Enable Unifi UDM/UDR Unifi DHCP V6 client to pass options to ISPs like Orange, by extracting values from V4 DHCP client options that you've already set in the UI.
This mod is needed as there is no possibility to configure DHCP v6 client options in the WAN section of Unifi's GUI.
It should work on any UDM/UDMPro/UDR after 2.4.x.
The mod is automaticaly re-applied after a reboot, and even after Unifi OS firmware updates if you install the specific udm-boot package of this repo.
Table of contents :
- DHCP V6 options
- How does it work ?
- Build a odhcp6c supporting CoS
- Download dhcpv6-mod files
- Install/update dhcpv6-mod files
- Activate DHCPv6 WAN client
- Install udm-boot package
- Rollback (if needed)
Here are the 4 DHCP options that are propagated from V4 to V6 with needed transformations, e.g. headers specified by RFC8415 for options 16 and 1) :
| Name | Opt V4 | Opt V6 | Header V6 | Value (from V4) | Example of odhcp6c argument |
|---|---|---|---|---|---|
| Vendor class | 60 | 16 | 0000040E 0005 (4-byte IANA enterprise# + 2-byte length) | Vendor class string in hex | -V 000000040E0005736167656D (here 5 bytes ASCII hex code for 'sagem') |
| Client identifier | 61 | 1 | 0003 0001 (DUID type LL + hw type ethernet | Mac Address Clone (UI) | -c 00030001xxxxxxxxxxxx (6 bytes in hex for cloned macaddr) |
| User class | 77 | 15 | None, because -u already adds 2-byte length field (e.g. 002B) | When using -u, pass a string (not hexstring) | -u FSVDSL_livebox.Internet.softathome.LiveboxN (here 43 or 0x2b bytes as hexstring) |
| Authentication | 90 | 11 | None | Authentication in hexstring (same as V4 opt 90 without ':') | -x 11:00....xx (70 bytes in hexstring for auth) |
As a prerequisite, of course, you must have entered the needed DHCP V4 WAN options (60, 61, 77 and 90), using Unifi's GUI WAN1 settings, as they are needed to generate V6 options.
- From the UDR/UDM, build a more recent version of
odhcp6c(from openwrt repo) that has the-Koption in order to pass a CoS for DHCP requests - Replace Unifi's
/usr/sbin/odhcp6cby our own shell scriptodhcp6c.sh, that :- generates valid DHCP V6 options by fetching the V4 options values from
ubios-udapi-serverconfig file - prepare the V6 options with needed prefixes and formats
- finally,
execthe new/data/local/bin/odhcp6cwe just built
- generates valid DHCP V6 options by fetching the V4 options values from
- In addition, install our own
udm-bootDebian package (and systemd service) that will re-apply dhcpv6-mod even after a Unifi OS firmware update
First (if not already done), install git and cmake on the UDM/UDR :
apt-get install -y git cmakeThen make a new odhcp6c executable locally (here in root's home directory), from the openwrt repo, and deploy it in /data/local/bin :
cd
git clone https://github.com/openwrt/odhcp6c.git
cd odhcp6c
cmake .
make
mkdir -p /data/local/bin
cp -p odhcp6c /data/local/bin[OPTIONAL] You can delete the source code (not needed for our purpose) :
rm -rf /root/odhcp6c
We will install the files in the /data/dhcpv6-mod directory (persisted after reboots/upgrades).
You can either use git to clone this repo :
cd /data
git clone https://github.com/fgero/dhcpv6-mod.git...or alternatively download the files with curl :
cd /data
curl -sL https://github.com/fgero/dhcpv6-mod/archive/refs/heads/main.tar.gz | tar -xvz
mv dhcpv6-mod-main dhcpv6-mod
Go to the directory we just cloned :
cd /data/dhcpv6-modNow we can save and replace Unifi's /usr/sbin/odhcp6c by our own shell script odhcp6c.sh (that will prepare V6 args and exec the new odhcp6c exec we just built), by runnning this script :
./05-replace-odhcp6c.shAlternatively, if you want to update /usr/sbin/odhcp6c with a new version of odhcp6c.sh you must do like this (otherwise the script will refuse to overwrite /usr/sbin) :
./05-replace-odhcp6c.sh --updateThe script will only do something if there's a difference between /usr/sbin/odhcp6c and /data/dhcpv6-mod/odhcp6c.sh : in that case, the 05-replace-odhcp6c.sh will restart both dhcp v4 and v6 clients. This will simply re-launch a discover phase for both (as V4/V6 constistency is needed in case of Orange), without interrupting the connection.
In the UI, go to Network > Settings > Internet > Primary (WAN1)
You must already have set VLAN ID (832 for Orange), DHCP client options (V4) 60/77/90, DHCP CoS 6.
Now you need to set "IPv6 Connection" to "DHCPv6" (instead of Disabled) and "Prefix Delegation Size" to 56 (instead of 64), like so :
Then, the ubios-udapi-server process should fork, in addition to udhcpc (V4 client), a new process running our own odhcp6c with all the parameters passed, like so :
# ps -ef | grep dhcp
root 2574251 4134 0 Jun18 ? 00:00:00 /usr/bin/busybox-legacy/udhcpc --foreground --interface eth4.832 --script /usr/share/ubios-udapi-server/ubios-udhcpc-script --decline-script /usr/share/ubios-udapi-server/ubios-udhcpc-decline-script -r <publicIPv4> -y 6 --vendorclass sagem -x 77:<userclass_hex> -x 90:<auth>
root 2574252 4134 0 Jun18 ? 00:00:00 /data/local/bin/odhcp6c -a -f -K6 -R -r11,17,23,24 -V <pfx+vendorclass> -c <pfx+clientid> -u <userclass_string> -x 11:<auth> -v -s /usr/share/ubios-udapi-server/ubios-odhcp6c-script -D -P 56 eth4.832You can check the DHCP discover & lease in the system log :
# grep -e dhcpc -e odhcp6c /var/log/daemon.log
(...)
2023-06-18T17:01:51+02:00 UDR odhcp6c[2574252]: Starting SOLICIT transaction (timeout 4294967295s, max rc 0)
2023-06-18T17:01:51+02:00 UDR odhcp6c[2574252]: Got a valid ADVERTISE after 10ms
2023-06-18T17:01:51+02:00 UDR odhcp6c[2574252]: IA_PD 0001 T1 87555 T2 483840
2023-06-18T17:01:51+02:00 UDR odhcp6c[2574252]: 2a01:xxxx:xxx:xxxx::/56 preferred 604800 valid 604800
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: Starting REQUEST transaction (timeout 4294967295s, max rc 10)
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: Send REQUEST message (elapsed 0ms, rc 0)
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: Got a valid REPLY after 231ms
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: IA_PD 0001 T1 87555 T2 483840
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: 2a01:xxxx:xxx:xxxx::/56 preferred 604800 valid 604800
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: T1 87555s, T2 483840s, T3 604800s
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: entering stateful-mode on eth4.832
2023-06-18T17:01:52+02:00 UDR odhcp6c[2574252]: Starting <POLL> transaction (timeout 87555s, max rc 0)
(...)
2023-06-18T17:02:04+02:00 UDR ubios-udapi-server[2574251]: udhcpc: broadcasting select for 90.XX.XX.XXX, server 80.10.239.9
2023-06-18T17:02:04+02:00 UDR ubios-udapi-server[2574251]: udhcpc: lease of 90.XX.XX.XXX obtained from 80.10.239.9, lease time 604800
(...)Here you asked and got a /56 prefix (7 bytes), like 2a01:xxxx:xxx:xx00:, and the 8th byte (00) is reserved by your router/box, you can use 01 to FF (254 subnets of /64)
If this does not work, you can try to reset both DHCP v4 and v6 sequences (apparently Orange wants that):
killall udhcpc odhcp6c Even after getting a V6 lease, your WAN interface will not get a public IPV6 address, this is expected (apparently) in a V4+V6 (double stack) situation.
[OPTIONAL] If you want to use IPV6 also within your LAN, you must configure one of your Networks in the UI, with IPv6 Interace Type set to "Prefix Delegation", RA enabled, et leave the rest as default.
It the V6 lease is OK, then you must ensure that our odhcp6c hack is maintained even after a reboot.
You could do that using these instructions, from the unifios-utilities repo, but this does not survive a firmware update (see issue #1).
So I would suggest to do simply this :
cd /data/dhcpv6-mod/udm-boot
./install_udm_boot.shThis will add the udm-boot package (provided as a .deb file in this repo) to the ubnt-dpkg-cache facility, so that it is restored if missing after a firmware update reboot.
The package itself, when installed, puts the udm-boot.service file in /lib/systemd/system/udm-boot.service and enable+start the udm-boot service with systemctl.
Then you can add ".sh" files in the /data/on_boot.d/ directory so that they are executed at boot.
In our case, we need to replace at each reboot the /usr/sbin/odhcp6c executable (that is automatically restored by Unifi each time) by our script. For that we must copy the 05-replace-odhcp6c.sh script :
mkdir -p /data/on_boot.d
cp -p /data/dhcpv6-mod/05-replace-odhcp6c.sh /data/on_boot.d
When you update your applications from Unifi UI, wget commands are lauched in order to download the new firmware binaries.
Unfortunately, right now at least, the IPV6 endpoints of fw-download.ubnt.com are unreachable.
And, as Unifi does not use wget options like --connect-timeout=01 or the --prefer-family=IPv4, the default is to try the first adress returned by the DNS resolver (which is IPV6) and never timeout.
So we need to use the .wgetrc file to change the default behaviour of wget commands (until Unifi does something)
NOTE : if you used the 05-replace-odhcp6c.sh script to install, as you should have, then it's already done, this is for information or check :
grep -sq '^prefer-family' /root/.wgetrc || echo 'prefer-family = IPv4' >> /root/.wgetrc
In the UI, go to Network > Settings > Internet > Primary (WAN1)
Set "IPv6 Connection" to "Disabled" (instead of DHCPv6)
The odhcp6c process should stop within a few seconds.
Also deactivate IPv6 in LAN if you have set that.
You can reactivate it later by changing the same setting to "DHCPv6".