Swap Unifi custom firmware with modified firmware to use GPON-ONU on 3rd party OLT
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7.6 KiB

Modify Ufiber UF-Instant

This repo will contains modified RootFS and files used to convert UF-INSTANT SFP GPON stick from Vendor Lock-in on UFiber products to an open solution that can interact with 3rd party OLT. Please note that on the market there are ready OOB (out-of-the-box) alternatives, you can take a lot at Anime4000 repo with all other information and compatible sticks. GUI on the modded firmware was made by Anime4000 :)

All mods are just for fun, I am absolutely not responsible if your stick will die after the procedure :)

Original Firmwares from Ubiquiti

All files were extracted from OLT original firmware. rootfs files can be extracted with unsquashfs (parts of squashfs-tools)

Partition Layout

MTD layout of UF-INSTANT is a little bit different from other Realtek Stick:

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00040000 00001000 "boot"
mtd1: 00002000 00001000 "env"
mtd2: 00002000 00001000 "env2"
mtd3: 0003c000 00001000 "config"
mtd4: 00300000 00001000 "k0"
mtd5: 004b0000 00001000 "r0"
mtd6: 00300000 00001000 "k1"
mtd7: 004b0000 00001000 "r1"
mtd8: 00010000 00001000 "hw"
mtd9: 00010000 00001000 "sec"
mtd10: 00001000 00001000 "Partition_010"
mtd11: 00001000 00001000 "Partition_011"
mtd12: 00300000 00001000 "linux"
mtd13: 004b0000 00001000 "rootfs"

mtd0 -> u-Boot
mtd1/2 -> u-Boot Configuration
mtd3 -> /var/config mount point where all stick configurations are saved
mtd4-5 -> kernel0/rootfs0, for the first image. This can be booted setting flags "sw_commit/sw_active" to 0 on u-Boot configuration
mtd6-7 -> kernel1/rootfs2, for the second image. This can be booted setting flags "sw_commit/sw_active" to 1 on u-Boot configuration
mtd8 -> used by Europa Driver (laser controller), it contains all information about laser calibration, pay attention because is uniq for each stick!
mtd9 -> partition used by original UF-INSTANT firmware to write parameters, not used by modified firmware
mtd10-13 -> overlay partitions

UART console (for access u-Boot\Linux OS in case of emergency)

UART credits to @robkegeenen

Firmware switching

It's possible to switch between the two images in two ways:

1 - changing env sw_active and sw_commit env from u-Boot prompt (can be done using UART console
2 - changing env sw_active and sw_commit from running Linux using command nv setenv

Env Value Boot Bank
sw_active & sw_commit 0 kernel0/root0
sw_active & sw_commit 1 kernel1/root1

nv setenv sw_active 0 && nv setenv sw_commit 0 && reboot <-- these commands switch to first image (if booted from second), using 1 doing the reverse

Factory reset after 10 boot

The stick with original firmware and without any other modification, use an u-Boot env called bootlimit that is configured with a value of 10. There is another variable called bootcount, this one is increased on each CPU reset. When bootlimit == bootcount, u-Boot format partition mtd3 and tries to download new configuration from tftpboot. With the modified firmware, that is using mtd3 for configuration, create a little headache.

To avoid this problem there are two solutions:

1 - reset bootcount env on each boot of Linux OS, adding the command nv setenv bootcount 0 on rc35 file
2 - disable bootlimit env setting it to 0. Can be done with command nv setenv bootlimit 0 on Linux OS

I prefer first approach, because if you screw up the mtd3 partition with wrongs values, doing a fast swap for ten times (avoiding full Linux OS boot) will erase config partition and after OS boot, all parameters return to factory defaults

Factory default parameters

Env Value
LAN_SDS_MODE 1 (Fiber 1G)

Flashing Custom Root FS


If you have stick with stock firmware, you can login using ssh\telnet to IP with these credentials ubnt/ubnt
Verify with this command the installed images:

nv getenv | grep sw_ver

You should have an output like this:


So in this case the stick has already version 4.3.1 onboard (we will just need to preserv k0/k1 partitions). Now verify which boot bank are you using with this command:

nv getenv | egrep "sw_active=|sw_commit="

You should have an output like this:


We are currently running image0 on mtd4/5 (refer to partition layout)

Now make sure you have nc command on your computer and follow this steps to write custom image on image1 partition

  • on the telnet\ssh session on UF-INSTANT, go to cd /tmp
  • run this command: nc -l -p 1234 > mtd7 (if you are on image1, use mtd5 as name)
  • on your computer, go where the custom root fs is downloaded rootfs_MOD_UFINST_220505 (you can found it under folder Modified RootFS - md5 4ae50a56f5c4768ea5ac95d4298a01ba)
  • run this command: nc 1234 < rootfs_MOD_UFINST_220505
  • when done, on the telnet\ssh session your nc command has exited, you have a file called mtd7 (or mtd5), run an md5sum on that file and compare the md5 with the original one, ONLY IF these are equal proceed with the next step
  • now we need to erase mtd3 (config) and mtd7 (rootfs of image1) with these commands: flash_eraseall mtd3 && flash_eraseall mtd7 (replace with mtd5 if you are doing from image1)
  • after each erase complete, you should still into /tmp directory and run this command: cat mtd7 > /dev/mtd7 (replace with mtd5 if you are doing from image1)
  • if there is no output error, we can activate the new rootfs and reboot on it. To do this run these commands: nv setenv sw_active 1 && nv setenv sw_commit 1 && reboot
  • after about 2 minutes you should reach the stick via WebUI or telnet at IP NOTE: WebUI doesn't work if there is no fiber attached

If everything is working (obviously you have to setup the stick in the right way, I mean change GPON s/n, OLT mode and so on), you can follow the same proceedure for the other bank, or leave untouched. This will give you a fast way to restore the stick to its factory default just doing a cat of original rootFS to the modified one. Please rember that if you go back to stock firmware, it's mandatory to erase mtd3 partion BEFORE rebooting.

Basic configuration of the stick

Here is a example of commands that you can do via telnet to configure the stick, on each change a reboot is mandatory to apply:

  flash set GPON_SN YOURSN
  flash set OMCI_FAKE_OK 1
  flash set OMCI_OLT_MODE 1
  flash set PON_VENDOR_ID HWTC

For a full list and explanation, please refert to Anime4000 repo here: https://github.com/Anime4000/RTL960x/blob/main/Docs/FLASH_GETSET_INFO.md

Customize RootFS

If you want, you can unsquash the custom RootFS and customized as you like (may be you want change WebUI colors or something else). Remember to unsquash the file with root users because there are some special files that need super user permission, here is the two commands to extract/repack the file that then can be flashed on the stick:


unsquashfs rootfs_MOD_UFINST_220505 this will create a folder called squashfs-root where you will find all the OS files inside


mksquashfs squashfs-root rootfs_MOD_UFINST_XXYYZZ -b 131072 -comp lzma