# BIND 9 ### Contents 1. [Introduction](#intro) 1. [Reporting bugs and getting help](#help) 1. [Contributing to BIND](#contrib) 1. [BIND 9.11 features](#features) 1. [Building BIND](#build) 1. [macOS](#macos) 1. [Compile-time options](#opts) 1. [Automated testing](#testing) 1. [Documentation](#doc) 1. [Change log](#changes) 1. [Acknowledgments](#ack) ### Introduction BIND (Berkeley Internet Name Domain) is a complete, highly portable implementation of the DNS (Domain Name System) protocol. The BIND name server, `named`, is able to serve as an authoritative name server, recursive resolver, DNS forwarder, or all three simultaneously. It implements views for split-horizon DNS, automatic DNSSEC zone signing and key management, catalog zones to facilitate provisioning of zone data throughout a name server constellation, response policy zones (RPZ) to protect clients from malicious data, response rate limiting (RRL) and recursive query limits to reduce distributed denial of service attacks, and many other advanced DNS features. BIND also includes a suite of administrative tools, including the `dig` and `delv` DNS lookup tools, `nsupdate` for dynamic DNS zone updates, `rndc` for remote name server administration, and more. BIND 9 is a complete re-write of the BIND architecture that was used in versions 4 and 8. Internet Systems Consortium ([https://www.isc.org](https://www.isc.org)), a 501(c)(3) public benefit corporation dedicated to providing software and services in support of the Internet infrastructure, developed BIND 9 and is responsible for its ongoing maintenance and improvement. BIND is open source software licenced under the terms of ISC License for all versions up to and including BIND 9.10, and the Mozilla Public License version 2.0 for all subsequent verisons. For a summary of features introduced in past major releases of BIND, see the file [HISTORY](HISTORY.md). For a detailed list of changes made throughout the history of BIND 9, see the file [CHANGES](CHANGES). See [below](#changes) for details on the CHANGES file format. For up-to-date release notes and errata, see [http://www.isc.org/software/bind9/releasenotes](http://www.isc.org/software/bind9/releasenotes) ### Reporting bugs and getting help To report non-security-sensitive bugs or request new features, you may open an Issue in the BIND 9 project on the [ISC GitLab server](https://gitlab.isc.org) at [https://gitlab.isc.org/isc-projects/bind9](https://gitlab.isc.org/isc-projects/bind9). Please note that, unless you explicitly mark the newly created Issue as "confidential", it will be publicly readable. Please do not include any information in bug reports that you consider to be confidential unless the issue has been marked as such. In particular, if submitting the contents of your configuration file in a non-confidential Issue, it is advisable to obscure key secrets: this can be done automatically by using `named-checkconf -px`. If the bug you are reporting is a potential security issue, such as an assertion failure or other crash in `named`, please do *NOT* use GitLab to report it. Instead, please send mail to [security-officer@isc.org](mailto:security-officer@isc.org). Professional support and training for BIND are available from ISC at [https://www.isc.org/support](https://www.isc.org/support). To join the __BIND Users__ mailing list, or view the archives, visit [https://lists.isc.org/mailman/listinfo/bind-users](https://lists.isc.org/mailman/listinfo/bind-users). If you're planning on making changes to the BIND 9 source code, you may also want to join the __BIND Workers__ mailing list, at [https://lists.isc.org/mailman/listinfo/bind-workers](https://lists.isc.org/mailman/listinfo/bind-workers). ### Contributing to BIND ISC maintains a public git repository for BIND; details can be found at [http://www.isc.org/git/](http://www.isc.org/git/). Information for BIND contributors can be found in the following files: - General information: [doc/dev/contrib.md](doc/dev/contrib.md) - BIND 9 code style: [doc/dev/style.md](doc/dev/style.md) - BIND architecture and developer guide: [doc/dev/dev.md](doc/dev/dev.md) Patches for BIND may be submitted as [Merge Requests](https://gitlab.isc.org/isc-projects/bind9/merge_requests) in the [ISC GitLab server](https://gitlab.isc.org) at at [https://gitlab.isc.org/isc-projects/bind9/merge_requests](https://gitlab.isc.org/isc-projects/bind9/merge_requests). By default, external contributors don't have ability to fork BIND in the GitLab server, but if you wish to contribute code to BIND, you may request permission to do so. Thereafter, you can create git branches and directly submit requests that they be reviewed and merged. If you prefer, you may also submit code by opening a [GitLab Issue](https://gitlab.isc.org/isc-projects/bind9/issues) and including your patch as an attachment, preferably generated by `git format-patch`. ### BIND 9.11 features BIND 9.11.0 includes a number of changes from BIND 9.10 and earlier releases. New features include: * Added support for Catalog Zones, a new method for provisioning servers: a list of zones to be served is stored in a DNS zone, along with their configuration parameters. Changes to the catalog zone are propagated to slaves via normal AXFR/IXFR, whereupon the zones that are listed in it are automatically added, deleted or reconfigured. * Added support for "dnstap", a fast and flexible method of capturing and logging DNS traffic. * Added support for "dyndb", a new API for loading zone data from an external database, developed by Red Hat for the FreeIPA project. * "fetchlimit" quotas are now compiled in by default. These are for the use of recursive resolvers that are are under high query load for domains whose authoritative servers are nonresponsive or are experiencing a denial of service attack: * `fetches-per-server` limits the number of simultaneous queries that can be sent to any single authoritative server. The configured value is a starting point; it is automatically adjusted downward if the server is partially or completely non-responsive. The algorithm used to adjust the quota can be configured via the "fetch-quota-params" option. * `fetches-per-zone` limits the number of simultaneous queries that can be sent for names within a single domain. (Note: Unlike `fetches-per-server`, this value is not self-tuning.) * New stats counters have been added to count queries spilled due to these quotas. * Added a new `dnssec-keymgr` key mainenance utility, which can generate or update keys as needed to ensure that a zone's keys match a defined DNSSEC policy. * The experimental "SIT" feature in BIND 9.10 has been renamed "COOKIE" and is no longer optional. EDNS COOKIE is a mechanism enabling clients to detect off-path spoofed responses, and servers to detect spoofed-source queries. Clients that identify themselves using COOKIE options are not subject to response rate limiting (RRL) and can receive larger UDP responses. * SERVFAIL responses can now be cached for a limited time (defaulting to 1 second, with an upper limit of 30). This can reduce the frequency of retries when a query is persistently failing. * Added an `nsip-wait-recurse` switch to RPZ. This causes NSIP rules to be skipped if a name server IP address isn't in the cache yet; the address will be looked up and the rule will be applied on future queries. * Added a Python RNDC module. This allows multiple commands to sent over a persistent RNDC channel, which saves time. * The `controls` block in named.conf can now grant read-only `rndc` access to specified clients or keys. Read-only clients could, for example, check `rndc status` but could not reconfigure or shut down the server. * `rndc` commands can now return arbitrarily large amounts of text to the caller. * The zone serial number of a dynamically updatable zone can now be set via `rndc signing -serial `. This allows inline-signing zones to be set to a specific serial number. * The new `rndc nta` command can be used to set a Negative Trust Anchor (NTA), disabling DNSSEC validation for a specific domain; this can be used when responses from a domain are known to be failing validation due to administrative error rather than because of a spoofing attack. Negative trust anchors are strictly temporary; by default they expire after one hour, but can be configured to last up to one week. * `rndc delzone` can now be used on zones that were not originally created by "rndc addzone". * `rndc modzone` reconfigures a single zone, without requiring the entire server to be reconfigured. * `rndc showzone` displays the current configuration of a zone. * `rndc managed-keys` can be used to check the status of RFC 5001 managed trust anchors, or to force trust anchors to be refreshed. * `max-cache-size` can now be set to a percentage of available memory. The default is 90%. * Update forwarding performance has been improved by allowing a single TCP connection to be shared by multiple updates. * The EDNS Client Subnet (ECS) option is now supported for authoritative servers; if a query contains an ECS option then ACLs containing `geoip` or `ecs` elements can match against the the address encoded in the option. This can be used to select a view for a query, so that different answers can be provided depending on the client network. * The EDNS EXPIRE option has been implemented on the client side, allowing a slave server to set the expiration timer correctly when transferring zone data from another slave server. * The key generation and manipulation tools (`dnssec-keygen`, `dnssec-settime`, `dnssec-importkey`, `dnssec-keyfromlabel`) now take `-Psync` and `-Dsync` options to set the publication and deletion times of CDS and CDNSKEY parent-synchronization records. Both `named` and `dnssec-signzone` can now publish and remove these records at the scheduled times. * A new `minimal-any` option reduces the size of UDP responses for query type ANY by returning a single arbitrarily selected RRset instead of all RRsets. * A new `masterfile-style` zone option controls the formatting of text zone files: When set to `full`, a zone file is dumped in single-line-per-record format. * `serial-update-method` can now be set to `date`. On update, the serial number will be set to the current date in YYYYMMDDNN format. * `dnssec-signzone -N date` sets the serial number to YYYYMMDDNN. * `named -L ` causes named to send log messages to the specified file by default instead of to the system log. * `dig +ttlunits` prints TTL values with time-unit suffixes: w, d, h, m, s for weeks, days, hours, minutes, and seconds. * `dig +unknownformat` prints dig output in RFC 3597 "unknown record" presentation format. * `dig +ednsopt` allows dig to set arbitrary EDNS options on requests. * `dig +ednsflags` allows dig to set yet-to-be-defined EDNS flags on requests. * `mdig` is an alternate version of dig which sends multiple pipelined TCP queries to a server. Instead of waiting for a response after sending a query, it sends all queries immediately and displays responses in the order received. * `serial-query-rate` no longer controls NOTIFY messages. These are separately controlled by `notify-rate` and `startup-notify-rate`. * `nsupdate` now performs `check-names` processing by default on records to be added. This can be disabled with `check-names no`. * The statistics channel now supports DEFLATE compression, reducing the size of the data sent over the network when querying statistics. * New counters have been added to the statistics channel to track the sizes of incoming queries and outgoing responses in histogram buckets, as specified in RSSAC002. * A new NXDOMAIN redirect method (option `nxdomain-redirect`) has been added, allowing redirection to a specified DNS namespace instead of a single redirect zone. * When starting up, named now ensures that no other named process is already running. * Files created by named to store information, including `mkeys` and `nzf` files, are now named after their corresponding views unless the view name contains characters incompatible with use as a filename. Old style filenames (based on the hash of the view name) will still work. #### BIND 9.11.1 BIND 9.11.1 is a maintenance release, and addresses the security flaws disclosed in CVE-2016-6170, CVE-2016-8864, CVE-2016-9131, CVE-2016-9147, CVE-2016-9444, CVE-2016-9778, CVE-2017-3135, CVE-2017-3136, CVE-2017-3137 and CVE-2017-3138. #### BIND 9.11.2 BIND 9.11.2 is a maintenance release, and addresses the security flaws disclosed in CVE-2017-3140, CVE-2017-3141, CVE-2017-3142 and CVE-2017-3143. It also addresses several bugs related to the use of an LMDB database to store data related to zones added via `rndc addzone` or catalog zones. #### BIND 9.11.3 BIND 9.11.3 is a maintenance release, and addresses the security flaw disclosed in CVE-2017-3145. #### BIND 9.11.4 BIND 9.11.4 is a maintenance release, and addresses the security flaw disclosed in CVE-2018-5738. #### BIND 9.11.5 BIND 9.11.5 is a maintenance release, and also addresses CVE-2018-5741 by correcting faulty documentation and introducing the following new feature: * New `krb5-selfsub` and `ms-selfsub` rule types for `update-policy` statements allow updating of subdomains based on a Kerberos or Active Directory machine principal. #### BIND 9.11.5-P1 BIND 9.11.5-P1 addresses a potentially serious flaw which could cause faulty NSEC3 chains to be regenerated after a change to the DNSSEC signing key of a zone. #### BIND 9.11.5-P2, 9.11.5-P3 These were both withdrawn prior to release. #### BIND 9.11.5-P4 BIND 9.11.5-P4 addresses the security flaws disclosed in CVE-2018-5744, CVE-2018-5745 and CVE-2019-6465. ### Building BIND BIND requires a UNIX or Linux system with an ANSI C compiler, basic POSIX support, and a 64-bit integer type. Successful builds have been observed on many versions of Linux and UNIX, including RedHat, Fedora, Debian, Ubuntu, SuSE, Slackware, FreeBSD, NetBSD, OpenBSD, Mac OS X, Solaris, HP-UX, AIX, SCO OpenServer, and OpenWRT. BIND is also available for Windows XP, 2003, 2008, and higher. See `win32utils/readme1st.txt` for details on building for Windows systems. To build on a UNIX or Linux system, use: $ ./configure $ make If you're planning on making changes to the BIND 9 source, you should run `make depend`. If you're using Emacs, you might find `make tags` helpful. Several environment variables that can be set before running `configure` will affect compilation: |Variable|Description | |--------------------|-----------------------------------------------| |`CC`|The C compiler to use. `configure` tries to figure out the right one for supported systems.| |`CFLAGS`|C compiler flags. Defaults to include -g and/or -O2 as supported by the compiler. Please include '-g' if you need to set `CFLAGS`. | |`STD_CINCLUDES`|System header file directories. Can be used to specify where add-on thread or IPv6 support is, for example. Defaults to empty string.| |`STD_CDEFINES`|Any additional preprocessor symbols you want defined. Defaults to empty string. For a list of possible settings, see the file [OPTIONS](OPTIONS.md).| |`LDFLAGS`|Linker flags. Defaults to empty string.| |`BUILD_CC`|Needed when cross-compiling: the native C compiler to use when building for the target system.| |`BUILD_CFLAGS`|Optional, used for cross-compiling| |`BUILD_CPPFLAGS`|| |`BUILD_LDFLAGS`|| |`BUILD_LIBS`|| #### macOS Building on macOS assumes that the "Command Tools for Xcode" is installed. This can be downloaded from https://developer.apple.com/download/more/ or if you have Xcode already installed you can run "xcode-select --install". This will add /usr/include to the system and install the compiler and other tools so that they can be easily found. #### Compile-time options To see a full list of configuration options, run `configure --help`. On most platforms, BIND 9 is built with multithreading support, allowing it to take advantage of multiple CPUs. You can configure this by specifying `--enable-threads` or `--disable-threads` on the `configure` command line. The default is to enable threads, except on some older operating systems on which threads are known to have had problems in the past. (Note: Prior to BIND 9.10, the default was to disable threads on Linux systems; this has now been reversed. On Linux systems, the threaded build is known to change BIND's behavior with respect to file permissions; it may be necessary to specify a user with the -u option when running `named`.) To build shared libraries, specify `--with-libtool` on the `configure` command line. Certain compiled-in constants and default settings can be increased to values better suited to large servers with abundant memory resources (e.g, 64-bit servers with 12G or more of memory) by specifying `--with-tuning=large` on the `configure` command line. This can improve performance on big servers, but will consume more memory and may degrade performance on smaller systems. For the server to support DNSSEC, you need to build it with crypto support. To use OpenSSL, you should have OpenSSL 1.0.2e or newer installed. If the OpenSSL library is installed in a nonstandard location, specify the prefix using "--with-openssl=<PREFIX>" on the configure command line. To use a PKCS#11 hardware service module for cryptographic operations, specify the path to the PKCS#11 provider library using "--with-pkcs11=<PREFIX>", and configure BIND with "--enable-native-pkcs11". To support the HTTP statistics channel, the server must be linked with at least one of the following: libxml2 [http://xmlsoft.org](http://xmlsoft.org) or json-c [https://github.com/json-c](https://github.com/json-c). If these are installed at a nonstandard location, specify the prefix using `--with-libxml2=/prefix` or `--with-libjson=/prefix`. To support compression on the HTTP statistics channel, the server must be linked against libzlib. If this is installed in a nonstandard location, specify the prefix using `--with-zlib=/prefix`. To support storing configuration data for runtime-added zones in an LMDB database, the server must be linked with liblmdb. If this is installed in a nonstandard location, specify the prefix using "with-lmdb=/prefix". To support GeoIP location-based ACLs, the server must be linked with libGeoIP. This is not turned on by default; BIND must be configured with "--with-geoip". If the library is installed in a nonstandard location, use specify the prefix using "--with-geoip=/prefix". For DNSTAP packet logging, you must have installed libfstrm [https://github.com/farsightsec/fstrm](https://github.com/farsightsec/fstrm) and libprotobuf-c [https://developers.google.com/protocol-buffers](https://developers.google.com/protocol-buffers), and BIND must be configured with "--enable-dnstap". Portions of BIND that are written in Python, including `dnssec-keymgr`, `dnssec-coverage`, `dnssec-checkds`, and some of the system tests, require the 'argparse' and 'ply' modules to be available. 'argparse' is a standard module as of Python 2.7 and Python 3.2. 'ply' is available from [https://pypi.python.org/pypi/ply](https://pypi.python.org/pypi/ply). On some platforms it is necessary to explicitly request large file support to handle files bigger than 2GB. This can be done by using `--enable-largefile` on the `configure` command line. Support for the "fixed" rrset-order option can be enabled or disabled by specifying `--enable-fixed-rrset` or `--disable-fixed-rrset` on the configure command line. By default, fixed rrset-order is disabled to reduce memory footprint. If your operating system has integrated support for IPv6, it will be used automatically. If you have installed KAME IPv6 separately, use `--with-kame[=PATH]` to specify its location. `make install` will install `named` and the various BIND 9 libraries. By default, installation is into /usr/local, but this can be changed with the `--prefix` option when running `configure`. You may specify the option `--sysconfdir` to set the directory where configuration files like `named.conf` go by default, and `--localstatedir` to set the default parent directory of `run/named.pid`. For backwards compatibility with BIND 8, `--sysconfdir` defaults to `/etc` and `--localstatedir` defaults to `/var` if no `--prefix` option is given. If there is a `--prefix` option, sysconfdir defaults to `$prefix/etc` and localstatedir defaults to `$prefix/var`. ### Automated testing A system test suite can be run with `make test`. The system tests require you to configure a set of virtual IP addresses on your system (this allows multiple servers to run locally and communicate with one another). These IP addresses can be configured by running the command `bin/tests/system/ifconfig.sh up` as root. Some tests require Perl and the Net::DNS and/or IO::Socket::INET6 modules, and will be skipped if these are not available. Some tests require Python and the 'dnspython' module and will be skipped if these are not available. See bin/tests/system/README for further details. Unit tests are implemented using Automated Testing Framework (ATF). To run them, use `configure --with-atf`, then run `make test` or `make unit`. ### Documentation The *BIND 9 Administrator Reference Manual* is included with the source distribution, in DocBook XML, HTML and PDF format, in the `doc/arm` directory. Some of the programs in the BIND 9 distribution have man pages in their directories. In particular, the command line options of `named` are documented in `bin/named/named.8`. Frequently (and not-so-frequently) asked questions and their answers can be found in the ISC Knowledge Base at [https://kb.isc.org](https://kb.isc.org). Additional information on various subjects can be found in other `README` files throughout the source tree. ### Change log A detailed list of all changes that have been made throughout the development BIND 9 is included in the file CHANGES, with the most recent changes listed first. Change notes include tags indicating the category of the change that was made; these categories are: |Category |Description | |-------------- |-----------------------------------------------| | [func] | New feature | | [bug] | General bug fix | | [security] | Fix for a significant security flaw | | [experimental] | Used for new features when the syntax or other aspects of the design are still in flux and may change | | [port] | Portability enhancement | | [maint] | Updates to built-in data such as root server addresses and keys | | [tuning] | Changes to built-in configuration defaults and constants to improve performance | | [performance] | Other changes to improve server performance | | [protocol] | Updates to the DNS protocol such as new RR types | | [test] | Changes to the automatic tests, not affecting server functionality | | [cleanup] | Minor corrections and refactoring | | [doc] | Documentation | | [contrib] | Changes to the contributed tools and libraries in the 'contrib' subdirectory | | [placeholder] | Used in the master development branch to reserve change numbers for use in other branches, e.g. when fixing a bug that only exists in older releases | In general, [func] and [experimental] tags will only appear in new-feature releases (i.e., those with version numbers ending in zero). Some new functionality may be backported to older releases on a case-by-case basis. All other change types may be applied to all currently-supported releases. ### Acknowledgments * The original development of BIND 9 was underwritten by the following organizations: Sun Microsystems, Inc. Hewlett Packard Compaq Computer Corporation IBM Process Software Corporation Silicon Graphics, Inc. Network Associates, Inc. U.S. Defense Information Systems Agency USENIX Association Stichting NLnet - NLnet Foundation Nominum, Inc. * This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. [http://www.OpenSSL.org/](http://www.OpenSSL.org/) * This product includes cryptographic software written by Eric Young (eay@cryptsoft.com) * This product includes software written by Tim Hudson (tjh@cryptsoft.com)