# BIND 10 Guide

Administrator Reference for BIND 10
2010-2012
Internet Systems Consortium, Inc.

BIND 10 is a framework that features Domain Name System (DNS) suite and Dynamic Host Configuration Protocol (DHCP) servers with development managed by Internet Systems Consortium (ISC). It includes DNS libraries, modular components for controlling authoritative and recursive DNS servers, and experimental DHCPv4 and DHCPv6 servers.

This is the reference guide for BIND 10 version &__VERSION__;. The most up-to-date version of this document (in PDF, HTML, and plain text formats), along with other documents for BIND 10, can be found at .

This is the reference guide for BIND 10 version &__VERSION__;.

## Preface

### Acknowledgements

ISC would like to acknowledge generous support for BIND 10 development of DHCPv4 and DHCPv6 components provided by Comcast.

## Introduction

BIND is the popular implementation of a DNS server, developer interfaces, and DNS tools. BIND 10 is a rewrite of BIND 9 and ISC DHCP. BIND 10 is written in C++ and Python and provides a modular environment for serving, maintaining, and developing DNS and DHCP. BIND 10 provides a EDNS0- and DNSSEC-capable authoritative DNS server and a caching recursive name server which also provides forwarding. It also provides experimental DHCPv4 and DHCPv6 servers.

This guide covers BIND 10 version &__VERSION__;.

### Supported Platforms

BIND 10 builds have been tested on (in no particular order) Debian GNU/Linux 6 and unstable, Ubuntu 9.10, NetBSD 5, Solaris 10 and 11, FreeBSD 7 and 8, CentOS Linux 5.3, MacOS 10.6 and 10.7, and OpenBSD 5.1.

It has been tested on Sparc, i386, and amd64 hardware platforms.

It is planned for BIND 10 to build, install and run on Windows and standard Unix-type platforms.

### Required Software at Run-time

Running BIND 10 uses various extra software which may not be provided in some operating systems' default installations nor standard packages collections. You may need to install this required software separately. (For the build requirements, also see .)

BIND 10 requires at least Python 3.1 (). It also works with Python 3.2.

BIND 10 uses the Botan crypto library for C++ (). It requires at least Botan version 1.8.

BIND 10 uses the log4cplus C++ logging library (). It requires at least log4cplus version 1.0.3.

The authoritative DNS server uses SQLite3 (). It needs at least SQLite version 3.3.9.

The `b10-ddns`, `b10-xfrin`, `b10-xfrout`, and `b10-zonemgr` components require the libpython3 library and the Python _sqlite3.so module (which is included with Python). Python modules need to be built for the corresponding Python 3.

### Starting and Stopping the Server

BIND 10 is modular. Part of this modularity is accomplished using multiple cooperating processes which, together, provide the server functionality. This is a change from the previous generation of BIND software, which used a single process.

At first, running many different processes may seem confusing. However, these processes are started, stopped, and maintained by a single command, `bind10`. This command starts a master process which will start other required processes and other processes when configured. The processes that may be started by the `bind10` command have names starting with "b10-", including:

- `b10-auth` &mdash; Authoritative DNS server. This process serves DNS requests.

- `b10-cfgmgr` &mdash; Configuration manager. This process maintains all of the configuration for BIND 10.

- `b10-cmdctl` &mdash; Command and control service. This process allows external control of the BIND 10 system.

- `b10-ddns` &mdash; Dynamic DNS update service. This process is used to handle incoming DNS update requests to allow granted clients to update zones for which BIND 10 is serving as a primary server.

- `b10-msgq` &mdash; Message bus daemon. This process coordinates communication between all of the other BIND 10 processes.

- `b10-resolver` &mdash; Recursive name server. This process handles incoming DNS queries and provides answers from its cache or by recursively doing remote lookups.

- `b10-sockcreator` &mdash; Socket creator daemon. This process creates sockets used by network-listening BIND 10 processes.

- `b10-stats` &mdash; Statistics collection daemon. This process collects and reports statistics data.

- `b10-stats-httpd` &mdash; HTTP server for statistics reporting. This process reports statistics data in XML format over HTTP.

- `b10-xfrin` &mdash; Incoming zone transfer service. This process is used to transfer a new copy of a zone into BIND 10, when acting as a secondary server.

- `b10-xfrout` &mdash; Outgoing zone transfer service. This process is used to handle transfer requests to send a local zone to a remote secondary server.

- `b10-zonemgr` &mdash; Secondary zone manager. This process keeps track of timers and other necessary information for BIND 10 to act as a slave server.

These do not need to be manually started independently.

### Managing BIND 10

Once BIND 10 is running, a few commands are used to interact directly with the system:

- `bindctl` &mdash; Interactive administration interface. This is a low-level command-line tool which allows a developer or an experienced administrator to control BIND 10.

- `b10-loadzone` &mdash; Zone file loader. This tool will load standard masterfile-format zone files into BIND 10.

- `b10-cmdctl-usermgr` &mdash; User access control. This tool allows an administrator to authorize additional users to manage BIND 10.

The tools and modules are covered in full detail in this guide. In addition, manual pages are also provided in the default installation.

BIND 10 also provides libraries and programmer interfaces for C++ and Python for the message bus, configuration backend, and, of course, DNS. These include detailed developer documentation and code examples.

## Quick start

This quickly covers the standard steps for installing and deploying BIND 10. For further details, full customizations, and troubleshooting, see the respective chapters in the BIND 10 guide.

### Quick start guide for authoritative DNS service

1. Install required run-time and build dependencies.

2. Download the BIND 10 source tar file from .

3. Extract the tar file:

       $ gzcat bind10-VERSION.tar.gz | tar -xvf -

4. Go into the source and run configure:

       $ cd bind10-VERSION
         $ ./configure

5. Build it:

       $ make

6. Install it as root (to default /usr/local):

       $ make install

7. Start the server (as root):

       $ /usr/local/sbin/bind10

8. DNS and DHCP components are not started in the default configuration. In another console, enable the authoritative DNS service (by using the `bindctl` utility to configure the `b10-auth` component to run):

       $ bindctl

   (Login with the provided default username and password.)

       > config add Boss/components b10-auth
       > config set Boss/components/b10-auth/special auth
       > config set Boss/components/b10-auth/kind needed
       > config commit
       > quit

9. Test it; for example:

       $ dig @127.0.0.1 -c CH -t TXT version.bind

10. Load desired zone file(s), for example:

        $ b10-loadzone your.zone.example.org

11. Test the new zone.

## Installation

### Packages

Some operating systems or software package vendors may provide ready-to-use, pre-built software packages for the BIND 10 suite. Installing a pre-built package means you do not need to install build-only prerequisites and do not need to make the software.

FreeBSD ports, NetBSD pkgsrc, and Debian testing package collections provide all the prerequisite packages.

### Install Hierarchy

The following is the standard, common layout of the complete BIND 10 installation:

- `bin/` &mdash; general tools and diagnostic clients.

- `etc/bind10-devel/` &mdash; configuration files.

- `lib/` &mdash; libraries and python modules.

- `libexec/bind10-devel/` &mdash; executables that a user wouldn't normally run directly and are not run independently. These are the BIND 10 modules which are daemons started by the `bind10` tool.

- `sbin/` &mdash; commands used by the system administrator.

- `share/bind10-devel/` &mdash; configuration specifications.

- `share/doc/bind10-devel/` &mdash; this guide and other supplementary documentation.

- `share/man/` &mdash; manual pages (online documentation).

- `var/bind10-devel/` &mdash; data source and configuration databases.

### Building Requirements

In addition to the run-time requirements (listed in ), building BIND 10 from source code requires various development include headers and program development tools.

Some operating systems have split their distribution packages into a run-time and a development package. You will need to install the development package versions, which include header files and libraries, to build BIND 10 from source code.

Building from source code requires the Boost build-time headers (). At least Boost version 1.35 is required.

To build BIND 10, also install the Botan (at least version 1.8) and the log4cplus (at least version 1.0.3) development include headers.

Building BIND 10 also requires a C++ compiler and standard development headers, make, and pkg-config. BIND 10 builds have been tested with GCC g++ 3.4.3, 4.1.2, 4.1.3, 4.2.1, 4.3.2, and 4.4.1; Clang++ 2.8; and Sun C++ 5.10.

Visit the user-contributed wiki at for system-specific installation tips.

### Installation from source

BIND 10 is open source software written in C++ and Python. It is freely available in source code form from ISC as a downloadable tar file or via BIND 10's Git code revision control service. (It may also be available in pre-compiled ready-to-use packages from operating system vendors.)

#### Download Tar File

Downloading a release tar file is the recommended method to obtain the source code.

The BIND 10 releases are available as tar file downloads from . Periodic development snapshots may also be available.

#### Retrieve from Git

Downloading this "bleeding edge" code is recommended only for developers or advanced users. Using development code in a production environment is not recommended.

When using source code retrieved via Git, additional software will be required: automake (v1.11 or newer), libtoolize, and autoconf (2.59 or newer). These may need to be installed.

The latest development code (and temporary experiments and un-reviewed code) is available via the BIND 10 code revision control system. This is powered by Git and all the BIND 10 development is public. The leading development is done in the master branch.

The code can be checked out from `git://git.bind10.isc.org/bind10`; for example:

    $ git clone git://git.bind10.isc.org/bind10

When checking out the code from the code version control system, it doesn't include the generated configure script, Makefile.in files, nor their related build files. They can be created by running `autoreconf` with the `--install` switch. This will run `autoconf`, `aclocal`, `libtoolize`, `autoheader`, `automake`, and related commands.

#### Configure before the build

BIND 10 uses the GNU Build System to discover build environment details. To generate the makefiles using the defaults, simply run:

    $ ./configure

Run `./configure` with the `--help` switch to view the different options. Some commonly-used options are:

--prefix

  Define the installation location (the default is `/usr/local/`).

--with-boost-include

  Define the path to find the Boost headers.

--with-pythonpath

  Define the path to Python 3.1 if it is not in the standard execution path.

--with-gtest

  Enable building the C++ Unit Tests using the Google Tests framework. Optionally this can define the path to the gtest header files and library.

For example, the following configures it to find the Boost headers, find the Python interpreter, and sets the installation location:

    $ ./configure \
          --with-boost-include=/usr/pkg/include \
          --with-pythonpath=/usr/pkg/bin/python3.1 \
          --prefix=/opt/bind10

If the configure fails, it may be due to missing or old dependencies.

For notes on configuring and building DHCPv6 with MySQL see .

#### Build

After the configure step is complete, to build the executables from the C++ code and prepare the Python scripts, run:

    $ make

#### Install

To install the BIND 10 executables, support files, and documentation, run:

    $ make install

The install step may require superuser privileges.

If required, run `ldconfig` as root with `/usr/local/lib` (or with ${prefix}/lib if configured with --prefix) in `/etc/ld.so.conf` (or the relevant linker cache configuration file for your OS):

    $ ldconfig

If you do not run `ldconfig` where it is required, you may see errors like the following:

    	      program: error while loading shared libraries: libb10-something.so.1:
    	      cannot open shared object file: No such file or directory

## Starting BIND 10 with `bind10`

BIND 10 provides the `bind10` command which starts up the required processes. `bind10` will also restart some processes that exit unexpectedly. This is the only command needed to start the BIND 10 system.

After starting the `b10-msgq` communications channel, `bind10` connects to it, runs the configuration manager, and reads its own configuration. Then it starts the other modules.

The `b10-sockcreator`, `b10-msgq` and `b10-cfgmgr` services make up the core. The `b10-msgq` daemon provides the communication channel between every part of the system. The `b10-cfgmgr` daemon is always needed by every module, if only to send information about themselves somewhere, but more importantly to ask about their own settings, and about other modules. The `b10-sockcreator` daemon helps allocate Internet addresses and ports as needed for BIND 10 network services.

In its default configuration, the `bind10` master process will also start up `b10-cmdctl` for administration tools to communicate with the system, and `b10-stats` for statistics collection. The DNS and DHCP servers are not started by default. The configuration of components to start is covered in .

### Starting BIND 10

To start the BIND 10 service, simply run `bind10` as root. It will run in the foreground and your shell prompt will not be available. It will output various log messages as it starts up and is used. Run it with the `--verbose` switch to get additional debugging or diagnostic output.

If the setproctitle Python module is detected at start up, the process names for the Python-based daemons will be renamed to better identify them instead of just python. This is not needed on some operating systems.

## Command channel

The BIND 10 components use the `b10-msgq` message routing daemon to communicate with other BIND 10 components. The `b10-msgq` implements what is called the Command Channel. Processes intercommunicate by sending messages on the command channel. Example messages include shutdown, get configurations, and set configurations. This Command Channel is not used for DNS message passing. It is used only to control and monitor the BIND 10 system.

Administrators do not communicate directly with the `b10-msgq` daemon. By default, BIND 10 uses a UNIX domain socket file named `/usr/local/var/bind10-devel/msg_socket` for this interprocess communication.

## Configuration manager

The configuration manager, `b10-cfgmgr`, handles all BIND 10 system configuration. It provides persistent storage for configuration, and notifies running modules of configuration changes.

The `b10-auth` and `b10-xfrin` daemons and other components receive their configurations from the configuration manager over the `b10-msgq` command channel.

The administrator doesn't connect to it directly, but uses a user interface to communicate with the configuration manager via `b10-cmdctl`'s REST-ful interface. `b10-cmdctl` is covered in .

The current release only provides `bindctl` as a user interface to `b10-cmdctl`. Upcoming releases will provide another interactive command-line interface and a web-based interface.

The `b10-cfgmgr` daemon can send all specifications and all current settings to the `bindctl` client (via `b10-cmdctl`). `b10-cfgmgr` relays configurations received from `b10-cmdctl` to the appropriate modules.

The stored configuration file is at `/usr/local/var/bind10-devel/b10-config.db`. (The directory is what was defined at build configure time for `--localstatedir`. The default is `/usr/local/var/`.) The format is loosely based on JSON and is directly parseable python, but this may change in a future version. This configuration data file is not manually edited by the administrator.

The configuration manager does not have any command line arguments. Normally it is not started manually, but is automatically started using the `bind10` master process (as covered in ).

## Remote control daemon

`b10-cmdctl` is the gateway between administrators and the BIND 10 system. It is a HTTPS server that uses standard HTTP Digest Authentication for username and password validation. It provides a REST-ful interface for accessing and controlling BIND 10.

When `b10-cmdctl` starts, it firsts asks `b10-cfgmgr` about what modules are running and what their configuration is (over the `b10-msgq` channel). Then it will start listening on HTTPS for clients &mdash; the user interface &mdash; such as `bindctl`.

`b10-cmdctl` directly sends commands (received from the user interface) to the specified component. Configuration changes are actually commands to `b10-cfgmgr` so are sent there.

The HTTPS server requires a private key, such as a RSA PRIVATE KEY. The default location is at `/usr/local/etc/bind10-devel/cmdctl-keyfile.pem`. (A sample key is at `/usr/local/share/bind10-devel/cmdctl-keyfile.pem`.) It also uses a certificate located at `/usr/local/etc/bind10-devel/cmdctl-certfile.pem`. (A sample certificate is at `/usr/local/share/bind10-devel/cmdctl-certfile.pem`.) This may be a self-signed certificate or purchased from a certification authority.

The HTTPS server doesn't support a certificate request from a client (at this time). The `b10-cmdctl` daemon does not provide a public service. If any client wants to control BIND 10, then a certificate needs to be first received from the BIND 10 administrator. The BIND 10 installation provides a sample PEM bundle that matches the sample key and certificate.

The `b10-cmdctl` daemon also requires the user account file located at `/usr/local/etc/bind10-devel/cmdctl-accounts.csv`. This comma-delimited file lists the accounts with a user name, hashed password, and salt. (A sample file is at `/usr/local/share/bind10-devel/cmdctl-accounts.csv`. It contains the user named root with the password bind10.)

The administrator may create a user account with the `b10-cmdctl-usermgr` tool.

By default the HTTPS server listens on the localhost port 8080. The port can be set by using the `--port` command line option. The address to listen on can be set using the `--address` command line argument. Each HTTPS connection is stateless and times out in 1200 seconds by default. This can be redefined by using the `--idle-timeout` command line argument.

### Configuration specification for b10-cmdctl

The configuration items for `b10-cmdctl` are: `accounts_file` which defines the path to the user accounts database (the default is `/usr/local/etc/bind10-devel/cmdctl-accounts.csv`); `cert_file` which defines the path to the PEM certificate file (the default is `/usr/local/etc/bind10-devel/cmdctl-certfile.pem`); and `key_file` which defines the path to the PEM private key file (the default is `/usr/local/etc/bind10-devel/cmdctl-keyfile.pem`).

## Control and configure user interface

For the current release, `bindctl` is the only user interface. It is expected that upcoming releases will provide another interactive command-line interface and a web-based interface for controlling and configuring BIND 10.

`bindctl` has an internal command history, as well as tab-completion for most of the commands and arguments. However, these are only enabled if the python readline module is available on the system. If not, neither of these features will be supported.

The `bindctl` tool provides an interactive prompt for configuring, controlling, and querying the BIND 10 components. It communicates directly with a REST-ful interface over HTTPS provided by `b10-cmdctl`. It doesn't communicate to any other components directly.

### bindctl command-line options

-a <address>, --address=<address>

  IP address that BIND 10's `b10-cmdctl` module is listening on. By default, this is 127.0.0.1.

-c <certificate file>, --certificate-chain=<certificate file>

  PEM-formatted server certificate file. When this option is given, `bindctl` will verify the server certificate using the given file as the root of the certificate chain. If not specified, `bindctl` does not validate the certificate.

--csv-file-dir=<csv file>

  `bindctl` stores the username and password for logging in in a file called `default_user.csv`; this option specifies the directory where this file is stored and read from. When not specified, `~/.bind10/` is used.

  Currently, this file contains an unencrypted password.

-h, --help

  Shows a short overview of the command-line options of `bindctl`, and exits.

--version

  Shows the version of `bindctl`, and exits.

-p <port number>, --port=<port number>

  Port number that BIND 10's `b10-cmdctl` module is listening on. By default, this is port 8080.

### General syntax of bindctl commands

The `bindctl` tool is an interactive command-line tool, with dynamic commands depending on the BIND 10 modules that are running. There are a number of fixed commands that have no module and that are always available.

The general syntax of a command is

    <module> <command> [argument(s)]

For example, the Boss module has a 'shutdown' command to shut down BIND 10, with an optional argument 'help':

    > Boss shutdown help
    Command  shutdown 	(Shut down BIND 10)
    		help (Get help for command)
    This command has no parameters

There are no mandatory arguments, only the optional 'help'.

### Bindctl help

help
is both a command and an option that is available to all other commands. When run as a command directly, it shows the available modules.

    > help
    usage: <module name> <command name> [param1 = value1 [, param2 = value2]]
    Type Tab character to get the hint of module/command/parameters.
    Type "help(? h)" for help on bindctl.
    Type "<module_name> help" for help on the specific module.
    Type "<module_name> <command_name> help" for help on the specific command.

    Available module names:
    (list of modules)

When 'help' is used as a command to a module, it shows the supported commands for the module; for example:

    > Boss help
    Module  Boss 	Master process
    Available commands:
        help        Get help for module.
        shutdown    Shut down BIND 10
        ping        Ping the boss process
        show_processes
                List the running BIND 10 processes

And when added to a module command, it shows the description and parameters of that specific command; for example:

    > Auth loadzone help
    Command  loadzone 	((Re)load a specified zone)
    		help (Get help for command)
    Parameters:
        class (string, optional)
        origin (string, mandatory)

### Command arguments

Commands can have arguments, which can be either optional or mandatory. They can be specified by name (e.g. `<command> <argument name>=<argument value>`), or positionally, (e.g. `<command> <argument value 1> <argument value 2>`).

`<command> help` shows the arguments a command supports and which of those are mandatory, and in which order the arguments are expected if positional arguments are used.

For example, the `loadzone` command of the Auth module, as shown in the last example of the previous section, has two arguments, one of which is optional. The positional arguments in this case are class first and origin second; for example:

    > Auth loadzone IN example.com.

But since the class is optional (defaulting to IN), leaving it out works as well:

    > Auth loadzone example.com.

The arguments can also be provided with their names, in which case the order does not matter:

    > Auth loadzone origin="example.com." class="IN"

### Module commands

Each module has its own set of commands (if any), which will only be available if the module is running. For instance, the Auth module has a `loadzone` command. The commands a module provides are documented in this guide in the section of that module or in the module's corresponding manual page.

### Configuration commands

Configuration commands are used to view and change the configuration of BIND 10 and its modules. Module configuration is only shown if that module is running, but similar to commands, there are a number of top-level configuration items that are always available (for instance `tsig_keys` and `data_sources`).

Configuration changes (set, unset, add and remove) are done locally first, and have no immediate effect. The changes can be viewed with `config diff`, and either reverted (`config revert`), or committed (`config commit`). In the latter case, all local changes are submitted to the configuration manager, which verifies them, and if they are accepted, applied and saved in persistent storage.

When identifying items in configuration commands, the format is

    Module/example/item

Sub-elements of names, lists and sets (see ) are separated with the '/' character, and list indices are identified with [<index>]; for example:

    Module/example/list[2]/foo

#### List of configuration commands

The following configuration commands are available:

show [all] [item name]

  Shows the current configuration of the given item. If 'all' is given, it will recurse through the entire set, and show every nested value.

show_json [item name]

  Shows the full configuration of the given item in JSON format.

add <item name> [value]

  Add an entry to configuration list or a named set (see ). When adding to a list, the command has one optional argument, a value to add to the list. The value must be in correct JSON and complete. When adding to a named set, it has one mandatory parameter (the name to add), and an optional parameter value, similar to when adding to a list. In either case, when no value is given, an entry will be constructed with default values.

remove

  Remove an item from a configuration list or a named set. When removing an item for a list, either the index needs to be specified, or the complete value of the element to remove must be specified (in JSON format).

set <item name> <value>

  Directly set the value of the given item to the given value.

unset <item name>

  Remove any user-specified value for the given item.

diff

  Show all current local changes that have not been committed yet.

revert

  Revert all local changes without committing them.

commit

  Send all local changes to the configuration manager, which will validate them, and apply them if validation succeeds.

go

  Go to a specific configuration part, similar to the 'cd' command in a shell.

  There are a number of problems with the current implementation of go within `bindctl`, and we recommend not using it for general cases.

#### Configuration data types

Configuration data can be of different types, which can be modified in ways that depend on the types. There are a few syntax restrictions on these types, but only basic ones. Modules may impose additional restrictions on the values of elements.

integer

  A basic integer; can be set directly with `config set`, to any integer value.

real

  A basic floating point number; can be set directly with `config set`, to any floating point value.

boolean

  A basic boolean value; can be set directly with `config set`, to either `true` or `false`.

string

  A basic string value; can be set directly with `config set,` so any string. Double quotation marks are optional.

null

  This is a special type representing 'no value at all'; usable in compound structures that have optional elements that are not set.

maps

  Maps are (pre-defined) compound collections of other elements of any other type. They are not usually modified directly, but their elements are. Every top-level element for a module is a map containing the configuration values for that map, which can themselves be maps again. For instance, the Auth module configuration is a map containing the elements '`listen_on`' (list) and '`tcp_recv_timeout`' (integer). When changing one of its values, they can be modified directly with `config set Auth/tcp_recv_timeout 3000`.

  Some map entries are optional. If they are, and currently have a value, the value can be unset by using either `config unset <item name>` or `config set <item name> null`.

  Maps can be modified as a whole, but using the full JSON representation of the entire map to set.

  Since this involves a lot of text, this is usually not recommended.

  Another example is the Logging virtual module, which is, like any module, a map, but it only contains one element: a list of loggers. Normally, an administrator would only modify that list (or its elements) directly, but it is possible to set the entire map in one command; for example: `config set Logging { "loggers": [] }`

list

  A list is a compound list of other elements of the same type. Elements can be added with `config add <list name> [value]`, and removed with `config remove <list name> [value]` or `config remove <list name><index>`. The index is of the form square bracket, number, square bracket (e.g. `[0]`), and it immediately follows the list name (there is no separator or space between them). List indices start with 0 for the first element.

  For addition, if the value is omitted, an entry with default values will be added. For removal, either the index or the full value (in JSON format) needs to be specified.

  Lists can also be used with `config set`, but like maps, only by specifying the entire list value in JSON format.

  For example, this command shows the port number used for the second element of the list `listen_on` in the Auth module: `config show Auth/listen_on[1]/port`

named set

  Named sets are similar to lists, in that they are sets of elements of the same type, but they are not indexed by numbers, but by strings.

  Values can be added with `config add <item name> <string> [value]` where 'string' is the name of the element. If 'value' is ommitted, default values will be used. Elements can be removed with `config remove <item name> <string>`

  Elements in a named set can be addressed similarly to maps.

  For example, the `Boss/components` elements is a named set; adding, showing, and then removing an element can be done with the following three commands (note the '/'-character versus the space before 'example_module'):

  `config add Boss/components example_module`

  `config show Boss/components/example_module`

  `config remove Boss/components example_module`

any

  The 'any' type is a special type that can have any form. Apart from that, it must consist of elements as described in this chapter, there is no restriction on which element types are used. This type is used in places where different data formats could be used. Element modification commands depend on the actual type of the value. For instance, if the value of an 'any' element is a list, `config add` and `config remove` work as for other lists.

### The execute command

The `execute` command executes a set of commands, either from a file or from a pre-defined set. Currently, the only predefined set is `init_authoritative_server`, which adds `b10-auth`, `b10-xfrin`, and `b10-xfrout` to the set of components to be started by BIND 10. This pre-defined set does not commit the changes, so these modules do not show up for commands or configuration until the user enters `config commit` after `execute init_authoritative_server`. For example:

    > execute init_authoritative_server

    > execute file /tmp/example_commands

The optional argument `show` displays the exact set of commands that would be executed; for example:

    > execute init_authoritative_server show
    !echo adding Authoritative server component
    config add /Boss/components b10-auth
    config set /Boss/components/b10-auth/kind needed
    config set /Boss/components/b10-auth/special auth
    !echo adding Xfrin component
    config add /Boss/components b10-xfrin
    config set /Boss/components/b10-xfrin/address Xfrin
    config set /Boss/components/b10-xfrin/kind dispensable
    !echo adding Xfrout component
    config add /Boss/components b10-xfrout
    config set /Boss/components/b10-xfrout/address Xfrout
    config set /Boss/components/b10-xfrout/kind dispensable
    !echo adding Zone Manager component
    config add /Boss/components b10-zonemgr
    config set /Boss/components/b10-zonemgr/address Zonemgr
    config set /Boss/components/b10-zonemgr/kind dispensable
    !echo Components added. Please enter "config commit" to
    !echo finalize initial setup and run the components.

The optional `show` argument may also be used when executing a script from a file; for example:

    > execute file /tmp/example_commands show

#### Execute directives

Within sets of commands to be run with the `execute` command, a number of directives are supported:

!echo <string>

  Prints the given string to `bindctl`'s output.

!verbose on

  Enables verbose mode; all following commands that are to be executed are also printed.

!verbose off

  Disables verbose mode; following commands that are to be executed are no longer printed.

#### Notes on execute scripts

Within scripts, you can add or remove modules with the normal configuration commands for `Boss/components`. However, as module configuration and commands do not show up until the module is running, it is currently not possible to add a module and set its configuration in one script. This will be addressed in the future, but for now the only option is to add and configure modules in separate commands and execute scripts.

## Common configuration elements

Some things are configured in the same or similar manner across many modules. So we show them here in one place.

### TSIG keys

TSIG is a way to sign requests and responses in DNS. It is defined in RFC 2845 and uses symmetric cryptography to sign the DNS messages. If you want to make any use of TSIG (to authenticate transfers or DDNS, for example), you need to set up shared secrets between the endpoints.

BIND 10 uses a global key ring for the secrets. It doesn't currently mean they would be stored differently, they are just in one place of the configuration.

#### Key anatomy and syntax

Each key has three attributes. One is a name by which it is referred both in DNS packets and the rest of the configuration. Another is the algorithm used to compute the signature. And the last part is a base64 encoded secret, which might be any blob of data.

The parts are written into a string, concatenated together by colons. So if you wanted to have a key called "example.key", used as a HMAC-MD5 key with secret "secret", you'd write it as:

    "example.key.:c2VjcmV0:hmac-md5"

The HMAC-MD5 algorithm is the default, so you can omit it. You could write the same key as:

    "example.key.:c2VjcmV0"

You can also use these algorithms (which may not be omitted from the key definition if used):

- hmac-sha1
- hmac-sha224
- hmac-sha256
- hmac-sha384
- hmac-sha512

The name of the key must be a valid DNS name.

#### Key ring

The key ring lives in the configuration in "tsig_keys/keys". Most of the system uses the keys from there &mdash; ACLs, authoritative server to sign responses to signed queries, and `b10-xfrin` and `b10-xfrout` to sign transfers.

The key ring is just a list of strings, each describing one key. So, to add a new key, you can do this:

    > config add tsig_keys/keys "example.key.:c2VjcmV0"
    > config show tsig_keys/keys
    tsig_keys/keys[0]   "example.key.:c2VjcmV0" string  (modified)
    > config commit

You can keep as many keys as you want in the key ring, but each must have a different name.

### ACLs

An ACL, or Access Control List, is a way to describe if a request is allowed or disallowed. The principle is, there's a list of rules. Each rule is a name-value mapping (a dictionary, in the JSON terminology). Each rule must contain exactly one mapping called "action", which describes what should happen if the rule applies. There may be more mappings, calld matches, which describe the conditions under which the rule applies.

When there's a query, the first rule is examined. If it matches, the action in it is taken. If not, next rule is examined. If there are no more rules to examine, a default action is taken.

There are three possible "action" values. The "ACCEPT" value means the query is handled. If it is "REJECT", the query is not answered, but a polite error message is sent back (if that makes sense in the context). The "DROP" action acts like a black hole. The query is not answered and no error message is sent.

If there are multiple matching conditions inside the rule, all of them must be satisfied for the rule to apply. This can be used, for example, to require the query to be signed by a TSIG key and originate from given address.

This is encoded in form of JSON. Semi-formal description could look something like this. It is described in more details below.

    ACL := [ RULE, RULE, ... ]
    RULE := { "action": "ACCEPT"|"REJECT"|"DROP", MATCH, MATCH, ... }
    RULE_RAW := { MATCH, MATCH, ... }
    MATCH := FROM_MATCH|KEY_MATCH|NOT_MATCH|OR_MATCH|AND_MATCH|...
    FROM_MATCH := "from": [RANGE, RANGE, RANGE, ...] | RANGE
    RANGE := "<ip range>"
    KEY_MATCH := "key": [KEY, KEY, KEY, ...] | KEY
    KEY := "<key name>"
    NOT_MATCH := "NOT": RULE_RAW
    OR_MATCH := "ANY": [ RULE_RAW, RULE_RAW, ... ]
    AND_MATCH := "ALL": [ RULE_RAW, RULE_RAW, ... ]

#### Matching properties

The first thing you can check against is the source address of request. The name is `from` and the value is a string containing either a single IPv4 or IPv6 address, or a range in the usual slash notation (eg. "192.0.2.0/24").

The other is TSIG key by which the message was signed. The ACL contains only the name (under the name "key"), the key itself must be stored in the global key ring (see ). This property is applicable only to the DNS context.

More properties to match are planned &mdash; the destination address, ports, matches against the packet content.

#### More complicated matches

From time to time, you need to express something more complex than just a single address or key.

You can specify a list of values instead of single value. Then the property needs to match at least one of the values listed &mdash; so you can say "from": ["192.0.2.0/24", "2001:db8::/32"] to match any address in the ranges set aside for documentation. The keys or any future properties will work in a similar way.

If that is not enough, you can compose the matching conditions to logical expressions. They are called "ANY", "ALL" and "NOT". The "ANY" and "ALL" ones contain lists of subexpressions &mdash; each subexpression is a similar dictionary, just not containing the "action" element. The "NOT" contains single subexpression. Their function should be obvious &mdash; "NOT" matches if and only if the subexpression does not match. The "ALL" matches exactly when each of the subexpressions matches and "ANY" when at least one matches.

#### Examples

All the examples here is just the JSON representing the ACL, nicely formatted and split across lines. They are out of any surrounding context. This is similar to what you'd get from `config show_json` called on the entry containing the ACL.

In the first example, the ACL accepts queries from two known hosts. Each host has an IP addresses (both IPv4 and IPv6) and a TSIG key. Other queries are politely rejected. The last entry in the list has no conditions &mdash; making it match any query.

    [
      {
        "from": ["192.0.2.1", "2001:db8::1"],
        "key": "first.key",
        "action": "ACCEPT"
      },
      {
        "from": ["192.0.2.2", "2001:db8::2"],
        "key": "second.key",
        "action": "ACCEPT"
      },
      {
        "action": "REJECT"
      }
    ]

Now we show two ways to accept only the queries from private ranges. This is the same as rejecting anything that is outside.

    [
      {
        "from": [
          "10.0.0.0/8",
          "172.16.0.0/12",
          "192.168.0.0/16",
          "fc00::/7"
        ],
        "action": "ACCEPT"
      },
      {
        "action": "REJECT"
      }
    ]

    [
      {
        "NOT": {
           "ANY": [
             {"from": "10.0.0.0/8"},
             {"from": "172.16.0.0/12"},
             {"from": "192.168.0.0/16"},
             {"from": "fc00::/7"}
           ]
        },
        "action": "REJECT"
      },
      {
        "action": "ACCEPT"
      }
    ]

#### Interaction with `bindctl`

Currently, `bindctl` has hard time coping with the variable nature of the ACL syntax. This technical limitation makes it impossible to edit parts of the entries. You need to set the whole entry at once, providing the whole JSON value.

This limitation is planned to be solved soon at least partially.

You'd do something like this to create the second example. Note that the whole JSON must be on a single line.

    > config add somewhere/acl
    > config set somewhere/acl[0] { "from": [ "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "fc00::/7" ], "action": "ACCEPT" }
    > config add somewhere/acl
    > config set somewhere/acl[1] { "action": "REJECT" }
    > config commit

## bind10 Control and Configuration

This chapter explains how to control and configure the `bind10` parent. The startup of this resident process that runs the BIND 10 daemons is covered in .

### Stopping bind10

The BIND 10 suite may be shut down by stopping the parent `bind10` process. This may be done by running the `Boss shutdown` command at the `bindctl` prompt.

### Configuration to start processes

The processes to be used can be configured for `bind10` to start, with the exception of the required `b10-sockcreator`, `b10-msgq` and `b10-cfgmgr` components. The configuration is in the `Boss/components` section. Each element represents one component, which is an abstraction of a process.

To add a process to the set, let's say the resolver (which is not started by default), you would do this:

    > config add Boss/components b10-resolver
    > config set Boss/components/b10-resolver/special resolver
    > config set Boss/components/b10-resolver/kind needed
    > config set Boss/components/b10-resolver/priority 10
    > config commit

Now, what it means. We add an entry called b10-resolver. It is both a name used to reference this component in the configuration and the name of the process to start. Then we set some parameters on how to start it.

The `special` setting is for components that need some kind of special care during startup or shutdown. Unless specified, the component is started in a usual way. This is the list of components that need to be started in a special way, with the value of special used for them:

#### Special startup components

Component | Special | Description
--- | --- | ---
b10-auth | auth | Authoritative DNS server
b10-resolver | resolver | DNS resolver
b10-cmdctl | cmdctl | Command control (remote control interface)

The `kind` specifies how a failure of the component should be handled. If it is set to dispensable (the default unless you set something else), it will get started again if it fails. If it is set to needed and it fails at startup, the whole `bind10` shuts down and exits with an error exit code. But if it fails some time later, it is just started again. If you set it to core, you indicate that the system is not usable without the component and if such component fails, the system shuts down no matter when the failure happened. This is the behavior of the core components (the ones you can't turn off), but you can declare any other components as core as well if you wish (but you can turn these off, they just can't fail).

The `priority` defines order in which the components should start. The ones with higher numbers are started sooner than the ones with lower ones. If you don't set it, 0 (zero) is used as the priority. Usually, leaving it at the default is enough.

There are other parameters we didn't use in our example. One of them is `address`. It is the address used by the component on the `b10-msgq` message bus. The special components already know their address, but the usual ones don't. The address is by convention the thing after b10-, with the first letter capitalized (eg. `b10-stats` would have Stats as its address).

The last one is `process`. It is the name of the process to be started. It defaults to the name of the component if not set, but you can use this to override it. (The special components also already know their executable name.)

The configuration is quite powerful, but that includes a lot of space for mistakes. You could turn off the `b10-cmdctl`, but then you couldn't change it back the usual way, as it would require it to be running (you would have to find and edit the configuration directly). Also, some modules might have dependencies: `b10-stats-httpd` needs `b10-stats`, `b10-xfrout` needs `b10-auth` to be running, etc.

In short, you should think twice before disabling something here.

It is possible to start some components multiple times (currently `b10-auth` and `b10-resolver`). You might want to do that to gain more performance (each one uses only single core). Just put multiple entries under different names, like this, with the same config:

    > config add Boss/components b10-resolver-2
    > config set Boss/components/b10-resolver-2/special resolver
    > config set Boss/components/b10-resolver-2/kind needed
    > config commit

However, this is work in progress and the support is not yet complete. For example, each resolver will have its own cache, each authoritative server will keep its own copy of in-memory data and there could be problems with locking the sqlite database, if used. The configuration might be changed to something more convenient in future. Other components don't expect such a situation, so it would probably not do what you want. Such support is yet to be implemented.

The running processes started by `bind10` may be listed by running `Boss show_processes` using `bindctl`.

## Authoritative Server

The `b10-auth` is the authoritative DNS server. It supports EDNS0, DNSSEC, IPv6, and SQLite3 and in-memory zone data backends. Normally it is started by the `bind10` master process.

### Server Configurations

`b10-auth` is configured via the `b10-cfgmgr` configuration manager. The module name is Auth. The configuration data items are:

database_file

  This is an optional string to define the path to find the SQLite3 database file. Note: This may be a temporary setting because the DNS server can use various data source backends.

datasources

  `datasources` configures data sources. The list items include: `type` to define the required data source type (such as memory); `class` to optionally select the class (it defaults to IN); and `zones` to define the `file` path name, the `filetype` (sqlite3 to load from a SQLite3 database file or text to load from a master text file), and the `origin` (default domain).

  By default, this is empty.

  Currently this is only used for the memory data source. Only the IN class is supported at this time. By default, the memory data source is disabled. Also, currently the zone file must be canonical such as generated by `named-compilezone -D`, or must be an SQLite3 database.

listen_on

  `listen_on` is a list of addresses and ports for `b10-auth` to listen on. The list items are the `address` string and `port` number. By default, `b10-auth` listens on port 53 on the IPv6 (::) and IPv4 (0.0.0.0) wildcard addresses.

  The default configuration is currently not appropriate for a multi-homed host. In case you have multiple public IP addresses, it is possible the query UDP packet comes through one interface and the answer goes out through another. The answer will probably be dropped by the client, as it has a different source address than the one it sent the query to. The client would fallback on TCP after several attempts, which works well in this situation, but is clearly not ideal.

  There are plans to solve the problem such that the server handles it by itself. But until it is actually implemented, it is recommended to alter the configuration &mdash; remove the wildcard addresses and list all addresses explicitly. Then the server will answer on the same interface the request came on, preserving the correct address.

tcp_recv_timeout

  `tcp_recv_timeout` is the timeout used on incoming TCP connections, in milliseconds. If the query is not sent within this time, the connection is closed. Setting this to 0 will disable TCP timeouts completely.

The configuration commands are:

loadzone

  `loadzone` tells `b10-auth` to load or reload a zone file. The arguments include: `class` which optionally defines the class (it defaults to IN); `origin` is the domain name of the zone; and `datasrc` optionally defines the type of datasource (it defaults to memory).

  Currently this only supports the IN class and the memory data source.

getstats

  `getstats` requests `b10-auth` to send its statistics data to b10-stats 8 as a response of the command.

shutdown

  Stop the authoritative DNS server. This has an optional `pid` argument to select the process ID to stop. (Note that the BIND 10 boss process may restart this service if configured.)

### Data Source Backends

Bind 10 has the concept of data sources. A data source is a place where authoritative zone data reside and where they can be served from. This can be a master file, a database or something completely different.

Once a query arrives, `b10-auth` goes through a configured list of data sources and finds the one containing a best matching zone. From the equally good ones, the first one is taken. This data source is then used to answer the query.

In the current release, `b10-auth` can serve data from a SQLite3 data source backend and from master files. Upcoming versions will be able to use multiple different data sources, such as MySQL and Berkeley DB.

The configuration is located in data_sources/classes. Each item there represents one RR class and a list used to answer queries for that class. The default contains two classes. The CH class contains a static data source &mdash; one that serves things like AUTHORS.BIND.. The IN class contains single SQLite3 data source with database file located at `/usr/local/var/bind10-devel/zone.sqlite3`.

Each data source has several options. The first one is `type`, which specifies the type of data source to use. Valid types include the ones listed below, but BIND 10 uses dynamically loaded modules for them, so there may be more in your case. This option is mandatory.

Another option is `params`. This option is type specific; it holds different data depending on the type above. Also, depending on the type, it could be possible to omit it.

There are two options related to the so-called cache. If you enable cache, zone data from the data source are loaded into memory. Then, when answering a query, `b10-auth` looks into the memory only instead of the data source, which speeds answering up. The first option is `cache-enable`, a boolean value turning the cache on and off (off is the default). The second one, `cache-zones`, is a list of zone origins to load into in-memory.

#### Data source types

As mentioned, the type used by default is sqlite3. It has single configuration option inside `params` &mdash; `database_file`, which contains the path to the SQLite3 file containing the data.

Another type is called MasterFiles. This one is slightly special. The data are stored in RFC1034 master files. Because answering directly from them would be impractical, this type mandates the cache to be enabled. Also, the list of zones (`cache-zones`) should be omitted. The `params` is a dictionary mapping from zone origins to the files they reside in.

#### Examples

As this is one of the more complex configurations of BIND 10, we show some examples. They all assume they start with default configuration.

First, let's disable the static data source (VERSION.BIND and friends). As it is the only data source in the CH class, we can remove the whole class.

    > config remove data_sources/classes CH
    > config commit

Another one, let's say our default data source contains zones example.org. and example.net.. We want them to be served from memory to make the answering faster.

    > config set data_sources/classes/IN[0]/cache-enable true
    > config add data_sources/classes/IN[0]/cache-zones example.org.
    > config add data_sources/classes/IN[0]/cache-zones example.net.
    > config commit

Now every time the zone in the data source is changed by the operator, the authoritative server needs to be told to reload it, by

    > Auth loadzone example.org

You don't need to do this when the zone is modified by `b10-xfrin`; it does so automatically.

Now, the last example is when there are master files we want to serve in addition to whatever is inside the SQLite3 database.

    > config add data_sources/classes/IN
    > config set data_sources/classes/IN[1]/type MasterFiles
    > config set data_sources/classes/IN[1]/cache-enable true
    > config set data_sources/classes/IN[1]/params { "example.org": "/path/to/example.org", "example.com": "/path/to/example.com" }
    > config commit

Initially, a map value has to be set, but this value may be an empty map. After that, key/value pairs can be added with 'config add' and keys can be removed with 'config remove'. The initial value may be an empty map, but it has to be set before zones are added or removed.

    > config set data_sources/classes/IN[1]/params {}
    > config add data_sources/classes/IN[1]/params another.example.org /path/to/another.example.org
    > config add data_sources/classes/IN[1]/params another.example.com /path/to/another.example.com
    > config remove data_sources/classes/IN[1]/params another.example.org

`bindctl`. To reload a zone, you the same command as above.

There's also `Auth/database_file` configuration variable, pointing to a SQLite3 database file. This is no longer used by `b10-auth`, but it is left in place for now, since other modules use it. Once `b10-xfrin`, `b10-xfrout` and `b10-ddns` are ported to the new configuration, this will disappear. But for now, make sure that if you use any of these modules, the new and old configuration correspond. The defaults are consistent, so unless you tweaked either the new or the old configuration, you're good.

### Loading Master Zones Files

RFC 1035 style DNS master zone files may imported into a BIND 10 SQLite3 data source by using the `b10-loadzone` utility.

`b10-loadzone` supports the following special directives (control entries):

$INCLUDE

  Loads an additional zone file. This may be recursive.

$ORIGIN

  Defines the relative domain name.

$TTL

  Defines the time-to-live value used for following records that don't include a TTL.

The `-o` argument may be used to define the default origin for loaded zone file records.

In the current release, only the SQLite3 back end is used by `b10-loadzone`. By default, it stores the zone data in `/usr/local/var/bind10-devel/zone.sqlite3` unless the `-d` switch is used to set the database filename. Multiple zones are stored in a single SQLite3 zone database.

If you reload a zone already existing in the database, all records from that prior zone disappear and a whole new set appears.

## Incoming Zone Transfers

Incoming zones are transferred using the `b10-xfrin` process which is started by `bind10`. When received, the zone is stored in the corresponding BIND 10 data source, and its records can be served by `b10-auth`. In combination with `b10-zonemgr` (for automated SOA checks), this allows the BIND 10 server to provide secondary service.

The `b10-xfrin` process supports both AXFR and IXFR. Due to some implementation limitations of the current development release, however, it only tries AXFR by default, and care should be taken to enable IXFR.

### Configuration for Incoming Zone Transfers

In practice, you need to specify a list of secondary zones to enable incoming zone transfers for these zones (you can still trigger a zone transfer manually, without a prior configuration (see below)).

For example, to enable zone transfers for a zone named "example.com" (whose master address is assumed to be 2001:db8::53 here), run the following at the `bindctl` prompt:

    > config add Xfrin/zones
    > config set Xfrin/zones[0]/name "example.com"
    > config set Xfrin/zones[0]/master_addr "2001:db8::53"
    > config commit

(We assume there has been no zone configuration before).

### TSIG

If you want to use TSIG for incoming transfers, a system wide TSIG key ring must be configured (see ). To specify a key to use, set tsig_key value to the name of the key to use from the key ring. > `config set Xfrin/zones[0]/tsig_key "`example.key`"`

### Enabling IXFR

As noted above, `b10-xfrin` uses AXFR for zone transfers by default. To enable IXFR for zone transfers for a particular zone, set the `use_ixfr` configuration parameter to true. In the above example of configuration sequence, you'll need to add the following before performing `commit`:

    > config set Xfrin/zones[0]/use_ixfr true

One reason why IXFR is disabled by default in the current release is because it does not support automatic fallback from IXFR to AXFR when it encounters a primary server that doesn't support outbound IXFR (and, not many existing implementations support it). Another, related reason is that it does not use AXFR even if it has no knowledge about the zone (like at the very first time the secondary server is set up). IXFR requires the "current version" of the zone, so obviously it doesn't work in this situation and AXFR is the only workable choice. The current release of `b10-xfrin` does not make this selection automatically. These features will be implemented in a near future version, at which point we will enable IXFR by default.

### Secondary Manager

The `b10-zonemgr` process is started by `bind10`. It keeps track of SOA refresh, retry, and expire timers and other details for BIND 10 to perform as a slave. When the `b10-auth` authoritative DNS server receives a NOTIFY message, `b10-zonemgr` may tell `b10-xfrin` to do a refresh to start an inbound zone transfer. The secondary manager resets its counters when a new zone is transferred in.

Access control (such as allowing notifies) is not yet provided. The primary/secondary service is not yet complete.

The following example shows using `bindctl` to configure the server to be a secondary for the example zone:

    > config add Zonemgr/secondary_zones
    > config set Zonemgr/secondary_zones[0]/name "example.com"
    > config commit

If the zone does not exist in the data source already (i.e. no SOA record for it), `b10-zonemgr` will automatically tell `b10-xfrin` to transfer the zone in.

### Trigger an Incoming Zone Transfer Manually

To manually trigger a zone transfer to retrieve a remote zone, you may use the `bindctl` utility. For example, at the `bindctl` prompt run:

    > Xfrin retransfer zone_name="foo.example.org" master=192.0.2.99

### Incoming Transfers with In-memory Datasource

In the case of an incoming zone transfer, the received zone is first stored in the corresponding BIND 10 datasource. In case the secondary zone is served by an in-memory datasource with an SQLite3 backend, `b10-auth` is automatically sent a `loadzone` command to reload the corresponding zone into memory from the backend.

The administrator doesn't have to do anything for `b10-auth` to serve the new version of the zone, except for the configuration such as the one described in .

## Outbound Zone Transfers

The `b10-xfrout` process is started by `bind10`. When the `b10-auth` authoritative DNS server receives an AXFR or IXFR request, `b10-auth` internally forwards the request to `b10-xfrout`, which handles the rest of this request processing. This is used to provide primary DNS service to share zones to secondary name servers. The `b10-xfrout` is also used to send NOTIFY messages to secondary servers.

A global or per zone `transfer_acl` configuration can be used to control accessibility of the outbound zone transfer service. By default, `b10-xfrout` allows any clients to perform zone transfers for any zones.

    > config show Xfrout/transfer_acl
    Xfrout/transfer_acl[0]	{"action": "ACCEPT"}	any	(default)

If you want to require TSIG in access control, a system wide TSIG key ring must be configured (see ). In this example, we allow client matching both the IP address and key.

    > config set tsig_keys/keys ["key.example:<base64-key>"]
    > config set Xfrout/zone_config[0]/transfer_acl [{"action": "ACCEPT", "from": "192.0.2.1", "key": "key.example"}]
    > config commit

Both `b10-xfrout` and `b10-auth` will use the system wide key ring to check TSIGs in the incoming messages and to sign responses.

For further details on ACL configuration, see .

The way to specify zone specific configuration (ACLs, etc) is likely to be changed.

## Dynamic DNS Update

BIND 10 supports the server side of the Dynamic DNS Update (DDNS) protocol as defined in RFC 2136. This service is provided by the `b10-ddns` component, which is started by the `bind10` process if configured so.

When the `b10-auth` authoritative DNS server receives an UPDATE request, it internally forwards the request to `b10-ddns`, which handles the rest of this request processing. When the processing is completed, `b10-ddns` will send a response to the client as specified in RFC 2136 (NOERROR for successful update, REFUSED if rejected due to ACL check, etc). If the zone has been changed as a result, it will internally notify `b10-xfrout` so that other secondary servers will be notified via the DNS NOTIFY protocol. In addition, if `b10-auth` serves the updated zone (as described in ), `b10-ddns` will also notify `b10-auth` so that `b10-auth` will re-cache the updated zone content if necessary.

The `b10-ddns` component supports requests over both UDP and TCP, and both IPv6 and IPv4; for TCP requests, however, it terminates the TCP connection immediately after each single request has been processed. Clients cannot reuse the same TCP connection for multiple requests. (This is a current implementation limitation of `b10-ddns`. While RFC 2136 doesn't specify anything about such reuse of TCP connection, there is no reason for disallowing it as RFC 1035 generally allows multiple requests sent over a single TCP connection. BIND 9 supports such reuse.)

As of this writing `b10-ddns` does not support update forwarding for secondary zones. If it receives an update request for a secondary zone, it will immediately return a not implemented response.

For feature completeness, update forwarding should be eventually supported. But currently it's considered a lower priority task and there is no specific plan of implementing this feature.

### Enabling Dynamic Update

First off, it must be made sure that a few components on which `b10-ddns` depends are configured to run, which are `b10-auth` and `b10-zonemgr`. In addition, `b10-xfrout` should also be configured to run; otherwise the notification after an update (see above) will fail with a timeout, suspending the DDNS service while `b10-ddns` waits for the response (see the description of the DDNS_UPDATE_NOTIFY_FAIL log message for further details). If BIND 10 is already configured to provide authoritative DNS service they should normally be configured to run already.

Second, for the obvious reason dynamic update requires that the underlying data source storing the zone data be writable. In the current implementation this means the zone must be stored in an SQLite3-based data source. Also, in this current version, the `b10-ddns` component configures itself with the data source referring to the `database_file` configuration parameter of `b10-auth`. So this information must be configured correctly before starting `b10-ddns`.

The way to configure data sources is now being revised. Configuration on the data source for DDNS will be very likely to be changed in a backward incompatible manner in a near future version.

In general, if something goes wrong regarding the dependency described above, `b10-ddns` will log the related event at the warning or error level. It's advisable to check the log message when you first enable DDNS or if it doesn't work as you expect to see if there's any warning or error log message.

Next, to enable the DDNS service, `b10-ddns` needs to be explicitly configured to run. It can be done by using the `bindctl` utility. For example:

    > config add Boss/components b10-ddns
    > config set Boss/components/b10-ddns/address DDNS
    > config set Boss/components/b10-ddns/kind dispensable
    > config commit

In theory `kind` could be omitted because "dispensable" is its default. But there's some peculiar behavior (which should be a bug and should be fixed eventually; see Trac ticket #2064) with `bindctl` and you'll still need to specify that explicitly. Likewise, `address` may look unnecessary because `b10-ddns` would start and work without specifying it. But for it to shutdown gracefully this parameter should also be specified.

### Access Control

By default, `b10-ddns` rejects any update requests from any clients by returning a REFUSED response. To allow updates to take effect, an access control rule (called update ACL) with a policy allowing updates must explicitly be configured. Update ACL must be configured per zone basis in the `zones` configuration parameter of `b10-ddns`. This is a list of per-zone configurations regarding DDNS. Each list element consists of the following parameters:

origin

  The zone's origin name

class

  The RR class of the zone (normally IN, and in that case can be omitted in configuration)

update_acl

  List of access control rules (ACL) for the zone

The syntax of the ACL is the same as ACLs for other components. Specific examples are given below.

In general, an update ACL rule that allows an update request should be configured with a TSIG key. This is an example update ACL that allows updates to the zone named example.org (of default RR class IN) from clients that send requests signed with a TSIG whose key name is "key.example.org" (and refuses all others):

    > config add DDNS/zones
    > config set DDNS/zones[0]/origin example.org
    > config add DDNS/zones[0]/update_acl {"action": "ACCEPT", "key": "key.example.org"}
    > config commit

The TSIG key must be configured system wide (see ).

The full description of ACLs can be found in .

The `b10-ddns` component accepts an ACL rule that just allows updates from a specific IP address (i.e., without requiring TSIG), but this is highly discouraged (remember that requests can be made over UDP and spoofing the source address of a UDP packet is often pretty easy). Unless you know what you are doing and that you can accept its consequence, any update ACL rule that allows updates should have a TSIG key in its constraints.

Currently update ACL can only control updates per zone basis; it's not possible to specify access control with higher granularity such as for particular domain names or specific types of RRs.

Contrary to what RFC 2136 (literally) specifies, `b10-ddns` checks the update ACL before checking the prerequisites of the update request. This is a deliberate implementation decision. This counter intuitive specification has been repeatedly discussed among implementers and in the IETF, and it is now widely agreed that it does not make sense to strictly follow that part of RFC. One known specific bad result of following the RFC is that it could leak information about which name or record exists or does not exist in the zone as a result of prerequisite checks even if a zone is somehow configured to reject normal queries from arbitrary clients. There have been other troubles that could have been avoided if the ACL could be checked before the prerequisite check.

### Miscellaneous Operational Issues

Unlike BIND 9, BIND 10 currently does not support automatic re-signing of DNSSEC-signed zone when it's updated via DDNS. It could be possible to re-sign the updated zone afterwards or make sure the update request also updates related DNSSEC records, but that will be pretty error-prone operation. In general, it's not advisable to allow DDNS for a signed zone at this moment.

Also unlike BIND 9, it's currently not possible to freeze a zone temporarily in order to suspend DDNS while you manually update the zone. If you need to make manual updates to a dynamic zone, you'll need to temporarily reject any updates to the zone via the update ACLs.

Dynamic updates are only applicable to primary zones. In order to avoid updating secondary zones via DDNS requests, `b10-ddns` refers to the secondary_zones configuration of `b10-zonemgr`. Zones listed in secondary_zones will never be updated via DDNS regardless of the update ACL configuration; `b10-ddns` will return a NOTAUTH (server not authoritative for the zone) response. If you have a "conceptual" secondary zone whose content is a copy of some external source but is not updated via the standard zone transfers and therefore not listed in secondary_zones, be careful not to allow DDNS for the zone; it would be quite likely to lead to inconsistent state between different servers. Normally this should not be a problem because the default update ACL rejects any update requests, but you may want to take an extra care about the configuration if you have such type of secondary zones.

The difference of two versions of a zone, before and after a DDNS transaction, is automatically recorded in the underlying data source, and can be retrieved in the form of outbound IXFR. This is done automatically; it does not require specific configuration to make this possible.

## Recursive Name Server

The `b10-resolver` process is started by `bind10`.

The main `bind10` process can be configured to select to run either the authoritative or resolver or both. By default, it doesn't start either one. You may change this using `bindctl`, for example:

    > config add Boss/components b10-resolver
    > config set Boss/components/b10-resolver/special resolver
    > config set Boss/components/b10-resolver/kind needed
    > config set Boss/components/b10-resolver/priority 10
    > config commit

The master `bind10` will stop and start the desired services.

By default, the resolver listens on port 53 for 127.0.0.1 and ::1. The following example shows how it can be configured to listen on an additional address (and port):

    > config add Resolver/listen_on
    > config set Resolver/listen_on[2]/address "192.168.1.1"
    > config set Resolver/listen_on[2]/port 53
    > config commit

(Replace the 2 as needed; run `config show Resolver/listen_on` if needed.)

### Access Control

By default, the `b10-resolver` daemon only accepts DNS queries from the localhost (127.0.0.1 and ::1). The `Resolver/query_acl` configuration may be used to reject, drop, or allow specific IPs or networks. See .

The following session is an example of extending the ACL to also allow queries from 192.0.2.0/24:

    > config show Resolver/query_acl
    Resolver/query_acl[0]   {"action": "ACCEPT", "from": "127.0.0.1"}   any (default)
    Resolver/query_acl[1]   {"action": "ACCEPT", "from": "::1"} any (default)
    > config add Resolver/query_acl
    > config set Resolver/query_acl[2] {"action": "ACCEPT", "from": "192.0.2.0/24"}
    > config add Resolver/query_acl
    > config show Resolver/query_acl
    Resolver/query_acl[0]   {"action": "ACCEPT", "from": "127.0.0.1"}   any (modified)
    Resolver/query_acl[1]   {"action": "ACCEPT", "from": "::1"} any (modified)
    Resolver/query_acl[2]   {"action": "ACCEPT", "from": "192.0.2.0/24"}  any (modified)
    Resolver/query_acl[3]   {"action": "REJECT"}    any (modified)
    > config commit

Note that we didn't set the value of the last final rule (query_acl[3]) -- in the case of resolver, rejecting all queries is the default value of a new rule. In fact, this rule can even be omitted completely, as the default, when a query falls off the list, is rejection.

### Forwarding

To enable forwarding, the upstream address and port must be configured to forward queries to, such as:

    > config set Resolver/forward_addresses [{ "address": "192.168.1.1", "port": 53 }]
    > config commit

(Replace 192.168.1.1 to point to your full resolver.)

Normal iterative name service can be re-enabled by clearing the forwarding address(es); for example:

    > config set Resolver/forward_addresses []
    > config commit

## DHCPv4 Server

Dynamic Host Configuration Protocol for IPv4 (DHCP or DHCPv4) and Dynamic Host Configuration Protocol for IPv6 (DHCPv6) are protocols that allow one node (server) to provision configuration parameters to many hosts and devices (clients). To ease deployment in larger networks, additional nodes (relays) may be deployed that facilitate communication between servers and clients. Even though principles of both DHCPv4 and DHCPv6 are somewhat similar, these are two radically different protocols. BIND 10 offers server implementations for both DHCPv4 and DHCPv6. This chapter is about DHCP for IPv4. For a description of the DHCPv6 server, see .

The DHCPv4 server component is currently under intense development. You may want to check out BIND 10 DHCP (Kea) wiki and recent posts on BIND 10 developers mailing list.

The DHCPv4 and DHCPv6 components in BIND 10 architecture are internally code named Kea.

As of November 2012, the DHCPv4 component is a skeleton server. That means that while it is capable of performing DHCP configuration, it is not fully functional. In particular, it does not have a functional lease database. This means that they will assign the same, fixed, hardcoded addresses to any client that will ask. See for a detailed description.

### DHCPv4 Server Usage

BIND 10 has provided the DHCPv4 server component since December 2011. It is a skeleton server and can be described as an early prototype that is not fully functional yet. It is mature enough to conduct first tests in lab environment, but it has significant limitations. See for details.

`b10-dhcp4` is a BIND 10 component and is being run under BIND 10 framework. To add a DHCPv4 process to the set of running BIND 10 services, you can use following commands in `bindctl`:

    > config add Boss/components b10-dhcp4
    > config set Boss/components/b10-dhcp4/kind dispensable
    > config commit

To stop running `b10-dhcp4`, please use the following command:

    > config remove Boss/components b10-dhcp4
    > config commit

During start-up the server will detect available network interfaces and will attempt to open UDP sockets on all interfaces that are up, running, are not loopback, and have IPv4 address assigned.

The server will then listen to incoming traffic. Currently supported client messages are DISCOVER and REQUEST. The server will respond to them with OFFER and ACK, respectively.

Since the DHCPv4 server opens privileged ports, it requires root access. Make sure you run this daemon as root.

### DHCPv4 Server Configuration

Once the server is started, it can be configured. To view the current configuration, use the following command in `bindctl`:

    > config show Dhcp4

When starting Dhcp4 daemon for the first time, the default configuration will be available. It will look similar to this:

    > config show Dhcp4
    Dhcp4/interface/                list    (default)
    Dhcp4/renew-timer        1000   integer	(default)
    Dhcp4/rebind-timer       2000   integer	(default)
    Dhcp4/preferred-lifetime 3000   integer	(default)
    Dhcp4/valid-lifetime	 4000   integer	(default)
    Dhcp4/subnet4	         []     list    (default)

To change one of the parameters, simply follow the usual `bindctl` procedure. For example, to make the leases longer, change their valid-lifetime parameter:

    > config set Dhcp4/valid-lifetime 7200
    > config commit

Please note that most Dhcp4 parameters are of global scope and apply to all defined subnets, unless they are overridden on a per-subnet basis.

The essential role of DHCPv4 server is address assignment. The server has to be configured with at least one subnet and one pool of dynamic addresses to be managed. For example, assume that the server is connected to a network segment that uses the 192.0.2.0/24 prefix. The Administrator of that network has decided that addresses from range 192.0.2.10 to 192.0.2.20 are going to be managed by the Dhcp4 server. Such a configuration can be achieved in the following way:

    > config add Dhcp4/subnet4
    > config set Dhcp4/subnet4[0]/subnet "192.0.2.0/24"
    > config set Dhcp4/subnet4[0]/pool [ "192.0.2.10 - 192.0.2.20" ]
    > config commit

Note that subnet is defined as a simple string, but the pool parameter is actually a list of pools: for this reason, the pool definition is enclosed in square brackets, even though only one range of addresses is specified.

It is possible to define more than one pool in a subnet: continuing the previous example, further assume that 192.0.2.64/26 should be also be managed by the server. It could be written as 192.0.2.64 to 192.0.2.127. Alternatively, it can be expressed more simply as 192.0.2.64/26. Both formats are supported by Dhcp4 and can be mixed in the pool list. For example, one could define the following pools:

    > config set Dhcp4/subnet4[0]/pool [ "192.0.2.10-192.0.2.20", "192.0.2.64/26" ]
    > config commit

The number of pools is not limited, but for performance reasons it is recommended to use as few as possible. Space and tabulations in pool definitions are ignored, so spaces before and after hyphen are optional. They can be used to improve readability.

The server may be configured to serve more than one subnet. To add a second subnet, use a command similar to the following:

    > config add Dhcp4/subnet4
    > config set Dhcp4/subnet4[1]/subnet "192.0.3.0/24"
    > config set Dhcp4/subnet4[1]/pool [ "192.0.3.0/24" ]
    > config commit

Arrays are counted from 0. subnet[0] refers to the subnet defined in the previous example. The `config add Dhcp4/subnet4` adds another (second) subnet. It can be referred to as `Dhcp4/subnet4[1]`. In this example, we allow server to dynamically assign all addresses available in the whole subnet.

When configuring a DHCPv4 server using prefix/length notation, please pay attention to the boundary values. When specifying that the server should use a given pool, it will be able to allocate also first (typically network address) and the last (typically broadcast address) address from that pool. In the aforementioned example of pool 192.0.3.0/24, both 192.0.3.0 and 192.0.3.255 addresses may be assigned as well. This may be invalid in some network configurations. If you want to avoid this, please use min-max notation.

Note: Although configuration is now accepted, it is not internally used by they server yet. At this stage of development, the only way to alter server configuration is to modify its source code. To do so, please edit src/bin/dhcp6/dhcp4_srv.cc file, modify the following parameters and recompile:

    const std::string HARDCODED_LEASE = "192.0.2.222"; // assigned lease
    const std::string HARDCODED_NETMASK = "255.255.255.0";
    const uint32_t    HARDCODED_LEASE_TIME = 60; // in seconds
    const std::string HARDCODED_GATEWAY = "192.0.2.1";
    const std::string HARDCODED_DNS_SERVER = "192.0.2.2";
    const std::string HARDCODED_DOMAIN_NAME = "isc.example.com";
    const std::string HARDCODED_SERVER_ID = "192.0.2.1";

Lease database and configuration support is planned for end of 2012.

### Supported standards

The following standards and draft standards are currently supported:

- RFC2131: Supported messages are DISCOVER, OFFER, REQUEST, and ACK.

- RFC2132: Supported options are: PAD (0), END(255), Message Type(53), DHCP Server Identifier (54), Domain Name (15), DNS Servers (6), IP Address Lease Time (51), Subnet mask (1), and Routers (3).

### DHCPv4 Server Limitations

These are the current limitations of the DHCPv4 server software. Most of them are reflections of the early stage of development and should be treated as not implemented yet, rather than actual limitations.

- During initial IPv4 node configuration, the server is expected to send packets to a node that does not have IPv4 address assigned yet. The server requires certain tricks (or hacks) to transmit such packets. This is not implemented yet, therefore DHCPv4 server supports relayed traffic only (that is, normal point to point communication).

- `b10-dhcp4` provides a single, fixed, hardcoded lease to any client that asks. There is no lease manager implemented. If two clients request addresses, they will both get the same fixed address.

- `b10-dhcp4` does not support any configuration mechanisms yet. The whole configuration is currently hardcoded. The only way to tweak configuration is to directly modify source code. See see for details.

- Upon start, the server will open sockets on all interfaces that are not loopback, are up and running and have IPv4 address.

- PRL (Parameter Request List, a list of options requested by a client) is currently ignored and server assigns DNS SERVER and DOMAIN NAME options.

- `b10-dhcp4` does not support BOOTP. That is a design choice. This limitation is permanent. If you have legacy nodes that can't use DHCP and require BOOTP support, please use the latest version of ISC DHCP via .

- Interface detection is currently working on Linux only. See for details.

- `b10-dhcp4` does not verify that assigned address is unused. According to RFC2131, the allocating server should verify that address is no used by sending ICMP echo request.

- Address renewal (RENEW), rebinding (REBIND), confirmation (CONFIRM), duplication report (DECLINE) and release (RELEASE) are not supported yet.

- DNS Update is not supported yet.

- -v (verbose) command line option is currently the default, and cannot be disabled.

## DHCPv6 Server

The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) is specified in RFC3315. BIND 10 provides a DHCPv6 server implementation that is described in this chapter. For a description of the DHCPv4 server implementation, see .

The DHCPv6 server component is currently under intense development. You may want to check out BIND 10 DHCP (Kea) wiki and recent posts on BIND 10 developers mailing list.

As of November 2012, the DHCPv6 component is partially functioning, having the following capabilities:

- DHCPv6 server able to allocate leases (but not renew them).

- Some configuration available through the BIND 10 configuration mechanism.

- Lease storage in a MySQL database.

### DHCPv6 Server Build and Installation

DHCPv6 is part of the BIND 10 suite of programs and is built as part of the build of BIND 10. With the use of MySQL, some additional installation steps are needed:

#### Install MySQL

Install MySQL according to the instructions for your system. The client development libraries must be installed.

#### Build and Install BIND 10

Build and install BIND 10 as described in , with the following modification: to enable the MySQL database code, the "configure" step (see ), specify the location of the MySQL configuration program "mysql_config" with the "--with-mysql-config" switch, i.e.

    ./configure [other-options] --with-dhcp-mysql

...if MySQL was installed in the default location, or:

    ./configure [other-options] --with-dhcp-mysql=<path-to-mysql_config>

...if not.

#### Create MySQL Database and BIND 10 User

The next task is to create both the DHCPv6 lease database and the user under which the DHCPv6 server will access it. Although the intention is to have the name of the database and the user configurable, at the moment they are hard-coded as "kea", as is the associated password. ("kea" is an internal code name for BIND 10 DHCP.) There are a number of steps required:

1. Log into MySQL as "root":

    $ mysql -u root -p
    Enter password:
       :
    mysql>

2. Create the database:

    mysql> CREATE DATABASE kea;

3. Create the database tables:

    mysql> CONNECT kea;
    mysql> SOURCE <path-to-bind10>/share/bind10-devel/dhcpdb_create.mysql

4. Create the user under which BIND 10 will access the database and grant it access to the database tables:

    mysql> CREATE USER 'kea'@'localhost' IDENTIFIED BY 'kea';
    mysql> GRANT ALL ON kea.* TO 'kea'@'localhost';

5. Exit MySQL:

    mysql> quit
    Bye
    $

### DHCPv6 Server Usage

`b10-dhcp6` is a BIND 10 component and is being run under BIND 10 framework. To add a DHCPv6 process to the set of running BIND 10 services, you can use following commands in `bindctl`:

    > config add Boss/components b10-dhcp6
    > config set Boss/components/b10-dhcp6/kind dispensable
    > config commit

To stop running `b10-dhcp6`, use the following command:

    > config remove Boss/components b10-dhcp6
    > config commit

During start-up the server will detect available network interfaces and will attempt to open UDP sockets on all interfaces that are up, running, are not loopback, are multicast-capable, and have IPv6 address assigned. It will then listen to incoming traffic. The currently supported client messages are SOLICIT and REQUEST. The server will respond to them with ADVERTISE and REPLY, respectively.

Since the DHCPv6 server opens privileged ports, it requires root access. Make sure you run this daemon as root.

### DHCPv6 Server Configuration

Once the server has been started, it can be configured. To view the current configuration, use the following command in `bindctl`:

    > config show Dhcp6

When starting the Dhcp6 daemon for the first time, the default configuration will be available. It will look similar to this:

    > config show Dhcp6
    Dhcp6/interface	         "eth0" string	(default)
    Dhcp6/renew-timer        1000   integer	(default)
    Dhcp6/rebind-timer       2000   integer	(default)
    Dhcp6/preferred-lifetime 3000   integer	(default)
    Dhcp6/valid-lifetime	 4000   integer	(default)
    Dhcp6/subnet6	         []     list    (default)

To change one of the parameters, simply follow the usual `bindctl` procedure. For example, to make the leases longer, change their valid-lifetime parameter:

    > config set Dhcp6/valid-lifetime 7200
    > config commit

Most Dhcp6 parameters are of global scope and apply to all defined subnets, unless they are overridden on a per-subnet basis.

The essential role of a DHCPv6 server is address assignment. For this, the server has to be configured with at least one subnet and one pool of dynamic addresses to be managed. For example, assume that the server is connected to a network segment that uses the 2001:db8:1::/64 prefix. The Administrator of that network has decided that addresses from range 2001:db8:1::1 to 2001:db8:1::ffff are going to be managed by the Dhcp6 server. Such a configuration can be achieved in the following way:

    > config add Dhcp6/subnet6
    > config set Dhcp6/subnet6[0]/subnet "2001:db8:1::/64"
    > config set Dhcp6/subnet6[0]/pool [ "2001:db8:1::0 - 2001:db8:1::ffff" ]
    > config commit

Note that subnet is defined as a simple string, but the pool parameter is actually a list of pools: for this reason, the pool definition is enclosed in square brackets, even though only one range of addresses is specified.

It is possible to define more than one pool in a subnet: continuing the previous example, further assume that 2001:db8:1:0:5::/80 should be also be managed by the server. It could be written as 2001:db8:1:0:5:: to 2001:db8:1::5:ffff:ffff:ffff, but typing so many 'f's is cumbersome. It can be expressed more simply as 2001:db8:1:0:5::/80. Both formats are supported by Dhcp6 and can be mixed in the pool list. For example, one could define the following pools:

    > config set Dhcp6/subnet6[0]/pool [ "2001:db8:1::1 - 2001:db8:1::ffff", "2001:db8:1:0:5::/80" ]
    > config commit

The number of pools is not limited, but for performance reasons it is recommended to use as few as possible.

The server may be configured to serve more than one subnet. To add a second subnet, use a command similar to the following:

    > config add Dhcp6/subnet6
    > config set Dhcp6/subnet6[1]/subnet "2001:db8:beef::/48"
    > config set Dhcp6/subnet6[1]/pool [ "2001:db8:beef::/48" ]
    > config commit

Arrays are counted from 0. subnet[0] refers to the subnet defined in the previous example. The `config add Dhcp6/subnet6` adds another (second) subnet. It can be referred to as `Dhcp6/subnet6[1]`. In this example, we allow server to dynamically assign all addresses available in the whole subnet. Although very wasteful, it is certainly a valid configuration to dedicate the whole /48 subnet for that purpose.

When configuring a DHCPv6 server using prefix/length notation, please pay attention to the boundary values. When specifying that the server should use a given pool, it will be able to allocate also first (typically network address) address from that pool. For example for pool 2001:db8::/64 the 2001:db8:: address may be assigned as well. If you want to avoid this, please use min-max notation.

Options can also be configured: the following commands configure the DNS-SERVERS option for all subnets with the following addresses: 2001:db8:1::1 and 2001:db8:1::2

    > config add Dhcp6/option-data
    > config set Dhcp6/option-data[0]/name "dns-servers"
    > config set Dhcp6/option-data[0]/code 23
    > config set Dhcp6/option-data[0]/data "2001 0DB8 0001 0000 0000 0000
            0000 0001 2001 0DB8 0001 0000 0000 0000 0000 0002"
    > config commit

(The value for the setting of the "data" element is split across two lines in this document for clarity: when entering the command, all the string should be entered on the same line.)

Currently the only way to set option data is to specify the data as a string of hexadecimal digits. It is planned to allow alternative ways of specifying the data as a comma-separated list, e.g. "2001:db8:1::1,2001:db8:1::2".

As with global settings, it is also possible to override options on a per-subnet basis, e.g. the following commands override the global DNS servers option for a particular subnet, setting a single DNS server with address 2001:db8:1::3.

    > config add Dhcp6/subnet6[0]/option-data
    > config set Dhcp6/subnet6[0]/option-data[0]/name "dns-servers"
    > config set Dhcp6/subnet6[0]/option-data[0]/code 23
    > config set Dhcp6/subnet6[0]/option-data[0]/data "2001 0DB8 0001 0000
            0000 0000 0000 0003"
    > config commit

(As before, the setting of the "data" element has been split across two lines for clarity.)

With this version of BIND 10, there are a number of known limitations and problems in the DHCPv6 server. See .

### Supported DHCPv6 Standards

The following standards and draft standards are currently supported:

- RFC3315: Supported messages are SOLICIT, ADVERTISE, REQUEST, and REPLY. Supported options are SERVER_ID, CLIENT_ID, IA_NA, and IAADDRESS.

- RFC3646: Supported option is DNS_SERVERS.

### DHCPv6 Server Limitations

These are the current limitations and known problems with the the DHCPv6 server software. Most of them are reflections of the early stage of development and should be treated as not implemented yet, rather than actual limitations.

- The DHCPv6 server has only been tested on Debian operating systems. There are known problems with the handling of packets in CentOS and RHEL.

- Relayed traffic is not supported.

- `b10-dhcp6` only supports a limited number of configuration options.

- On startup, the DHCPv6 server does not get the full configuration from BIND 10. To remedy this, after starting BIND 10, modify any parameter and commit the changes, e.g.

      > config show Dhcp6/renew-timer
      Dhcp6/renew-timer	1000	integer	(default)
      > config set Dhcp6/renew-timer 1001
      > config commit

- Upon start, the server will open sockets on all interfaces that are not loopback, are up, running and are multicast capable and have IPv6 address. Support for multiple interfaces is not coded in reception routines yet, so if you are running this code on a machine that has many interfaces and `b10-dhcp6` happens to listen on wrong interface, the easiest way to work around this problem is to turn down other interfaces. This limitation will be fixed shortly.

- ORO (Option Request Option, a list of options requested by a client) is currently unsupported.

- Temporary addresses are not supported.

- Prefix delegation is not supported.

- Address renewal (RENEW), rebinding (REBIND), confirmation (CONFIRM), duplication report (DECLINE) and release (RELEASE) are not supported.

- DNS Update is not supported.

- Interface detection is currently working on Linux only. See for details.

## libdhcp++ library

libdhcp++ is a common library written in C++ that handles many DHCP-related tasks, including

- DHCPv4 and DHCPv6 packets parsing, manipulation and assembly

- Option parsing, manipulation and assembly

- Network interface detection

- Socket operations such as creation, data transmission and reception and socket closing.

While this library is currently used by `b10-dhcp4` and `b10-dhcp6` only, it is designed to be a portable, universal library, useful for any kind of DHCP-related software.

### Interface detection

Both the DHCPv4 and DHCPv6 components share network interface detection routines. Interface detection is currently only supported on Linux systems.

For non-Linux systems, there is currently a stub implementation provided. The interface manager detects loopback interfaces only as their name (lo or lo0) can be easily predicted. Please contact the BIND 10 development team if you are interested in running DHCP components on systems other than Linux.

## Statistics

The `b10-stats` process is started by `bind10`. It periodically collects statistics data from various modules and aggregates it.

This stats daemon provides commands to identify if it is running, show specified or all statistics data, and show specified or all statistics data schema.

For example, using `bindctl`:

    > Stats show
    {
        "Auth": {
            "opcode.iquery": 0,
            "opcode.notify": 10,
            "opcode.query": 869617,
            ...
            "queries.tcp": 1749,
            "queries.udp": 867868
        },
        "Boss": {
            "boot_time": "2011-01-20T16:59:03Z"
        },
        "Stats": {
            "boot_time": "2011-01-20T16:59:05Z",
            "last_update_time": "2011-01-20T17:04:05Z",
            "lname": "4d3869d9_a@jreed.example.net",
            "report_time": "2011-01-20T17:04:06Z",
            "timestamp": 1295543046.823504
        }
    }

## Logging

### Logging configuration

The logging system in BIND 10 is configured through the Logging module. All BIND 10 modules will look at the configuration in Logging to see what should be logged and to where.

#### Loggers

Within BIND 10, a message is logged through a component called a "logger". Different parts of BIND 10 log messages through different loggers, and each logger can be configured independently of one another.

In the Logging module, you can specify the configuration for zero or more loggers; any that are not specified will take appropriate default values.

The three most important elements of a logger configuration are the `name` (the component that is generating the messages), the `severity` (what to log), and the `output_options` (where to log).

##### name (string)

Each logger in the system has a name, the name being that of the component using it to log messages. For instance, if you want to configure logging for the resolver module, you add an entry for a logger named Resolver. This configuration will then be used by the loggers in the Resolver module, and all the libraries used by it.

If you want to specify logging for one specific library within the module, you set the name to module.library. For example, the logger used by the nameserver address store component has the full name of Resolver.nsas. If there is no entry in Logging for a particular library, it will use the configuration given for the module.

To illustrate this, suppose you want the cache library to log messages of severity DEBUG, and the rest of the resolver code to log messages of severity INFO. To achieve this you specify two loggers, one with the name Resolver and severity INFO, and one with the name Resolver.cache with severity DEBUG. As there are no entries for other libraries (e.g. the nsas), they will use the configuration for the module (Resolver), so giving the desired behavior.

One special case is that of a module name of * (asterisks), which is interpreted as any module. You can set global logging options by using this, including setting the logging configuration for a library that is used by multiple modules (e.g. *.config specifies the configuration library code in whatever module is using it).

If there are multiple logger specifications in the configuration that might match a particular logger, the specification with the more specific logger name takes precedence. For example, if there are entries for for both * and Resolver, the resolver module &mdash; and all libraries it uses &mdash; will log messages according to the configuration in the second entry (Resolver). All other modules will use the configuration of the first entry (*). If there was also a configuration entry for Resolver.cache, the cache library within the resolver would use that in preference to the entry for Resolver.

One final note about the naming. When specifying the module name within a logger, use the name of the module as specified in `bindctl`, e.g. Resolver for the resolver module, Xfrout for the xfrout module, etc. When the message is logged, the message will include the name of the logger generating the message, but with the module name replaced by the name of the process implementing the module (so for example, a message generated by the Auth.cache logger will appear in the output with a logger name of b10-auth.cache).

##### severity (string)

This specifies the category of messages logged. Each message is logged with an associated severity which may be one of the following (in descending order of severity):

- FATAL

- ERROR

- WARN

- INFO

- DEBUG

When the severity of a logger is set to one of these values, it will only log messages of that severity, and the severities above it. The severity may also be set to NONE, in which case all messages from that logger are inhibited.

##### output_options (list)

Each logger can have zero or more `output_options`. These specify where log messages are sent to. These are explained in detail below.

The other options for a logger are:

##### debuglevel (integer)

When a logger's severity is set to DEBUG, this value specifies what debug messages should be printed. It ranges from 0 (least verbose) to 99 (most verbose).

If severity for the logger is not DEBUG, this value is ignored.

##### additive (true or false)

If this is true, the `output_options` from the parent will be used. For example, if there are two loggers configured; Resolver and Resolver.cache, and `additive` is true in the second, it will write the log messages not only to the destinations specified for Resolver.cache, but also to the destinations as specified in the `output_options` in the logger named Resolver.

#### Output Options

The main settings for an output option are the `destination` and a value called `output`, the meaning of which depends on the destination that is set.

##### destination (string)

The destination is the type of output. It can be one of:

- console

- file

- syslog

##### output (string)

Depending on what is set as the output destination, this value is interpreted as follows:

`destination` is console

  The value of output must be one of stdout (messages printed to standard output) or stderr (messages printed to standard error).

  Note: if output is set to stderr and a lot of messages are produced in a short time (e.g. if the logging level is set to DEBUG), you may occasionally see some messages jumbled up together. This is due to a combination of the way that messages are written to the screen and the unbuffered nature of the standard error stream. If this occurs, it is recommended that output be set to stdout.

`destination` is file

  The value of output is interpreted as a file name; log messages will be appended to this file.

`destination` is syslog

  The value of output is interpreted as the `syslog` facility (e.g. local0) that should be used for log messages.

The other options for `output_options` are:

###### flush (true of false)

Flush buffers after each log message. Doing this will reduce performance but will ensure that if the program terminates abnormally, all messages up to the point of termination are output.

###### maxsize (integer)

Only relevant when destination is file, this is maximum file size of output files in bytes. When the maximum size is reached, the file is renamed and a new file opened. (For example, a ".1" is appended to the name &mdash; if a ".1" file exists, it is renamed ".2", etc.)

If this is 0, no maximum file size is used.

###### maxver (integer)

Maximum number of old log files to keep around when rolling the output file. Only relevant when `destination` is file.

#### Example session

In this example we want to set the global logging to write to the file `/var/log/my_bind10.log`, at severity WARN. We want the authoritative server to log at DEBUG with debuglevel 40, to a different file (`/tmp/debug_messages`).

Start `bindctl`.

    ["login success "]
    > config show Logging
    Logging/loggers	[]	list

By default, no specific loggers are configured, in which case the severity defaults to INFO and the output is written to stderr.

Let's first add a default logger:

    > config add Logging/loggers
    > config show Logging
    Logging/loggers/	list	(modified)

The loggers value line changed to indicate that it is no longer an empty list:

    > config show Logging/loggers
    Logging/loggers[0]/name	""	string	(default)
    Logging/loggers[0]/severity	"INFO"	string	(default)
    Logging/loggers[0]/debuglevel	0	integer	(default)
    Logging/loggers[0]/additive	false	boolean	(default)
    Logging/loggers[0]/output_options	[]	list	(default)

The name is mandatory, so we must set it. We will also change the severity as well. Let's start with the global logger.

    > config set Logging/loggers[0]/name *
    > config set Logging/loggers[0]/severity WARN
    > config show Logging/loggers
    Logging/loggers[0]/name	"*"	string	(modified)
    Logging/loggers[0]/severity	"WARN"	string	(modified)
    Logging/loggers[0]/debuglevel	0	integer	(default)
    Logging/loggers[0]/additive	false	boolean	(default)
    Logging/loggers[0]/output_options	[]	list	(default)

Of course, we need to specify where we want the log messages to go, so we add an entry for an output option.

    >  config add Logging/loggers[0]/output_options
    >  config show Logging/loggers[0]/output_options
    Logging/loggers[0]/output_options[0]/destination	"console"	string	(default)
    Logging/loggers[0]/output_options[0]/output	"stdout"	string	(default)
    Logging/loggers[0]/output_options[0]/flush	false	boolean	(default)
    Logging/loggers[0]/output_options[0]/maxsize	0	integer	(default)
    Logging/loggers[0]/output_options[0]/maxver	0	integer	(default)

These aren't the values we are looking for.

    >  config set Logging/loggers[0]/output_options[0]/destination file
    >  config set Logging/loggers[0]/output_options[0]/output /var/log/bind10.log
    >  config set Logging/loggers[0]/output_options[0]/maxsize 204800
    >  config set Logging/loggers[0]/output_options[0]/maxver 8

Which would make the entire configuration for this logger look like:

    >  config show all Logging/loggers
    Logging/loggers[0]/name	"*"	string	(modified)
    Logging/loggers[0]/severity	"WARN"	string	(modified)
    Logging/loggers[0]/debuglevel	0	integer	(default)
    Logging/loggers[0]/additive	false	boolean	(default)
    Logging/loggers[0]/output_options[0]/destination	"file"	string	(modified)
    Logging/loggers[0]/output_options[0]/output	"/var/log/bind10.log"	string	(modified)
    Logging/loggers[0]/output_options[0]/flush	false	boolean	(default)
    Logging/loggers[0]/output_options[0]/maxsize	204800	integer	(modified)
    Logging/loggers[0]/output_options[0]/maxver	8	integer	(modified)

That looks OK, so let's commit it before we add the configuration for the authoritative server's logger.

    >  config commit

Now that we have set it, and checked each value along the way, adding a second entry is quite similar.

    >  config add Logging/loggers
    >  config set Logging/loggers[1]/name Auth
    >  config set Logging/loggers[1]/severity DEBUG
    >  config set Logging/loggers[1]/debuglevel 40
    >  config add Logging/loggers[1]/output_options
    >  config set Logging/loggers[1]/output_options[0]/destination file
    >  config set Logging/loggers[1]/output_options[0]/output /tmp/auth_debug.log
    >  config commit

And that's it. Once we have found whatever it was we needed the debug messages for, we can simply remove the second logger to let the authoritative server use the same settings as the rest.

    >  config remove Logging/loggers[1]
    >  config commit

And every module will now be using the values from the logger named *.

### Logging Message Format

Each message written by BIND 10 to the configured logging destinations comprises a number of components that identify the origin of the message and, if the message indicates a problem, information about the problem that may be useful in fixing it.

Consider the message below logged to a file:

    2011-06-15 13:48:22.034 ERROR [b10-resolver.asiolink]
        ASIODNS_OPENSOCK error 111 opening TCP socket to 127.0.0.1(53)

Note: the layout of messages written to the system logging file (syslog) may be slightly different. This message has been split across two lines here for display reasons; in the logging file, it will appear on one line.)

The log message comprises a number of components:

2011-06-15 13:48:22.034

  The date and time at which the message was generated.

ERROR

  The severity of the message.

[b10-resolver.asiolink]

  The source of the message. This comprises two components: the BIND 10 process generating the message (in this case, `b10-resolver`) and the module within the program from which the message originated (which in the example is the asynchronous I/O link module, asiolink).

ASIODNS_OPENSOCK

  The message identification. Every message in BIND 10 has a unique identification, which can be used as an index into the BIND 10 Messages Manual () from which more information can be obtained.

error 111 opening TCP socket to 127.0.0.1(53)

  A brief description of the cause of the problem. Within this text, information relating to the condition that caused the message to be logged will be included. In this example, error number 111 (an operating system-specific error number) was encountered when trying to open a TCP connection to port 53 on the local system (address 127.0.0.1). The next step would be to find out the reason for the failure by consulting your system's documentation to identify what error number 111 means.