When Starting AD Domain Controller (samba-ad-dc) on Ubuntu 18 with Samba 4.7, It Fails Due to DNS Errors

$ sudo systemctl start samba-ad-dc

When starting samba-ad-dc, you might see the following in /var/log/samba/log.smbd or /var/log/samba/%m:

[2018/09/04 10:15:54.282382,  0] ../source4/smbd/server.c:620(binary_smbd_main)
  samba: using 'standard' process model
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
[2018/09/04 10:15:54.331785,  0] ../source4/smbd/service_stream.c:360(stream_setup_socket)
samba: setproctitle not initialized, please either call setproctitle_init() or link against libbsd-ctor.
  Failed to listen on 0.0.0.0:53 - NT_STATUS_ADDRESS_ALREADY_ASSOCIATED
[2018/09/04 10:15:54.336989,  0] ../source4/dns_server/dns_server.c:648(dns_add_socket)
  Failed to bind to 0.0.0.0:53 TCP - NT_STATUS_ADDRESS_ALREADY_ASSOCIATED

It appears that port 53 couldn't be used.

```bash $ sudo lsof -i:53 ```

When you run this command, you might see:

COMMAND   PID            USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
systemd-r 483 systemd-resolve   12u  IPv4  16576      0t0  UDP 127.0.0.53:domain
systemd-r 483 systemd-resolve   13u  IPv4  16577      0t0  TCP 127.0.0.53:domain (LISTEN)

The process systemd-resolve is using port 53.

Therefore, you need to stop it:

```bash sudo systemctl stop systemd-resolved sudo systemctl disable systemd-resolved ``` ```bash $ sudo systemctl stop samba-ad-dc $ sudo systemctl start samba-ad-dc ``` ```bash $ sudo lsof -i:53 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME samba 2674 root 36u IPv6 39433 0t0 TCP *:domain (LISTEN) samba 2674 root 38u IPv6 39434 0t0 UDP *:domain samba 2674 root 39u IPv4 39435 0t0 TCP *:domain (LISTEN) samba 2674 root 40u IPv4 39436 0t0 UDP *:domain ```

Now port 53 is available.

References:

https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1690099

https://askubuntu.com/questions/898605/how-to-disable-systemd-resolved-and-resolve-dns-with-dnsmasq