On Mon, Oct 13, 2025 at 07:13:35PM +0300, Martin-Éric Racine wrote: > On Sun, 10 Aug 2025 18:53:34 +0200 =?utf-8?q?Marvin_G=C3=BClker?= > <[email protected]> wrote: > > Package: ifupdown > > Version: 0.8.44 > > Severity: normal > > X-Debbugs-Cc: [email protected] > > > > Dear Maintainer, > > > > I just upgraded to Debian Trixie. The release notes say that > > isc-dhcp-client is deprecated and should be replaced with dhcpcd-base. > > I tried, but it appears to be incompatible with my network > > configuration, which uses stateful DHCPv6. This is on a server which > > uses the venerable ifupdown with this configuration in > > /etc/network/interfaces: > > > > # This file describes the network interfaces available on your system > > # and how to activate them. For more information, see interfaces(5). > > > > source /etc/network/interfaces.d/* > > > > # The loopback network interface > > auto lo > > iface lo inet loopback > > > > # The primary network interface > > allow-hotplug enp2s0 > > iface enp2s0 inet dhcp > > iface enp2s0 inet6 dhcp > > > > Trying to raise enp2s0 on boot fails with this log: > > With dhcpcd one only needs one line to handle both IPv4 and IPv6. Can > you try commenting either the inet or intet6 line and see if this > fixes it?
This sounds like an implementation detail of dhcpcd; relying on it breaks the ifupdown contract with the user. It's nice that dhcpcd can do both together but that mode should be selected as an optimisation by ifupdown when both inet and inet6 stanzas request dhcp. There are many combinations that users might select and stateful dhcp for both is probably not the main one: DHCPv4+SLAAC+RDNSS and DHCPv4+SLACC+statelessDHCP being both more common and other options also being possible like DHCPv4 + manual configuration because v4 is on NAT and v6 wants a well-(locally-)defined address.
