HOWTO: Revert a CPE510 to Pharos

I had no problem installing AREDN on a CPE510 V3.20/3.28 (Software says one, sticker on device says newer), but I could not revert to Pharos using the file upload feature in the AREDN web interface. I think this is typical of Pharos devices. 

I tried using use the following dnsmasq command after setting the wired ethernet connection to 192.168.2.1/255.255.255.0:

dnsmasq -i enp2s0 -u root --log-dhcp --bootp-dynamic --dhcp-range=192.168.2.110,192.168.2.120 -d -p0 -K --dhcp-boot=recovery.bin --enable-tftp --tftp-root=/tftp/

But what seemed to be happening is that dnsmasq undid the static ip on enp2s0 and reverted the interface to a dhcp client config:

dnsmasq-dhcp: DHCP packet received on enp2s0 which has no address

I could see the bootp/dhcp packets coming from the CPE, but now the laptop interface had no IP address. 

To get Pharos back, I followed the procedure outlined at https://www.tp-link.com/fr-be/support/faq/844 but adapted it to used the Fedora tftpd I have on my laptop since I don't know much about dnsmasq. There is probably a way to do this with dsnmasq but I will leave it to others.

1) Install and enable tftp/tftpd on Fedora as per the generic fedora/centos instructions
2) Copy the specific Pharos software .bin file for your device to /var/lib/tftpboot and rename it "recovery.bin"
3) Optional: create a tiny file in /var/lib/tftpboot and try downloading it with "tftp localhost".
4) Make a device to device ethernet connection to the device with the static address 192.168.0.100/255.255.255.0 on your host.
5) Power the Pharos device on, the press and hold the reset button while powering it back up again.
6) The Pharos device LEDs will flash in various patterns. I have no idea what they mean so I monitored the progress of the tftpd upload and reboot with tcpdump. When the Pharos device appeared to be done with the upload I released the reset button and the Pharos device appeared at IP address 192.168.0.254.

The TP-Link procedure in the above link uses a Windows tftp server called Tftpd32.exe, monitoring the tftp uplaod for completion is a little more straightforward with that app. Any old tftp server ought to work, including dnsmasq, if configured appropriately. 

Hope this helps.