OpenWrt images don't generate ULA prefix

usefive · January 10, 2025, 5:33pm

While configuring OpenWrt, I noticed that the ULA prefix is not being auto generated. According to this post [Solved] Auto-generate ULA Prefix on compiled firmware - #5 by jow - For Developers - OpenWrt Forum by Jow, it is generated automatically upon first boot if the network config has ula_prefix set to auto.

I believe all that is needed would be to add the following to the network configuration located at /etc/config/network:

config globals 'globals'
        option ula_prefix 'auto'

Otherwise the generation code could be adapted to set it, that’s here: openwrt/package/base-files/files/etc/uci-defaults/12_network-generate-ula at 17b0d1379a3cd4a2e2dbefa7d0f9bc281269f97e · openwrt/openwrt · GitHub

jarrodu · January 11, 2025, 6:22am

It looks like it would be an easy change.

github.com

lxc/lxc-ci/blob/main/images/openwrt.yaml#L312


      
                content: |-
                  lxc.arch = {{ image.architecture_kernel }}
          
          files:
          - path: /etc/hostname
            generator: hostname
          
          - path: /etc/hosts
            generator: hosts
          
          - path: /etc/config/network
            generator: dump
            content: |-
              config interface 'loopback'
                  option ifname 'lo'
                  option proto 'static'
                  option ipaddr '127.0.0.1'
                  option netmask '255.0.0.0'
          
              config interface 'wan'
                  option ifname 'eth0'

Have you tested it yet? How are you launching your VM?

usefive · January 11, 2025, 1:55pm

I tested it successfully with the container image.

Create: incus create images:openwrt/23.05 owrt-test
Edit the config: incus file edit owrt-test/etc/config/network, adding the following:

config globals 'globals'
        option ula_prefix 'auto'

Start: incus start owrt-test
Check: incus exec owrt-test cat /etc/config/network, the ula_prefix should change from auto to something like fdb0:b828:a551::/48.