Re: DHCPv6 IA_PD - how-to

 ---- On Wed, 24 Jul 2024 02:48:15 +0100  Karl Denninger  wrote --- 
 >     I'd like to replicate this that is currently being sent up via      dhcp6c, which is not quite-clear to me from the docs on how to do      that.
 >     #
 >       # This configuration will attempt to get /56 or a /60 from the
 >       # ISP and assign a /64 internally.
 >       # Note that if you have a /60 you can have four /64s defined; if      you have a
 >       # /56 then obviously you can have 16 internal networks.  For most      "house"
 >       # size networks four separate delineations is enough, for most      "moderate"
 >       # sized corporate environments 16 is enough.  BE AWARE THAT THE      SLA-LEN MUST
 >       # MATCH THE DIFFERENCE BETWEEN THE LOCAL PREFIX AND THE REMOTE      ONE!  If
 >       # you ask for a /56 then sla-len is 8, if you ask for a /60 then      the sla-len
 >       # is 4 (difference between the requested prefix length and 64,      respectively.)
 >       #
 >       
 >       interface igb0 {
 >            send ia-pd 1;
 >            send ia-na 1;
 >            send rapid-commit;
 >            script "/usr/local/etc/dhcp6c.script";
 >       };
 >       
 >       id-assoc na 1 {
 >       
 >       };
 >       
 >       id-assoc pd 1 {
 >         prefix ::/56 1800;
 >       
 >         prefix-interface igb1 {
 >           sla-id 0;
 >           sla-len 8;
 >         };
 >         
 >       };
 >     
 >     igb1 is the "normal" internal network; igb0 is the external one.
 >     The ISP hands out /56s (although at one time I could choose      either a /56 or /60); I have routines in the script file that then      generate dynamic updates for DNS so the gateway has its pointers      updated if/when the address changes (I run my own zones)
 >     
 >     Its not entirely-clear how to replicate that in the config file for dhcpcd; I can figure out the script I'm sure, but the base config is not clear to me.

So you would add this to the bottom of the default dhcpcd.conf file:

interface igb0
  ia_na
  ia_pd 0/::/56 igb1/0/64

That mirrors your config exactly apart from requesting a specific lifetime which dhcpcd doesn't support for PD.
rapid commit is enabled already in the default dhcpcd.conf file.
You could then edit /etc/dhcpcd.exit-hook to handle your DDNS.

You might be able to get away with this lighter config as well, based on what you said:
interface igb0
  ia_na
  ia_pd 0 igb1

Any pointers on now to make this more clear in dhcpcd.conf(5) are welcome.
Good luck!

Roy