My home internet connection is going through a router provided by my ISP. It gets a ::/56 ipv6 prefix assigned dynamically by my ISP every night.
Behind that router I have a debian bullseye box for subnet management and firewalling etc. It also provides ipv6 subnets by requesting a prefix with dhclient from the router provided by my ISP.
By default, the debian box requests a ::/62 prefix leaving me four subnets in total. Now I would like to request a prefix of ::/57 instead of ::/62 so the debian box manages the majority of the original ::/56 prefix.
Unfortunately I can't figure out how to do that.
I found the command line option --prefix-len-hint in dhclient(8) which apparently should do exactly that. However, I don't have a clue how to set that option in /etc/dhcp/dhclient.conf or elsewhere.
Consulting dhclient.conf(5) and dhcp-options(5) didn't help. The closest option I found there was described with:
option dhcp6.ia-prefix string;
The ia-prefix option is placed inside ia-pd options in order to identify the prefix(es) allocated to the client. It is not directly edited in dhcpd.conf(5) or dhclient.conf(5), but rather is manufactured and consumed by the software.
That is not very helpful to me and leaves me clueless.
Can someone please tell me how to put command line options of dhclient into /etc/dhcp/dhclient.conf or point me into the right direction for changing the default prefix length of ::/62?
Thank you very much!
