Mdthbs

I'm currently neck deep in building an internet gateway out of an old fanless, headless Intel Atom/ITX computer I had laying around. My ISP provides ipv6 and ipv4 resolution via dhcp. They also provide an IPv6 prefix. My goal is to have a ipv4 and ipv6 provided by my ISP's DCHP facing the internet, a static v4 ip facing the lan hosting it's own DHCP server, and a DHCPv6 server providing assignment of addresses within the prefix provided by my isp and setting it's own lan-side v6 ip to <prefix>::1/64. I want to use dhcpv6 instead of router advertisement because I will be setting up ddns managed by my new gateway as well as radius and a few other odds an ends... some of which will be used to determine what ip clients end up with. The final wrinkle is that it must be resilient to disconnects and reconnects of the ethernet which I currently have managed by ifplugd. I want this to function as a network appliance: minimal need for me to perform maintenance beyond security updates. Plug-and-go.

I currently have everything working on the ipv4 side. Like clockwork. The gateway itself has a fully functioning dual-stack connection to the internet and can access resources both via ipv4 and ipv6. I've also implemented a netfilter based firewall for both ipv4 and ipv6. I've even got the lan side assigned a static-private ipv4 address and a <prefix>::1/64 address. And I can provide clients on my lan with an ipv4 address, dns, domain, gateway and all the rest via DHCP.

What I can't do is provide IPv6 addresses in the range of <prefix>::0/64 to clients via dhcp. I'm stuck with the reality that dhcpd needs me to set a static name server, static gateway, and static prefix in it's config file... yet all of those are dynamically assigned based on the prefix given by my ISP. I've been through the dhcpd.conf manpage a number of times now and I don't see anything offering a way to assign these dynamically. That dhcpcd stores it's lease data in binary format doesn't help matters.

My next step is to write some scripts, and probably a systemd unit or two, to manage querying the data I need from dhcpcd and (re)starting dhcpd with the appropriate flags. But this is clunky and I fear all the ways it could quirk out on what is meant to be a plug-and-go unit. If I have to ssh into my gateway later to fix something... it means I've failed.

I've also considered scrapping everything I have so far and switching to an all-in-one solution like WIDE... but I'm uncertain about WIDE's ability to integrate with bind, radius, and the like. It would be a real pita to tear down all my existing work, spend time learning and configuring WIDE, get past the current problem... and then find out something else I planned isn't possible with WIDE.

Am I just missing the obvious here? If so, what am I missing? Can WIDE or another all-in-one DCHP client/server provide for my lofty goals? Is kludging together some scripts to bridge the gap (and custom units to solve race conditions) between dhcpcd and dhcpd the best way?

P.S. Before anyone asks, I started off trying to use dhclient on the wan side (sticking with ISC tools for dns/dhcp), but it didn't want to resolve ipv6 and ipv4 on the same interface and wouldn't let me query an v6 ip and a v6 prefix at the same time. Probably my fault... but I gave up and switched to dhcpcd as a result.