FreeBSD-11 local_unbound stops resolving

[Dave Cottlehuber]

On Tue, 8 Aug 2017, at 18:45, James B. Byrne via freebsd-questions
wrote:
> I have a reoccurring issue with my recently installed FreeBSD
> workstation.  The local_unbound dns service ceases to provide dns
> entries to the local resolver after some period of time; measured in
> many hours or days.  I have checked the pf firewall logs and that is
> not blocking any traffic relating to DNS that I can detect.
> 
> If I re-run local-unbound-setup then local_unbound again resolves.  If
> I restart the local_unbound service then dns resolution again works.
> 
> I cannot see anything in /var/log/messages that indicate that the
> unbound service has a problem and the service is indeed running when I
> encounter the issue.
> 
> We have many other FreeBSD-11 hosts running local unbound and I have
> not noticed this issue anywhere else.

Is this workstation using a DHCP assigned address perhaps? I've seen
this on pfsense too when the external interface is restarted, perhaps a
similar thing is happening here. At least you should be able to
correlate this with loss of dns.

If so, you may be able to work around this by prepending your DNS
servers into your dhclient.conf on the workstation; here's my wlan0 
config. I use this to avoid crappy wifi DNS providers when travelling,
DNScrypt would be a better solution I guess.

# /etc/dhclient.conf
# https://www.freebsd.org/cgi/man.cgi?query=dhclient.conf
interface "wlan0" {
   send host-name "your.host.name";
   send dhcp-lease-time 864000;
   supersede domain-search "skunkwerks.at";
   prepend domain-name-servers 172.16.1.1, 4.2.2.2;
   request subnet-mask, broadcast-address, time-offset, routers,
	domain-search, domain-name, domain-name-servers, host-name;
   require subnet-mask, domain-name-servers;
}