Installing Cucumber on Ubiquiti UniFi AC

This guide covers installing Cucumber on compatible UniFi APs including:

  • Ubiquiti UniFi AC Lite
  • Ubiquiti UniFi AC Long Range
  • Ubiquiti UniFi AC Pro

Note: The UniFi ACs have no TFTP upgrade possible yet. This means you will need to use SSH.
If you don't know how to use this, we would advise not installing.

You will need the following:


1

Downgrading Ubiquiti Version

IMPORTANT, PLEASE NOTE:
Flashing will fail if your Ubiquiti firmware is version 3.4.8 and above. You can download version 3.4.7 here:
https://s3-eu-west-1.amazonaws.com/ps-firmware/_other_/firmware/U7PG2/3.4.7.3284/firmware.bin

To downgrade, first SCP the firmware to the /tmp/ folder on your AP by running the following, making sure to replace firmware.bin with the name of the firmware. The default username and password are ubnt but this may be different if you have changed it:

scp firmware.bin ubnt@192.168.1.20:/tmp/

Next, SSH into your AP by running the following, replacing ubnt and 192.168.1.20 with the username and IP address of your AP. The default username and password are ubnt and ubnt.

ssh ubnt@192.168.1.20

Then run the following command, making sure to replace firmware.bin with the name of the firmware:

fwupdate.real -m /tmp/firmware.bin -d

Then wait for the flashing progress to complete before disconnecting any cables.


2

Installing Cucumber

To start off with SCP the firmware to the /tmp/ with the following command, making sure to replace firmware.bin with the name of the firmware:

scp firmware.bin ubnt@192.168.1.20:/tmp/

Now SSH into your AP by running the following, replacing ubnt and 192.168.1.20 with the username and IP address of your AP. The default username and password are ubnt and ubnt.

ssh ubnt@192.168.1.20

Next, run the following command, making sure to replace firmware.bin with the name of the firmware:

mtd -r write /tmp/FIRMWARE-IMAGE.bin kernel0

Your terminal should look similar to the above.

Once the AP has rebooted, please leave it for a short period while it runs through its first boot stages. 

Once that is complete, run through the steps again this time flashing to kernel1:

mtd -r write /tmp/FIRMWARE-IMAGE.bin kernel1

Once the AP has rebooted and shows a solid light, you should be good to disconnect it.


Troubleshooting

If your AP still boots into UniFi firmware after you have installed Cucumber, this is most likely due to one of two things:

1. Your AP was running a Ubiquiti firmware version 3.4.8 and above before you flashed with Cucumber

To resolve this issue, you will need do the following:

  • Follow stage 1 of the guide, and flash the AP with a Ubiquiti firmware version 3.4.7 or below

2. The AP is swapping to its second partition

To resolve this issue, you will need do the following:

  • Follow stage 1 of the guide, and flash the AP with a Ubiquiti firmware version 3.4.7 or below
  • Once the flash is complete, factory reset the AP by holding the reset button for 20-25 seconds
  • Once your AP has factory reset, run through stage 2 again and reflash your AP with Cucumber