Hi Vincent, On Thu, Oct 23, 2025 at 09:27:54PM +0200, Vincent Danjean wrote: > As I've a multi-ISP config, I want to share here a bit of my config, > as an example of unusual config. > > For one of my ISP, I've the following config: > iface en-rezine inet6 auto > dhcp 1 > accept_ra 0 > > dhcp is required as my ISP only gives me a local-link address > (via DHCP) I think there are some misconceptions in your config or my understanding of how the pieces fit together. Assuming you're currently using isc-dhcp-client: - DHCP(v6) is not involved in link-local assignment the kernel does it. - `dhcp 1` is stateless DHCP and will not assign an address on it's own. - `accept_ra 0` will prevent kernel SLAAC address and (default) route creation entirely, leaving no address configuration method enabled (other than link-local). Further, no stateful DHCPv6 client will be enabled by RA flag M being advertised by the network since that's not supported by dhclient AFAIK. > and also a /48 via prefix delegation (in DHCP), - `request_prefix` defaults to OFF in both method auto and dhcp. None of what you describe should be working. Something other than ifupdown+dhclient must be making this work. Do you have dhcpcd installed without knowing it? :-) > but do not get any specific IPv6 within the /48 directly > (via SLAAC nor via DHCP) > I ignore RA as I configure a local radvd daemon (I've a multi-ISP config) > > I'm using isc-dhcp-client. I hope, but not test, that dhcpcd also > handle prefix delegation correctly. Supporting `request_prefix` with dhcpcd is on my TODO list. You can easily drop down to dhcpcd.conf even without support in ifupdown though. > Also note that I'm a user of the /etc/dhcp/dhclient-enter-hooks.d > interface. Due to the multi-ISP setup, I remove with a script > the default IPv4 route classically added by DHCP for my different ISP. > The routing is manually handled by shorewall config. Makes sense. I'd be happy to support the old dhclient-*-hooks.d interface, but we need to review all the existing scripts in Debian to make sure nothing will break spectacularly. Could you help review them for compatibility if I look at where the incompatibilities with dhcpcd's hook environment might lie? Thanks, --Daniel
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