Control: retitle -1: ifupdown: dhcpcd-base causes 'inet6 auto' (SLAAC) to use IPv6 privacy addresses
Hi Thorsten,
Thanks for keeping an eye on the situation here :-).
The recent stable-update was does not claim to fix any of the dhcpd
integration issues. Only the default installation with isc-dhcp-client got
fixes. The larger dhcpcd integration work has gotten stuck for lack of time
and energy.
In any case you're likeley observing the expected behaviour of
dhcpcd-base's default configuration:
$ grep ^slaac /etc/dhcpcd.conf
slaac private
I'm of the opinion this is a bad default for Debian and have raised this
before, however our dhcpd Maintainer disagrees and thus it remains.
(Note to self: https://lists.debian.org/debian-devel/2024/09/msg00194.html
"Replacing isc-dhcp-client with dhcpcd-base (Was: ifupdown maintenance)")
What you want there is "slaac hwaddr".
Since the discussion in Sept. 2024 I've learned we can actually override
this on the ifupdown side (using --slaac=hwaddr in the dhcpcd cmdline).
I'm not a fan of introducing that divergence because doing so makes
user-intent coming from /etc/dhcpcd.conf ineffective as the dhcpcd cmdline
args take precedence.
I'd still like to find a better solution, but in my experience dhcpcd
remains uncooperative in this area so it's difficult to get motivated to
try and do something about it.
Thanks,
--Daniel
On Sat, Mar 21, 2026 at 12:23:32AM +0100, Thorsten Glaser wrote:
> Package: ifupdown
> Version: 0.8.44+deb13u1
> Severity: normal
> X-Debbugs-Cc: [email protected]
>
> I’m still getting the wrong IP address:
>
> 3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
> group default qlen 1000
> link/ether bc:cd:99:00:3d:18 brd ff:ff:ff:ff:ff:ff
> altname wlp2s0
> altname wlxbccd99003d18
> inet 192.168.1.5/24 brd 192.168.1.255 scope global dynamic noprefixroute
> wlan0
> valid_lft 72997sec preferred_lft 62197sec
> inet6 fe80::a0b4:89cb:7b12:18e/64 scope link
> valid_lft forever preferred_lft forever
>
> Expected: fe80::becd:99ff:fe00:3d18
>
> The relevant network config snippet is:
>
> iface wlan0 inet dhcp
> wireless-power off
> wireless-essid …
> wpa-ssid …
> wpa-psk …
>
> iface wlan0 inet6 auto
>
>
>
>
> -- Package-specific info:
> --- /etc/network/interfaces:
> # interfaces(5) file used by ifup(8) and ifdown(8)
> # Include files from /etc/network/interfaces.d:
> source /etc/network/interfaces.d/*
>
> # The loopback network interface
> auto lo
> iface lo inet loopback
>
> # Ethernet, only on demand though
> iface eth0 inet dhcp
>
> --- /etc/network/interfaces.d/*:
> cat: /etc/network/interfaces.d/Wfarm: Permission denied
> cat: /etc/network/interfaces.d/Woben: Permission denied
> cat: /etc/network/interfaces.d/Wunten: Permission denied
> cat: /etc/network/interfaces.d/b1: Permission denied
> cat: /etc/network/interfaces.d/diensthandy: Permission denied
>
> --- up and down scripts installed:
> /etc/network/if-down.d:
> total 12
> lrwxrwxrwx 1 root root 33 Mar 11 2025 bridge ->
> /usr/lib/bridge-utils/ifupdown.sh
> -rwxr-xr-x 1 root root 1677 Jun 29 2025 clamav-freshclam-ifupdown
> -rwxr-xr-x 1 root root 207 Apr 23 2025 postfix
> -rwxr-xr-x 1 root root 759 Aug 20 2024 resolved
> lrwxrwxrwx 1 root root 32 Mar 22 2025 wpasupplicant ->
> ../../wpa_supplicant/ifupdown.sh
>
> /etc/network/if-post-down.d:
> total 4
> lrwxrwxrwx 1 root root 33 Mar 11 2025 bridge ->
> /usr/lib/bridge-utils/ifupdown.sh
> -rwxr-xr-x 1 root root 1413 Jul 24 2024 wireless-tools
> lrwxrwxrwx 1 root root 32 Mar 22 2025 wpasupplicant ->
> ../../wpa_supplicant/ifupdown.sh
>
> /etc/network/if-pre-up.d:
> total 12
> lrwxrwxrwx 1 root root 33 Mar 11 2025 bridge ->
> /usr/lib/bridge-utils/ifupdown.sh
> -rwxr-xr-x 1 root root 348 Apr 30 2025 ethtool
> -rwxr-xr-x 1 root root 4185 Jul 24 2024 wireless-tools
> lrwxrwxrwx 1 root root 32 Mar 22 2025 wpasupplicant ->
> ../../wpa_supplicant/ifupdown.sh
>
> /etc/network/if-up.d:
> total 32
> -rwxr-xr-x 1 root root 1677 Jun 29 2025 clamav-freshclam-ifupdown
> -rwxr-xr-x 1 root root 1689 Apr 30 2025 ethtool
> -rwxr-xr-x 1 root root 4586 Mar 10 2025 mountnfs
> -rw-r--r-- 1 root root 142 Mar 23 2015 openntpd
> -rwxr-xr-x 1 root root 207 Apr 23 2025 postfix
> -rwxr-xr-x 1 root root 4665 Aug 20 2024 resolved
> lrwxrwxrwx 1 root root 32 Mar 22 2025 wpasupplicant ->
> ../../wpa_supplicant/ifupdown.sh
>
>
> -- System Information:
> Debian Release: 13.4
> APT prefers stable-updates
> APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500,
> 'proposed-updates'), (500, 'stable')
> Architecture: amd64 (x86_64)
>
> Kernel: Linux 6.12.74+deb13+1-amd64 (SMP w/16 CPU threads; PREEMPT)
> Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
> Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
> Shell: /bin/sh linked to /usr/bin/dash
> Init: sysvinit (via /sbin/init)
>
> Versions of packages ifupdown depends on:
> ii adduser 3.152
> ii iproute2 6.15.0-1
> ii libc6 2.41-12+deb13u2
>
> Versions of packages ifupdown recommends:
> ii dhcpcd-base [dhcp-client] 1:10.1.0-11+deb13u2
>
> Versions of packages ifupdown suggests:
> pn ppp <none>
> pn rdnssd <none>
>
> -- no debconf information
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