Adding DHCPv6-PD support to DD-WRT

by geekagent

I got my new buffalo router this week, and surprisingly, no-one had documented how to do DHCPv6 with Prefix Delegation. I managed to get it working so I thought I would document it so others can find it.

Edit: I added a check to make sure dhcp6c is only running once. My router ended up running multiple copies and having them interfere with each other


  1. Set up jffs. You’ll be using it through the rest of these steps
  2. Copy /usr/bin/ipkg /jffs
  3. Edit /jffs/ipkg and change
  4. Copy /etc/ipkg.conf /jffs
  5. Edit /jffs/ipkg.conf and add the following source:
    src openwrt-trunk
    comment out the whiterussian source.
  6. jffs update and install needed packges:
    # IPKG_CONF_DIR=/jffs /jffs ipkg update
    # IPKG_CONF_DIR=/jffs /jffs ipkg install wide-dhcpv6-client
    # IPKG_CONF_DIR=/jffs /jffs ipkg install rdisc6
  7. Put the following in /jffs/etc/config/dhcp6c.wanup:
    if [ ! -f /tmp/var/run/ ] ; then
      dhcp6c -c /jffs/etc/dhcp6/dhcp6c.conf -p /tmp/var/run/ vlan2
  8. Put the following in /jffs/etc/config/rdisc6.wanup:
    echo 2 > /proc/sys/net/ipv6/conf/vlan2/accept_ra
  9. Make those scripts executable. # chmod 755 /jff/etc/config/*.wanup
  10. Put the following in /jffs/etc/dhcp6/dhcp6c.conf:
    interface vlan2 {
      send rapid-commit;
      send ia-pd 0;
      send ia-na 0;
      request domain-name-servers, domain-name;
      script "/jffs/etc/dhcp6/dhcp6c-script";
    id-assoc pd 0 {
      prefix-interface br0 {
        sla-id 0;
        sla-len 0;
    id-assoc na 0 {};
  11. Put the following in /jffs/etc/dhcp6/dhcp6c-script:
    if [ -f /var/run/ ] ; then
    	kill -HUP `cat /var/run/`;
  12. Make dhcp6c-script executable.
  13. Make sure ipv6 is enabled in the web interface, along with radvd. Put the following as radvd.conf:
    interface br0 {
      AdvSendAdvert on;
      prefix ::/64 {};
      RDNSS 2001:558:FEED::1 2001:558:FEED::2 {};
  14. Replace the nameservers above if this isn’t for comcast. It’s probably possible with a little work to re-write radvd.conf dynamically based on the received dns servers. This works for now.
  15. Reboot

If you run into an issue following these steps, please contact me. Note that I tried several things first and attempted to distill the results down to instructions. It’s possible that in trying something, I did something relevant that I didn’t record here.