Release Notes for BIND Version 9.16.2

Introduction

BIND 9.16 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.

Note on Version Numbering

As of BIND 9.13/9.14, BIND has adopted the "odd-unstable/even-stable"
release numbering convention. BIND 9.16 contains new features added during
the BIND 9.15 development process. Henceforth, the 9.16 branch will be
limited to bug fixes and new feature development will proceed in the
unstable 9.17 branch.

Supported Platforms

To build on UNIX-like systems, BIND 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.

The libuv asynchronous I/O library and the OpenSSL cryptography library
must be available for the target platform. A PKCS#11 provider can be used
instead of OpenSSL 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.

More information can be found in the PLATFORMS.md file that is included in
the source distribution of BIND 9. If your compiler and system libraries
provide the above features, BIND 9 should compile and run. If that isn't
the case, the BIND development team will generally accept patches that add
support for systems that are still supported by their respective vendors.

Download

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.

Notes for BIND 9.16.2

Security Fixes

  * DNS rebinding protection was ineffective when BIND 9 is configured as
    a forwarding DNS server. Found and responsibly reported by Tobias
    Klein. [GL #1574]

Known Issues

  * We have received reports that in some circumstances, receipt of an
    IXFR can cause the processing of queries to slow significantly. Some
    of these were related to RPZ processing, which has been fixed in this
    release (see below). Others appear to occur where there are
    NSEC3-related changes (such as an operator changing the NSEC3 salt
    used in the hash calculation). These are being investigated. [GL
    #1685]

Feature Changes

  * The previous DNSSEC sign statistics used lots of memory. The number of
    keys to track is reduced to four per zone, which should be enough for
    99% of all signed zones. [GL #1179]

Bug Fixes

  * When an RPZ policy zone was updated via zone transfer and a large
    number of records was deleted, named could become nonresponsive for a
    short period while deleted names were removed from the RPZ summary
    database. This database cleanup is now done incrementally over a
    longer period of time, reducing such delays. [GL #1447]

  * When trying to migrate an already-signed zone from auto-dnssec
    maintain to one based on dnssec-policy, the existing keys were
    immediately deleted and replaced with new ones. As the key rollover
    timing constraints were not being followed, it was possible that some
    clients would not have been able to validate responses until all old
    DNSSEC information had timed out from caches. BIND now looks at the
    time metadata of the existing keys and incorporates it into its DNSSEC
    policy operation. [GL #1706]

Notes for BIND 9.16.1

Known Issues

  * UDP network ports used for listening can no longer simultaneously be
    used for sending traffic. An example configuration which triggers this
    issue would be one which uses the same address:port pair for listen-on
    (-v6) statements as for notify-source(-v6) or transfer-source(-v6).
    While this issue affects all operating systems, it only triggers log
    messages (e.g. "unable to create dispatch for reserved port") on some
    of them. There are currently no plans to make such a combination of
    settings work again.

Feature Changes

  * The system-provided POSIX Threads read-write lock implementation is
    now used by default instead of the native BIND 9 implementation.
    Please be aware that glibc versions 2.26 through 2.29 had a bug that
    could cause BIND 9 to deadlock. A fix was released in glibc 2.30, and
    most current Linux distributions have patched or updated glibc, with
    the notable exception of Ubuntu 18.04 (Bionic) which is a work in
    progress. If you are running on an affected operating system, compile
    BIND 9 with --disable-pthread-rwlock until a fixed version of glibc is
    available. [GL !3125]

Bug Fixes

  * Fixed re-signing issues with inline zones which resulted in records
    being re-signed late or not at all.

Notes for BIND 9.16.0

Note: this section only lists changes from BIND 9.14 (the previous stable
branch of BIND).

New Features

  * A new asynchronous network communications system based on libuv is now
    used by named for listening for incoming requests and responding to
    them. This change will make it easier to improve performance and
    implement new protocol layers (for example, DNS over TLS) in the
    future. [GL #29]

  * The new dnssec-policy option allows the configuration of a key and
    signing policy (KASP) for zones. This option enables named to generate
    new keys as needed and automatically roll both ZSK and KSK keys. (Note
    that the syntax for this statement differs from the DNSSEC policy used
    by dnssec-keymgr.) [GL #1134]

  * In order to clarify the configuration of DNSSEC keys, the trusted-keys
    and managed-keys statements have been deprecated, and the new
    trust-anchors statement should now be used for both types of key.

    When used with the keyword initial-key, trust-anchors has the same
    behavior as managed-keys, i.e., it configures a trust anchor that is
    to be maintained via RFC 5011.

    When used with the new keyword static-key, trust-anchors has the same
    behavior as trusted-keys, i.e., it configures a permanent trust anchor
    that will not automatically be updated. (This usage is not recommended
    for the root key.) [GL #6]

  * Two new keywords have been added to the trust-anchors statement:
    initial-ds and static-ds. These allow the use of trust anchors in DS
    format instead of DNSKEY format. DS format allows trust anchors to be
    configured for keys that have not yet been published; this is the
    format used by IANA when announcing future root keys.

    As with the initial-key and static-key keywords, initial-ds configures
    a dynamic trust anchor to be maintained via RFC 5011, and static-ds
    configures a permanent trust anchor. [GL #6] [GL #622]

  * dig, mdig and delv can all now take a +yaml option to print output in
    a detailed YAML format. [GL #1145]

  * dig now has a new command line option: +[no]unexpected. By default,
    dig won't accept a reply from a source other than the one to which it
    sent the query. Add the +unexpected argument to enable it to process
    replies from unexpected sources. [RT #44978]

  * dig now accepts a new command line option, +[no]expandaaaa, which
    causes the IPv6 addresses in AAAA records to be printed in full
    128-bit notation rather than the default RFC 5952 format. [GL #765]

  * Statistics channel groups can now be toggled. [GL #1030]

Feature Changes

  * When static and managed DNSSEC keys were both configured for the same
    name, or when a static key was used to configure a trust anchor for
    the root zone and dnssec-validation was set to the default value of
    auto, automatic RFC 5011 key rollovers would be disabled. This
    combination of settings was never intended to work, but there was no
    check for it in the parser. This has been corrected, and it is now a
    fatal configuration error. [GL #868]

  * DS and CDS records are now generated with SHA-256 digests only,
    instead of both SHA-1 and SHA-256. This affects the default output of
    dnssec-dsfromkey, the dsset files generated by dnssec-signzone, the DS
    records added to a zone by dnssec-signzone based on keyset files, the
    CDS records added to a zone by named and dnssec-signzone based on
    "sync" timing parameters in key files, and the checks performed by
    dnssec-checkds. [GL #1015]

  * named will now log a warning if a static key is configured for the
    root zone. [GL #6]

  * A SipHash 2-4 based DNS Cookie (RFC 7873) algorithm has been added and
    made default. Old non-default HMAC-SHA based DNS Cookie algorithms
    have been removed, and only the default AES algorithm is being kept
    for legacy reasons. This change has no operational impact in most
    common scenarios. [GL #605]

    If you are running multiple DNS servers (different versions of BIND 9
    or DNS servers from multiple vendors) responding from the same IP
    address (anycast or load-balancing scenarios), make sure that all the
    servers are configured with the same DNS Cookie algorithm and same
    Server Secret for the best performance.

  * The information from the dnssec-signzone and dnssec-verify commands is
    now printed to standard output. The standard error output is only used
    to print warnings and errors, and in case the user requests the signed
    zone to be printed to standard output with the -f - option. A new
    configuration option -q has been added to silence all output on
    standard output except for the name of the signed zone. [GL #1151]

  * The DNSSEC validation code has been refactored for clarity and to
    reduce code duplication. [GL #622]

  * Compile-time settings enabled by the --with-tuning=large option for
    configure are now in effect by default. Previously used default
    compile-time settings can be enabled by passing --with-tuning=small to
    configure. [GL !2989]

  * JSON-C is now the only supported library for enabling JSON support for
    BIND statistics. The configure option has been renamed from
    --with-libjson to --with-json-c. Set the PKG_CONFIG_PATH environment
    variable accordingly to specify a custom path to the json-c library,
    as the new configure option does not take the library installation
    path as an optional argument. [GL #855]

  * ./configure no longer sets --sysconfdir to /etc or --localstatedir to
    /var when --prefix is not specified and the aforementioned options are
    not specified explicitly. Instead, Autoconf's defaults of $prefix/etc
    and $prefix/var are respected. [GL #658]

Removed Features

  * The dnssec-enable option has been obsoleted and no longer has any
    effect. DNSSEC responses are always enabled if signatures and other
    DNSSEC data are present. [GL #866]

  * DNSSEC Lookaside Validation (DLV) is now obsolete. The
    dnssec-lookaside option has been marked as deprecated; when used in
    named.conf, it will generate a warning but will otherwise be ignored.
    All code enabling the use of lookaside validation has been removed
    from the validator, delv, and the DNSSEC tools. [GL #7]

  * The cleaning-interval option has been removed. [GL !1731]

License

BIND 9 is open source software licensed under the terms of the Mozilla
Public License, version 2.0 (see the LICENSE 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/contact/.

End of Life

The end of life date for BIND 9.16 has not yet been determined. At some
point in the future BIND 9.16 will be designated as an Extended Support
Version (ESV). Until then, the current 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.

Thank You

Thank you to everyone who assisted us in making this release possible.
