appropriate key. Unfortunately, it seems you can’t download the key with curl(1) or wget(1), so you’ll have to get that from your browser directly.

It’s always a good idea to check the key fingerprint as obtained through another connection, like your 3G network instead of your home wifi.

$ gpg openwrt.asc
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
pub   rsa4096 2018-05-16 [SC] [expires: 2020-05-15]
    6768C55E79B032D77A28DA5F0F20257417E1CE16
uid           OpenWrt Release Builder (18.06 Signing Key) <[email protected]>

If all is good, you can import the key.

$ gpg --import openwrt.asc
gpg: key 0F20257417E1CE16: public key "OpenWrt Release Builder (18.06 Signing Key) <[email protected]>" imported
gpg: Total number processed: 1
gpg:               imported: 1

Download/verify image

Download the factory firmware, sum and signature files. Refer to the device page to find the latest version.

$ wget https://downloads.openwrt.org/releases/18.06.1/targets/brcm2708/bcm2710/openwrt-18.06.1-brcm2708-bcm2710-rpi-3-ext4-factory.img.gz
$ wget https://downloads.openwrt.org/releases/18.06.1/targets/brcm2708/bcm2710/sha256sums
$ wget https://downloads.openwrt.org/releases/18.06.1/targets/brcm2708/bcm2710/sha256sums.asc

Verify the sha sum and gpg signature

$ sha256sum --ignore-missing -c sha256sums
openwrt-18.06.1-brcm2708-bcm2710-rpi-3-ext4-factory.img.gz: OK

$ gpg --verify sha256sums.asc
gpg: assuming signed data in 'sha256sums'
gpg: Signature made Fri 17 Aug 2018 03:31:45 PM CEST
gpg:                using RSA key 0F20257417E1CE16
gpg: Good signature from "OpenWrt Release Builder (18.06 Signing Key) <[email protected]>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 6768 C55E 79B0 32D7 7A28  DA5F 0F20 2574 17E1 CE16

The GPG warning above indicates that the key is not trusted. That is normal, since we only imported it. However a quick check of the fingerprint won’t hurt.

Make the bootable SD card

Danger

Make sure to write to the correct device. Use dmesg | tail to figure out which device you just inserted.

$ gzip -d openwrt-18.06.1-brcm2708-bcm2710-rpi-3-ext4-factory.img.gz
$ sudo dd if=openwrt-18.06.1-brcm2708-bcm2710-rpi-3-ext4-factory.img of=/dev/sdb bs=1M status=progress; sync

First login

The device will need a minute or two to boot. Wait until your computer gets an IP address.

Warning

The device will act as a DHCP server once powered up. You might want to keep it off your existing network until it’s configured.

SSH into the device and change the root password.

$ ssh [email protected]
The authenticity of host '192.168.1.1 (192.168.1.1)' can't be established.
RSA key fingerprint is SHA256:yJruTSql8kyzbKkcC0Ai8EKage9Sb3910wsyPaOlrBk.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.1' (RSA) to the list of known hosts.

... motd

[email protected]:~# passwd
Changing password for root
New password:
Retype password:
passwd: password for root changed by root

To facilitate initial setup, you may choose to set OpenWRT to be a DHCP client instead of sever.

# uci set network.lan.proto=dhcp
# uci commit
# /etc/init.d/network restart