# 10. Building BIND 9

To build on a Unix or Linux system, use:

    $ autoreconf -fi ### (only if building from the git repository)
    $ ./configure
    $ make

Several environment variables affect compilation, and they can be set before running `configure`. The most significant ones are:

Variable | Description
--- | ---
`CC` | The C compiler to use. `configure` tries to figure out the right one for supported systems.
`CFLAGS` | The C compiler flags. Defaults to include -g and/or -O2 as supported by the compiler. Please include `-g` if `CFLAGS` needs to be set.
`LDFLAGS` | The linker flags. Defaults to an empty string.

Additional environment variables affecting the build are listed at the end of the `configure` help text, which can be obtained by running the command:

    $ ./configure --help

If using Emacs, the `make tags` command may be helpful.

## 10.1. Required Libraries

To build BIND 9, the following packages must be installed:

- `libcrypto`, `libssl`

- `libuv`

- `perl`

- `pkg-config` / `pkgconfig` / `pkgconf`

BIND 9.18 requires `libuv` 1.0.0 or higher; using `libuv` >= 1.40.0 is recommended. Compiling or running with `libuv` 1.35.0 or 1.36.0 is not supported, as this could lead to an assertion failure in the UDP receive code. On older systems an updated `libuv` package needs to be installed from sources, such as EPEL, PPA, or other native sources. The other option is to build and install `libuv` from source.

OpenSSL 1.0.2e or newer is required. 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, `engine_pkcs11` from the OpenSC project must be compiled and used.

To build BIND from the git repository, the following tools must also be installed:

- `autoconf` (includes `autoreconf`)

- `automake`

- `libtool`

## 10.2. Optional Features

To see a full list of configuration options, run `configure --help`.

To improve performance, use of the `jemalloc` library (http://jemalloc.net/) is strongly recommended.

To support DNS over HTTPS (DoH), the server must be linked with `libnghttp2` (https://nghttp2.org/). If the library is unavailable, `--disable-doh` can be used to disable DoH support.

To support the HTTP statistics channel, the server must be linked with at least one of the following libraries: `libxml2` (https://gitlab.gnome.org/GNOME/libxml2/-/wikis/home) or `json-c` (https://github.com/json-c/json-c). If these are installed at a nonstandard location, then:

- for `libxml2`, specify the prefix using `--with-libxml2=/prefix`,

- for `json-c`, adjust `PKG_CONFIG_PATH`.

To support compression on the HTTP statistics channel, the server must be linked against `zlib` (https://zlib.net/). 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` (https://github.com/LMDB/lmdb). If this is installed in a nonstandard location, specify the prefix using `--with-lmdb=/prefix`.

To support MaxMind GeoIP2 location-based ACLs, the server must be linked with `libmaxminddb` (https://maxmind.github.io/libmaxminddb/). This is turned on by default if the library is found; if the library is installed in a nonstandard location, specify the prefix using `--with-maxminddb=/prefix`. GeoIP2 support can be switched off with `--disable-geoip`.

For DNSTAP packet logging, `libfstrm` (https://github.com/farsightsec/fstrm) and `libprotobuf-c` (https://protobuf.dev) must be installed, and BIND must be configured with `--enable-dnstap`.

To support internationalized domain names in `dig`, `libidn2` (https://www.gnu.org/software/libidn/#libidn2) must be installed. If the library is installed in a nonstandard location, specify the prefix using `--with-libidn2=/prefix` or adjust `PKG_CONFIG_PATH`.

For line editing in `nsupdate` and `nslookup`, either the `readline` (https://tiswww.case.edu/php/chet/readline/rltop.html) or the `libedit` library (https://www.thrysoee.dk/editline/) must be installed. If these are installed at a nonstandard location, adjust `PKG_CONFIG_PATH`. `readline` is used by default, and `libedit` can be explicitly requested using `--with-readline=libedit`.

Certain compiled-in constants and default settings can be decreased to values better suited to small machines, e.g. OpenWRT boxes, by specifying `--with-tuning=small` on the `configure` command line. This decreases memory usage by using smaller structures, but degrades performance.

On Linux, process capabilities are managed in user space using the `libcap` library (https://git.kernel.org/pub/scm/libs/libcap/libcap.git/), which can be installed on most Linux systems via the `libcap-dev` or `libcap-devel` package. Process capability support can also be disabled by configuring with `--disable-linux-caps`.

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.

The `--enable-querytrace` option causes `named` to log every step while processing every query. The `--enable-singletrace` option turns on the same verbose tracing, but allows an individual query to be separately traced by setting its query ID to 0. These options should only be enabled when debugging, because they have a significant negative impact on query performance.

`make install` installs `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`.

The option `--sysconfdir` can be specified to set the directory where configuration files such as `named.conf` go by default; `--localstatedir` can be used to set the default parent directory of `run/named.pid`. `--sysconfdir` defaults to `$prefix/etc` and `--localstatedir` defaults to `$prefix/var`.

## 10.3. macOS

Building on macOS assumes that the “Command Tools for Xcode” are installed. These can be downloaded from https://developer.apple.com/xcode/resources/ or, if Xcode is already installed, simply run `xcode-select --install`. (Note that an Apple ID may be required to access the download page.)