From: David Demelier <markand@malikania.fr>
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Subject: dhcpcd not updating /etc/resolv.conf
Message-Id: <B3F902EF-8956-4E30-A1BA-7D7B254459E3@malikania.fr>
Date: Thu, 29 Apr 2021 08:04:21 +0200
To: ~alpine/users@lists.alpinelinux.org

Hey there,

For some reasons I could not get dhcpcd to update /etc/resolv.conf on =
Alpine 3.13 (aarch64) on a Raspberry Pi.

The system:

Linux vanille 5.10.29-0-rpi4 #1-Alpine SMP PREEMPT Mon Apr 12 15:55:08 =
UTC 2021 aarch64 Linux


The daemon acquire a lease correctly in both eth0 and wlan0 and set =
default route, IP address and such (I can ping every IP address) but for =
some reasons the resolv.conf file is empty.

Example of syslog messages when it receives DHCP lease:

Apr 28 22:42:11 vanille daemon.info [3203]: wlan0: connected to Access =
Point `Bbox-4D2019EB'
Apr 28 22:42:11 vanille daemon.info [3203]: eth0: waiting for carrier
Apr 28 22:42:11 vanille daemon.info [3203]: DUID =
00:01:00:01:27:87:66:06:dc:a6:32:5f:6f:dc
Apr 28 22:42:11 vanille daemon.info [3203]: wlan0: IAID 32:5f:6f:dc
Apr 28 22:42:11 vanille daemon.info [3203]: wlan0: adding address =
fe80::dea6:32ff:fe5f:6fdc
Apr 28 22:42:11 vanille daemon.info [3203]: wlan0: soliciting an IPv6 =
router
Apr 28 22:42:12 vanille daemon.info [3203]: wlan0: rebinding lease of =
192.168.1.97
Apr 28 22:42:12 vanille daemon.info [3203]: wlan0: probing address =
192.168.1.97/24
Apr 28 22:42:17 vanille daemon.info [3203]: wlan0: leased 192.168.1.97 =
for 86400 seconds
Apr 28 22:42:17 vanille daemon.info [3203]: wlan0: adding route to =
192.168.1.0/24
Apr 28 22:42:17 vanille daemon.info [3203]: wlan0: adding default route =
via 192.168.1.254
Apr 28 22:42:17 vanille daemon.info [3203]: forked to background, child =
pid 3221
Apr 28 22:42:25 vanille daemon.warn [3221]: wlan0: no IPv6 Routers =
available

And the ip a show:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen =
1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host=20
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP =
qlen 1000
    link/ether dc:a6:32:5f:6f:da brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.95/24 brd 192.168.1.255 scope global dynamic eth0
       valid_lft 86054sec preferred_lft 75254sec
    inet6 fe80::dea6:32ff:fe5f:6fda/64 scope link=20
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast =
state UP qlen 1000
    link/ether dc:a6:32:5f:6f:dc brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.97/24 brd 192.168.1.255 scope global dynamic wlan0
       valid_lft 86071sec preferred_lft 75271sec
    inet6 fe80::dea6:32ff:fe5f:6fdc/64 scope link=20
       valid_lft forever preferred_lft forever

And the resolv.conf once done:

# Generated by dhcpcd
# /etc/resolv.conf.head can replace this line
# /etc/resolv.conf.tail can replace this line

The /etc/dhcpcd.conf is quite simple:

hostname

interface eth0
	metric 10

interface wlan0
	metric 20

If I install openresolv, dhcpcd calls it but the generated file is also =
empty (only the header changes). However using busybox=E2=80=99s udhcpd =
works fine and generates the appropriate nameserver line in =
/etc/resolv.conf.

I=E2=80=99ve been using dhcpcd for years without any problems on many =
machines but now I=E2=80=99m completely out of ideas about this problem. =
I also prefer dhcpcd over busybox=E2=80=99s udhcpd/ifplugng because it =
does a very good job about hotplugging interfaces and non blocking boot =
(also offers a GTK UI).

Any idea would be appreciated.=