On Mon, Sep 01, 2025 at 10:15:13PM +0100, Simon Kelley wrote: > On 8/26/25 16:03, Petr Menšík via Dnsmasq-discuss wrote: > > Hello! > > > > I were just debugging one of our old tests, which tested whether dnsmasq > > --dhcp-relay worked. Both for IPv6 and IPv4 addresses. But that test > > were written with dhclient originally and worked fined with that. > > > > But you might know ISC dhcp client is deprecated and unsupported. There > > is a nice alternative still supported, dhcpcd. But it requires on > > difference and that is presence of Router Advertisement Managed flag > > set. > > > > dnsmasq has support for --enable-ra to send exactly such advertisements, > > which will then dhcpcd use to query DHCP server. The problem I see is it > > requires configured --dhcp-range for the network. > > > > But using --dhcp-relay and --dhcp-range do not make sense on the same > > network, right? > > Right. > > > Unfortunately dhcpcd just won't even try to send DHCP request to > > multicast address, until it has indication from the network it should > > try it. > > > > I think it would make sense to extend --enable-ra to send RA also from > > local addresses specified by --dhcp-relay address. > > Agreed. > > > Or at least have it explicitly enabled by --ra-param=<device>. The > > similar problem seems to have --dhcp-range=::,static. That won't be used > > by dhcpcd also, because it did not match correct network. > > The --dhcp-range=::,static problem, I don't understand. More explanation > would be good. > > > > > Would be patches implementing this desired? Do you know any different > > option, how to test dnsmasq --dhcp-relay with dhcpcd? > > Definitely will look at patches. I just looked at what needs to be done, and > came up with a five-line addition that looked good, but then realised that > all the timer infrastructure supporting unsolicited RAs is predicated on > having a struct dhcp_context. > > The simplest way to fix that might be to add a struct dhcp_relay * to struct > dhcp_context and create a context for each relay address with a flag set to > avoid it's being used anywhere else than in the RA code. > > It's a bit messy. I'll keep working on it unless you'd like to have a go. > > If you're working on testing dhcp relay, maybe have a look at the new > --dhcp-split-relay option that's in the bleeding edge code. That's IPv4 > only.
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