dhcpv6-mod

This project enables Unifi UDM/UDR to provide required DHCP V6 client options to ISPs (like Orange France), including by extracting values from V4 DHCP client options you've already set in Unifi UI.

This mod was developed because there's no way to configure DHCP v6 client options in the WAN section of Unifi's UI.

It should work on any UDM/UDMPro/UDR with at least UnifiOS 2.4.x (3.x is recommended as I can no longer test in 2.x).

For Orange France, or any other ISP that requires a non-zero CoS for DHCP requests, you need to be in UnifiOS 3.1.12 at least (because DHCP v4 renew was not working before this release)

If you're not using Orange France ISP, it's now possible to configure your own DHCPv6 options (see the Initialize DHCPv6 config file section).

Warning After any non-documentation commit of this repository, or if you update your config file, or after a firmware update reboot, don't forget to run the ./install-dhcpv6-mod.sh command again (see Install or update dhcpv6-mod).

 
 

Table of Contents

• How does it work ?
• Build a odhcp6c supporting CoS
• Download dhcpv6-mod files
• Initialize DHCPv6 config file
• Install (or update) dhcpv6-mod
• Activate DHCPv6 WAN client
• Check IPv6 lease and connectivity
• Rollback (if needed)  
   

How does it work ?

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As a prerequisite, you must have entered the needed DHCP V4 WAN options (for Orange : 60, 61, 77 and 90), using Unifi's GUI WAN1 settings, as they are needed to generate V6 options.

Then we will :

• Build a more recent version of odhcp6c (from openwrt repo) that has the -K option in order to pass a CoS for DHCP requests
• Replace Unifi's /usr/sbin/odhcp6c by our own shell script odhcp6c.sh, which will :
  • fetch the DHCPv4 options values from ubios-udapi-server state file
  • prepare the DHCPv6 options with required formats, customizable via a configuration file
  • finally, exec the new /data/local/bin/odhcp6c (the one we just built), with all the adequate options

 
 

On the UDM/UDR, build a version of odhcp6c supporting CoS

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NEW The /usr/sbin/odhcp6c provided by Unifi now supports the -K option to pass a CoS option for DHCP v6, as needed for Orange ISP. So, if you are in v3.2.9 or newer you do not need to perform this step anymore : Skip to next section (Download dhcpv6-mod).

First (if not already done), install git and cmake on the UDM/UDR :

apt-get install -y git cmake file

Then, 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

Check that our new odhcp6c supports the CoS option (the line with '-K' should be displayed) :

# /data/local/bin/odhcp6c -h 2>&1 | grep priority
	-K <sk-prio>	Set packet kernel priority (0)

[OPTIONAL] You can delete the source code (not needed for our purpose) :

rm -rf /root/odhcp6c

 
 

Download dhcpv6-mod files

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Install the repo files in the /data/dhcpv6-mod directory (/data is persisted after reboots including firmwares upgrades).

You can either use git to clone this repo (recommended) :

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

 
 

Initialize DHCP V6 configuration file

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If you are using Orange France ISP, then you may skip this section and move to the next one (Install/update dhcpv6-mod files), as the installation script will create the /data/local/etc/dhcpv6.conf config file for you, with Orange settings by default.

If you are NOT using Orange France ISP, the first time you install dhcpv6-mod, you must create and customize the /data/local/etc/dhcpv6.conf file yourself before moving to the next section (installation), which will not overwrite it.

Please read the CONFIGURE.md documentation page, which describes how to create your own config file.

 
 

Install (or update) dhcpv6-mod

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Go to the directory we just cloned, and run the install/update script :

cd /data/dhcpv6-mod
./install-dhcpv6-mod.sh

This command must be issued :

• when installing dhcpv6-mod for the first time, of course
• when dhcpv6-mod repository gets an update commit (except if limited to documentation)
• when you update your configuration file (/data/local/etc/dhcpv6.conf)
• after a firmware update reboot (not a normal reboot, which does not uninstall dhcpv6-mod)

Note install-dhcpv6-mod will initially create the /data/local/etc/dhcpv6.conf configuration file (ONLY if it doesn't already existe), using dhcpv6-orange.conf file content

In fact, the ./install-dhcpv6-mod.sh command can be run at any time : it will only update /usr/sbin/odhcp6c with a new version of odhcp6c.sh if one of the following is true :

• file /usr/sbin/odhcp6c is older than odhcp6c.sh
• process odhcp6c is older than odhcp6c.sh

In addition, if a DHCPv6 client process was already running, and if either one of the above conditions is true OR if config file is newer than the running process then the script will finish by calling ./restart-dhcp-clients.sh. This other script, that can also be called manually, will restart both DHCP v4 and v6 clients (full DHCP discover sequence for both, without interrupting the WAN connection). In that case, it is advisable to check WAN access and in particular Check IPv6 lease and connectivity

 
 

Activate DHCP V6 WAN client for the first time

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In the UI, go to Network > Settings > Internet > Primary (WAN1)

For Orange, you must already have set VLAN ID (832 for Orange), DHCP client options (V4) 60/77/90, and DHCP CoS 6. For non-Orange ISP, you must have a working WAN IPV4 connection, with all required options set in the UI.

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 (or /usr/sbin/odhcp6c-org if -K supported) 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 eth4.832

 
 

Check DHCP V6 lease and IPV6 WAN connectivity

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You can check the DHCP V6 discover process and lease in the system log :

grep -E 'dhcpc|odhcp6c|dhcpv6-mod' /var/log/daemon.log

Expected output (click to expand)

2023-07-17T15:45:26+02:00 UDR odhcp6c[2540864]: Starting RELEASE transaction (timeout 4294967295s, max rc 5)
2023-07-17T15:45:26+02:00 UDR odhcp6c[2540864]: Send RELEASE message (elapsed 0ms, rc 0)
2023-07-17T15:45:26+02:00 UDR ubios-udapi-server[2540863]: udhcpc: received SIGTERM
2023-07-17T15:45:26+02:00 UDR ubios-udapi-server[3018621]: udhcpc: started, v1.34.1
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Selected DHCPv6 client executable (with support for CoS) : /data/local/bin/odhcp6c
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Found ubios-udapi-server JSON config in /data/udapi-config/ubios-udapi-server/ubios-udapi-server.state
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Fetched DHCPv4 option 60 : length=5 value=s...m
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Fetched DHCPv4 option 77 : length=43 value=FSVDS...ebox3
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Fetched DHCPv4 option 90 : length=140 value=00000...xxxxx
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Fetched MAC Address Clone : length=12
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Fetched DHCPv4 CoS of 6
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Found dhcp6c options file /data/local/etc/dhcpv6.conf
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Generated DHCPv6 CoS of 6 (default is to set to the same value as DHCPv4 CoS)
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Generated DHCPv6 option 1 : length=20 value=0003...xxxx (clientid, -c )
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018621]: udhcpc: broadcasting discover
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018763]: [info ] ubios-dhcpc-decline-script: DHCP offer 90.xx.xx.xxx/21 on interface eth4.832, gateway: 90.xx.xx.1
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Generated DHCPv6 option 11 : length=140 value=00000...xxxxx (authentication, -x 11:)
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018763]: [info ] ubios-dhcpc-decline-script: DHCP offer 90.xx.xx.xxx/21 accepted
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018621]: udhcpc: broadcasting select for 90.xx.xx.xxx, server 80.xx.xxx.x
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Generated DHCPv6 option 15 : length=43 value=FSVDS...ebox3 (userclass, -u )
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Generated DHCPv6 option 16 : length=22 value=00000...7656D (vendorclass, -V )
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Successfully generated 4 DHCPv6 options using /data/local/etc/dhcpv6.conf
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018622]: [dhcpv6-mod] Launching exec /data/local/bin/odhcp6c -a -f -R -r17,23,24 -K6 -c 0003...xxxx -x 11:00000...xxxxx -u FSVDS...ebox3 -V 00000...7656D  -v -s /usr/share/ubios-udapi-server/ubios-odhcp6c-script -D -P 56 eth4.832
2023-07-17T15:45:27+02:00 UDR odhcp6c[3018622]: (re)starting transaction on eth4.832
2023-07-17T15:45:27+02:00 UDR ubios-udapi-server[3018621]: udhcpc: lease of 90.xx.xx.xxx obtained from 80.xx.xxx.x, lease time 604800
2023-07-17T15:45:28+02:00 UDR odhcp6c[3018622]: Starting SOLICIT transaction (timeout 4294967295s, max rc 0)
2023-07-17T15:45:28+02:00 UDR odhcp6c[3018622]: Got a valid ADVERTISE after 13ms
2023-07-17T15:45:28+02:00 UDR odhcp6c[3018622]: IA_NA 0001 T1 0 T2 0
2023-07-17T15:45:28+02:00 UDR odhcp6c[3018622]: IA_PD 0001 T1 84672 T2 483840
2023-07-17T15:45:28+02:00 UDR odhcp6c[3018622]: 2a01:xxxx:xxx:xxxx::/56 preferred 604800 valid 604800
2023-07-17T15:45:30+02:00 UDR odhcp6c[3018622]: Starting SOLICIT transaction (timeout 4294967295s, max rc 0)
2023-07-17T15:45:30+02:00 UDR odhcp6c[3018622]: Got a valid ADVERTISE after 10ms
2023-07-17T15:45:30+02:00 UDR odhcp6c[3018622]: IA_PD 0001 T1 84672 T2 483840
2023-07-17T15:45:30+02:00 UDR odhcp6c[3018622]: 2a01:xxxx:xxx:xxxx::/56 preferred 604800 valid 604800
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: Starting REQUEST transaction (timeout 4294967295s, max rc 10)
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: Send REQUEST message (elapsed 0ms, rc 0)
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: Got a valid REPLY after 124ms
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: IA_PD 0001 T1 84672 T2 483840
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: 2a01:xxxx:xxx:xxxx::/56 preferred 604800 valid 604800
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: T1 84672s, T2 483840s, T3 604800s
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: entering stateful-mode on eth4.832
2023-07-17T15:45:31+02:00 UDR odhcp6c[3018622]: Starting <POLL> transaction (timeout 84672s, max rc 0)

In that output, valid for Orange, we can see that 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 again both DHCP v4 and v6 sequences :

./restart-dhcp-clients.sh

Explanation : this scripts sends a SIGUSR2 to udhcpc to force a DHCPv4 RELEASE, as Unifi does not set the -R option to do that before stopping. Then it sends a SIGTERM to both udhcpc and odhcp6c, so both process will stop (odhcp6c will perform a RELEASE before) and immediately be restarted by ubios-udapi-server, starting a full DISCOVER sequence for V4 and V6.

Then we can look at the result a few seconds later :

grep -E 'dhcpc|odhcp6c|dhcpv6-mod' /var/log/daemon.log

If you just need to check the log generated by odhcp6c.sh, in order to see DHCPv6 option generation :

grep dhcpv6-mod /var/log/daemon.log

 

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. And ping -6 will not work unless you do the following :

If you want to use IPV6 also within your LAN, or even just to test IPv6 connectivity, you must configure your Networks in the UI (at least the Default Network) with IPv6 Interface Type set to Prefix Delegation instead of None.

Warning As a first step I strongly suggest to only change the Default Network and leave unchecked Router Advertisment (RA) (ie. disabled), this is probably safer

Then, if you do that, after a few seconds, you can check if the main bridge (br0) got an IPv6 address, and test WAN IPv6 connectivity from the UDR/UDM :

# ip -6 addr show scope global dynamic
47: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 2a01:xxxx:xxx:xxxx::1/64 scope global dynamic
       valid_lft 541988sec preferred_lft 541988sec
# ping -6 google.com
PING google.com(par10s22-in-x0e.1e100.net (2a00:1450:4007:80e::200e)) 56 data bytes
64 bytes from par10s22-in-x0e.1e100.net (2a00:1450:4007:80e::200e): icmp_seq=1 ttl=117 time=2.38 ms
(...)
# curl -6 ipv6.google.com -I
HTTP/1.1 200 OK
(...)

 
 

[OPTIONAL] Fully activate IPV6 on your LAN (Router Advertisment)

In the previous section, you already have set IPv6 Interface Type to Prefix Delegation, but with RA disabled, and you could validate the WAN IPv6 connectivity.

Next, you can optionnaly check Router Advertisment (RA) (so enable RA) for some Network(s) when you want devices to dynamically get IPv6 addresses.

Note This can lead to issues in some use cases, depending on your LAN and WLAN devices configurations...you'll have to carefully test everything

 
 

Note about avoiding Unifi firmware IPV6 download endpoints not reachable

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When you update your applications from Unifi UI, wget commands are launched in the background, to download the new firmware binaries.

Unfortunately, as of July 2023 at least, Unifi's IPV6 endpoints for fw-download.ubnt.com are unreachable. And, as Unifi does not use wget options like --connect-timeout=10 or the --prefer-family=IPv4, the default is to try the first adress returned by the DNS resolver, which is IPV6 in our case, and this will wait forever and not perform the desired update

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 install-dhcpv6-mod.sh script to install, as you should have, then the fix is already done for you, this is for information or check)

grep -sq '^prefer-family' /root/.wgetrc || echo 'prefer-family = IPv4' >> /root/.wgetrc

 
 

Rollback (if needed)

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In the UI, go to Network > Settings > Internet > Primary (WAN1), and set "IPv6 Connection" to "Disabled" (instead of DHCPv6).

Do the same with any Network for which you have enabled "IPv6 Interface Type" to any other than "Disabled".

Then, the odhcp6c process should stop within a few seconds.

You can reactivate it later by changing the same setting to "DHCPv6".