dhcpcd-discuss

Hi Nathan, sorry for the late reply

On 03/06/2020 16:46, Nathan O'Meara wrote:
> I am using dhcpcd 8.1.9 on Gentoo to manage the WAN interface on my router, as 
> well as to delegate the IPv6 prefixes assigned by DHCPv6 to my internal 
> interfaces (which have statically configured ipv4 addresses using gentoo’s 
> net-scripts).
>
> I technically only have two physical interfaces, wan0 and lan0, but lan0 is 
> configured with multiple VLANs.  Occasionally, usually do to switch software 
> updates, but sometimes due to other causes, the lan0 physical interfaces loses 
> link for a few minutes.  After the link is re-established, the static IPv4 
> addresses are present, but the delegated ipv6 addresses are missing.  A side 
> effect here is in this state, if I restart dhcpcd or restart the entire system, 
> the DHCP lease seems to be stuck requesting a /64 instead of the previous /56, 
> until I clear out the wan0.lease6 file and restart dhcpcd.
>
> I would like to retain the separation between using dhcpcd for my wan (and 
> prefix delegation), while retaining the distribution-specific config for the 
> internal static/vlan addresses.  Is it possible to configure dhcpcd to 
> re-establish the PD addresses on the internal interfaces when they come back up, 
> without using dhcpcd to configure their IPv4 addresses?

It should be doing this by default.
When an interface comes up, it asks any other interfaces "do you have a 
delegaton for me?" and then rocks with it.
For example this:

allow interfaces eth0
interface eth0
   ia_pd 1 eth1 eth2

So dhcpcd only operates on eth0 directly.
It will "activate" eth1 and eth2 for delegation only.

> If the only way to fix this is to use dhcpcd fully administer the lan0* 
> interfaces, is there a way to manage them separately at runtime?  For example, 
> currently I can restart dhcpcd to force a renewal of my wan0 interface, but that 
> only effects the ipv6 delegated addresses on the internal addresses, which 
> become invalid if the prefix is released, so that is correct behavior.  I do not 
> want to lose LAN connectivity when I simply need to restart the WAN interface.
>
> I have included my config file below in case I have any errors in it or old 
> config options that should be changed in the current version.
>
> Thanks.
>
> $ cat /etc/dhcpcd.conf | grep -v "^#"
>
> debug
>
> logfile /var/log/dhcpcd.log
>
> hostname
>
> duid
>
> waitip 6
>
> noipv6rs
>
> nodhcp
>
> nodhcp6
>
> noipv4ll
>
> option rapid_commit
>
> option domain_name_servers, domain_name, domain_search, host_name
>
> option classless_static_routes
>
> option interface_mtu
>
> require dhcp_server_identifier
>
> slaac private
>
> nohook lookup-hostname
>
> nohook resolv.conf
>
> interface wan0
>
> dhcp
>
> dhcp6
>
> ipv4ll
>
> ia_pd wan0/::/56 lan0/0/64 lan0.42/2/64 lan0.43/3/64 lan0.110/4/64 lan0.214/5/64 
> lan0.215/6/64

The bit you are missing is allow/deny to limit dhcpcd as per your request.

Roy