Configure Unbound as a local forwarder using DNS-over-TLS to forward queries.
This forwards DNS queries to a designated server for resolution according to the DNS domain name in the query rather than being handled by the initial server that was contacted by the client.
server: ########################################################################### # BASIC SETTINGS ########################################################################### # Time to live maximum for RRsets and messages in the cache. If the maximum # kicks in, responses to clients still get decrementing TTLs based on the # original (larger) values. When the internal TTL expires, the cache item # has expired. Can be set lower to force the resolver to query for data # often, and not trust (very large) TTL values. cache-max-ttl: 86400 # Time to live minimum for RRsets and messages in the cache. If the minimum # kicks in, the data is cached for longer than the domain owner intended, # and thus less queries are made to look up the data. Zero makes sure the # data in the cache is as the domain owner intended, higher values, # especially more than an hour or so, can lead to trouble as the data in # the cache does not match up with the actual data any more. cache-min-ttl: 300 # Set the working directory for the program. directory: "/opt/unbound/etc/unbound" # RFC 6891. Number of bytes size to advertise as the EDNS reassembly buffer # size. This is the value put into datagrams over UDP towards peers. # 4096 is RFC recommended. 1472 has a reasonable chance to fit within a # single Ethernet frame, thus lessing the chance of fragmentation # reassembly problems (usually seen as timeouts). Setting to 512 bypasses # even the most stringent path MTU problems, but is not recommended since # the amount of TCP fallback generated is excessive. edns-buffer-size: 1472 # Listen to for queries from clients and answer from this network interface # and port. interface: 0.0.0.0@53 # Rotates RRSet order in response (the pseudo-random number is taken from # the query ID, for speed and thread safety). rrset-roundrobin: yes # Drop user privileges after binding the port. username: "_unbound" ########################################################################### # LOGGING ########################################################################### # Do not print log lines to inform about local zone actions log-local-actions: no # Do not print one line per query to the log log-queries: no # Do not print one line per reply to the log log-replies: no # Do not print log lines that say why queries return SERVFAIL to clients log-servfail: no # Further limit logging logfile: /dev/null # Only log errors verbosity: 0 ########################################################################### # PRIVACY SETTINGS ########################################################################### # RFC 8198. Use the DNSSEC NSEC chain to synthesize NXDO-MAIN and other # denials, using information from previous NXDO-MAINs answers. In other # words, use cached NSEC records to generate negative answers within a # range and positive answers from wildcards. This increases performance, # decreases latency and resource utilization on both authoritative and # recursive servers, and increases privacy. Also, it may help increase # resilience to certain DoS attacks in some circumstances. aggressive-nsec: yes # Extra delay for timeouted UDP ports before they are closed, in msec. # This prevents very delayed answer packets from the upstream (recursive) # servers from bouncing against closed ports and setting off all sort of # close-port counters, with eg. 1500 msec. When timeouts happen you need # extra sockets, it checks the ID and remote IP of packets, and unwanted # packets are added to the unwanted packet counter. delay-close: 10000 # Prevent the unbound server from forking into the background as a daemon do-daemonize: no # Add localhost to the do-not-query-address list. do-not-query-localhost: no # Number of bytes size of the aggressive negative cache. neg-cache-size: 4M # Send minimum amount of information to upstream servers to enhance # privacy (best privacy). qname-minimisation: yes ########################################################################### # SECURITY SETTINGS ########################################################################### # Only give access to recursion clients from LAN IPs access-control: 127.0.0.1/32 allow access-control: 192.168.0.0/16 allow access-control: 172.16.0.0/12 allow access-control: 10.0.0.0/8 allow # access-control: fc00::/7 allow # access-control: ::1/128 allow # File with trust anchor for one zone, which is tracked with RFC5011 # probes. auto-trust-anchor-file: "var/root.key" # Enable chroot (i.e, change apparent root directory for the current # running process and its children) chroot: "/opt/unbound/etc/unbound" # Harden against algorithm downgrade when multiple algorithms are # advertised in the DS record. harden-algo-downgrade: yes # RFC 8020. returns nxdomain to queries for a name below another name that # is already known to be nxdomain. harden-below-nxdomain: yes # Require DNSSEC data for trust-anchored zones, if such data is absent, the # zone becomes bogus. If turned off you run the risk of a downgrade attack # that disables security for a zone. harden-dnssec-stripped: yes # Only trust glue if it is within the servers authority. harden-glue: yes # Ignore very large queries. harden-large-queries: yes # Perform additional queries for infrastructure data to harden the referral # path. Validates the replies if trust anchors are configured and the zones # are signed. This enforces DNSSEC validation on nameserver NS sets and the # nameserver addresses that are encountered on the referral path to the # answer. Experimental option. harden-referral-path: no # Ignore very small EDNS buffer sizes from queries. harden-short-bufsize: yes # Refuse id.server and hostname.bind queries hide-identity: yes # Refuse version.server and version.bind queries hide-version: yes # Report this identity rather than the hostname of the server. identity: "DNS" # These private network addresses are not allowed to be returned for public # internet names. Any occurrence of such addresses are removed from DNS # answers. Additionally, the DNSSEC validator may mark the answers bogus. # This protects against DNS Rebinding private-address: 10.0.0.0/8 private-address: 172.16.0.0/12 private-address: 192.168.0.0/16 private-address: 169.254.0.0/16 # private-address: fd00::/8 # private-address: fe80::/10 # private-address: ::ffff:0:0/96 # Enable ratelimiting of queries (per second) sent to nameserver for # performing recursion. More queries are turned away with an error # (servfail). This stops recursive floods (e.g., random query names), but # not spoofed reflection floods. Cached responses are not rate limited by # this setting. Experimental option. ratelimit: 1000 # Use this certificate bundle for authenticating connections made to # outside peers (e.g., auth-zone urls, DNS over TLS connections). tls-cert-bundle: /etc/ssl/certs/ca-certificates.crt # Set the total number of unwanted replies to eep track of in every thread. # When it reaches the threshold, a defensive action of clearing the rrset # and message caches is taken, hopefully flushing away any poison. # Unbound suggests a value of 10 million. unwanted-reply-threshold: 10000 # Use 0x20-encoded random bits in the query to foil spoof attempts. This # perturbs the lowercase and uppercase of query names sent to authority # servers and checks if the reply still has the correct casing. # This feature is an experimental implementation of draft dns-0x20. # Experimental option. use-caps-for-id: yes # Help protect users that rely on this validator for authentication from # potentially bad data in the additional section. Instruct the validator to # remove data from the additional section of secure messages that are not # signed properly. Messages that are insecure, bogus, indeterminate or # unchecked are not affected. val-clean-additional: yes ########################################################################### # PERFORMANCE SETTINGS ########################################################################### # https://nlnetlabs.nl/documentation/unbound/howto-optimise/ # # https://nlnetlabs.nl/news/2019/Feb/05/unbound-1.9.0-released/ # Number of slabs in the infrastructure cache. Slabs reduce lock contention # by threads. Must be set to a power of 2. infra-cache-slabs: 2 # Number of incoming TCP buffers to allocate per thread. Default # is 10. If set to 0, or if do-tcp is "no", no TCP queries from # clients are accepted. For larger installations increasing this # value is a good idea. incoming-num-tcp: 10 # Number of slabs in the key cache. Slabs reduce lock contention by # threads. Must be set to a power of 2. Setting (close) to the number # of cpus is a reasonable guess. key-cache-slabs: 2 # Number of bytes size of the message cache. # Unbound recommendation is to Use roughly twice as much rrset cache memory # as you use msg cache memory. msg-cache-size: 119173802 # Number of slabs in the message cache. Slabs reduce lock contention by # threads. Must be set to a power of 2. Setting (close) to the number of # cpus is a reasonable guess. msg-cache-slabs: 2 # The number of queries that every thread will service simultaneously. If # more queries arrive that need servicing, and no queries can be jostled # out (see jostle-timeout), then the queries are dropped. # This is best set at half the number of the outgoing-range. # This Unbound instance was compiled with libevent so it can efficiently # use more than 1024 file descriptors. num-queries-per-thread: 4096 # The number of threads to create to serve clients. # This is set dynamically at run time to effectively use available CPUs # resources num-threads: 1 # Number of ports to open. This number of file descriptors can be opened # per thread. # This Unbound instance was compiled with libevent so it can efficiently # use more than 1024 file descriptors. outgoing-range: 8192 # Number of bytes size of the RRset cache. # Use roughly twice as much rrset cache memory as msg cache memory rrset-cache-size: 238347605 # Number of slabs in the RRset cache. Slabs reduce lock contention by # threads. Must be set to a power of 2. rrset-cache-slabs: 2 # Do no insert authority/additional sections into response messages when # those sections are not required. This reduces response size # significantly, and may avoid TCP fallback for some responses. This may # cause a slight speedup. minimal-responses: yes # # Fetch the DNSKEYs earlier in the validation process, when a DS record # is encountered. This lowers the latency of requests at the expense of # little more CPU usage. prefetch: yes # Fetch the DNSKEYs earlier in the validation process, when a DS record is # encountered. This lowers the latency of requests at the expense of little # more CPU usage. prefetch-key: yes # Have unbound attempt to serve old responses from cache with a TTL of 0 in # the response without waiting for the actual resolution to finish. The # actual resolution answer ends up in the cache later on. serve-expired: yes # Open dedicated listening sockets for incoming queries for each thread and # try to set the SO_REUSEPORT socket option on each socket. May distribute # incoming queries to threads more evenly. so-reuseport: yes ########################################################################### # LOCAL ZONE ########################################################################### # Include file for local-data and local-data-ptr include: /opt/unbound/etc/unbound/a-records.conf ########################################################################### # FORWARD ZONE ########################################################################### forward-zone: # Forward all queries (except those in cache and local zone) to # upstream recursive servers name: "." # Queries to this forward zone use TLS forward-tls-upstream: yes # https://dnsprivacy.org/wiki/display/DP/DNS+Privacy+Test+Servers # Cloudflare forward-addr: 1.1.1.1@853#cloudflare-dns.com forward-addr: 1.0.0.1@853#cloudflare-dns.com #forward-addr: 2606:4700:4700::1111@853#cloudflare-dns.com #forward-addr: 2606:4700:4700::1001@853#cloudflare-dns.com # CleanBrowsing forward-addr: 185.228.168.9@853#security-filter-dns.cleanbrowsing.org forward-addr: 185.228.169.9@853#security-filter-dns.cleanbrowsing.org # forward-addr: 2a0d:2a00:1::2@853#security-filter-dns.cleanbrowsing.org # forward-addr: 2a0d:2a00:2::2@853#security-filter-dns.cleanbrowsing.org # Quad9 # forward-addr: 9.9.9.9@853#dns.quad9.net # forward-addr: 149.112.112.112@853#dns.quad9.net # forward-addr: 2620:fe::fe@853#dns.quad9.net # forward-addr: 2620:fe::9@853#dns.quad9.net # getdnsapi.net # forward-addr: 185.49.141.37@853#getdnsapi.net # forward-addr: 2a04:b900:0:100::37@853#getdnsapi.net # Surfnet # forward-addr: 145.100.185.15@853#dnsovertls.sinodun.com # forward-addr: 145.100.185.16@853#dnsovertls1.sinodun.com # forward-addr: 2001:610:1:40ba:145:100:185:15@853#dnsovertls.sinodun.com # forward-addr: 2001:610:1:40ba:145:100:185:16@853#dnsovertls1.sinodun.com remote-control: control-enable: no