DSM > Network > General Settings
Unbound.conf
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"
# If enabled, Unbound will respond with Extended DNS Error codes (RFC 8914).
# These EDEs attach informative error messages to a response for various
# errors.
# When the val-log-level: option is also set to 2, responses with Extended
# DNS Errors concerning DNSSEC failures that are not served from cache, will
# also contain a descriptive text message about the reason for the failure.
ede: yes
# If enabled, Unbound will attach an Extended DNS Error (RFC 8914)
# Code 3 - Stale Answer as EDNS0 option to the expired response.
# This will not attach the EDE code without setting ede: yes as well.
ede-serve-expired: yes
# 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.
# The actual buffer size is determined by msg-buffer-size (both for TCP and
# UDP). Do not set higher than that value.
# Default is 1232 which is the DNS Flag Day 2020 recommendation.
# Setting to 512 bypasses even the most stringent path MTU problems, but
# is seen as extreme, since the amount of TCP fallback generated is
# excessive (probably also for this resolver, consider tuning the outgoing
# tcp number).
edns-buffer-size: 1232
# 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
# If you want to log to a file, use:
# logfile: /opt/unbound/etc/unbound/unbound.log
# Set log location (using /dev/null further limits logging)
logfile: /dev/null
# Set logging level
# Level 0: No verbosity, only errors.
# Level 1: Gives operational information.
# Level 2: Gives detailed operational information including short information per query.
# Level 3: Gives query level information, output per query.
# Level 4: Gives algorithm level information.
# Level 5: Logs client identification for cache misses.
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"
# Deny queries of type ANY with an empty response.
deny-any: yes
# Harden against algorithm downgrade when multiple algorithms are
# advertised in the DS record.
harden-algo-downgrade: yes
# Harden against unknown records in the authority section and additional
# section. If no, such records are copied from the upstream and presented
# to the client together with the answer. If yes, it could hamper future
# protocol developments that want to add records.
harden-unknown-additional: 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
# If enabled the HTTP header User-Agent is not set. Use with caution
# as some webserver configurations may reject HTTP requests lacking
# this header. If needed, it is better to explicitly set the
# the http-user-agent.
hide-http-user-agent: no
# Refuse id.server and hostname.bind queries
hide-identity: yes
# Refuse version.server and version.bind queries
hide-version: yes
# Set the HTTP User-Agent header for outgoing HTTP requests. If
# set to "", the default, then the package name and version are
# used.
http-user-agent: "DNS"
# 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: 4
# 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: 4
# 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: 170671445
# 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: 4
# 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: 3
# 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: 341342890
# Number of slabs in the RRset cache. Slabs reduce lock contention by
# threads. Must be set to a power of 2.
rrset-cache-slabs: 4
# 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
# UDP queries that have waited in the socket buffer for a long time can be
# dropped. The time is set in seconds, 3 could be a good value to ignore old
# queries that likely the client does not need a reply for any more. This
# could happen if the host has not been able to service the queries for a
# while, i.e. Unbound is not running, and then is enabled again. It uses
# timestamp socket options.
sock-queue-timeout: 3
# 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
# include: /opt/unbound/etc/unbound/srv-records.conf
###########################################################################
# FORWARD ZONE
###########################################################################
# include: /opt/unbound/etc/unbound/forward-records.conf
remote-control:
control-enable: no
