Upgrade openwrt on Linksys WRT1200AC with extroot


  • WRT1200AC (this router) contains 2 partitions
  • Flashing the firmware through the Luci interface actually flashes the new firmware to the inactive partition


  • Download the bin file needed to upgrade the package
  • Create a list of all the installed packages on current version using opkg list-installed | cut -f 1 -d ' ' > /root/installed_packages.txt
  • Choose one of the following methods to flash:
    • Flash the file from the Luci interface
    • Download the file to the /tmp and then flash using sysupgrade /tmp/*.bin
  • After the flash and reboot, you will be in the partition that you wasn’t on before the flash, it will have all of your previous configs, but the extroot will not be there.
  • Hopefully, you will already have internet access at this point, if not, go ahead and setup internet.
  • Once your internet is up, you will need to run some commands to install packages needed to setup:
    • First, install packages that are necessary to setup extroot:
      opkg update && opkg install block-mount kmod-fs-ext4 kmod-usb-storage e2fsprogs kmod-usb-ohci kmod-usb-uhci fdisk
    • In my case I use f2fs for my extroot, which means I need extra packages, like mkf2fs to format the flash.
    • Now, format the device you plan to use for extroot, in my case, I ran mkf2fs /dev/sda1 cause the sda2 was used as swap.
    • At this point, copy the overlay to the newly formatted drive
      mkdir -p /tmp/introot
      mkdir -p /tmp/extroot
      mount --bind / /tmp/introot
      mount /dev/sda1 /tmp/extroot
      tar -C /tmp/introot -cvf - . | tar -C /tmp/extroot -xf -
      umount /tmp/introot
      umount /tmp/extroot
    • Regenerate fstab using block detect > /etc/config/fstab;
    • Reboot
    • You should have a working Openwrt with extroot now. Change opkg/distfeeds.conf to the corresponding upgraded version.
    • Now run opkg upgrade $(opkg list-upgradable | awk '($1 !~ "^kmod|Multiple") {print $1}') to keep base packages up-to-date.
    • And install all your backed up packages using cat /root/installed_packages.txt|xargs opkg install

Because I don’t use dnsmasq, this means once the steps above finishes, I will need to do some extra post installation steps

Post installation (More as a personal note):

  • Remove odhcpd-ipv6only package and install odhcpd, this will ensure IPv4 dhcp functionality, otherwise, there will only be ipv6 addresses allocated.

November 2021 Update: Updating to Openwrt 21.02

I upgraded Openwrt version 21.02 branch in September of this year. It wasn’t as easy as I had thought, but I had the problem solved after all. In release 21.02, Openwrt introduced what’s called DSA or Distributed Switch Architecture for this WRT1200AC device. To be honest, it is counter-intuitive to setup but it seems to be a more standard way when compared to the previous configuration.

The part that I have problem with is mostly the VLAN tagging. My network ISP requires tagged VLAN to be able to use the network, so for Openwrt, I will have to tag the WAN port with the VLAN id. I was able to get around it with the following block:

config device
option name 'wan'
option macaddr '<MAC_ADDRESS>'
config interface 'wan'
option device 'wan.10'
option proto 'pppoe'
option username '<PPPOE_USERNAME>'
option ipv6 '1'
option peerdns '0'
option password '<PPPOE_PASSWORD>'
list dns ''
config interface 'wan6'
option proto 'dhcpv6'
option reqaddress 'try'
option reqprefix 'auto'
option peerdns '0'
list dns '::1'
option device '@wan

It actually is quite straightforward once you get the idea of configuration. For example, in the above shared config, a device is a layer 2 in the networking stack while an interface is at layer 3. Here is Openwrt wiki’s explanation:

Devices are physical connections that convey bits/frames to other computers. They operate at layer 2 in the protocol stack, have a MAC address along with several other configurable parameters.
Network devices identify and configure hardware components of the device: individual Ethernet switch ports, wireless radios, USB networking devices, VLANs, or virtual ethernets.
Alternatively, bridge devices group several network devices together so they can be treated as a single entity. A bridge device functions like a separate unmanaged (hardware) switch, forwarding traffic between member ports as needed at the hardware level to maintain performance. Each physical port can be a member of only a single bridge device.
Interfaces route IP packets and operate at layer 3 in the protocol stack. An interface is associated with a single device that sends/receives its packets. Interfaces get their IP address parameters by the choice of protocol: Static, DHCP, PPP, 6in4, Wireguard, OpenVPN, etc.