BIND 9.14 is a stable branch of BIND. This document summarizes significant changes since the last production release on that branch.
Please see the file
CHANGES for a more
detailed list of changes and bug fixes.
As of BIND 9.13/9.14, BIND has adopted the "odd-unstable/even-stable" release numbering convention. BIND 9.14 contains new features added during the BIND 9.13 development process. Henceforth, the 9.14 branch will be limited to bug fixes and new feature development will proceed in the unstable 9.15 branch, and so forth.
Since 9.12, BIND has undergone substantial code refactoring and cleanup, and some very old code has been removed that supported obsolete operating systems and operating systems for which ISC is no longer able to perform quality assurance testing. Specifically, workarounds for UnixWare, BSD/OS, AIX, Tru64, SunOS, TruCluster, and IRIX have been removed.
On UNIX-like systems, BIND now requires support for POSIX.1c threads (IEEE Std 1003.1c-1995), the Advanced Sockets API for IPv6 (RFC 3542), and standard atomic operations provided by the C compiler.
More information can be found in the
file that is included in the source distribution of BIND 9. If your
platform compiler and system libraries provide the above features,
BIND 9 should compile and run. If that is not the case, the BIND
development team will generally accept patches that add support
for systems that are still supported by their respective vendors.
As of BIND 9.14, the BIND development team has also made cryptography (i.e., TSIG and DNSSEC) an integral part of the DNS server. The OpenSSL cryptography library must be available for the target platform. A PKCS#11 provider can be used instead for Public Key cryptography (i.e., DNSSEC signing and validation), but OpenSSL is still required for general cryptography operations such as hashing and random number generation.
The latest versions of BIND 9 software can always be found at https://www.isc.org/download/. There you will find additional information about each release, source code, and pre-compiled versions for Microsoft Windows operating systems.
To prevent exhaustion of server resources by a maliciously configured domain, the number of recursive queries that can be triggered by a request before aborting recursion has been further limited. Root and top-level domain servers are no longer exempt from the max-recursion-queries limit. Fetches for missing name server address records are limited to 4 for any domain. This issue was disclosed in CVE-2020-8616. [GL #1388]
Replaying a TSIG BADTIME response as a request could trigger an assertion failure. This was disclosed in CVE-2020-8617. [GL #1703]
DNS rebinding protection was ineffective when BIND 9 was configured as a forwarding DNS server. Found and responsibly reported by Tobias Klein. [GL #1574]
Set a limit on the number of concurrently served pipelined TCP queries. This flaw is disclosed in CVE-2019-6477. [GL #1264]
Added a new statistics variable tcp-highwater that reports the maximum number of simultaneous TCP clients BIND has handled while running. [GL #1206]
named could crash with an assertion failure if a forwarder returned a referral, rather than resolving the query, when QNAME minimization was enabled. This flaw is disclosed in CVE-2019-6476. [GL #1051]
A flaw in DNSSEC verification when transferring mirror zones could allow data to be incorrectly marked valid. This flaw is disclosed in CVE-2019-6475. [GL #1252]
A SipHash 2-4 based DNS Cookie (RFC 7873) algorithm has been added. [GL #605]
If you are running multiple DNS Servers (different versions of BIND 9 or DNS server from multiple vendors) responding from the same IP address (anycast or load-balancing scenarios), you'll have to make sure that all the servers are configured with the same DNS Cookie algorithm and same Server Secret for the best performance.
DS records included in DNS referral messages can now be validated and cached immediately, reducing the number of queries needed for a DNSSEC validation. [GL #964]
Cache database statistics counters could report invalid values when stale answers were enabled, because of a bug in counter maintenance when cache data becomes stale. The statistics counters have been corrected to report the number of RRsets for each RR type that are active, stale but still potentially served, or stale and marked for deletion. [GL #602]
Interaction between DNS64 and RPZ No Data rule (CNAME *.) could cause unexpected results; this has been fixed. [GL #1106]
named-checkconf now checks DNS64 prefixes to ensure bits 64-71 are zero. [GL #1159]
named-checkconf could crash during configuration if configured to use "geoip continent" ACLs with legacy GeoIP. [GL #1163]
named-checkconf now correctly reports a missing dnstap-output option when dnstap is set. [GL #1136]
Handle ETIMEDOUT error on connect() with a non-blocking socket. [GL #1133]
The new GeoIP2 API from MaxMind is now supported when BIND is compiled using configure --with-geoip2. The legacy GeoIP API can be used by compiling with configure --with-geoip instead. (Note that the databases for the legacy API are no longer maintained by MaxMind.)
The default path to the GeoIP2 databases will be set based
on the location of the libmaxminddb library;
for example, if it is in
then the default path will be
This value can be overridden in
using the geoip-directory option.
Some geoip ACL settings that were available with legacy GeoIP, including searches for netspeed, org, and three-letter ISO country codes, will no longer work when using GeoIP2. Supported GeoIP2 database types are country, city, domain, isp, and as. All of the databases support both IPv4 and IPv6 lookups. [GL #182]
Two new metrics have been added to the statistics-channel to report DNSSEC signing operations. For each key in each zone, the dnssec-sign counter indicates the total number of signatures named has generated using that key since server startup, and the dnssec-refresh counter indicates how many of those signatures were refreshed during zone maintenance, as opposed to having been generated as a result of a zone update. [GL #513]
A race condition could trigger an assertion failure when a large number of incoming packets were being rejected. This flaw is disclosed in CVE-2019-6471. [GL #942]
When qname-minimization was set to relaxed, some improperly configured domains would fail to resolve, but would have succeeded when minimization was disabled. named will now fall back to normal resolution in such cases, and also uses type A rather than NS for minimal queries in order to reduce the likelihood of encountering the problem. [GL #1055]
When trusted-keys and
managed-keys are both configured for the
same name, or when trusted-keys is used to
configure a trust anchor for the root zone and
dnssec-validation is set to the default
auto, automatic RFC 5011 key
rollovers will fail.
This combination of settings was never intended to work, but there was no check for it in the parser. This has been corrected; a warning is now logged. (In BIND 9.15 and higher this error will be fatal.) [GL #868]
In certain configurations, named could crash with an assertion failure if nxdomain-redirect was in use and a redirected query resulted in an NXDOMAIN from the cache. This flaw is disclosed in CVE-2019-6467. [GL #880]
The TCP client quota set using the tcp-clients option could be exceeded in some cases. This could lead to exhaustion of file descriptors. (CVE-2018-5743) [GL #615]
The new add-soa option specifies whether or not the response-policy zone's SOA record should be included in the additional section of RPZ responses. [GL #865]
Task manager and socket code have been substantially modified. The manager uses per-cpu queues for tasks and network stack runs multiple event loops in CPU-affinitive threads. This greatly improves performance on large systems, especially when using multi-queue NICs.
Support for QNAME minimization was added and enabled by default in relaxed mode, in which BIND will fall back to normal resolution if the remote server returns something unexpected during the query minimization process. This default setting might change to strict in the future.
A new plugin mechanism has been added to allow
extension of query processing functionality through the use of
external libraries. The new
plugin replaces the filter-aaaa feature that
was formerly implemented as a native part of BIND.
The plugin API is a work in progress and is likely to evolve as further plugins are implemented. [GL #15]
A new secondary zone option, mirror, enables named to serve a transferred copy of a zone's contents without acting as an authority for the zone. A zone must be fully validated against an active trust anchor before it can be used as a mirror zone. DNS responses from mirror zones do not set the AA bit ("authoritative answer"), but do set the AD bit ("authenticated data"). This feature is meant to facilitate deployment of a local copy of the root zone, as described in RFC 7706. [GL #33]
BIND now can be compiled against the libidn2 library to add IDNA2008 support. Previously, BIND supported IDNA2003 using the (now obsolete and unsupported) idnkit-1 library.
named now supports the "root key sentinel"
mechanism. This enables validating resolvers to indicate
which trust anchors are configured for the root, so that
information about root key rollover status can be gathered.
To disable this feature, add
root-key-sentinel no; to
named.conf. [GL #37]
The dnskey-sig-validity option allows the sig-validity-interval to be overriden for signatures covering DNSKEY RRsets. [GL #145]
When built on Linux, BIND now requires the libcap library to set process privileges. The adds a new compile-time dependency, which can be met on most Linux platforms by installing the libcap-dev or libcap-devel package. BIND can also be built without capability support by using configure --disable-linux-caps, at the cost of some loss of security.
The validate-except option specifies a list of domains beneath which DNSSEC validation should not be performed, regardless of whether a trust anchor has been configured above them. [GL #237]
Two new update policy rule types have been added krb5-selfsub and ms-selfsub which allow machines with Kerberos principals to update the name space at or below the machine names identified in the respective principals.
The new configure option --enable-fips-mode can be used to make BIND enable and enforce FIPS mode in the OpenSSL library. When compiled with such option the BIND will refuse to run if FIPS mode can't be enabled, thus this option must be only enabled for the systems where FIPS mode is available.
Two new configuration options min-cache-ttl and min-ncache-ttl has been added to allow the BIND 9 administrator to override the minimum TTL in the received DNS records (positive caching) and for storing the information about non-existent records (negative caching). The configured minimum TTL for both configuration options cannot exceed 90 seconds.
rndc status output now includes a reconfig/reload in progress status line if named configuration is being reloaded.
The new answer-cookie option, if set to
no, prevents named from
returning a DNS COOKIE option to a client, even if such an
option was present in the request. This is only intended as
a temporary measure, for use when named
shares an IP address with other servers that do not yet
support DNS COOKIE. A mismatch between servers on the same
address is not expected to cause operational problems, but the
option to disable COOKIE responses so that all servers have the
same behavior is provided out of an abundance of caution.
DNS COOKIE is an important security mechanism, and this option
should not be used to disable it unless absolutely necessary.
Workarounds for servers that misbehave when queried with EDNS have been removed, because these broken servers and the workarounds for their noncompliance cause unnecessary delays, increase code complexity, and prevent deployment of new DNS features. See https://dnsflagday.net for further details.
In particular, resolution will no longer fall back to plain DNS when there was no response from an authoritative server. This will cause some domains to become non-resolvable without manual intervention. In these cases, resolution can be restored by adding server clauses for the offending servers, specifying edns no or send-cookie no, depending on the specific noncompliance.
To determine which server clause to use, run the following commands to send queries to the authoritative servers for the broken domain:
dig soa <zone> @<server> +dnssec
dig soa <zone> @<server> +dnssec +nocookie
dig soa <zone> @<server> +noedns
If the first command fails but the second succeeds, the server most likely needs send-cookie no. If the first two fail but the third succeeds, then the server needs EDNS to be fully disabled with edns no.
Please contact the administrators of noncompliant domains and encourage them to upgrade their broken DNS servers. [GL #150]
Previously, it was possible to build BIND without thread support for old architectures and systems without threads support. BIND now requires threading support (either POSIX or Windows) from the operating system, and it cannot be built without threads.
filter-aaaa-on-v6 options have been removed
from named, and can no longer be
configured using native
However, loading the new
plugin and setting its parameters provides identical
named can no longer use the EDNS CLIENT-SUBNET option for view selection. In its existing form, the authoritative ECS feature was not fully RFC-compliant, and could not realistically have been deployed in production for an authoritative server; its only practical use was for testing and experimentation. In the interest of code simplification, this feature has now been removed.
The ECS option is still supported in dig and
mdig via the +subnet argument, and can be parsed
and logged when received by named, but
it is no longer used for ACL processing. The
geoip-use-ecs option is now obsolete;
a warning will be logged if it is used in
ecs tags in an ACL definition are
also obsolete, and will cause the configuration to fail to
load if they are used. [GL #32]
dnssec-keygen can no longer generate HMAC keys for TSIG authentication. Use tsig-keygen to generate these keys. [RT #46404]
Support for OpenSSL 0.9.x has been removed. OpenSSL version 1.0.0 or greater, or LibreSSL is now required.
The configure --enable-seccomp option, which formerly turned on system-call filtering on Linux, has been removed. [GL #93]
IPv4 addresses in forms other than dotted-quad are no longer accepted in master files. [GL #13] [GL #56]
IDNA2003 support via (bundled) idnkit-1.0 has been removed.
The "rbtdb64" database implementation (a parallel implementation of "rbt") has been removed. [GL #217]
The -r randomdev option to explicitly select random device has been removed from the ddns-confgen, rndc-confgen, nsupdate, dnssec-confgen, and dnssec-signzone commands.
The -p option to use pseudo-random data has been removed from the dnssec-signzone command.
Support for the RSAMD5 algorithm has been removed freom BIND as the usage of the RSAMD5 algorithm for DNSSEC has been deprecated in RFC6725, the security of the MD5 algorithm has been compromised, and its usage is considered harmful.
Support for the ECC-GOST (GOST R 34.11-94) algorithm has been removed from BIND, as the algorithm has been superseded by GOST R 34.11-2012 in RFC6986 and it must not be used in new deployments. BIND will neither create new DNSSEC keys, signatures and digests, nor it will validate them.
Support for DSA and DSA-NSEC3-SHA1 algorithms has been removed from BIND as the DSA key length is limited to 1024 bits and this is not considered secure enough.
named will no longer ignore "no-change" deltas when processing an IXFR stream. This had previously been permitted for compatibility with BIND 8, but now "no-change" deltas will trigger a fallback to AXFR as the recovery mechanism.
BIND 9 will no longer build on platforms that don't have proper IPv6 support. BIND 9 now also requires POSIX-compatible pthread support. Most of the platforms that lack these featuers are long past their end-of-lifew dates, and they are neither developed nor supported by their respective vendors.
The incomplete support for internationalization message catalogs has been removed from BIND. Since the internationalization was never completed, and no localized message catalogs were ever made available for the portions of BIND in which they could have been used, this change will have no effect except to simplify the source code. BIND's log messages and other output were already only available in English.
BIND will now always use the best CSPRNG (cryptographically-secure pseudo-random number generator) available on the platform where it is compiled. It will use the arc4random() family of functions on BSD operating systems, getrandom() on Linux and Solaris, CryptGenRandom on Windows, and the selected cryptography provider library (OpenSSL or PKCS#11) as the last resort. [GL #221]
The default setting for dnssec-validation is
auto, which activates DNSSEC
validation using the IANA root key. (The default can be changed
yes, which activates DNSSEC
validation only when keys are explicitly configured in
named.conf, by building BIND with
configure --disable-auto-validation.) [GL #30]
BIND can no longer be built without DNSSEC support. A cryptography provider (i.e., OpenSSL or a hardware service module with PKCS#11 support) must be available. [GL #244]
Zone types primary and
secondary are now available as synonyms for
master and slave,
named will now log a warning if the old root DNSSEC key is explicitly configured and has not been updated. [RT #43670]
dig +nssearch will now list name servers that have timed out, in addition to those that respond. [GL #64]
Up to 64 response-policy zones are now supported by default; previously the limit was 32. [GL #123]
Several configuration options for time periods can now use
TTL value suffixes (for example,
1d) in addition to an integer number of
seconds. These include
NSID logging (enabled by the request-nsid option) now has its own nsid category, instead of using the resolver category.
The rndc nta command could not differentiate between views of the same name but different class; this has been corrected with the addition of a -class option. [GL #105]
allow-recursion-on and allow-query-cache-on each now default to the other if only one of them is set, in order to be consistent with the way allow-recursion and allow-query-cache work. [GL #319]
When compiled with IDN support, the dig and nslookup commands now disable IDN processing when the standard output is not a TTY (i.e., when the output is not being read by a human). When running from a shell script, the command line options +idnin and +idnout may be used to enable IDN processing of input and output domain names, respectively. When running on a TTY, the +noidnin and +noidnout options may be used to disable IDN processing of input and output domain names.
The configuration option max-ncache-ttl cannot exceed seven days. Previously, larger values than this were silently lowered; now, they trigger a configuration error.
The new dig -r command line option
disables reading of the file
Zone signing and key maintenance events are now logged to the dnssec category rather than zone.
BIND is open source software licensed under the terms of the Mozilla
Public License, version 2.0 (see the
file for the full text).
The license requires that if you make changes to BIND and distribute them outside your organization, those changes must be published under the same license. It does not require that you publish or disclose anything other than the changes you have made to our software. This requirement does not affect anyone who is using BIND, with or without modifications, without redistributing it, nor anyone redistributing BIND without changes.
Those wishing to discuss license compliance may contact ISC at https://www.isc.org/mission/contact/.
BIND 9.16 has replaced 9.14 as the current stable version. This BIND release is the last one in the BIND 9.14 release train. For those needing long-term support, the current Extended Support Version (ESV) is BIND 9.11, which will be supported until at least December 2021. See https://kb.isc.org/docs/aa-00896 for details of ISC's software support policy.