unbound.conf(5) unbound 1.23.0 unbound.conf(5)
NAME
unbound.conf - Unbound 配置文件.
SYNOPSIS
unbound.conf
DESCRIPTION
unbound.conf 用于配置 unbound(8)。文件格式包含属性和值。某些属性内部包含其他属性。表示法为：attribute: value。
注释以 # 开头，并持续到行尾。空行和行首的空白将被忽略。
可以使用 unbound-checkconf(8) 工具在使用前检查 unbound.conf。
EXAMPLE
下面显示了一个示例配置文件。将其复制到 /etc/unbound/unbound.conf 并使用以下命令启动服务器：
$ unbound -c /etc/unbound/unbound.conf
大多数设置都是默认值。使用以下命令停止服务器：
$ kill `cat /etc/unbound/unbound.pid`
下面是一个最小的配置文件。源代码发行版包含一个带有所有选项的 extensive example.conf 文件。
# unbound.conf(5) unbound(8) 的配置文件。
server:
directory: "/etc/unbound"
username: unbound
# 确保 unbound 可以从 chroot 内部访问熵。
# 例如在 Linux 上使用这些命令（在 BSD 上，使用 devfs(8)）：
# mount --bind -n /dev/urandom /etc/unbound/dev/urandom
# 并且 mount --bind -n /dev/log /etc/unbound/dev/log
chroot: "/etc/unbound"
# logfile: "/etc/unbound/unbound.log" #取消注释以使用日志文件。
pidfile: "/etc/unbound/unbound.pid"
# verbosity: 1 # 取消注释并增加以获取更多日志记录。
# 监听所有接口，应答来自本地子网的查询。
interface: 0.0.0.0
interface: ::0
access-control: 10.0.0.0/8 allow
access-control: 2001:DB8::/64 allow
FILE FORMAT
关键字之间必须有空格。属性关键字以冒号“:”结尾。
属性后面跟着一个值，或者包含它的属性（在这种情况下它被称为一个子句）。
子句可以在整个文件（或包含的文件）中重复，以将属性分组到同一个子句下。
可以使用 include: 指令包含文件。
它可以出现在任何地方，接受单个文件名作为参数。
处理将继续，就好像被包含文件中的文本被复制到配置文件的那个位置一样。
如果同时使用 chroot，则使用被包含文件的完整路径名有效；
如果守护进程启动的目录等于其 chroot/工作目录，或者在 include 语句之前用 directory: dir 指定了工作目录，
则被包含文件的相对路径名也有效。
可以使用通配符包含多个文件，请参阅 glob(7)。
对于更结构化的包含选项，可以使用 include-toplevel: 指令。
这将关闭当前活动的任何子句（如果有），并强制在被包含的文件中以及此指令之后使用子句。
Server Options
这些选项属于服务器配置中的`server:`部分。
verbosity: <number>
详细程度等级，0级表示无详细信息，仅显示错误。
1级提供操作信息。
2级则包含详细的操作信息，每条查询都有简短说明。
3级深入到查询层面，逐条输出查询信息。
4级揭示算法层面的信息。
5级记录缓存未命中时的客户端标识。
默认级别为1。详细程度也可通过命令行提升，详见unbound(8)手册。
statistics-interval: <seconds>
打印统计信息到日志的间隔秒数，针对每个线程。
设置为0或""以禁用此功能，默认情况下是禁用的。
直方图统计信息仅在统计间隔期间有回复发送时才会打印，
而请求列表统计信息则会在每个间隔打印（但可能为0）。
这是因为中位数计算需要存在数据。
statistics-cumulative: <yes or no>
若启用此选项，统计信息将自Unbound启动起累计，
且在记录统计后不清除统计计数器。默认设置为`no`。
extended-statistics: <yes or no>
若启用，将从unbound-control(8)打印扩展统计信息。
默认设置为`no`，因为跟踪更多统计信息需要时间。
计数器在unbound-control(8)中列出。
statistics-inhibit-zero: <yes or no>
若启用，值为0的选定扩展统计信息将被抑制
不会在unbound-control(8)中打印。这些包括
查询类型、查询类、查询操作码、回答rcodes（除了
NOERROR、FORMERR、SERVFAIL、NXDOMAIN、NOTIMPL、REFUSED）和RPZ
操作。默认设置为`yes`。
num-threads: <number>
创建用于服务客户端的线程数量。若无需多线程，请设置为1。
port: <port number>
服务器响应查询的端口号，默认为53。
interface: <ip address or interface name [@port]>
用于连接网络的接口。此接口用于监听来自客户端的查询，
并从中向客户端提供响应。可多次指定以在多个接口上工作。
若未指定，则默认监听本地主机。若使用接口名称而非IP地址，
则采用该接口上的所有IP地址列表。在重新加载（kill -HUP）时，
接口不会变更，仅重启时生效。可通过@端口号（接口与端口号间无空格）指定端口，
未指定时则使用默认端口（来自port设置）。
ip-address: <ip address or interface name [@port]>
与 interface 相同：（以便于与nsd.conf兼容）。
interface-automatic: <yes or no>
监听所有（当前及未来）接口上的所有地址，
检测UDP查询的源接口并将其复制到回复中。
这与ip-transparent非常相似，但此选项服务于所有接口，
而使用ip-transparent时，您可以选择Unbound在哪些（未来）接口上提供服务。
此功能尚处于实验阶段，需要您的操作系统支持特定的套接字选项。
默认值为`no`。
interface-automatic-ports: <string>
列出interface-automatic监听的端口号。
若为空，则默认监听默认端口。
端口号在字符串中以空格分隔，默认值为""。
此设置可用于让interface-automatic处理接口，
并通过在列表中包含正常端口号来监听该端口，
同时也可通过将HTTPS或DNS over TLS的端口号加入列表，实现对它们的监听。
outgoing-interface: <ip address or ip6 netblock>
用于连接网络的接口。
此接口用于向权威服务器发送查询并接收其回复。
可多次指定以在多个接口上工作。
若未指定，则默认使用所有接口。
您可以在`interface:`和`outgoing-interface:`行中指定相同的接口，
这些接口将同时用于两种目的。
为防止欺骗，出站查询会通过随机选择的出站接口发送。
若指定的是IPv6网段而非单个IPv6地址，
则外发的UDP查询将采用从该网段中随机选取的源地址，以应对欺骗攻击。
此功能要求该IPv6网段需路由至运行Unbound的主机，
并且操作系统需支持非特权非本地绑定（目前仅Linux支持）。
可通过多个`outgoing-interface:`选项指定多个网段，
但切勿同时指定单个IPv6地址与IPv6网段，否则随机化机制将失效。
建议结合`prefer-ip6: yes`使用，以提高选择IPv6域名服务器进行查询的可能性。
在Linux系统上，需执行以下两条命令，
以便利用`freebind`套接字选项接收指定IPv6网段的流量：
`ip -6 addr add 你的网段/64 dev lo && ip -6 route add local 你的网段/64 dev lo`。
outgoing-range: <number>
要打开的端口数量。
每个线程可打开的文件描述符数量至少为1，默认值取决于编译选项。
较大的数值需要操作系统提供额外资源。
为了获得最佳性能，建议设置一个非常大的值，并利用libevent来实现这一目标。
outgoing-port-permit: <port number or range>
允许 Unbound 打开此端口或端口范围，用于发送查询。
允许更多的出站端口能增强抵御欺骗攻击的能力。
请确保这些端口不被其他守护进程占用。
默认情况下，仅使用 IANA 未分配的 1024 以上端口。
请提供一个端口号或“低-高”形式的范围，中间不要有空格。
`outgoing-port-permit` 和 `outgoing-port-avoid` 语句按照配置文件的顺序逐行处理，
将允许的端口加入并从允许的端口集合中减去避免的端口。
处理开始时，允许的端口集合包含非 IANA 分配的、高于 1024 的端口。
outgoing-port-avoid: <port number or range>
不允许Unbound打开此端口或端口范围用于发送查询。
使用此选项可确保Unbound不会占用其他守护进程所需的端口。
该端口在所有出站接口上均被避开，包括IPv4和IPv6。
默认情况下，仅使用IANA未分配的1024以上端口。
请提供一个端口号或“低-高”形式的范围，中间不要有空格。
outgoing-num-tcp: <number>
为每个线程分配的外发TCP缓冲区数量。
默认值为10。
若设置为0，或当do-tcp为“否”时，将不会向权威服务器发送TCP查询。
对于较大规模的部署，建议适当增加此值。
incoming-num-tcp: <number>
为每个线程分配的入站TCP缓冲区数量。
默认值为10。若设置为0，或当do-tcp为“否”时，将不会接受来自客户端的TCP查询。
对于较大规模的部署，建议适当增加此值。
edns-buffer-size: <number>
作为EDNS重组缓冲区大小通告的字节数。
此值用于通过UDP向对等方发送的数据报中。
实际缓冲区大小由msg-buffer-size决定（适用于TCP和UDP）。
请勿设置高于该值。默认值为1232，这是2020年DNS标志日的推荐值。
设置为512可以规避最严格的路径MTU问题，但被视为极端做法，
因为由此产生的TCP回退量过大（可能也适用于此解析器，建议调整出站TCP数量）。
max-udp-size: <number>
最大UDP响应大小（不适用于TCP响应）。
65536表示禁用UDP响应大小上限，始终采用客户端的选择。
建议值范围为512至4096。
默认值为1232，该默认值与edns-buffer-size的默认设置相同。
stream-wait-size: <number>
用于等待流缓冲区的最大字节数。默认值为4兆字节。
纯数字表示字节，可附加'k'、'm'或'g'分别表示千字节、兆字节或吉字节（1兆字节为1024*1024字节）。
由于TCP和TLS流会排队多个结果，这些缓冲区占用的内存总量不会超过此数值，否则将丢弃响应。
此设置用于管理服务器在高负载下的总内存使用量，同时每个连接上可排队的请求数量也受到限制，
额外的请求将在TCP缓冲区中等待。
msg-buffer-size: <number>
消息缓冲区的字节大小，默认设置为65552字节，
足以容纳64Kb的数据包，这是DNS消息的最大尺寸。
任何超过此大小的消息都无法发送或接收。
为了节省内存，可以减小此值，但某些对DNS数据的请求，
如针对大型资源记录的查询，可能会导致向客户端返回SERVFAIL（服务失败）响应。
msg-cache-size: <number>
消息缓存的大小字节数，默认值为4兆字节。
纯数字表示字节数，可附加'k'、'm'或'g'分别表示千字节、兆字节或吉字节（1兆字节等于1024*1024字节）。
msg-cache-slabs: <number>
消息缓存中的分片数量。分片通过减少线程间的锁争用来提升性能。
必须设置为2的幂次方。将其设置为接近CPU核心数的值是一个合理的估计。
num-queries-per-thread: <number>
每个线程同时处理的查询数量。若需服务的查询超出此限，
且无法通过竞争超时机制（参见jostle-timeout）移除已有查询，则新查询将被丢弃。
此举促使客户端在超时后重新发送请求，为服务器留出时间处理现有查询。
默认值依据编译选项而定，通常为512或1024。
jostle-timeout: <msec>
当服务器非常繁忙时使用的超时设置。该值通常设定为能确保一次往返权威服务器的时长。
若查询请求过多，则允许50%的查询完成执行，而另外50%若已超出其允许时间，则会被新到达的查询替换。
此机制旨在防止因慢查询或高查询率导致的服务拒绝。
默认值为200毫秒。
其效果是，对于耗时较长的查询，其每秒查询率（qps）大约为（每线程查询数/2）除以（此类长查询的平均时间）。
而对于短查询，其qps可达到（每线程查询数/2）除以（以整秒计的jostletimeout），
默认情况下约为（1024/2）* 5 = 2560 qps每线程。
delay-close: <msec>
在UDP端口因超时被关闭前，额外延迟时间以毫秒计。
默认值为0，即不启用此功能。
此设置旨在防止来自上游（递归）服务器的延迟响应数据包撞击已关闭的端口，
从而触发各种关闭端口的计数器，例如1500毫秒。
当发生超时时，系统需要额外的套接字来检查数据包的ID和远程IP，
不符合条件的数据包将被计入无效数据包计数器。
udp-connect: <yes or no>
为UDP套接字执行连接操作，以减轻ICMP侧信道泄露风险。默认设置为`yes`。
unknown-server-time-limit: <msec>
等待未知服务器响应的毫秒时间。
若您处于较慢的卫星链路环境下，可适当增加此值，例如设为1128毫秒。
这样能避免因超时导致每次初始查询都需要重新发起。默认值为376毫秒。
discard-timeout: <msec>
递归请求被丢弃的等待时间，以毫秒计。
此举旨在防止大量回复堆积。
这些请求不会收到回复，工作项将继续递归。
如果启用了服务过期客户端超时，建议此值稍大一些。
建议值为1900毫秒。值为0则禁用此功能。默认值为1900毫秒。
wait-limit: <number>
每个IP地址可等待递归回复的数量。
这为每个IP地址设置了等待递归回复的速率限制，防止大量查询积压等待返回至单一目的地。
若值为0，则禁用等待限制。默认值为1000。
wait-limit-cookie: <number>
对于发送带有有效DNS Cookie查询的IP地址，可等待递归处理的回复数量。
由于Cookie验证了客户端地址，此限制可适当提高，默认值为10000。
wait-limit-netblock: <netblock> <number>
网段等待限制。若未指定，则采用默认的等待限制值。
系统会根据最具体的网段来确定限制，这对于为特定组、个人或服务器覆盖默认设置非常有用。
值为-1时，表示该网段无等待限制。
默认情况下，回环地址的等待限制网段为-1，即不受限，因为它与网络其他部分隔离，防止伪造数据包。
回环地址127.0.0.0/8和::1/128默认设置为-1。
wait-limit-cookie-netblock: <netblock> <number>
当查询带有DNS cookie时，针对网段的等待限制。
若未指定，则采用wait-limit-cookie的值。值为-1时，该网段无等待限制。
默认情况下，回环地址127.0.0.0/8和::1/128的等待限制设置为-1。
so-rcvbuf: <number>
如果非零，则设置SO_RCVBUF套接字选项，以在UDP端口53的入站查询上获取更多缓冲区空间。
这样，在繁忙服务器上的短暂流量高峰不会导致丢包（参见netstat -su中的计数器）。
默认值为0（使用系统值）。否则，指定请求的字节数，在繁忙服务器上可尝试“4m”。
操作系统会设定一个上限，
在Linux上，Unbound需要root权限才能突破此限制，或者管理员可以使用sysctl net.core.rmem_max进行调整。
在BSD系统中，需修改/etc/sysctl.conf中的kern.ipc.maxsockbuf。
在OpenBSD上，需更改头文件并重新编译内核。
在Solaris上，使用ndd -set /dev/udp udp_max_buf 8388608进行设置。
so-sndbuf: <number>
若非0，则设置SO_SNDBUF套接字选项，以在UDP端口53的对外查询中获取更多缓冲区空间。
这对于非常繁忙的服务器而言，能有效应对应答流量的突发高峰，
否则可能会记录“发送：资源暂时不可用”的错误，且通过netstat -su也能观察到缓冲区溢出的情况。
默认值为0（使用系统设定值）。指定请求的字节数，在极其繁忙的服务器上可尝试“4m”。
操作系统会设定一个上限，
在Linux上，Unbound需要root权限才能突破此限制，或者管理员可以使用sysctl net.core.wmem_max进行调整。
在BSD和Solaris系统中，更改方式与so-rcvbuf类似。
so-reuseport: <yes or no>
若选择`yes`，则为每个线程开启专用的监听套接字以接收查询，
并尝试在每个套接字上设置SO_REUSEPORT选项。
此举可能更均匀地分配查询至各线程。
默认设置为`yes`。
在Linux系统中，此功能支持内核版本>=3.9。
其他系统如FreeBSD、OSX也可能适用。您可在任何平台及内核上启用此功能，
系统将尝试打开端口并在编译时若该选项可用则传递之；
若成功则使用，失败则静默继续（除非详细级别为3），不采用该选项。
在极高负载情况下，关闭此选项可能更利于查询的均匀分配，此现象在Linux系统（4.4.x版本）中有报告。
ip-transparent: <yes or no>
如果是，则在Unbound监听入站流量的套接字上使用IP_TRANSPARENT套接字选项。
默认情况下为`no`。此选项允许您绑定到非本地接口，
例如，对于将来会存在但目前不存在的IP地址，配合主机故障转移配置使用。
这与interface-automatic非常相似，但后者服务于所有接口，
而通过此选项，您可以选择Unbound将在哪些（未来）接口上提供服务。
在某些系统上，此选项需要Unbound以root权限启动。
在FreeBSD系统上，该选项使用IP_BINDANY，在OpenBSD系统上则使用SO_BINDANY。
ip-freebind: <yes or no>
如果是，则在监听未绑定地址的套接字上使用IP_FREEBIND选项。
默认情况下为`no`。此选项允许您绑定到非本地或不存在的IP地址，例如当网络接口或IP地址不可用时。
该选项仅存在于Linux系统中，同时也可使用类似的ip-transparent选项。
ip-dscp: <number>
传出IP数据包头中区分服务字段（DS）内的区分服务代码点（DSCP）值。
该字段取代了过时的IPv4服务类型字段及IPv6流量类别字段。
rrset-cache-size: <number>
RRset缓存的大小以字节数计，默认值为4兆字节。
纯数字表示字节，可附加'k'、'm'或'g'分别表示千字节、兆字节或吉字节（1兆字节等于1024*1024字节）。
rrset-cache-slabs: <number>
RRset缓存中的slab数量。slab通过减少线程间的锁争用来提升性能。必须设置为2的幂次方。
cache-max-ttl: <seconds>
RRsets和消息在缓存中的最大生存时间（TTL），默认值为86400秒（1天）。
当TTL到期时，缓存项即视为过期。
可通过设置更低的TTL值，强制解析器频繁查询数据，而不依赖（过大的）TTL值。
下游客户端同样会看到这一较低的TTL设置。
cache-min-ttl: <seconds>
RRsets和消息在缓存中的最小生存时间。默认值为0。
若启用最小值，数据将被缓存超过域名所有者预期的时间，从而减少查询次数以查找数据。
设置为零确保缓存中的数据符合域名所有者的意图，
而较高的值，尤其是超过一小时左右，可能导致缓存数据与实际数据不再匹配，从而引发问题。
cache-max-negative-ttl: <seconds>
负响应的生存时间上限，这些响应在授权部分包含一个时间受限的SOA记录。
默认值为3600秒。此设置适用于nxdomain（域名不存在）和nodata（无数据）类型的应答。
cache-min-negative-ttl: <seconds>
负面响应的最小生存时间，这些响应在权威部分包含一个有时间限制的SOA记录。
默认值为0（禁用）。如果此功能被禁用且配置了cache-min-ttl，则后者将生效。
在这种情况下，您可以将其设置为1以遵循上游的TTL。
此设置适用于nxdomain和nodata类型的应答。
infra-host-ttl: <seconds>
主机缓存中条目的生存时间。该缓存包含往返时间、故障状态及EDNS支持信息。默认值为900。
infra-cache-slabs: <number>
基础设施缓存中的slab数量。slab通过减少线程间的锁争用来提升性能，必须设置为2的幂次方。
infra-cache-numhosts: <number>
缓存信息的主机数量，默认值为10000。
infra-cache-min-rtt: <msec>
基础设施缓存中动态重传超时计算的下限值，默认设置为50毫秒。
若使用需更长时间进行递归名称解析的转发器，请适当增加此值。
infra-cache-max-rtt: <msec>
基础设施缓存中动态重传超时计算的上限值，默认设置为2分钟。
infra-keep-probing: <yes or no>
若启用此功能，服务器将持续对已宕机的主机进行探测，采用一次一探的模式。
默认设置为`no`。
对于已宕机的主机，例如在单次探测期间未响应者，将被标记为宕机状态，
并可能需要等待 infra-host-ttl 时间后才会再次被探测。
define-tag: <"list of tags">
定义可与本地区域（local-zone）和访问控制（access-control）一同使用的标签。
将列表用引号（""）括起，并在标签之间留出空格。
do-ip4: <yes or no>
启用或禁用是否响应或发起ip4查询。默认设置为`yes`。
do-ip6: <yes or no>
启用或禁用是否响应或发起IPv6查询。默认设置为`yes`。
若禁用，则不会在IPv6上响应查询，也不会通过IPv6向互联网域名服务器发送查询。
此选项可用于关闭IPv6传输以发送DNS流量，但不会影响DNS流量的内容，其中可能包含IPv4和IPv6地址。
prefer-ip4: <yes or no>
若启用此选项，将优先使用IPv4传输向互联网域名服务器发送DNS查询。
默认设置为`no`。
当服务器所在的IPv6网段（整个/64）并非由单一运营商所有，
且该网段/64的信誉存在问题时，此选项尤为有用，
此时使用IPv4可利用上游服务器已有的IPv4过滤机制。
prefer-ip6: <yes or no>
若启用，将优先使用IPv6传输向互联网域名服务器发送DNS查询。默认设置为否。
do-udp: <yes or no>
启用或禁用是否响应或发起UDP查询。默认设置为`yes`。
do-tcp: <yes or no>
启用或禁用TCP查询的应答与发起，默认设置为`yes`。
tcp-mss: <number>
服务器响应查询时，TCP套接字的最大段大小（MSS）。
设置低于以太网常见MSS的值（例如1220）可解决路径MTU问题。
需注意，并非所有平台都支持通过套接字选项设置MSS（TCP_MAXSEG）。
默认情况下，MSS由接口MTU及服务器与客户端之间的协商决定，采用系统默认值。
outgoing-tcp-mss: <number>
TCP套接字用于发出查询（从Unbound到其他服务器）的最大段大小（MSS）。
设置低于以太网常见MSS的值（例如1220）可解决路径MTU问题。
需要注意的是，并非所有平台都支持通过套接字选项设置MSS（TCP_MAXSEG）。
默认情况下，MSS由接口MTU及Unbound与其他服务器之间的协商决定，采用系统默认值。
tcp-idle-timeout: <msec>
Unbound在TCP连接上等待查询的时长，若超时则关闭连接。
此选项默认值为30000毫秒。
当空闲的入站TCP缓冲区数量低于配置总数的50%时，该选项值会逐步降低：
首先降至配置值的1%，若空闲缓冲区进一步低于总数的35%，则降至配置值的0.2%，
最终若空闲缓冲区低于总数的20%，则降至0。
无论采用何种选项值，最小超时时间均保持为200毫秒。
若启用了edns-tcp-keepalive，此设置将被edns-tcp-keepalive-timeout覆盖。
tcp-reuse-timeout: <msec>
Unbound 期间将保持与权威服务器的 TCP 持久连接开启。此选项默认值为 60000 毫秒。
max-reuse-tcp-queries: <number>
在持久TCP连接上可发送的最大查询数量，此选项默认设置为200次查询。
tcp-auth-query-timeout: <number>
TCP查询认证服务器的超时时间，以毫秒为单位。此选项默认值为3000毫秒。
edns-tcp-keepalive: <yes or no>
启用或禁用EDNS TCP保持连接功能。默认设置为`no`。
edns-tcp-keepalive-timeout: <msec>
当启用edns-tcp-keepalive时，此设置将覆盖tcp-idle-timeout。
若客户端支持EDNS TCP保持连接选项，Unbound会向客户端发送超时值，
以促使客户端在服务器超时前关闭连接。
此选项默认值为120000毫秒。
sock-queue-timeout: <sec>
在套接字缓冲区中等待过久的UDP查询可被丢弃。
默认值为0，即禁用此功能。
时间以秒为单位设置，3秒可能是一个合适的值，用于忽略那些客户端可能已不再需要回复的旧查询。
这种情况可能发生在主机暂时无法处理查询时，例如Unbound未运行，之后又重新启用。
该功能利用了时间戳套接字选项。
tcp-upstream: <yes or no>
启用或禁用上游查询是否仅使用TCP进行传输。
默认设置为`no`。在隧道场景中非常有用。
如果设置为否，您可以通过分别使用forward-tcp-upstream或stub-tcp-upstream，
仅为选定的转发区域或存根区域指定TCP传输。
udp-upstream-without-downstream: <yes or no>
即使do-udp设置为否，也启用UDP上行。
默认情况下为否，此设置不会改变任何现有配置。
对于TLS服务提供商而言，若希望禁止UDP下行但需通过UDP获取上行数据，此功能尤为实用。
tls-upstream: <yes or no>
启用或禁用上游查询是否仅使用TLS进行传输。
默认值为`no`。在隧道场景中非常有用。
TLS包含以TCP线格式传输的纯DNS数据。
另一台服务器必须支持此功能（参见tls-service-key）。
如果启用此选项，还需配置tls-cert-bundle或使用tls-win-cert、tls-system-cert加载CA证书，
否则连接无法进行身份验证。
此选项为所有上游查询启用TLS，但如果不设置此选项，
可以通过forward-tls-upstream为特定转发区域单独配置TLS，
同样适用于stub-tls-upstream。如果启用了tls-upstream选项，
则对所有转发和存根区域生效，此时forward-tls-upstream和stub-tls-upstream选项将被忽略，
视为已设置为`yes`。
ssl-upstream: <yes or no>
tls-upstream 的替代语法。若配置文件中两者均存在，则以最后一项为准。
tls-service-key: <file>
若启用此功能，服务器将在通过tls-port或https-port隐式或显式标记的TCP端口上
提供DNS-over-TLS或DNS-over-HTTPS服务。
配置文件必须包含TLS会话的私钥，公钥证书则位于tls-service-pem文件中，且若指定了tls-service-key，
也必须同时指定。
默认值为空，即关闭状态。
启用或禁用此服务需重启服务器（仅重载配置不够），因为密钥读取需在持有root权限及chroot（如有）之前进行。
通过tls-port:和https-port:隐式或显式启用的端口不提供常规的DNS TCP服务。
Unbound需编译时包含libnghttp2以支持DNS-over-HTTPS。
ssl-service-key: <file>
tls-service-key 的替代语法。
tls-service-pem: <file>
用于TLS服务的公钥证书pem文件。默认值为""，表示关闭。
ssl-service-pem: <file>
tls-service-pem 的替代语法。
tls-port: <number>
提供TCP TLS服务的端口号，默认为853，只有配置了该端口号作为@number的接口才能获得TLS服务。
ssl-port: <number>
tls端口的替代语法。
tls-cert-bundle: <file>
若为空或""，则不使用任何文件。
请将其设置为证书包文件，例如"/etc/pki/tls/certs/ca-bundle.crt"。
这些证书用于验证与外部对等方建立的连接，如认证区域URL及DNS over TLS连接。
该文件在启动时、权限降级和chroot之前被读取。
ssl-cert-bundle: <file>
tls-cert-bundle 的替代语法。
tls-win-cert: <yes or no>
将系统证书添加到认证所需的证书包中。
若无证书包，则仅使用这些证书。
默认情况下不启用此功能。
在Windows系统上，此选项会使用证书存储中的证书。
在其他系统上，请使用`tls-cert-bundle`选项来启用系统证书。
tls-system-cert: <yes or no>
此设置与tls-win-cert设置相同，只是名称不同，因为它并非专为Windows设计。
tls-additional-port: <portnr>
将端口号列为tls-additional-port，并在定义接口时（例如使用@port后缀），
作为此端口号，它们将提供DNS over TLS服务。
可列出多个，每个端口号单独一行声明。
tls-session-ticket-keys: <file>
若非空，则列出包含80字节随机内容的文件，
这些文件用于为使用Unbound服务器的客户端执行TLS会话恢复。
这些文件内含有TLS会话票据的密钥。
首个密钥用于加密和解密TLS会话票据，其余密钥仅用于解密。
通过生成新的首个文件，并在其后暂时保留旧文件以允许解密，可以实现密钥的轮换。
待客户端不再使用旧密钥后，即可移除旧密钥。
创建此类文件的一种方法是使用命令`dd if=/dev/random bs=1 count=80 of=ticket.dat`。
若需创建第二个密钥，其前16字节应与旧密钥不同，这部分用于标识密钥。
随后是32字节的随机数据作为AES密钥，再接着32字节的随机数据作为HMAC密钥。
tls-ciphers: <string with cipher list>
设置服务TLS时允许的加密套件列表。使用""表示默认值，且此为默认设置。
tls-ciphersuites: <string with ciphersuites list>
设置服务TLS时允许的加密套件列表，适用于较新的TLS 1.3连接。
使用""表示采用默认值，这也是默认设置。
pad-responses: <yes or no>
若启用此功能，包含EDNS填充选项的TLS服务查询将导致响应被填充至最接近pad-responses-block-size指定大小的倍数。默认设置为`yes`。
pad-responses-block-size: <number>
用于填充通过TLS服务的响应的块大小。仅对填充查询的响应进行填充。默认值为468。
pad-queries: <yes or no>
若启用此功能，所有通过TLS上游发送的查询将被填充至最接近pad-queries-block-size指定大小的倍数。
默认设置为`yes`。
pad-queries-block-size: <number>
用于填充通过TLS上游发送的查询的块大小，默认值为128。
tls-use-sni: <yes or no>
启用或禁用在TLS连接上发送SNI扩展。默认值为`yes`。更改此值需重新加载配置。
https-port: <number>
提供DNS-over-HTTPS服务的端口号，默认443，只有配置了该端口号作为@number的接口才能获得HTTPS服务。
http-endpoint: <endpoint string>
提供DNS-over-HTTPS服务的HTTP端点，默认为"/dns-query"。
http-max-streams: <number of streams>
用于DNS-over-HTTPS连接的HTTP/2 SETTINGS帧中SETTINGS_MAX_CONCURRENT_STREAMS参数的数值，默认设置为100。
http-query-buffer-size: <size in bytes>
所有HTTP/2查询缓冲区合并使用的最大字节数。
这些缓冲区包含等待请求流完成的（部分）DNS查询。
对于超出此限制的流，将发送RST_STREAM帧。
默认值为4兆字节。纯数字表示字节，可附加'k'、'm'或'g'分别表示千字节、兆字节或吉字节（1兆字节等于1024*1024字节）。
http-response-buffer-size: <size in bytes>
所有HTTP/2响应缓冲区合并使用的最大字节数。
这些缓冲区包含等待写回客户端的DNS响应。
对于超出此限制的流，将发送RST_STREAM帧。默认值为4兆字节。
纯数字表示字节，可附加'k'、'm'或'g'分别表示千字节、兆字节或吉字节（1兆字节等于1024*1024字节）。
http-nodelay: <yes or no>
在用于提供DNS-over-HTTPS服务的套接字上设置TCP_NODELAY选项。若该选项不可用，则忽略。默认值为`yes`。
http-notls-downstream: <yes or no>
禁用下游DNS-over-HTTP连接的TLS使用。适用于本地后端服务器。默认设置为`no`。
proxy-protocol-port: <portnr>
将端口号列为代理协议端口（proxy-protocol-port），
并在定义接口时，如使用@port后缀，指定为此端口号，
这些接口将支持并预期接收PROXYv2协议。
在此情况下，代理地址仅用于网络通信及初始的访问控制列表（ACL，检查代理本身是否被配置拒绝）。
随后，被代理的地址（如有）将作为真实客户端地址，
并在日志记录、ACL、DNSTAP、RPZ及IP限速等适用场景中使用。
PROXYv2协议支持UDP和TCP/TLS监听接口，但在DoH、DoQ或DNSCrypt监听接口上不支持PROXYv2。
可列出多个端口，每个端口单独一行声明。
quic-port: <number>
The port number on which to provide DNS-over-QUIC service, de-
fault 853, only interfaces configured with that port number as
@number get the QUIC service. The interface uses QUIC for the
UDP traffic on that port number.
quic-size: <size in bytes>
Maximum number of bytes for all QUIC buffers and data combined.
Default is 8 megabytes. A plain number is in bytes, append 'k',
'm' or 'g' for kilobytes, megabytes or gigabytes (1024*1024
bytes in a megabyte). New connections receive connection refused
when the limit is exceeded. New streams are reset when the limit
is exceeded.
use-systemd: <yes or no>
Enable or disable systemd socket activation. Default is no.
do-daemonize: <yes or no>
Enable or disable whether the Unbound server forks into the
background as a daemon. Set the value to no when Unbound runs
as systemd service. Default is yes.
tcp-connection-limit: <IP netblock> <limit>
Allow up to limit simultaneous TCP connections from the given
netblock. When at the limit, further connections are accepted
but closed immediately. This option is experimental at this
time.
access-control: <IP netblock> <action>
Specify treatment of incoming queries from their originating IP
address. Queries can be allowed to have access to this server
that gives DNS answers, or refused, with other actions possible.
The IP address range can be specified as a netblock, it is pos-
sible to give the statement several times in order to specify
the treatment of different netblocks.
The netblock is given as an IP4 or IP6 address with /size ap-
pended for a classless network block. The action can be deny,
refuse, allow, allow_setrd, allow_snoop, allow_cookie,
deny_non_local or refuse_non_local. The most specific netblock
match is used, if none match refuse is used. The order of the
access-control statements therefore does not matter.
The deny action stops queries from hosts from that netblock.
The refuse action stops queries too, but sends a DNS rcode RE-
FUSED error message back.
The allow action gives access to clients from that netblock. It
gives only access for recursion clients (which is what almost
all clients need). Nonrecursive queries are refused.
The allow action does allow nonrecursive queries to access the
local-data that is configured. The reason is that this does not
involve the Unbound server recursive lookup algorithm, and sta-
tic data is served in the reply. This supports normal opera-
tions where nonrecursive queries are made for the authoritative
data. For nonrecursive queries any replies from the dynamic
cache are refused.
The allow_setrd action ignores the recursion desired (RD) bit
and treats all requests as if the recursion desired bit is set.
Note that this behavior violates RFC 1034 which states that a
name server should never perform recursive service unless asked
via the RD bit since this interferes with trouble shooting of
name servers and their databases. This prohibited behavior may
be useful if another DNS server must forward requests for spe-
cific zones to a resolver DNS server, but only supports stub do-
mains and sends queries to the resolver DNS server with the RD
bit cleared.
The allow_snoop action gives nonrecursive access too. This give
both recursive and non recursive access. The name allow_snoop
refers to cache snooping, a technique to use nonrecursive
queries to examine the cache contents (for malicious acts).
However, nonrecursive queries can also be a valuable debugging
tool (when you want to examine the cache contents). In that case
use allow_snoop for your administration host.
The allow_cookie action allows access only to UDP queries that
contain a valid DNS Cookie as specified in RFC 7873 and RFC
9018, when the answer-cookie option is enabled. UDP queries
containing only a DNS Client Cookie and no Server Cookie, or an
invalid DNS Cookie, will receive a BADCOOKIE response including
a newly generated DNS Cookie, allowing clients to retry with
that DNS Cookie. The allow_cookie action will also accept re-
quests over stateful transports, regardless of the presence of
an DNS Cookie and regardless of the answer-cookie setting. UDP
queries without a DNS Cookie receive REFUSED responses with the
TC flag set, that may trigger fall back to TCP for those
clients.
By default only localhost (the 127.0.0.0/8 IP netblock, not the
loopback interface) is implicitly allowed, the rest is refused.
The default is refused, because that is protocol-friendly. The
DNS protocol is not designed to handle dropped packets due to
policy, and dropping may result in (possibly excessive) retried
queries.
The deny_non_local and refuse_non_local settings are for hosts
that are only allowed to query for the authoritative local-data,
they are not allowed full recursion but only the static data.
With deny_non_local, messages that are disallowed are dropped,
with refuse_non_local they receive error code REFUSED.
access-control-tag: <IP netblock> <"list of tags">
Assign tags to access-control elements. Clients using this ac-
cess control element use localzones that are tagged with one of
these tags. Tags must be defined in define-tags. Enclose list
of tags in quotes ("") and put spaces between tags. If ac-
cess-control-tag is configured for a netblock that does not have
an access-control, an access-control element with action allow
is configured for this netblock.
access-control-tag-action: <IP netblock> <tag> <action>
Set action for particular tag for given access control element.
If you have multiple tag values, the tag used to lookup the ac-
tion is the first tag match between access-control-tag and lo-
cal-zone-tag where "first" comes from the order of the define-
tag values.
access-control-tag-data: <IP netblock> <tag> <"resource record string">
Set redirect data for particular tag for given access control
element.
access-control-view: <IP netblock> <view name>
Set view for given access control element.
interface-action: <ip address or interface name [@port]> <action>
Similar to access-control: but for interfaces.
The action is the same as the ones defined under access-con-
trol:. Interfaces are refused by default. By default only lo-
calhost (the 127.0.0.0/8 IP netblock, not the loopback inter-
face) is implicitly allowed through the default access-control:
behavior. This also means that any attempt to use the inter-
face-*: options for the loopback interface will not work as they
will be overridden by the implicit default "access-control:
127.0.0.0/8 allow" option.
Note that the interface needs to be already specified with in-
terface: and that any access-control*: setting overrides all in-
terface-*: settings for targeted clients.
interface-tag: <ip address or interface name [@port]> <"list of tags">
Similar to access-control-tag: but for interfaces.
Note that the interface needs to be already specified with in-
terface: and that any access-control*: setting overrides all in-
terface-*: settings for targeted clients.
interface-tag-action: <ip address or interface name [@port]> <tag> <ac-
tion>
Similar to access-control-tag-action: but for interfaces.
Note that the interface needs to be already specified with in-
terface: and that any access-control*: setting overrides all in-
terface-*: settings for targeted clients.
interface-tag-data: <ip address or interface name [@port]> <tag> <"re-
source record string">
Similar to access-control-tag-data: but for interfaces.
Note that the interface needs to be already specified with in-
terface: and that any access-control*: setting overrides all in-
terface-*: settings for targeted clients.
interface-view: <ip address or interface name [@port]> <view name>
Similar to access-control-view: but for interfaces.
Note that the interface needs to be already specified with in-
terface: and that any access-control*: setting overrides all in-
terface-*: settings for targeted clients.
chroot: <directory>
If chroot is enabled, you should pass the configfile (from the
commandline) as a full path from the original root. After the
chroot has been performed the now defunct portion of the config
file path is removed to be able to reread the config after a re-
load.
All other file paths (working dir, logfile, roothints, and key
files) can be specified in several ways: as an absolute path
relative to the new root, as a relative path to the working di-
rectory, or as an absolute path relative to the original root.
In the last case the path is adjusted to remove the unused por-
tion.
The pidfile can be either a relative path to the working direc-
tory, or an absolute path relative to the original root. It is
written just prior to chroot and dropping permissions. This al-
lows the pidfile to be /var/run/unbound.pid and the chroot to be
/var/unbound, for example. Note that Unbound is not able to re-
move the pidfile after termination when it is located outside of
the chroot directory.
Additionally, Unbound may need to access /dev/urandom (for en-
tropy) from inside the chroot.
If given a chroot is done to the given directory. The chroot is
by default set to "/usr/local/etc/unbound". If you give "" no
chroot is performed.
username: <name>
If given, after binding the port the user privileges are
dropped. Default is "unbound". If you give username: "" no user
change is performed.
If this user is not capable of binding the port, reloads (by
signal HUP) will still retain the opened ports. If you change
the port number in the config file, and that new port number re-
quires privileges, then a reload will fail; a restart is needed.
directory: <directory>
Sets the working directory for the program. Default is "/usr/lo-
cal/etc/unbound". On Windows the string "%EXECUTABLE%" tries to
change to the directory that unbound.exe resides in. If you
give a server: directory: dir before include: file statements
then those includes can be relative to the working directory.
logfile: <filename>
If "" is given, logging goes to stderr, or nowhere once daemo-
nized. The logfile is appended to, in the following format:
[seconds since 1970] unbound[pid:tid]: type: message.
If this option is given, the use-syslog is option is set to
"no". The logfile is reopened (for append) when the config file
is reread, on SIGHUP.
use-syslog: <yes or no>
Sets Unbound to send log messages to the syslogd, using sys-
log(3). The log facility LOG_DAEMON is used, with identity "un-
bound". The logfile setting is overridden when use-syslog is
turned on. The default is to log to syslog.
log-identity: <string>
If "" is given (default), then the name of the executable, usu-
ally "unbound" is used to report to the log. Enter a string to
override it with that, which is useful on systems that run more
than one instance of Unbound, with different configurations, so
that the logs can be easily distinguished against.
log-time-ascii: <yes or no>
Sets logfile lines to use a timestamp in UTC ascii. Default is
no, which prints the seconds since 1970 in brackets. No effect
if using syslog, in that case syslog formats the timestamp
printed into the log files.
log-time-iso: <yes or no>
Log time in ISO8601 format, if log-time-ascii: yes is also set.
Default is no.
log-queries: <yes or no>
Prints one line per query to the log, with the log timestamp and
IP address, name, type and class. Default is no. Note that it
takes time to print these lines which makes the server (signifi-
cantly) slower. Odd (nonprintable) characters in names are
printed as '?'.
log-replies: <yes or no>
Prints one line per reply to the log, with the log timestamp and
IP address, name, type, class, return code, time to resolve,
from cache and response size. Default is no. Note that it
takes time to print these lines which makes the server (signifi-
cantly) slower. Odd (nonprintable) characters in names are
printed as '?'.
log-tag-queryreply: <yes or no>
Prints the word 'query' and 'reply' with log-queries and
log-replies. This makes filtering logs easier. The default is
off (for backwards compatibility).
log-destaddr: <yes or no>
Prints the destination address, port and type in the log-replies
output. This disambiguates what type of traffic, eg. udp or
tcp, and to what local port the traffic was sent to.
log-local-actions: <yes or no>
Print log lines to inform about local zone actions. These lines
are like the local-zone type inform prints out, but they are
also printed for the other types of local zones.
log-servfail: <yes or no>
Print log lines that say why queries return SERVFAIL to clients.
This is separate from the verbosity debug logs, much smaller,
and printed at the error level, not the info level of debug info
from verbosity.
pidfile: <filename>
The process id is written to the file. Default is "/usr/lo-
cal/etc/unbound/unbound.pid". So,
kill -HUP `cat /usr/local/etc/unbound/unbound.pid`
triggers a reload,
kill -TERM `cat /usr/local/etc/unbound/unbound.pid`
gracefully terminates.
root-hints: <filename>
Read the root hints from this file. Default is nothing, using
builtin hints for the IN class. The file has the format of zone
files, with root nameserver names and addresses only. The de-
fault may become outdated, when servers change, therefore it is
good practice to use a root-hints file.
hide-identity: <yes or no>
If enabled id.server and hostname.bind queries are refused.
identity: <string>
Set the identity to report. If set to "", the default, then the
hostname of the server is returned.
hide-version: <yes or no>
If enabled version.server and version.bind queries are refused.
version: <string>
Set the version to report. If set to "", the default, then the
package version is returned.
hide-http-user-agent: <yes or no>
If enabled the HTTP header User-Agent is not set. Use with cau-
tion as some webserver configurations may reject HTTP requests
lacking this header. If needed, it is better to explicitly set
the http-user-agent below.
http-user-agent: <string>
Set the HTTP User-Agent header for outgoing HTTP requests. If
set to "", the default, then the package name and version are
used.
nsid: <string>
Add the specified nsid to the EDNS section of the answer when
queried with an NSID EDNS enabled packet. As a sequence of hex
characters or with ascii_ prefix and then an ascii string.
hide-trustanchor: <yes or no>
If enabled trustanchor.unbound queries are refused.
target-fetch-policy: <"list of numbers">
Set the target fetch policy used by Unbound to determine if it
should fetch nameserver target addresses opportunistically. The
policy is described per dependency depth.
The number of values determines the maximum dependency depth
that Unbound will pursue in answering a query. A value of -1
means to fetch all targets opportunistically for that dependency
depth. A value of 0 means to fetch on demand only. A positive
value fetches that many targets opportunistically.
Enclose the list between quotes ("") and put spaces between num-
bers. The default is "3 2 1 0 0". Setting all zeroes, "0 0 0 0
0" gives behaviour closer to that of BIND 9, while setting "-1
-1 -1 -1 -1" gives behaviour rumoured to be closer to that of
BIND 8.
harden-short-bufsize: <yes or no>
Very small EDNS buffer sizes from queries are ignored. Default
is yes, as described in the standard.
harden-large-queries: <yes or no>
Very large queries are ignored. Default is no, since it is legal
protocol wise to send these, and could be necessary for opera-
tion if TSIG or EDNS payload is very large.
harden-glue: <yes or no>
Will trust glue only if it is within the servers authority. De-
fault is yes.
harden-unverified-glue: <yes or no>
Will trust only in-zone glue. Will try to resolve all out of
zone (<unverfied>) glue. Will fallback to the original glue if
unable to resolve. Default is no.
harden-dnssec-stripped: <yes or no>
Require DNSSEC data for trust-anchored zones, if such data is
absent, the zone becomes bogus. If turned off, and no DNSSEC
data is received (or the DNSKEY data fails to validate), then
the zone is made insecure, this behaves like there is no trust
anchor. You could turn this off if you are sometimes behind an
intrusive firewall (of some sort) that removes DNSSEC data from
packets, or a zone changes from signed to unsigned to badly
signed often. If turned off you run the risk of a downgrade at-
tack that disables security for a zone. Default is yes.
harden-below-nxdomain: <yes or no>
From RFC 8020 (with title "NXDOMAIN: There Really Is Nothing Un-
derneath"), returns nxdomain to queries for a name below another
name that is already known to be nxdomain. DNSSEC mandates no-
error for empty nonterminals, hence this is possible. Very old
software might return nxdomain for empty nonterminals (that usu-
ally happen for reverse IP address lookups), and thus may be in-
compatible with this. To try to avoid this only DNSSEC-secure
nxdomains are used, because the old software does not have
DNSSEC. Default is yes. The nxdomain must be secure, this
means nsec3 with optout is insufficient.
harden-referral-path: <yes or no>
Harden the referral path by performing additional queries for
infrastructure data. Validates the replies if trust anchors are
configured and the zones are signed. This enforces DNSSEC vali-
dation on nameserver NS sets and the nameserver addresses that
are encountered on the referral path to the answer. Default no,
because it burdens the authority servers, and it is not RFC
standard, and could lead to performance problems because of the
extra query load that is generated. Experimental option. If
you enable it consider adding more numbers after the tar-
get-fetch-policy to increase the max depth that is checked to.
harden-algo-downgrade: <yes or no>
Harden against algorithm downgrade when multiple algorithms are
advertised in the DS record. This works by first choosing only
the strongest DS digest type as per RFC 4509 (Unbound treats the
highest algorithm as the strongest) and then expecting signa-
tures from all the advertised signing algorithms from the chosen
DS(es) to be present. If no, allows any one supported algorithm
to validate the zone, even if other advertised algorithms are
broken. Default is no. RFC 6840 mandates that zone signers
must produce zones signed with all advertised algorithms, but
sometimes they do not. RFC 6840 also clarifies that this re-
quirement is not for validators and validators should accept any
single valid path. It should thus be explicitly noted that this
option violates RFC 6840 for DNSSEC validation and should only
be used to perform a signature completeness test to support
troubleshooting. Using this option may break DNSSEC resolution
with non-RFC6840-conforming signers and/or in multi-signer con-
figurations that don't send all the advertised signatures.
harden-unknown-additional: <yes or no>
Harden against unknown records in the authority section and ad-
ditional section. Default is no. 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.
use-caps-for-id: <yes or no>
Use 0x20-encoded random bits in the query to foil spoof at-
tempts. This perturbs the lowercase and uppercase of query
names sent to authority servers and checks if the reply still
has the correct casing. Disabled by default. This feature is
an experimental implementation of draft dns-0x20.
caps-exempt: <domain>
Exempt the domain so that it does not receive caps-for-id per-
turbed queries. For domains that do not support 0x20 and also
fail with fallback because they keep sending different answers,
like some load balancers. Can be given multiple times, for dif-
ferent domains.
caps-whitelist: <domain>
Alternate syntax for caps-exempt.
qname-minimisation: <yes or no>
Send minimum amount of information to upstream servers to en-
hance privacy. Only send minimum required labels of the QNAME
and set QTYPE to A when possible. Best effort approach; full
QNAME and original QTYPE will be sent when upstream replies with
a RCODE other than NOERROR, except when receiving NXDOMAIN from
a DNSSEC signed zone. Default is yes.
qname-minimisation-strict: <yes or no>
QNAME minimisation in strict mode. Do not fall-back to sending
full QNAME to potentially broken nameservers. A lot of domains
will not be resolvable when this option in enabled. Only use if
you know what you are doing. This option only has effect when
qname-minimisation is enabled. Default is no.
aggressive-nsec: <yes or no>
Aggressive NSEC uses the DNSSEC NSEC chain to synthesize NXDO-
MAIN and other denials, using information from previous NXDO-
MAINs answers. Default is yes. It helps to reduce the query
rate towards targets that get a very high nonexistent name
lookup rate.
private-address: <IP address or subnet>
Give IPv4 of IPv6 addresses or classless subnets. These are ad-
dresses on your private network, and are not allowed to be re-
turned for public internet names. Any occurrence of such ad-
dresses are removed from DNS answers. Additionally, the DNSSEC
validator may mark the answers bogus. This protects against
so-called DNS Rebinding, where a user browser is turned into a
network proxy, allowing remote access through the browser to
other parts of your private network. Some names can be allowed
to contain your private addresses, by default all the local-data
that you configured is allowed to, and you can specify addi-
tional names using private-domain. No private addresses are en-
abled by default. We consider to enable this for the RFC1918
private IP address space by default in later releases. That
would enable private addresses for 10.0.0.0/8 172.16.0.0/12
192.168.0.0/16 169.254.0.0/16 fd00::/8 and fe80::/10, since the
RFC standards say these addresses should not be visible on the
public internet. Turning on 127.0.0.0/8 would hinder many spam-
blocklists as they use that. Adding ::ffff:0:0/96 stops
IPv4-mapped IPv6 addresses from bypassing the filter.
private-domain: <domain name>
Allow this domain, and all its subdomains to contain private ad-
dresses. Give multiple times to allow multiple domain names to
contain private addresses. Default is none.
unwanted-reply-threshold: <number>
If set, a total number of unwanted replies is kept track of in
every thread. When it reaches the threshold, a defensive action
is taken and a warning is printed to the log. The defensive ac-
tion is to clear the rrset and message caches, hopefully flush-
ing away any poison. A value of 10 million is suggested. De-
fault is 0 (turned off).
do-not-query-address: <IP address>
Do not query the given IP address. Can be IP4 or IP6. Append
/num to indicate a classless delegation netblock, for example
like 10.2.3.4/24 or 2001::11/64.
do-not-query-localhost: <yes or no>
If yes, localhost is added to the do-not-query-address entries,
both IP6 ::1 and IP4 127.0.0.1/8. If no, then localhost can be
used to send queries to. Default is yes.
prefetch: <yes or no>
If yes, cache hits on message cache elements that are on their
last 10 percent of their TTL value trigger a prefetch to keep
the cache up to date. Default is no. Turning it on gives about
10 percent more traffic and load on the machine, but popular
items do not expire from the cache.
prefetch-key: <yes or no>
If yes, fetch the DNSKEYs earlier in the validation process,
when a DS record is encountered. This lowers the latency of re-
quests. It does use a little more CPU. Also if the cache is
set to 0, it is no use. Default is no.
deny-any: <yes or no>
If yes, deny queries of type ANY with an empty response. De-
fault is no. If disabled, Unbound responds with a short list of
resource records if some can be found in the cache and makes the
upstream type ANY query if there are none.
rrset-roundrobin: <yes or no>
If yes, Unbound rotates RRSet order in response (the random num-
ber is taken from the query ID, for speed and thread safety).
Default is yes.
minimal-responses: <yes or no>
If yes, Unbound does not 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 which may cause a slight speedup.
The default is yes, even though the DNS protocol RFCs mandate
these sections, and the additional content could save roundtrips
for clients that use the additional content. However these sec-
tions are hardly used by clients. Enabling prefetch can benefit
clients that need the additional content by trying to keep that
content fresh in the cache.
disable-dnssec-lame-check: <yes or no>
If true, disables the DNSSEC lameness check in the iterator.
This check sees if RRSIGs are present in the answer, when dnssec
is expected, and retries another authority if RRSIGs are unex-
pectedly missing. The validator will insist in RRSIGs for
DNSSEC signed domains regardless of this setting, if a trust an-
chor is loaded.
module-config: <"module names">
Module configuration, a list of module names separated by
spaces, surround the string with quotes (""). The modules can be
respip, validator, or iterator (and possibly more, see below).
Setting this to just "iterator" will result in a non-validating
server. Setting this to "validator iterator" will turn on
DNSSEC validation. The ordering of the modules is significant,
the order decides the order of processing. You must also set
trust-anchors for validation to be useful. Adding respip to the
front will cause RPZ processing to be done on all queries. The
default is "validator iterator".
Most modules that need to be listed here have to be listed at
the beginning of the line. The subnetcachedb module has to be
listed just before the iterator. The python module can be
listed in different places, it then processes the output of the
module it is just before. The dynlib module can be listed pretty
much anywhere, it is only a very thin wrapper that allows dy-
namic libraries to run in its place.
trust-anchor-file: <filename>
File with trusted keys for validation. Both DS and DNSKEY en-
tries can appear in the file. The format of the file is the
standard DNS Zone file format. Default is "", or no trust an-
chor file.
auto-trust-anchor-file: <filename>
File with trust anchor for one zone, which is tracked with
RFC5011 probes. The probes are run several times per month,
thus the machine must be online frequently. The initial file
can be one with contents as described in trust-anchor-file. The
file is written to when the anchor is updated, so the Unbound
user must have write permission. Write permission to the file,
but also to the directory it is in (to create a temporary file,
which is necessary to deal with filesystem full events), it must
also be inside the chroot (if that is used).
trust-anchor: <"Resource Record">
A DS or DNSKEY RR for a key to use for validation. Multiple en-
tries can be given to specify multiple trusted keys, in addition
to the trust-anchor-files. The resource record is entered in
the same format as 'dig' or 'drill' prints them, the same format
as in the zone file. Has to be on a single line, with "" around
it. A TTL can be specified for ease of cut and paste, but is ig-
nored. A class can be specified, but class IN is default.
trusted-keys-file: <filename>
File with trusted keys for validation. Specify more than one
file with several entries, one file per entry. Like trust-an-
chor-file but has a different file format. Format is BIND-9
style format, the trusted-keys { name flag proto algo "key"; };
clauses are read. It is possible to use wildcards with this
statement, the wildcard is expanded on start and on reload.
trust-anchor-signaling: <yes or no>
Send RFC8145 key tag query after trust anchor priming. Default
is yes.
root-key-sentinel: <yes or no>
Root key trust anchor sentinel. Default is yes.
domain-insecure: <domain name>
Sets domain name to be insecure, DNSSEC chain of trust is ig-
nored towards the domain name. So a trust anchor above the do-
main name can not make the domain secure with a DS record, such
a DS record is then ignored. Can be given multiple times to
specify multiple domains that are treated as if unsigned. If
you set trust anchors for the domain they override this setting
(and the domain is secured).
This can be useful if you want to make sure a trust anchor for
external lookups does not affect an (unsigned) internal domain.
A DS record externally can create validation failures for that
internal domain.
val-override-date: <rrsig-style date spec>
Default is "" or "0", which disables this debugging feature. If
enabled by giving a RRSIG style date, that date is used for ver-
ifying RRSIG inception and expiration dates, instead of the cur-
rent date. Do not set this unless you are debugging signature
inception and expiration. The value -1 ignores the date alto-
gether, useful for some special applications.
val-sig-skew-min: <seconds>
Minimum number of seconds of clock skew to apply to validated
signatures. A value of 10% of the signature lifetime (expira-
tion - inception) is used, capped by this setting. Default is
3600 (1 hour) which allows for daylight savings differences.
Lower this value for more strict checking of short lived signa-
tures.
val-sig-skew-max: <seconds>
Maximum number of seconds of clock skew to apply to validated
signatures. A value of 10% of the signature lifetime (expira-
tion - inception) is used, capped by this setting. Default is
86400 (24 hours) which allows for timezone setting problems in
stable domains. Setting both min and max very low disables the
clock skew allowances. Setting both min and max very high makes
the validator check the signature timestamps less strictly.
val-max-restart: <number>
The maximum number the validator should restart validation with
another authority in case of failed validation. Default is 5.
val-bogus-ttl: <number>
The time to live for bogus data. This is data that has failed
validation; due to invalid signatures or other checks. The TTL
from that data cannot be trusted, and this value is used in-
stead. The value is in seconds, default 60. The time interval
prevents repeated revalidation of bogus data.
val-clean-additional: <yes or no>
Instruct the validator to remove data from the additional sec-
tion of secure messages that are not signed properly. Messages
that are insecure, bogus, indeterminate or unchecked are not af-
fected. Default is yes. Use this setting to protect the users
that rely on this validator for authentication from potentially
bad data in the additional section.
val-log-level: <number>
Have the validator print validation failures to the log. Re-
gardless of the verbosity setting. Default is 0, off. At 1,
for every user query that fails a line is printed to the logs.
This way you can monitor what happens with validation. Use a
diagnosis tool, such as dig or drill, to find out why validation
is failing for these queries. At 2, not only the query that
failed is printed but also the reason why Unbound thought it was
wrong and which server sent the faulty data.
val-permissive-mode: <yes or no>
Instruct the validator to mark bogus messages as indeterminate.
The security checks are performed, but if the result is bogus
(failed security), the reply is not withheld from the client
with SERVFAIL as usual. The client receives the bogus data. For
messages that are found to be secure the AD bit is set in
replies. Also logging is performed as for full validation. The
default value is "no".
ignore-cd-flag: <yes or no>
Instruct Unbound to ignore the CD flag from clients and refuse
to return bogus answers to them. Thus, the CD (Checking Dis-
abled) flag does not disable checking any more. This is useful
if legacy (w2008) servers that set the CD flag but cannot vali-
date DNSSEC themselves are the clients, and then Unbound pro-
vides them with DNSSEC protection. The default value is "no".
disable-edns-do: <yes or no>
Disable the EDNS DO flag in upstream requests. It breaks DNSSEC
validation for Unbound's clients. This results in the upstream
name servers to not include DNSSEC records in their replies and
could be helpful for devices that cannot handle DNSSEC informa-
tion. When the option is enabled, clients that set the DO flag
receive no EDNS record in the response to indicate the lack of
support to them. If this option is enabled but Unbound is al-
ready configured for DNSSEC validation (i.e., the validator mod-
ule is enabled; default) this option is implicitly turned off
with a warning as to not break DNSSEC validation in Unbound.
Default is no.
serve-expired: <yes or no>
If enabled, Unbound attempts to serve old responses from cache
with a TTL of serve-expired-reply-ttl in the response. By de-
fault the expired answer will be used after a resolution attempt
errored out or is taking more than serve-expired-client-timeout
to resolve. Default is "no".
serve-expired-ttl: <seconds>
Limit serving of expired responses to configured seconds after
expiration. 0 disables the limit. This option only applies
when serve-expired is enabled. A suggested value per RFC 8767
is between 86400 (1 day) and 259200 (3 days). The default is
86400.
serve-expired-ttl-reset: <yes or no>
Set the TTL of expired records to the serve-expired-ttl value
after a failed attempt to retrieve the record from upstream.
This makes sure that the expired records will be served as long
as there are queries for it. Default is "no".
serve-expired-reply-ttl: <seconds>
TTL value to use when replying with expired data. If serve-ex-
pired-client-timeout is also used then it is RECOMMENDED to use
30 as the value (RFC 8767). The default is 30.
serve-expired-client-timeout: <msec>
Time in milliseconds before replying to the client with expired
data. This essentially enables the serve-stale behavior as
specified in RFC 8767 that first tries to resolve before immedi-
ately responding with expired data. Setting this to 0 will dis-
able this behavior and instead serve the expired record immedi-
ately from the cache before attempting to refresh it via resolu-
tion. Default is 1800.
serve-original-ttl: <yes or no>
If enabled, Unbound will always return the original TTL as re-
ceived from the upstream name server rather than the decrement-
ing TTL as stored in the cache. This feature may be useful if
Unbound serves as a front-end to a hidden authoritative name
server. Enabling this feature does not impact cache expiry, it
only changes the TTL Unbound embeds in responses to queries.
Note that enabling this feature implicitly disables enforcement
of the configured minimum and maximum TTL, as it is assumed
users who enable this feature do not want Unbound to change the
TTL obtained from an upstream server. Thus, the values set us-
ing cache-min-ttl and cache-max-ttl are ignored. Default is
"no".
val-nsec3-keysize-iterations: <"list of values">
List of keysize and iteration count values, separated by spaces,
surrounded by quotes. Default is "1024 150 2048 150 4096 150".
This determines the maximum allowed NSEC3 iteration count before
a message is simply marked insecure instead of performing the
many hashing iterations. The list must be in ascending order and
have at least one entry. If you set it to "1024 65535" there is
no restriction to NSEC3 iteration values. This table must be
kept short; a very long list could cause slower operation.
zonemd-permissive-mode: <yes or no>
If enabled the ZONEMD verification failures are only logged and
do not cause the zone to be blocked and only return servfail.
Useful for testing out if it works, or if the operator only
wants to be notified of a problem without disrupting service.
Default is no.
add-holddown: <seconds>
Instruct the auto-trust-anchor-file probe mechanism for RFC5011
autotrust updates to add new trust anchors only after they have
been visible for this time. Default is 30 days as per the RFC.
del-holddown: <seconds>
Instruct the auto-trust-anchor-file probe mechanism for RFC5011
autotrust updates to remove revoked trust anchors after they
have been kept in the revoked list for this long. Default is 30
days as per the RFC.
keep-missing: <seconds>
Instruct the auto-trust-anchor-file probe mechanism for RFC5011
autotrust updates to remove missing trust anchors after they
have been unseen for this long. This cleans up the state file
if the target zone does not perform trust anchor revocation, so
this makes the auto probe mechanism work with zones that perform
regular (non-5011) rollovers. The default is 366 days. The
value 0 does not remove missing anchors, as per the RFC.
permit-small-holddown: <yes or no>
Debug option that allows the autotrust 5011 rollover timers to
assume very small values. Default is no.
key-cache-size: <number>
Number of bytes size of the key cache. Default is 4 megabytes.
A plain number is in bytes, append 'k', 'm' or 'g' for kilo-
bytes, megabytes or gigabytes (1024*1024 bytes in a megabyte).
key-cache-slabs: <number>
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.
neg-cache-size: <number>
Number of bytes size of the aggressive negative cache. Default
is 1 megabyte. A plain number is in bytes, append 'k', 'm' or
'g' for kilobytes, megabytes or gigabytes (1024*1024 bytes in a
megabyte).
unblock-lan-zones: <yes or no>
Default is disabled. If enabled, then for private address
space, the reverse lookups are no longer filtered. This allows
Unbound when running as dns service on a host where it provides
service for that host, to put out all of the queries for the
'lan' upstream. When enabled, only localhost, 127.0.0.1 reverse
and ::1 reverse zones are configured with default local zones.
Disable the option when Unbound is running as a (DHCP-) DNS net-
work resolver for a group of machines, where such lookups should
be filtered (RFC compliance), this also stops potential data
leakage about the local network to the upstream DNS servers.
insecure-lan-zones: <yes or no>
Default is disabled. If enabled, then reverse lookups in pri-
vate address space are not validated. This is usually required
whenever unblock-lan-zones is used.
local-zone: <zone> <type>
Configure a local zone. The type determines the answer to give
if there is no match from local-data. The types are deny,
refuse, static, transparent, redirect, nodefault, typetranspar-
ent, inform, inform_deny, inform_redirect, always_transparent,
block_a, always_refuse, always_nxdomain, always_null, noview,
and are explained below. After that the default settings are
listed. Use local-data: to enter data into the local zone. An-
swers for local zones are authoritative DNS answers. By default
the zones are class IN.
If you need more complicated authoritative data, with referrals,
wildcards, CNAME/DNAME support, or DNSSEC authoritative service,
setup a stub-zone for it as detailed in the stub zone section
below. A stub-zone can be used to have unbound send queries to
another server, an authoritative server, to fetch the informa-
tion. With a forward-zone, unbound sends queries to a server
that is a recursive server to fetch the information. With an
auth-zone a zone can be loaded from file and used, it can be
used like a local-zone for users downstream, or the auth-zone
information can be used to fetch information from when resolving
like it is an upstream server. The forward-zone and auth-zone
options are described in their sections below. If you want to
perform filtering of the information that the users can fetch,
the local-zone and local-data statements allow for this, but
also the rpz functionality can be used, described in the RPZ
section.
deny Do not send an answer, drop the query. If there is a match
from local data, the query is answered.
refuse
Send an error message reply, with rcode REFUSED. If there is
a match from local data, the query is answered.
static
If there is a match from local data, the query is answered.
Otherwise, the query is answered with nodata or nxdomain.
For a negative answer a SOA is included in the answer if
present as local-data for the zone apex domain.
transparent
If there is a match from local data, the query is answered.
Otherwise if the query has a different name, the query is re-
solved normally. If the query is for a name given in local-
data but no such type of data is given in localdata, then a
noerror nodata answer is returned. If no local-zone is given
local-data causes a transparent zone to be created by de-
fault.
typetransparent
If there is a match from local data, the query is answered.
If the query is for a different name, or for the same name
but for a different type, the query is resolved normally.
So, similar to transparent but types that are not listed in
local data are resolved normally, so if an A record is in the
local data that does not cause a nodata reply for AAAA
queries.
redirect
The query is answered from the local data for the zone name.
There may be no local data beneath the zone name. This an-
swers queries for the zone, and all subdomains of the zone
with the local data for the zone. It can be used to redirect
a domain to return a different address record to the end
user, with local-zone: "example.com." redirect and lo-
cal-data: "example.com. A 127.0.0.1" queries for www.exam-
ple.com and www.foo.example.com are redirected, so that users
with web browsers cannot access sites with suffix exam-
ple.com.
inform
The query is answered normally, same as transparent. The
client IP address (@portnumber) is printed to the logfile.
The log message is: timestamp, unbound-pid, info: zonename
inform IP@port queryname type class. This option can be used
for normal resolution, but machines looking up infected names
are logged, eg. to run antivirus on them.
inform_deny
The query is dropped, like 'deny', and logged, like 'inform'.
Ie. find infected machines without answering the queries.
inform_redirect
The query is redirected, like 'redirect', and logged, like
'inform'. Ie. answer queries with fixed data and also log
the machines that ask.
always_transparent
Like transparent, but ignores local data and resolves nor-
mally.
block_a
Like transparent, but ignores local data and resolves nor-
mally all query types excluding A. For A queries it uncondi-
tionally returns NODATA. Useful in cases when there is a
need to explicitly force all apps to use IPv6 protocol and
avoid any queries to IPv4.
always_refuse
Like refuse, but ignores local data and refuses the query.
always_nxdomain
Like static, but ignores local data and returns nxdomain for
the query.
always_nodata
Like static, but ignores local data and returns nodata for
the query.
always_deny
Like deny, but ignores local data and drops the query.
always_null
Always returns 0.0.0.0 or ::0 for every name in the zone.
Like redirect with zero data for A and AAAA. Ignores local
data in the zone. Used for some block lists.
noview
Breaks out of that view and moves towards the global local
zones for answer to the query. If the view first is no,
it'll resolve normally. If view first is enabled, it'll
break perform that step and check the global answers. For
when the view has view specific overrides but some zone has
to be answered from global local zone contents.
nodefault
Used to turn off default contents for AS112 zones. The other
types also turn off default contents for the zone. The 'node-
fault' option has no other effect than turning off default
contents for the given zone. Use nodefault if you use ex-
actly that zone, if you want to use a subzone, use transpar-
ent.
The default zones are localhost, reverse 127.0.0.1 and ::1, the
home.arpa, the resolver.arpa, the service.arpa, the onion, test, in-
valid and the AS112 zones. The AS112 zones are reverse DNS zones for
private use and reserved IP addresses for which the servers on the in-
ternet cannot provide correct answers. They are configured by default
to give nxdomain (no reverse information) answers. The defaults can be
turned off by specifying your own local-zone of that name, or using the
'nodefault' type. Below is a list of the default zone contents.
localhost
The IP4 and IP6 localhost information is given. NS and SOA
records are provided for completeness and to satisfy some DNS
update tools. Default content:
local-zone: "localhost." redirect
local-data: "localhost. 10800 IN NS localhost."
local-data: "localhost. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
local-data: "localhost. 10800 IN A 127.0.0.1"
local-data: "localhost. 10800 IN AAAA ::1"
reverse IPv4 loopback
Default content:
local-zone: "127.in-addr.arpa." static
local-data: "127.in-addr.arpa. 10800 IN NS localhost."
local-data: "127.in-addr.arpa. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
local-data: "1.0.0.127.in-addr.arpa. 10800 IN
PTR localhost."
reverse IPv6 loopback
Default content:
local-zone: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa." static
local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
NS localhost."
local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
PTR localhost."
home.arpa (RFC 8375)
Default content:
local-zone: "home.arpa." static
local-data: "home.arpa. 10800 IN NS localhost."
local-data: "home.arpa. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
resolver.arpa (RFC 9462)
Default content:
local-zone: "resolver.arpa." static
local-data: "resolver.arpa. 10800 IN NS localhost."
local-data: "resolver.arpa. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
service.arpa (draft-ietf-dnssd-srp-25)
Default content:
local-zone: "service.arpa." static
local-data: "service.arpa. 10800 IN NS localhost."
local-data: "service.arpa. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
onion (RFC 7686)
Default content:
local-zone: "onion." static
local-data: "onion. 10800 IN NS localhost."
local-data: "onion. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
test (RFC 6761)
Default content:
local-zone: "test." static
local-data: "test. 10800 IN NS localhost."
local-data: "test. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
invalid (RFC 6761)
Default content:
local-zone: "invalid." static
local-data: "invalid. 10800 IN NS localhost."
local-data: "invalid. 10800 IN
SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
reverse RFC1918 local use zones
Reverse data for zones 10.in-addr.arpa, 16.172.in-addr.arpa
to 31.172.in-addr.arpa, 168.192.in-addr.arpa. The lo-
cal-zone: is set static and as local-data: SOA and NS records
are provided.
reverse RFC3330 IP4 this, link-local, testnet and broadcast
Reverse data for zones 0.in-addr.arpa, 254.169.in-addr.arpa,
2.0.192.in-addr.arpa (TEST NET 1), 100.51.198.in-addr.arpa
(TEST NET 2), 113.0.203.in-addr.arpa (TEST NET 3),
255.255.255.255.in-addr.arpa. And from 64.100.in-addr.arpa
to 127.100.in-addr.arpa (Shared Address Space).
reverse RFC4291 IP6 unspecified
Reverse data for zone
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.
reverse RFC4193 IPv6 Locally Assigned Local Addresses
Reverse data for zone D.F.ip6.arpa.
reverse RFC4291 IPv6 Link Local Addresses
Reverse data for zones 8.E.F.ip6.arpa to B.E.F.ip6.arpa.
reverse IPv6 Example Prefix
Reverse data for zone 8.B.D.0.1.0.0.2.ip6.arpa. This zone is
used for tutorials and examples. You can remove the block on
this zone with:
local-zone: 8.B.D.0.1.0.0.2.ip6.arpa. nodefault
You can also selectively unblock a part of the zone by making
that part transparent with a local-zone statement. This also
works with the other default zones.
local-data: "<resource record string>"
Configure local data, which is served in reply to queries for it.
The query has to match exactly unless you configure the local-zone
as redirect. If not matched exactly, the local-zone type deter-
mines further processing. If local-data is configured that is not
a subdomain of a local-zone, a transparent local-zone is config-
ured. For record types such as TXT, use single quotes, as in lo-
cal-data: 'example. TXT "text"'.
If you need more complicated authoritative data, with referrals,
wildcards, CNAME/DNAME support, or DNSSEC authoritative service,
setup a stub-zone for it as detailed in the stub zone section be-
low.
local-data-ptr: "IPaddr name"
Configure local data shorthand for a PTR record with the reversed
IPv4 or IPv6 address and the host name. For example "192.0.2.4
www.example.com". TTL can be inserted like this: "2001:DB8::4
7200 www.example.com"
local-zone-tag: <zone> <"list of tags">
Assign tags to localzones. Tagged localzones will only be applied
when the used access-control element has a matching tag. Tags must
be defined in define-tags. Enclose list of tags in quotes ("")
and put spaces between tags. When there are multiple tags it
checks if the intersection of the list of tags for the query and
local-zone-tag is non-empty.
local-zone-override: <zone> <IP netblock> <type>
Override the localzone type for queries from addresses matching
netblock. Use this localzone type, regardless the type configured
for the local-zone (both tagged and untagged) and regardless the
type configured using access-control-tag-action.
response-ip: <IP-netblock> <action>
This requires use of the "respip" module.
If the IP address in an AAAA or A RR in the answer section of a
response matches the specified IP netblock, the specified action
will apply. <action> has generally the same semantics as that for
access-control-tag-action, but there are some exceptions.
Actions for response-ip are different from those for local-zone in
that in case of the former there is no point of such conditions as
"the query matches it but there is no local data". Because of
this difference, the semantics of response-ip actions are modified
or simplified as follows: The static, refuse, transparent, type-
transparent, and nodefault actions are invalid for response-ip.
Using any of these will cause the configuration to be rejected as
faulty. The deny action is non-conditional, i.e. it always results
in dropping the corresponding query. The resolution result before
applying the deny action is still cached and can be used for other
queries.
response-ip-data: <IP-netblock> <"resource record string">
This requires use of the "respip" module.
This specifies the action data for response-ip with action being
to redirect as specified by "resource record string". "Resource
record string" is similar to that of access-control-tag-action,
but it must be of either AAAA, A or CNAME types. If the IP-net-
block is an IPv6/IPv4 prefix, the record must be AAAA/A respec-
tively, unless it is a CNAME (which can be used for both versions
of IP netblocks). If it is CNAME there must not be more than one
response-ip-data for the same IP-netblock. Also, CNAME and other
types of records must not coexist for the same IP-netblock, fol-
lowing the normal rules for CNAME records. The textual domain
name for the CNAME does not have to be explicitly terminated with
a dot ("."); the root name is assumed to be the origin for the
name.
response-ip-tag: <IP-netblock> <"list of tags">
This requires use of the "respip" module.
Assign tags to response IP-netblocks. If the IP address in an
AAAA or A RR in the answer section of a response matches the spec-
ified IP-netblock, the specified tags are assigned to the IP ad-
dress. Then, if an access-control-tag is defined for the client
and it includes one of the tags for the response IP, the corre-
sponding access-control-tag-action will apply. Tag matching rule
is the same as that for access-control-tag and local-zones. Un-
like local-zone-tag, response-ip-tag can be defined for an IP-net-
block even if no response-ip is defined for that netblock. If
multiple response-ip-tag options are specified for the same IP-
netblock in different statements, all but the first will be ig-
nored. However, this will not be flagged as a configuration er-
ror, but the result is probably not what was intended.
Actions specified in an access-control-tag-action that has a
matching tag with response-ip-tag can be those that are "invalid"
for response-ip listed above, since access-control-tag-actions can
be shared with local zones. For these actions, if they behave
differently depending on whether local data exists or not in case
of local zones, the behavior for response-ip-data will generally
result in NOERROR/NODATA instead of NXDOMAIN, since the response-
ip data are inherently type specific, and non-existence of data
does not indicate anything about the existence or non-existence of
the qname itself. For example, if the matching tag action is sta-
tic but there is no data for the corresponding response-ip config-
uration, then the result will be NOERROR/NODATA. The only case
where NXDOMAIN is returned is when an always_nxdomain action ap-
plies.
ratelimit: <number or 0>
Enable ratelimiting of queries sent to nameserver for performing
recursion. If 0, the default, it is disabled. This option is ex-
perimental at this time. The ratelimit is in queries per second
that are allowed. More queries are turned away with an error
(servfail). This stops recursive floods, eg. random query names,
but not spoofed reflection floods. Cached responses are not rate-
limited by this setting. The zone of the query is determined by
examining the nameservers for it, the zone name is used to keep
track of the rate. For example, 1000 may be a suitable value to
stop the server from being overloaded with random names, and keeps
Unbound from sending traffic to the nameservers for those zones.
Configured forwarders are excluded from ratelimiting.
ratelimit-size: <memory size>
Give the size of the data structure in which the current ongoing
rates are kept track in. Default 4m. In bytes or use m(mega),
k(kilo), g(giga). The ratelimit structure is small, so this data
structure likely does not need to be large.
ratelimit-slabs: <number>
Give power of 2 number of slabs, this is used to reduce lock con-
tention in the ratelimit tracking data structure. Close to the
number of cpus is a fairly good setting.
ratelimit-factor: <number>
Set the amount of queries to rate limit when the limit is ex-
ceeded. If set to 0, all queries are dropped for domains where
the limit is exceeded. If set to another value, 1 in that number
is allowed through to complete. Default is 10, allowing 1/10
traffic to flow normally. This can make ordinary queries complete
(if repeatedly queried for), and enter the cache, whilst also mit-
igating the traffic flow by the factor given.
ratelimit-backoff: <yes or no>
If enabled, the ratelimit is treated as a hard failure instead of
the default maximum allowed constant rate. When the limit is
reached, traffic is ratelimited and demand continues to be kept
track of for a 2 second rate window. No traffic is allowed, ex-
cept for ratelimit-factor, until demand decreases below the con-
figured ratelimit for a 2 second rate window. Useful to set rate-
limit to a suspicious rate to aggressively limit unusually high
traffic. Default is off.
ratelimit-for-domain: <domain> <number qps or 0>
Override the global ratelimit for an exact match domain name with
the listed number. You can give this for any number of names.
For example, for a top-level-domain you may want to have a higher
limit than other names. A value of 0 will disable ratelimiting
for that domain.
ratelimit-below-domain: <domain> <number qps or 0>
Override the global ratelimit for a domain name that ends in this
name. You can give this multiple times, it then describes differ-
ent settings in different parts of the namespace. The closest
matching suffix is used to determine the qps limit. The rate for
the exact matching domain name is not changed, use rate-
limit-for-domain to set that, you might want to use different set-
tings for a top-level-domain and subdomains. A value of 0 will
disable ratelimiting for domain names that end in this name.
ip-ratelimit: <number or 0>
Enable global ratelimiting of queries accepted per IP address.
This option is experimental at this time. The ratelimit is in
queries per second that are allowed. More queries are completely
dropped and will not receive a reply, SERVFAIL or otherwise. IP
ratelimiting happens before looking in the cache. This may be use-
ful for mitigating amplification attacks. Clients with a valid
DNS Cookie will bypass the ratelimit. If a ratelimit for such
clients is still needed, ip-ratelimit-cookie can be used instead.
Default is 0 (disabled).
ip-ratelimit-cookie: <number or 0>
Enable global ratelimiting of queries accepted per IP address with
a valid DNS Cookie. This option is experimental at this time.
The ratelimit is in queries per second that are allowed. More
queries are completely dropped and will not receive a reply, SERV-
FAIL or otherwise. IP ratelimiting happens before looking in the
cache. This option could be useful in combination with al-
low_cookie in an attempt to mitigate other amplification attacks
than UDP reflections (e.g., attacks targeting Unbound itself)
which are already handled with DNS Cookies. If used, the value is
suggested to be higher than ip-ratelimit e.g., tenfold. Default
is 0 (disabled).
ip-ratelimit-size: <memory size>
Give the size of the data structure in which the current ongoing
rates are kept track in. Default 4m. In bytes or use m(mega),
k(kilo), g(giga). The ip ratelimit structure is small, so this
data structure likely does not need to be large.
ip-ratelimit-slabs: <number>
Give power of 2 number of slabs, this is used to reduce lock con-
tention in the ip ratelimit tracking data structure. Close to the
number of cpus is a fairly good setting.
ip-ratelimit-factor: <number>
Set the amount of queries to rate limit when the limit is ex-
ceeded. If set to 0, all queries are dropped for addresses where
the limit is exceeded. If set to another value, 1 in that number
is allowed through to complete. Default is 10, allowing 1/10
traffic to flow normally. This can make ordinary queries complete
(if repeatedly queried for), and enter the cache, whilst also mit-
igating the traffic flow by the factor given.
ip-ratelimit-backoff: <yes or no>
If enabled, the ratelimit is treated as a hard failure instead of
the default maximum allowed constant rate. When the limit is
reached, traffic is ratelimited and demand continues to be kept
track of for a 2 second rate window. No traffic is allowed, ex-
cept for ip-ratelimit-factor, until demand decreases below the
configured ratelimit for a 2 second rate window. Useful to set
ip-ratelimit to a suspicious rate to aggressively limit unusually
high traffic. Default is off.
outbound-msg-retry: <number>
The number of retries, per upstream nameserver in a delegation,
that Unbound will attempt in case a throwaway response is re-
ceived. No response (timeout) contributes to the retry counter.
If a forward/stub zone is used, this is the number of retries per
nameserver in the zone. Default is 5.
max-sent-count: <number>
Hard limit on the number of outgoing queries Unbound will make
while resolving a name, making sure large NS sets do not loop.
Results in SERVFAIL when reached. It resets on query restarts
(e.g., CNAME) and referrals. Default is 32.
max-query-restarts: <number>
Hard limit on the number of times Unbound is allowed to restart a
query upon encountering a CNAME record. Results in SERVFAIL when
reached. Changing this value needs caution as it can allow long
CNAME chains to be accepted, where Unbound needs to verify (re-
solve) each link individually. Default is 11.
iter-scrub-ns: <number>
Limit on the number of NS records allowed in an rrset of type NS,
from the iterator scrubber. This protects the internals of the re-
solver from overly large NS sets. Default is 20.
iter-scrub-cname: <number>
Limit on the number of CNAME, DNAME records in an answer, from the
iterator scrubber. This protects the internals of the resolver
from overly long indirection chains. Clips off the remainder of
the reply packet at that point. Default is 11.
max-global-quota: <number>
Limit on the number of upstream queries sent out for an incoming
query and its subqueries from recursion. It is not reset during
the resolution. When it is exceeded the query is failed and the
lookup process stops. Default is 200.
fast-server-permil: <number>
Specify how many times out of 1000 to pick from the set of fastest
servers. 0 turns the feature off. A value of 900 would pick from
the fastest servers 90 percent of the time, and would perform nor-
mal exploration of random servers for the remaining time. When
prefetch is enabled (or serve-expired), such prefetches are not
sped up, because there is no one waiting for it, and it presents a
good moment to perform server exploration. The fast-server-num op-
tion can be used to specify the size of the fastest servers set.
The default for fast-server-permil is 0.
fast-server-num: <number>
Set the number of servers that should be used for fast server se-
lection. Only use the fastest specified number of servers with the
fast-server-permil option, that turns this on or off. The default
is to use the fastest 3 servers.
answer-cookie: <yes or no>
If enabled, Unbound will answer to requests containing DNS Cookies
as specified in RFC 7873 and RFC 9018. Default is no.
cookie-secret: <128 bit hex string>
Server's secret for DNS Cookie generation. Useful to explicitly
set for servers in an anycast deployment that need to share the
secret in order to verify each other's Server Cookies. An example
hex string would be "000102030405060708090a0b0c0d0e0f". Default
is a 128 bits random secret generated at startup time. This op-
tion is ignored if a cookie-secret-file is present. In that case
the secrets from that file are used in DNS Cookie calculations.
cookie-secret-file: <filename>
File from which the secrets are read used in DNS Cookie calcula-
tions. When this file exists, the secrets in this file are used
and the secret specified by the cookie-secret option is ignored.
Enable it by setting a filename, like "/usr/local/etc/un-
bound_cookiesecrets.txt". The content of this file must be manip-
ulated with the add_cookie_secret, drop_cookie_secret and acti-
vate_cookie_secret commands to the unbound-control(8) tool. Please
see that manpage on how to perform a safe cookie secret rollover.
Default is "" (disabled).
edns-client-string: <IP netblock> <string>
Include an EDNS0 option containing configured ascii string in
queries with destination address matching the configured IP net-
block. This configuration option can be used multiple times. The
most specific match will be used.
edns-client-string-opcode: <opcode>
EDNS0 option code for the edns-client-string option, from 0 to
1. A value from the `Reserved for Local/Experimental` range
(65001-65534) should be used. Default is 65001.
ede: <yes or no>
If enabled, Unbound will respond with Extended DNS Error codes
(RFC8914). These EDEs provide additional information with a re-
sponse mainly for, but not limited to, DNS and DNSSEC errors.
When the val-log-level option is also set to 2, responses with Ex-
tended DNS Errors concerning DNSSEC failures will also contain a
descriptive text message about the reason for the failure. De-
fault is "no".
ede-serve-expired: <yes or no>
If enabled, Unbound will attach an Extended DNS Error (RFC8914)
Code 3 - Stale Answer as EDNS0 option to the expired response.
The ede option needs to be enabled as well for this to work. De-
fault is "no".
dns-error-reporting: <yes or no>
If enabled, Unbound will send DNS Error Reports (RFC9567). The
name servers need to express support by attaching the Report-Chan-
nel EDNS0 option on their replies specifying the reporting agent
for the zone. Any errors encountered during resolution that would
result in Unbound generating an Extended DNS Error (RFC8914) will
be reported to the zone's reporting agent. The ede option does
not need to be enabled for this to work. It is advised that the
qname-minimisation option is also enabled to increase privacy on
the outgoing reports. Default is "no".
Remote Control Options
In the remote-control: clause are the declarations for the remote con-
trol facility. If this is enabled, the unbound-control(8) utility can
be used to send commands to the running Unbound server. The server
uses these clauses to setup TLSv1 security for the connection. The un-
bound-control(8) utility also reads the remote-control section for op-
tions. To setup the correct self-signed certificates use the un-
bound-control-setup(8) utility.
control-enable: <yes or no>
The option is used to enable remote control, default is "no". If
turned off, the server does not listen for control commands.
control-interface: <ip address or interface name or path>
Give IPv4 or IPv6 addresses or local socket path to listen on for
control commands. If an interface name is used instead of an ip
address, the list of ip addresses on that interface are used. By
default localhost (127.0.0.1 and ::1) is listened to. Use 0.0.0.0
and ::0 to listen to all interfaces. If you change this and per-
missions have been dropped, you must restart the server for the
change to take effect.
If you set it to an absolute path, a unix domain socket is used.
This socket does not use the certificates and keys, so those files
need not be present. To restrict access, Unbound sets permissions
on the file to the user and group that is configured, the access
bits are set to allow the group members to access the control
socket file. Put users that need to access the socket in the that
group. To restrict access further, create a directory to put the
control socket in and restrict access to that directory.
control-port: <port number>
The port number to listen on for IPv4 or IPv6 control interfaces,
default is 8953. If you change this and permissions have been
dropped, you must restart the server for the change to take ef-
fect.
control-use-cert: <yes or no>
For localhost control-interface you can disable the use of TLS by
setting this option to "no", default is "yes". For local sockets,
TLS is disabled and the value of this option is ignored.
server-key-file: <private key file>
Path to the server private key, by default unbound_server.key.
This file is generated by the unbound-control-setup utility. This
file is used by the Unbound server, but not by unbound-control.
server-cert-file: <certificate file.pem>
Path to the server self signed certificate, by default un-
bound_server.pem. This file is generated by the unbound-con-
trol-setup utility. This file is used by the Unbound server, and
also by unbound-control.
control-key-file: <private key file>
Path to the control client private key, by default unbound_con-
trol.key. This file is generated by the unbound-control-setup
utility. This file is used by unbound-control.
control-cert-file: <certificate file.pem>
Path to the control client certificate, by default unbound_con-
trol.pem. This certificate has to be signed with the server cer-
tificate. This file is generated by the unbound-control-setup
utility. This file is used by unbound-control.
Stub Zone Options
There may be multiple stub-zone: clauses. Each with a name: and zero or
more hostnames or IP addresses. For the stub zone this list of name-
servers is used. Class IN is assumed. The servers should be authority
servers, not recursors; Unbound performs the recursive processing it-
self for stub zones.
The stub zone can be used to configure authoritative data to be used by
the resolver that cannot be accessed using the public internet servers.
This is useful for company-local data or private zones. Setup an au-
thoritative server on a different host (or different port). Enter a
config entry for Unbound with stub-addr: <ip address of host[@port]>.
The Unbound resolver can then access the data, without referring to the
public internet for it.
This setup allows DNSSEC signed zones to be served by that authorita-
tive server, in which case a trusted key entry with the public key can
be put in config, so that Unbound can validate the data and set the AD
bit on replies for the private zone (authoritative servers do not set
the AD bit). This setup makes Unbound capable of answering queries for
the private zone, and can even set the AD bit ('authentic'), but the AA
('authoritative') bit is not set on these replies.
Consider adding server: statements for domain-insecure: and for lo-
cal-zone: name nodefault for the zone if it is a locally served zone.
The insecure clause stops DNSSEC from invalidating the zone. The local
zone nodefault (or transparent) clause makes the (reverse-) zone bypass
Unbound's filtering of RFC1918 zones.
name: <domain name>
Name of the stub zone. This is the full domain name of the zone.
stub-host: <domain name>
Name of stub zone nameserver. Is itself resolved before it is
used. To use a nondefault port for DNS communication append '@'
with the port number. If tls is enabled, then you can append a
'#' and a name, then it'll check the tls authentication certifi-
cates with that name. If you combine the '@' and '#', the '@'
comes first. If only '#' is used the default port is the con-
figured tls-port.
stub-addr: <IP address>
IP address of stub zone nameserver. Can be IP 4 or IP 6. To use
a nondefault port for DNS communication append '@' with the port
number. If tls is enabled, then you can append a '#' and a
name, then it'll check the tls authentication certificates with
that name. If you combine the '@' and '#', the '@' comes first.
If only '#' is used the default port is the configured tls-port.
stub-prime: <yes or no>
This option is by default no. If enabled it performs NS set
priming, which is similar to root hints, where it starts using
the list of nameservers currently published by the zone. Thus,
if the hint list is slightly outdated, the resolver picks up a
correct list online.
stub-first: <yes or no>
If enabled, a query is attempted without the stub clause if it
fails. The data could not be retrieved and would have caused
SERVFAIL because the servers are unreachable, instead it is
tried without this clause. The default is no.
stub-tls-upstream: <yes or no>
Enabled or disable whether the queries to this stub use TLS for
transport. Default is no.
stub-ssl-upstream: <yes or no>
Alternate syntax for stub-tls-upstream.
stub-tcp-upstream: <yes or no>
If it is set to "yes" then upstream queries use TCP only for
transport regardless of global flag tcp-upstream. Default is
no.
stub-no-cache: <yes or no>
Default is no. If enabled, data inside the stub is not cached.
This is useful when you want immediate changes to be visible.
Forward Zone Options
There may be multiple forward-zone: clauses. Each with a name: and zero
or more hostnames or IP addresses. For the forward zone this list of
nameservers is used to forward the queries to. The servers listed as
forward-host: and forward-addr: have to handle further recursion for
the query. Thus, those servers are not authority servers, but are
(just like Unbound is) recursive servers too; Unbound does not perform
recursion itself for the forward zone, it lets the remote server do it.
Class IN is assumed. CNAMEs are chased by Unbound itself, asking the
remote server for every name in the indirection chain, to protect the
local cache from illegal indirect referenced items. A forward-zone en-
try with name "." and a forward-addr target will forward all queries to
that other server (unless it can answer from the cache).
name: <domain name>
Name of the forward zone. This is the full domain name of the
zone.
forward-host: <domain name>
Name of server to forward to. Is itself resolved before it is
used. To use a nondefault port for DNS communication append '@'
with the port number. If tls is enabled, then you can append a
'#' and a name, then it'll check the tls authentication certifi-
cates with that name. If you combine the '@' and '#', the '@'
comes first. If only '#' is used the default port is the con-
figured tls-port.
forward-addr: <IP address>
IP address of server to forward to. Can be IP 4 or IP 6. To use
a nondefault port for DNS communication append '@' with the port
number. If tls is enabled, then you can append a '#' and a
name, then it'll check the tls authentication certificates with
that name. If you combine the '@' and '#', the '@' comes first.
If only '#' is used the default port is the configured tls-port.
At high verbosity it logs the TLS certificate, with TLS enabled.
If you leave out the '#' and auth name from the forward-addr,
any name is accepted. The cert must also match a CA from the
tls-cert-bundle.
forward-first: <yes or no>
If a forwarded query is met with a SERVFAIL error, and this op-
tion is enabled, Unbound will fall back to normal recursive res-
olution for this query as if no query forwarding had been speci-
fied. The default is "no".
forward-tls-upstream: <yes or no>
Enabled or disable whether the queries to this forwarder use TLS
for transport. Default is no. If you enable this, also config-
ure a tls-cert-bundle or use tls-win-cert to load CA certs, oth-
erwise the connections cannot be authenticated.
forward-ssl-upstream: <yes or no>
Alternate syntax for forward-tls-upstream.
forward-tcp-upstream: <yes or no>
If it is set to "yes" then upstream queries use TCP only for
transport regardless of global flag tcp-upstream. Default is
no.
forward-no-cache: <yes or no>
Default is no. If enabled, data inside the forward is not
cached. This is useful when you want immediate changes to be
visible.
Authority Zone Options
Authority zones are configured with auth-zone:, and each one must have
a name:. There can be multiple ones, by listing multiple auth-zone
clauses, each with a different name, pertaining to that part of the
namespace. The authority zone with the name closest to the name looked
up is used. Authority zones can be processed on two distinct, non-ex-
clusive, configurable stages.
With for-downstream: yes (default), authority zones are processed after
local-zones and before cache. When used in this manner, Unbound re-
sponds like an authority server with no further processing other than
returning an answer from the zone contents. A notable example, in this
case, is CNAME records which are returned verbatim to downstream
clients without further resolution.
With for-upstream: yes (default), authority zones are processed after
the cache lookup, just before going to the network to fetch information
for recursion. When used in this manner they provide a local copy of
an authority server that speeds up lookups for that data during resolv-
ing.
If both options are enabled (default), client queries for an authority
zone are answered authoritatively from Unbound, while internal queries
that require data from the authority zone consult the local zone data
instead of going to the network.
An interesting configuration is for-downstream: no, for-upstream: yes
that allows for hyperlocal behavior where both client and internal
queries consult the local zone data while resolving. In this case, the
aforementioned CNAME example will result in a thoroughly resolved an-
swer.
Authority zones can be read from zonefile. And can be kept updated via
AXFR and IXFR. After update the zonefile is rewritten. The update
mechanism uses the SOA timer values and performs SOA UDP queries to de-
tect zone changes.
If the update fetch fails, the timers in the SOA record are used to
time another fetch attempt. Until the SOA expiry timer is reached.
Then the zone is expired. When a zone is expired, queries are SERV-
FAIL, and any new serial number is accepted from the primary (even if
older), and if fallback is enabled, the fallback activates to fetch
from the upstream instead of the SERVFAIL.
name: <zone name>
Name of the authority zone.
primary: <IP address or host name>
Where to download a copy of the zone from, with AXFR and IXFR.
Multiple primaries can be specified. They are all tried if one
fails. To use a nondefault port for DNS communication append
'@' with the port number. You can append a '#' and a name, then
AXFR over TLS can be used and the tls authentication certifi-
cates will be checked with that name. If you combine the '@'
and '#', the '@' comes first. If you point it at another Un-
bound instance, it would not work because that does not support
AXFR/IXFR for the zone, but if you used url: to download the
zonefile as a text file from a webserver that would work. If
you specify the hostname, you cannot use the domain from the
zonefile, because it may not have that when retrieving that
data, instead use a plain IP address to avoid a circular depen-
dency on retrieving that IP address.
master: <IP address or host name>
Alternate syntax for primary.
url: <url to zonefile>
Where to download a zonefile for the zone. With http or https.
An example for the url is "http://www.example.com/exam-
ple.org.zone". Multiple url statements can be given, they are
tried in turn. If only urls are given the SOA refresh timer is
used to wait for making new downloads. If also primaries are
listed, the primaries are first probed with UDP SOA queries to
see if the SOA serial number has changed, reducing the number of
downloads. If none of the urls work, the primaries are tried
with IXFR and AXFR. For https, the tls-cert-bundle and the
hostname from the url are used to authenticate the connection.
If you specify a hostname in the URL, you cannot use the domain
from the zonefile, because it may not have that when retrieving
that data, instead use a plain IP address to avoid a circular
dependency on retrieving that IP address. Avoid dependencies on
name lookups by using a notation like "http://192.0.2.1/unbound-
primaries/example.com.zone", with an explicit IP address.
allow-notify: <IP address or host name or netblockIP/prefix>
With allow-notify you can specify additional sources of noti-
fies. When notified, the server attempts to first probe and
then zone transfer. If the notify is from a primary, it first
attempts that primary. Otherwise other primaries are attempted.
If there are no primaries, but only urls, the file is downloaded
when notified. The primaries from primary: and url: statements
are allowed notify by default.
fallback-enabled: <yes or no>
Default no. If enabled, Unbound falls back to querying the in-
ternet as a resolver for this zone when lookups fail. For exam-
ple for DNSSEC validation failures.
for-downstream: <yes or no>
Default yes. If enabled, Unbound serves authority responses to
downstream clients for this zone. This option makes Unbound be-
have, for the queries with names in this zone, like one of the
authority servers for that zone. Turn it off if you want Un-
bound to provide recursion for the zone but have a local copy of
zone data. If for-downstream is no and for-upstream is yes,
then Unbound will DNSSEC validate the contents of the zone be-
fore serving the zone contents to clients and store validation
results in the cache.
for-upstream: <yes or no>
Default yes. If enabled, Unbound fetches data from this data
collection for answering recursion queries. Instead of sending
queries over the internet to the authority servers for this
zone, it'll fetch the data directly from the zone data. Turn it
on when you want Unbound to provide recursion for downstream
clients, and use the zone data as a local copy to speed up
lookups.
zonemd-check: <yes or no>
Enable this option to check ZONEMD records in the zone. Default
is disabled. The ZONEMD record is a checksum over the zone
data. This includes glue in the zone and data from the zone
file, and excludes comments from the zone file. When there is a
DNSSEC chain of trust, DNSSEC signatures are checked too.
zonemd-reject-absence: <yes or no>
Enable this option to reject the absence of the ZONEMD record.
Without it, when zonemd is not there it is not checked. It is
useful to enable for a nonDNSSEC signed zone where the operator
wants to require the verification of a ZONEMD, hence a missing
ZONEMD is a failure. The action upon failure is controlled by
the zonemd-permissive-mode option, for log only or also block
the zone. The default is no.
Without the option absence of a ZONEMD is only a failure when
the zone is DNSSEC signed, and we have a trust anchor, and the
DNSSEC verification of the absence of the ZONEMD fails. With
the option enabled, the absence of a ZONEMD is always a failure,
also for nonDNSSEC signed zones.
zonefile: <filename>
The filename where the zone is stored. If not given then no
zonefile is used. If the file does not exist or is empty, Un-
bound will attempt to fetch zone data (eg. from the primary
servers).
View Options
There may be multiple view: clauses. Each with a name: and zero or more
local-zone and local-data elements. Views can also contain view-first,
response-ip, response-ip-data and local-data-ptr elements. View can be
mapped to requests by specifying the view name in an access-con-
trol-view element. Options from matching views will override global op-
tions. Global options will be used if no matching view is found, or
when the matching view does not have the option specified.
name: <view name>
Name of the view. Must be unique. This name is used in ac-
cess-control-view elements.
local-zone: <zone> <type>
View specific local-zone elements. Has the same types and behav-
iour as the global local-zone elements. When there is at least
one local-zone specified and view-first is no, the default lo-
cal-zones will be added to this view. Defaults can be disabled
using the nodefault type. When view-first is yes or when a view
does not have a local-zone, the global local-zone will be used
including it's default zones.
local-data: "<resource record string>"
View specific local-data elements. Has the same behaviour as the
global local-data elements.
local-data-ptr: "IPaddr name"
View specific local-data-ptr elements. Has the same behaviour as
the global local-data-ptr elements.
view-first: <yes or no>
If enabled, it attempts to use the global local-zone and lo-
cal-data if there is no match in the view specific options. The
default is no.
Python Module Options
The python: clause gives the settings for the python(1) script module.
This module acts like the iterator and validator modules do, on queries
and answers. To enable the script module it has to be compiled into
the daemon, and the word "python" has to be put in the module-config:
option (usually first, or between the validator and iterator). Multiple
instances of the python module are supported by adding the word
"python" more than once.
If the chroot: option is enabled, you should make sure Python's library
directory structure is bind mounted in the new root environment, see
mount(8). Also the python-script: path should be specified as an ab-
solute path relative to the new root, or as a relative path to the
working directory.
python-script: <python file>
The script file to load. Repeat this option for every python
module instance added to the module-config: option.
Dynamic Library Module Options
The dynlib: clause gives the settings for the dynlib module. This mod-
ule is only a very small wrapper that allows dynamic modules to be
loaded on runtime instead of being compiled into the application. To
enable the dynlib module it has to be compiled into the daemon, and the
word "dynlib" has to be put in the module-config: option. Multiple in-
stances of dynamic libraries are supported by adding the word "dynlib"
more than once.
The dynlib-file: path should be specified as an absolute path relative
to the new path set by chroot: option, or as a relative path to the
working directory.
dynlib-file: <dynlib file>
The dynamic library file to load. Repeat this option for every
dynlib module instance added to the module-config: option.
DNS64 Module Options
The dns64 module must be configured in the module-config: directive
e.g., "dns64 validator iterator" and be compiled into the daemon to be
enabled. These settings go in the server: section.
dns64-prefix: <IPv6 prefix>
This sets the DNS64 prefix to use to synthesize AAAA records
with. It must be /96 or shorter. The default prefix is
64:ff9b::/96.
dns64-synthall: <yes or no>
Debug option, default no. If enabled, synthesize all AAAA
records despite the presence of actual AAAA records.
dns64-ignore-aaaa: <name>
List domain for which the AAAA records are ignored and the A
record is used by dns64 processing instead. Can be entered mul-
tiple times, list a new domain for which it applies, one per
line. Applies also to names underneath the name given.
NAT64 Operation
NAT64 operation allows using a NAT64 prefix for outbound requests to
IPv4-only servers. It is controlled by two options in the server: sec-
tion:
do-nat64: <yes or no>
Use NAT64 to reach IPv4-only servers. Consider also enabling
prefer-ip6 to prefer native IPv6 connections to nameservers.
Default no.
nat64-prefix: <IPv6 prefix>
Use a specific NAT64 prefix to reach IPv4-only servers. De-
faults to using the prefix configured in dns64-prefix, which in
turn defaults to 64:ff9b::/96. The prefix length must be one of
/32, /40, /48, /56, /64 or /96.
DNSCrypt Options
The dnscrypt: clause gives the settings of the dnscrypt channel. While
those options are available, they are only meaningful if Unbound was
compiled with --enable-dnscrypt. Currently certificate and secret/pub-
lic keys cannot be generated by Unbound. You can use dnscrypt-wrapper
to generate those: <https://github.com/cofyc/dnscrypt-wrapper/blob/mas->
ter/README.md#usage
dnscrypt-enable: <yes or no>
Whether or not the dnscrypt config should be enabled. You may
define configuration but not activate it. The default is no.
dnscrypt-port: <port number>
On which port should dnscrypt should be activated. Note that you
should have a matching interface option defined in the server
section for this port.
dnscrypt-provider: <provider name>
The provider name to use to distribute certificates. This is of
the form: 2.dnscrypt-cert.example.com.. The name MUST end with a
dot.
dnscrypt-secret-key: <path to secret key file>
Path to the time limited secret key file. This option may be
specified multiple times.
dnscrypt-provider-cert: <path to cert file>
Path to the certificate related to the dnscrypt-secret-keys.
This option may be specified multiple times.
dnscrypt-provider-cert-rotated: <path to cert file>
Path to a certificate that we should be able to serve existing
connection from but do not want to advertise over
dnscrypt-provider's TXT record certs distribution. A typical
use case is when rotating certificates, existing clients may
still use the client magic from the old cert in their queries
until they fetch and update the new cert. Likewise, it would al-
low one to prime the new cert/key without distributing the new
cert yet, this can be useful when using a network of servers us-
ing anycast and on which the configuration may not get updated
at the exact same time. By priming the cert, the servers can
handle both old and new certs traffic while distributing only
one. This option may be specified multiple times.
dnscrypt-shared-secret-cache-size: <memory size>
Give the size of the data structure in which the shared secret
keys are kept in. Default 4m. In bytes or use m(mega),
k(kilo), g(giga). The shared secret cache is used when a same
client is making multiple queries using the same public key. It
saves a substantial amount of CPU.
dnscrypt-shared-secret-cache-slabs: <number>
Give power of 2 number of slabs, this is used to reduce lock
contention in the dnscrypt shared secrets cache. Close to the
number of cpus is a fairly good setting.
dnscrypt-nonce-cache-size: <memory size>
Give the size of the data structure in which the client nonces
are kept in. Default 4m. In bytes or use m(mega), k(kilo),
g(giga). The nonce cache is used to prevent dnscrypt message
replaying. Client nonce should be unique for any pair of client
pk/server sk.
dnscrypt-nonce-cache-slabs: <number>
Give power of 2 number of slabs, this is used to reduce lock
contention in the dnscrypt nonce cache. Close to the number of
cpus is a fairly good setting.
EDNS Client Subnet Module Options
The ECS module must be configured in the module-config: directive e.g.,
"subnetcache validator iterator" and be compiled into the daemon to be
enabled. These settings go in the server: section.
If the destination address is allowed in the configuration Unbound will
add the EDNS0 option to the query containing the relevant part of the
client's address. When an answer contains the ECS option the response
and the option are placed in a specialized cache. If the authority in-
dicated no support, the response is stored in the regular cache.
Additionally, when a client includes the option in its queries, Unbound
will forward the option when sending the query to addresses that are
explicitly allowed in the configuration using send-client-subnet. The
option will always be forwarded, regardless the allowed addresses, if
client-subnet-always-forward is set to yes. In this case the lookup in
the regular cache is skipped.
The maximum size of the ECS cache is controlled by 'msg-cache-size' in
the configuration file. On top of that, for each query only 100 differ-
ent subnets are allowed to be stored for each address family. Exceeding
that number, older entries will be purged from cache.
Note that due to the nature of how EDNS Client Subnet works, by segre-
gating the client IP space in order to try and have tailored responses
for prefixes of unknown sizes, resolution and cache response perfor-
mance are impacted as a result. Usage of the subnetcache module should
only be enabled in installations that require such functionality where
the resolver and the clients belong to different networks. An example
of that is an open resolver installation.
This module does not interact with the serve-expired* and prefetch: op-
tions.
send-client-subnet: <IP address>
Send client source address to this authority. Append /num to in-
dicate a classless delegation netblock, for example like
10.2.3.4/24 or 2001::11/64. Can be given multiple times. Author-
ities not listed will not receive edns-subnet information, un-
less domain in query is specified in client-subnet-zone.
client-subnet-zone: <domain>
Send client source address in queries for this domain and its
subdomains. Can be given multiple times. Zones not listed will
not receive edns-subnet information, unless hosted by authority
specified in send-client-subnet.
client-subnet-always-forward: <yes or no>
Specify whether the ECS address check (configured using
send-client-subnet) is applied for all queries, even if the
triggering query contains an ECS record, or only for queries for
which the ECS record is generated using the querier address (and
therefore did not contain ECS data in the client query). If en-
abled, the address check is skipped when the client query con-
tains an ECS record. And the lookup in the regular cache is
skipped. Default is no.
max-client-subnet-ipv6: <number>
Specifies the maximum prefix length of the client source address
we are willing to expose to third parties for IPv6. Defaults to
56.
max-client-subnet-ipv4: <number>
Specifies the maximum prefix length of the client source address
we are willing to expose to third parties for IPv4. Defaults to
24.
min-client-subnet-ipv6: <number>
Specifies the minimum prefix length of the IPv6 source mask we
are willing to accept in queries. Shorter source masks result in
REFUSED answers. Source mask of 0 is always accepted. Default is
0.
min-client-subnet-ipv4: <number>
Specifies the minimum prefix length of the IPv4 source mask we
are willing to accept in queries. Shorter source masks result in
REFUSED answers. Source mask of 0 is always accepted. Default is
0.
max-ecs-tree-size-ipv4: <number>
Specifies the maximum number of subnets ECS answers kept in the
ECS radix tree. This number applies for each qname/qclass/qtype
tuple. Defaults to 100.
max-ecs-tree-size-ipv6: <number>
Specifies the maximum number of subnets ECS answers kept in the
ECS radix tree. This number applies for each qname/qclass/qtype
tuple. Defaults to 100.
Opportunistic IPsec Support Module Options
The IPsec module must be configured in the module-config: directive
e.g., "ipsecmod validator iterator" and be compiled into Unbound by us-
ing --enable-ipsecmod to be enabled. These settings go in the server:
section.
When Unbound receives an A/AAAA query that is not in the cache and
finds a valid answer, it will withhold returning the answer and instead
will generate an IPSECKEY subquery for the same domain name. If an an-
swer was found, Unbound will call an external hook passing the follow-
ing arguments:
QNAME
Domain name of the A/AAAA and IPSECKEY query. In string for-
mat.
IPSECKEY TTL
TTL of the IPSECKEY RRset.
A/AAAA
String of space separated IP addresses present in the A/AAAA
RRset. The IP addresses are in string format.
IPSECKEY
String of space separated IPSECKEY RDATA present in the
IPSECKEY RRset. The IPSECKEY RDATA are in DNS presentation
format.
The A/AAAA answer is then cached and returned to the client. If the
external hook was called the TTL changes to ensure it doesn't surpass
ipsecmod-max-ttl.
The same procedure is also followed when prefetch: is used, but the
A/AAAA answer is given to the client before the hook is called. ipsec-
mod-max-ttl ensures that the A/AAAA answer given from cache is still
relevant for opportunistic IPsec.
ipsecmod-enabled: <yes or no>
Specifies whether the IPsec module is enabled or not. The IPsec
module still needs to be defined in the module-config: direc-
tive. This option facilitates turning on/off the module without
restarting/reloading Unbound. Defaults to yes.
ipsecmod-hook: <filename>
Specifies the external hook that Unbound will call with sys-
tem(3). The file can be specified as an absolute/relative path.
The file needs the proper permissions to be able to be executed
by the same user that runs Unbound. It must be present when the
IPsec module is defined in the module-config: directive.
ipsecmod-strict: <yes or no>
If enabled Unbound requires the external hook to return a suc-
cess value of 0. Failing to do so Unbound will reply with SERV-
FAIL. The A/AAAA answer will also not be cached. Defaults to
no.
ipsecmod-max-ttl: <seconds>
Time to live maximum for A/AAAA cached records after calling the
external hook. Defaults to 3600.
ipsecmod-ignore-bogus: <yes or no>
Specifies the behaviour of Unbound when the IPSECKEY answer is
bogus. If set to yes, the hook will be called and the A/AAAA
answer will be returned to the client. If set to no, the hook
will not be called and the answer to the A/AAAA query will be
SERVFAIL. Mainly used for testing. Defaults to no.
ipsecmod-allow: <domain>
Allow the ipsecmod functionality for the domain so that the mod-
ule logic will be executed. Can be given multiple times, for
different domains. If the option is not specified, all domains
are treated as being allowed (default).
ipsecmod-whitelist: <domain>
Alternate syntax for ipsecmod-allow.
Cache DB Module Options
The Cache DB module must be configured in the module-config: directive
e.g., "validator cachedb iterator" and be compiled into the daemon with
--enable-cachedb. If this module is enabled and configured, the speci-
fied backend database works as a second level cache: When Unbound can-
not find an answer to a query in its built-in in-memory cache, it con-
sults the specified backend. If it finds a valid answer in the back-
end, Unbound uses it to respond to the query without performing itera-
tive DNS resolution. If Unbound cannot even find an answer in the
backend, it resolves the query as usual, and stores the answer in the
backend.
This module interacts with the serve-expired-* options and will reply
with expired data if Unbound is configured for that.
If Unbound was built with --with-libhiredis on a system that has in-
stalled the hiredis C client library of Redis, then the "redis" backend
can be used. This backend communicates with the specified Redis server
over a TCP connection to store and retrieve cache data. It can be used
as a persistent and/or shared cache backend. It should be noted that
Unbound never removes data stored in the Redis server, even if some
data have expired in terms of DNS TTL or the Redis server has cached
too much data; if necessary the Redis server must be configured to
limit the cache size, preferably with some kind of least-recently-used
eviction policy. Additionally, the redis-expire-records option can be
used in order to set the relative DNS TTL of the message as timeout to
the Redis records; keep in mind that some additional memory is used per
key and that the expire information is stored as absolute Unix time-
stamps in Redis (computer time must be stable). This backend uses syn-
chronous communication with the Redis server based on the assumption
that the communication is stable and sufficiently fast. The thread
waiting for a response from the Redis server cannot handle other DNS
queries. Although the backend has the ability to reconnect to the
server when the connection is closed unexpectedly and there is a con-
figurable timeout in case the server is overly slow or hangs up, these
cases are assumed to be very rare. If connection close or timeout hap-
pens too often, Unbound will be effectively unusable with this backend.
It's the administrator's responsibility to make the assumption hold.
The cachedb: clause gives custom settings of the cache DB module.
backend: <backend name>
Specify the backend database name. The default database is the
in-memory backend named "testframe", which, as the name sug-
gests, is not of any practical use. Depending on the build-time
configuration, "redis" backend may also be used as described
above.
secret-seed: <"secret string">
Specify a seed to calculate a hash value from query information.
This value will be used as the key of the corresponding answer
for the backend database and can be customized if the hash
should not be predictable operationally. If the backend data-
base is shared by multiple Unbound instances, all instances must
use the same secret seed. This option defaults to "default".
cachedb-no-store: <yes or no>
If the backend should be read from, but not written to. This
makes this instance not store dns messages in the backend. But
if data is available it is retrieved. The default is no.
cachedb-check-when-serve-expired: <yes or no>
If enabled, the cachedb is checked before an expired response is
returned. When serve-expired is enabled, without serve-ex-
pired-client-timeout, it then does not immediately respond with
an expired response from cache, but instead first checks the
cachedb for valid contents, and if so returns it. If the cachedb
also has no valid contents, the serve expired response is sent.
If also serve-expired-client-timeout is enabled, the expired re-
sponse is delayed until the timeout expires. Unless the lookup
succeeds within the timeout. The default is yes.
The following cachedb options are specific to the redis backend.
redis-server-host: <server address or name>
The IP (either v6 or v4) address or domain name of the Redis
server. In general an IP address should be specified as other-
wise Unbound will have to resolve the name of the server every
time it establishes a connection to the server. This option de-
faults to "127.0.0.1".
redis-server-port: <port number>
The TCP port number of the Redis server. This option defaults
to 6379.
redis-server-path: <unix socket path>
The unix socket path to connect to the Redis server. Off by de-
fault, and it can be set to "" to turn this off. Unix sockets
may have better throughput than the IP address option.
redis-server-password: "<password>"
The Redis AUTH password to use for the Redis server. Only rele-
vant if Redis is configured for client password authorisation.
Off by default, and it can be set to "" to turn this off.
redis-timeout: <msec>
The period until when Unbound waits for a response from the Re-
dis sever. If this timeout expires Unbound closes the connec-
tion, treats it as if the Redis server does not have the re-
quested data, and will try to re-establish a new connection
later. This option defaults to 100 milliseconds.
redis-command-timeout: <msec>
The timeout to use for Redis commands, in milliseconds. If 0,
it uses the redis-timeout value. The default is 0.
redis-connect-timeout: <msec>
The timeout to use for Redis connection set up, in milliseconds.
If 0, it uses the redis-timeout value. The default is 0.
redis-expire-records: <yes or no>
If Redis record expiration is enabled. If yes, Unbound sets
timeout for Redis records so that Redis can evict keys that have
expired automatically. If Unbound is configured with serve-ex-
pired and serve-expired-ttl is 0, this option is internally re-
verted to "no". Redis SETEX support is required for this option
(Redis >= 2.0.0). This option defaults to no.
redis-logical-db: <logical database index>
The logical database in Redis to use. These are databases in
the same Redis instance sharing the same configuration and per-
sisted in the same RDB/AOF file. If unsure about using this op-
tion, Redis documentation (https://redis.io/commands/select/)
suggests not to use a single Redis instance for multiple unre-
lated applications. The default database in Redis is 0 while
other logical databases need to be explicitly SELECT'ed upon
connecting. This option defaults to 0.
redis-replica-server-host: <server address or name>
The IP (either v6 or v4) address or domain name of the Redis
replica server. In general an IP address should be specified as
otherwise Unbound will have to resolve the name of the server
every time it establishes a connection to the server. This
server is treated as a read-only replica server (https://re-
dis.io/docs/management/replication/#read-only-replica). If
specified, all Redis read commands will go to this replica
server, while the write commands will go to the redis-server-
host. This option defaults to "" (disabled).
redis-replica-server-port: <port number>
The TCP port number of the Redis replica server. This option
defaults to 6379.
redis-replica-server-path: <unix socket path>
The unix socket path to connect to the Redis server. Off by de-
fault, and it can be set to "" to turn this off. Unix sockets
may have better throughput than the IP address option.
redis-replica-server-password: "<password>"
The Redis AUTH password to use for the Redis replica server.
Only relevant if Redis is configured for client password autho-
risation. Off by default, and it can be set to "" to turn this
off.
redis-replica-timeout: <msec>
The period until when Unbound waits for a response from the Re-
dis replica sever. If this timeout expires Unbound closes the
connection, treats it as if the Redis replica server does not
have the requested data, and will try to re-establish a new con-
nection later. This option defaults to 100 milliseconds.
redis-replica-command-timeout: <msec>
The timeout to use for Redis replica commands, in milliseconds.
If 0, it uses the redis-replica-timeout value. The default is
0.
redis-replica-connect-timeout: <msec>
The timeout to use for Redis replica connection set up, in mil-
liseconds. If 0, it uses the redis-replica-timeout value. The
default is 0.
redis-replica-logical-db: <logical database index>
Same as redis-logical-db but for the Redis replica server. This
option defaults to 0.
DNSTAP Logging Options
DNSTAP support, when compiled in by using --enable-dnstap, is enabled
in the dnstap: section. This starts an extra thread (when compiled
with threading) that writes the log information to the destination. If
Unbound is compiled without threading it does not spawn a thread, but
connects per-process to the destination.
dnstap-enable: <yes or no>
If dnstap is enabled. Default no. If yes, it connects to the
dnstap server and if any of the dnstap-log-..-messages options
is enabled it sends logs for those messages to the server.
dnstap-bidirectional: <yes or no>
Use frame streams in bidirectional mode to transfer DNSTAP mes-
sages. Default is yes.
dnstap-socket-path: <file name>
Sets the unix socket file name for connecting to the server that
is listening on that socket. Default is "".
dnstap-ip: <IPaddress[@port]>
If "", the unix socket is used, if set with an IP address (IPv4
or IPv6) that address is used to connect to the server.
dnstap-tls: <yes or no>
Set this to use TLS to connect to the server specified in
dnstap-ip. The default is yes. If set to no, TCP is used to
connect to the server.
dnstap-tls-server-name: <name of TLS authentication>
The TLS server name to authenticate the server with. Used when
dnstap-tls is enabled. If "" it is ignored, default "".
dnstap-tls-cert-bundle: <file name of cert bundle>
The pem file with certs to verify the TLS server certificate. If
"" the server default cert bundle is used, or the windows cert
bundle on windows. Default is "".
dnstap-tls-client-key-file: <file name>
The client key file for TLS client authentication. If "" client
authentication is not used. Default is "".
dnstap-tls-client-cert-file: <file name>
The client cert file for TLS client authentication. Default is
"".
dnstap-send-identity: <yes or no>
If enabled, the server identity is included in the log messages.
Default is no.
dnstap-send-version: <yes or no>
If enabled, the server version if included in the log messages.
Default is no.
dnstap-identity: <string>
The identity to send with messages, if "" the hostname is used.
Default is "".
dnstap-version: <string>
The version to send with messages, if "" the package version is
used. Default is "".
dnstap-sample-rate: <number>
The sample rate for log of messages, it logs only 1/N messages.
With 0 it is disabled. Default is 0. This is useful in a high
volume environment, where log functionality would otherwise not
be reliable. For example 10 would spend only 1/10th time on log-
ging, and 100 would only spend a hundredth of the time on log-
ging.
dnstap-log-resolver-query-messages: <yes or no>
Enable to log resolver query messages. Default is no. These
are messages from Unbound to upstream servers.
dnstap-log-resolver-response-messages: <yes or no>
Enable to log resolver response messages. Default is no. These
are replies from upstream servers to Unbound.
dnstap-log-client-query-messages: <yes or no>
Enable to log client query messages. Default is no. These are
client queries to Unbound.
dnstap-log-client-response-messages: <yes or no>
Enable to log client response messages. Default is no. These
are responses from Unbound to clients.
dnstap-log-forwarder-query-messages: <yes or no>
Enable to log forwarder query messages. Default is no.
dnstap-log-forwarder-response-messages: <yes or no>
Enable to log forwarder response messages. Default is no.
Response Policy Zone Options
Response Policy Zones are configured with rpz:, and each one must have
a name:. There can be multiple ones, by listing multiple RPZ clauses,
each with a different name. RPZ clauses are applied in order of config-
uration and any match from an earlier RPZ zone will terminate the RPZ
lookup. Note that a PASSTHRU action is still considered a match. The
respip module needs to be added to the module-config, e.g.: module-con-
fig: "respip validator iterator".
QNAME, Response IP Address, nsdname, nsip and clientip triggers are
supported. Supported actions are: NXDOMAIN, NODATA, PASSTHRU, DROP,
Local Data, tcp-only and drop. RPZ QNAME triggers are applied after
local-zones and before auth-zones.
The RPZ zone is a regular DNS zone formatted with a SOA start record as
usual. The items in the zone are entries, that specify what to act on
(the trigger) and what to do (the action). The trigger to act on is
recorded in the name, the action to do is recorded as the resource
record. The names all end in the zone name, so you could type the
trigger names without a trailing dot in the zonefile.
An example RPZ record, that answers example.com with NXDOMAIN
example.com CNAME .
The triggers are encoded in the name on the left
name query name
netblock.rpz-client-ip client IP address
netblock.rpz-ip response IP address in the answer
name.rpz-nsdname nameserver name
netblock.rpz-nsip nameserver IP address
The netblock is written as <netblocklen>.<ip address in reverse>. For
IPv6 use 'zz' for '::'. Specify individual addresses with scope length
of 32 or 128. For example, 24.10.100.51.198.rpz-ip is 198.51.100.10/24
and 32.10.zz.db8.2001.rpz-ip is 2001:db8:0:0:0:0:0:10/32.
The actions are specified with the record on the right
CNAME . nxdomain reply
CNAME *. nodata reply
CNAME rpz-passthru. do nothing, allow to continue
CNAME rpz-drop. the query is dropped
CNAME rpz-tcp-only. answer over TCP
A 192.0.2.1 answer with this IP address
Other records like AAAA, TXT and other CNAMEs (not rpz-..) can also be
used to answer queries with that content.
The RPZ zones can be configured in the config file with these settings
in the rpz: block.
name: <zone name>
Name of the authority zone.
primary: <IP address or host name>
Where to download a copy of the zone from, with AXFR and IXFR.
Multiple primaries can be specified. They are all tried if one
fails. To use a nondefault port for DNS communication append
'@' with the port number. You can append a '#' and a name, then
AXFR over TLS can be used and the tls authentication certifi-
cates will be checked with that name. If you combine the '@'
and '#', the '@' comes first. If you point it at another Un-
bound instance, it would not work because that does not support
AXFR/IXFR for the zone, but if you used url: to download the
zonefile as a text file from a webserver that would work. If
you specify the hostname, you cannot use the domain from the
zonefile, because it may not have that when retrieving that
data, instead use a plain IP address to avoid a circular depen-
dency on retrieving that IP address.
master: <IP address or host name>
Alternate syntax for primary.
url: <url to zonefile>
Where to download a zonefile for the zone. With http or https.
An example for the url is "http://www.example.com/exam-
ple.org.zone". Multiple url statements can be given, they are
tried in turn. If only urls are given the SOA refresh timer is
used to wait for making new downloads. If also primaries are
listed, the primaries are first probed with UDP SOA queries to
see if the SOA serial number has changed, reducing the number of
downloads. If none of the urls work, the primaries are tried
with IXFR and AXFR. For https, the tls-cert-bundle and the
hostname from the url are used to authenticate the connection.
allow-notify: <IP address or host name or netblockIP/prefix>
With allow-notify you can specify additional sources of noti-
fies. When notified, the server attempts to first probe and
then zone transfer. If the notify is from a primary, it first
attempts that primary. Otherwise other primaries are attempted.
If there are no primaries, but only urls, the file is downloaded
when notified. The primaries from primary: and url: statements
are allowed notify by default.
zonefile: <filename>
The filename where the zone is stored. If not given then no
zonefile is used. If the file does not exist or is empty, Un-
bound will attempt to fetch zone data (eg. from the primary
servers).
rpz-action-override: <action>
Always use this RPZ action for matching triggers from this zone.
Possible action are: nxdomain, nodata, passthru, drop, disabled
and cname.
rpz-cname-override: <domain>
The CNAME target domain to use if the cname action is configured
for rpz-action-override.
rpz-log: <yes or no>
Log all applied RPZ actions for this RPZ zone. Default is no.
rpz-log-name: <name>
Specify a string to be part of the log line, for easy referenc-
ing.
rpz-signal-nxdomain-ra: <yes or no>
Signal when a query is blocked by the RPZ with NXDOMAIN with an
unset RA flag. This allows certain clients, like dnsmasq, to
infer that the domain is externally blocked. Default is no.
for-downstream: <yes or no>
If enabled the zone is authoritatively answered for and queries
for the RPZ zone information are answered to downstream clients.
This is useful for monitoring scripts, that can then access the
SOA information to check if the RPZ information is up to date.
Default is no.
tags: <list of tags>
Limit the policies from this RPZ clause to clients with a match-
ing tag. Tags need to be defined in define-tag and can be as-
signed to client addresses using access-control-tag. Enclose
list of tags in quotes ("") and put spaces between tags. If no
tags are specified the policies from this clause will be applied
for all clients.
MEMORY CONTROL EXAMPLE
In the example config settings below memory usage is reduced. Some ser-
vice levels are lower, notable very large data and a high TCP load are
no longer supported. Very large data and high TCP loads are exceptional
for the DNS. DNSSEC validation is enabled, just add trust anchors. If
you do not have to worry about programs using more than 3 Mb of memory,
the below example is not for you. Use the defaults to receive full ser-
vice, which on BSD-32bit tops out at 30-40 Mb after heavy usage.
# example settings that reduce memory usage
server:
num-threads: 1
outgoing-num-tcp: 1 # this limits TCP service, uses less buffers.
incoming-num-tcp: 1
outgoing-range: 60 # uses less memory, but less performance.
msg-buffer-size: 8192 # note this limits service, 'no huge stuff'.
msg-cache-size: 100k
msg-cache-slabs: 1
rrset-cache-size: 100k
rrset-cache-slabs: 1
infra-cache-numhosts: 200
infra-cache-slabs: 1
key-cache-size: 100k
key-cache-slabs: 1
neg-cache-size: 10k
num-queries-per-thread: 30
target-fetch-policy: "2 1 0 0 0 0"
harden-large-queries: "yes"
harden-short-bufsize: "yes"
FILES
/usr/local/etc/unbound
default Unbound working directory.
/usr/local/etc/unbound
default chroot(2) location.
/usr/local/etc/unbound/unbound.conf
Unbound configuration file.
/usr/local/etc/unbound/unbound.pid
default Unbound pidfile with process ID of the running daemon.
unbound.log
Unbound log file. default is to log to syslog(3).
SEE ALSO
unbound(8), unbound-checkconf(8).
AUTHORS
Unbound was written by NLnet Labs. Please see CREDITS file in the dis-
tribution for further details.
NLnet Labs Apr 24, 2025 unbound.conf(5)