This is the reference guide for BIND 10 version 1.0.0.
Copyright © 2010-2013 Internet Systems Consortium, Inc.
Abstract
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 1.0.0. 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 http://bind10.isc.org/docs.
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List of Tables
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BIND 10 is a sponsored development project, and would not be possible without the generous support of the sponsors.
JPRS and CIRA are Patron Level sponsors.
AFNIC, CNNIC, CZ.NIC, DENIC eG, Google, RIPE NCC, Registro.br, .nz Registry Services, and Technical Center of Internet are current sponsors.
Afilias, IIS.SE, Nominet, and SIDN were founding sponsors of the project.
Support for BIND 10 development of the DHCPv4 and DHCPv6 components is provided by Comcast.
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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 1.0.0.
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.
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 Section 3.3, “Building Requirements”.)
BIND 10 requires at least Python 3.1 (http://www.python.org/). It also works with Python 3.2.
BIND 10 uses the Botan crypto library for C++ (http://botan.randombit.net/). It requires at least Botan version 1.8.
BIND 10 uses the log4cplus C++ logging library (http://log4cplus.sourceforge.net/). It requires at least log4cplus version 1.0.3.
The authoritative DNS server uses SQLite3 (http://www.sqlite.org/). 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.
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 by running a single command, bind10. This command starts a master process, b10-init, which will start other required processes and other processes when configured. The processes that may be started have names starting with "b10-", including:
These do not need to be manually started independently.
Once BIND 10 is running, a few commands are used to interact directly with the system:
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.
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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.
Extract the tar file:
$ gzcat bind10-VERSION
.tar.gz | tar -xvf -
Go into the source and run configure:
$cd bind10-
$VERSION
./configure
Build it:
$ make
Install it as root (to default /usr/local):
$ make install
Create a user for yourself:
$ cd /usr/local/etc/bind10/
$ /usr/local/sbin/b10-cmdctl-usermgr
Start the server (as root):
$ /usr/local/sbin/bind10
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 username and password you used above to create a user.)
>config add Init/components b10-auth
>config set Init/components/b10-auth/special auth
>config set Init/components/b10-auth/kind needed
>config commit
>quit
Test it; for example:
$ dig @127.0.0.1 -c CH -t TXT version.bind
Load desired zone file(s), for example:
$ b10-loadzone -c '{"database_file": "/usr/local/var/bind10/zone.sqlite3"}'
your.zone.example.org
your.zone.file
(If you use the sqlite3 data source with the default DB file, you can omit the -c option).
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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.
The following is the standard, common layout of the complete BIND 10 installation:
bin/
—
general tools and diagnostic clients.
etc/bind10/
—
configuration files.
lib/
—
libraries and python modules.
libexec/bind10/
—
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 b10-init master process.
sbin/
—
commands used by the system administrator.
share/bind10/
—
configuration specifications.
share/doc/bind10/
—
this guide and other supplementary documentation.
share/man/
—
manual pages (online documentation).
var/bind10/
—
data source and configuration databases.
In addition to the run-time requirements (listed in Section 1.2, “Required Software at Run-time”), 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 (http://www.boost.org/). 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 http://bind10.isc.org/wiki/SystemSpecificNotes for system-specific installation tips.
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.)
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 ftp://ftp.isc.org/isc/bind10/. Periodic development snapshots may also be available.
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.
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:
/usr/local/
).
For additional instructions concerning the building and installation of BIND 10 DHCP, see Section 16.1, “DHCP Database Installation and Configuration”.
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.
After the configure step is complete, to build the executables from the C++ code and prepare the Python scripts, run:
$ make
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
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BIND 10 is started with the bind10 command. It runs the b10-init daemon which starts up the required processes, and will also restart some processes that exit unexpectedly. bind10 is the only command needed to start the BIND 10 system.
After starting the b10-msgq communications channel, b10-init 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 b10-init 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 Section 10.2, “Configuration to start processes”.
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.
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/msg_socket
for this interprocess communication.
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 Chapter 7, Remote control daemon.
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/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 b10-init master process (as covered in Chapter 4, Starting BIND 10 with bind10).
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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 — the user interface — 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/cmdctl-keyfile.pem
.
(A sample key is at
/usr/local/share/bind10/cmdctl-keyfile.pem
.)
It also uses a certificate located at
/usr/local/etc/bind10/cmdctl-certfile.pem
.
(A sample certificate is at
/usr/local/share/bind10/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/cmdctl-accounts.csv
.
This comma-delimited file lists the accounts with a user name,
hashed password, and salt.
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.
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/cmdctl-accounts.csv
);
cert_file
which defines the path to the
PEM certificate file (the default is
/usr/local/etc/bind10/cmdctl-certfile.pem
);
and
key_file
which defines the path to the
PEM private key file (the default is
/usr/local/etc/bind10/cmdctl-keyfile.pem
).
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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.
<address>
, --address=<address>
<certificate file>
, --certificate-chain=<certificate file>
<csv file>
default_user.csv
;
this option specifies the directory where this file is
stored and read from. When not specified,
~/.bind10/
is used.
<port number>
, --port=<port number>
<module> <command> [argument(s)]
For example, the Init module has a 'shutdown' command to shut down
BIND 10, with an optional argument 'help':
> Init 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'.
> 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:
> Init help
Module Init Master process
Available commands:
help Get help for module.
shutdown Shut down BIND 10
ping Ping the Init 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)
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"
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 Section 8.6.2, “Configuration data types”) are separated with the '/'
character, and list indices are identified with [<index>
]; for example:
Module/example/list[2]/foo
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": [] }
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 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 Init/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 Init/components example_module
config show Init/components/example_module
config remove Init/components example_module
> 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 /Init/components b10-auth
config set /Init/components/b10-auth/kind needed
config set /Init/components/b10-auth/special auth
!echo adding Xfrin component
config add /Init/components b10-xfrin
config set /Init/components/b10-xfrin/address Xfrin
config set /Init/components/b10-xfrin/kind dispensable
!echo adding Xfrout component
config add /Init/components b10-xfrout
config set /Init/components/b10-xfrout/address Xfrout
config set /Init/components/b10-xfrout/kind dispensable
!echo adding Zone Manager component
config add /Init/components b10-zonemgr
config set /Init/components/b10-zonemgr/address Zonemgr
config set /Init/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
<string>
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Some things are configured in the same or similar manner across many modules. So we show them here in one place.
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.
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):
The name of the key must be a valid DNS name.
The key ring lives in the configuration in "tsig_keys/keys". Most of the system uses the keys from there — 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.
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, called 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, ... ]
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 Section 9.1.2, “Key ring”). This property is applicable only to the DNS context.
More properties to match are planned — the destination address, ports, matches against the packet content.
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 — 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 — each subexpression is a similar dictionary, just not containing the "action" element. The "NOT" contains single subexpression. Their function should be obvious — "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.
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 — 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" } ]
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
Table of Contents
This chapter explains how to control and configure the b10-init parent. The startup of this resident process that runs the BIND 10 daemons is covered in Chapter 4, Starting BIND 10 with bind10.
The BIND 10 suite may be shut down by stopping the
parent b10-init process. This may be done
by running the Init shutdown
command
at the bindctl prompt.
The processes to be used can be configured for
b10-init to start, with the exception
of the required b10-sockcreator,
b10-msgq and b10-cfgmgr
components.
The configuration is in the Init/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 Init/components b10-resolver
>config set Init/components/b10-resolver/special resolver
>config set Init/components/b10-resolver/kind needed
>config set Init/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:
Table 10.1. 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 b10-init 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 Init/components b10-resolver-2
>config set Init/components/b10-resolver-2/special resolver
>config set Init/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 b10-init
may be listed by running Init show_processes
using bindctl.
Table of Contents
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 b10-init master process.
b10-auth is configured via the b10-cfgmgr configuration manager. The module name is “Auth”. The configuration data items are:
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
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 — 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
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:
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.
pid
argument to
select the process ID to stop.
(Note that the BIND 10 init process may restart this service
if configured.)
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 — one that serves things like
“AUTHORS.BIND.”. The IN class contains single SQLite3
data source with database file located at
/usr/local/var/bind10/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.
As mentioned, the type used by default is “sqlite3”.
It has single configuration option inside params
— 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.
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.
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):
In the current release, only the SQLite3 back end is used by b10-loadzone. 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.
Table of Contents
Incoming zones are transferred using the b10-xfrin process which is started by b10-init. 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.
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).
config set Xfrin/zones[0]/tsig_key "example.key
"
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.
The b10-zonemgr process is started by b10-init. 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.
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
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 Section 11.2, “Data Source Backends”.
The b10-xfrout process is started by b10-init. 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 Section 9.1.2, “Key ring”). 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 Section 9.2, “ACLs”.
The way to specify zone specific configuration (ACLs, etc) is likely to be changed.
Table of Contents
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 b10-init 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 Section 11.2, “Data Source Backends”), 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.
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 Init/components b10-ddns
>config set Init/components/b10-ddns/address DDNS
>config set Init/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.
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:
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 Section 9.1, “TSIG keys”).
The full description of ACLs can be found in Section 9.2, “ACLs”.
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.
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.
Table of Contents
The b10-resolver is an experimental proof of concept.
The b10-resolver daemon provides an iterative caching and forwarding DNS server. The process is started by b10-init.
The main b10-init 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 Init/components b10-resolver
>config set Init/components/b10-resolver/special resolver
>config set Init/components/b10-resolver/kind needed
>config set Init/components/b10-resolver/priority 10
>config commit
The master b10-init process 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 53config commit
(Replace the “2
”
as needed; run “config show
Resolver/listen_on
” if needed.)
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 Section 9.2, “ACLs”.
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.
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
Table of Contents
The 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 two server implementations, one for DHCPv4 and one for DHCPv6.
This chapter covers those parts of BIND 10 that are common to both servers. DHCPv4-specific details are covered in Chapter 17, The DHCPv4 Server, while those details specific to DHCPv6 are described in Chapter 18, The DHCPv6 Server
In this release of BIND 10, the DHCPv4 and DHCPv6 servers must be considered experimental.
BIND 10 DHCP stores its leases in a lease database. The software has been written in a way that makes it possible to choose which database product should be used to store the lease information. At present, only support for MySQL is provided, and that support must be explicitly included when BIND 10 is built. This section covers the building of BIND 10 with MySQL and the creation of the lease database.
Install MySQL according to the instructions for your system. The client development libraries must be installed.
Build and install BIND 10 as described in Chapter 3, Installation, with the following modification: to enable the MySQL database code, at the "configure" step (see Section 3.4.3, “Configure before the build”), specify the location of the MySQL configuration program "mysql_config" with the "--with-dhcp-mysql" 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.
The next task is to create both the lease database and the user under which the servers will access it. A number of steps are required:
1. Log into MySQL as "root":
$mysql -u root -p
Enter password::
mysql>
2. Create the database:
mysql> CREATE DATABASE database-name
;
... database-name
is the name you have chosen for the database.
3. Create the database tables:
mysql>CONNECT
mysql>database-name
;SOURCE
path-to-bind10
/share/bind10/dhcpdb_create.mysql
4. Create the user under which BIND 10 will access the database (and give it a password), then grant it access to the database tables:
mysql>CREATE USER '
mysql>user-name
'@'localhost' IDENTIFIED BY 'password
';GRANT ALL ON
database-name
.* TO 'user-name
'@'localhost';
5. Exit MySQL:
mysql>quit
Bye$
Table of Contents
b10-dhcp4 is the BIND 10 DHCPv4 server and, like other parts of BIND 10, is configured through the bindctl program.
After starting BIND 10 and entering bindctl, the first step in configuring the server is to add it to the list of running BIND 10 services.
>config add Init/components b10-dhcp4
>config set Init/components/b10-dhcp4/kind dispensable
>config commit
To remove b10-dhcp4 from the set of running services, the b10-dhcp4 is removed from list of Init components:
>config remove Init/components b10-dhcp4
>config commit
On 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.
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 the DHCPv4 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/valid-lifetime 4000 integer (default)
Dhcp4/option-data [] list (default)
Dhcp4/lease-database/type "memfile" string (default)
Dhcp4/lease-database/name "" string (default)
Dhcp4/lease-database/user "" string (default)
Dhcp4/lease-database/host "" string (default)
Dhcp4/lease-database/password "" string (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.
All leases issued by the server are stored in the lease database. Currently, the only supported database is MySQL [1], and so the server must be configured to access the correct database with the appropriate credentials.
Database access information must be configured for the DHCPv4 server, even if it has already been configured for the DHCPv6 server. The servers store their information independently, so each server can use a separate database or both servers can use the same database.
Database configuration is controlled through the Dhcp4/lease-database parameters. The type of the database must be set to MySQL (although the string entered is "mysql"):
> config set Dhcp4/lease-database/type "mysql"
Next, the name of the database is to hold the leases must be set: this is the name used when the lease database was created (see Section 16.1.3, “Create MySQL Database and BIND 10 User”).
> config set Dhcp4/lease-database/name "database-name
"
If the database is located on a different system to the DHCPv4 server, the database host name must also be specified (although note that this configuration may have a severe impact on server performance):
> config set Dhcp4/lease-database/host "remote-host-name
"
The usual state of affairs will be to have the database on the same machine as the DHCPv4 server. In this case, set the value to the empty string (this is the default):
> config set Dhcp4/lease-database/host ""
Finally, the credentials of the account under which the server will access the database should be set:
>config set Dhcp4/lease-database/user "
>user-name
"config set Dhcp4/lease-database/password "
password
"
If there is no password to the account, set the password to the empty string "". (This is also the default.)
The password is echoed when entered and is stored in clear text in the BIND 10 configuration database. Improved password security will be added in a future version of BIND 10 DHCP
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 command 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 the "min-max" notation.
One of the major features of DHCPv4 server is to provide configuration options to clients. Although there are several options that require special behavior, most options are sent by the server only if the client explicitly requested them. The following example shows how to configure DNS servers, which is one of the most frequently used options. Options specified in this way are considered global and apply to all configured subnets.
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "domain-name-servers"
>config set Dhcp4/option-data[0]/code 6
>config set Dhcp4/option-data[0]/space "dhcp4"
>config set Dhcp4/option-data[0]/csv-format true
>config set Dhcp4/option-data[0]/data "192.0.3.1, 192.0.3.2"
>config commit
The first line creates new entry in option-data table. It contains information on all global options that the server is supposed to configure in all subnets. The second line specifies option name. For a complete list of currently supported names, see Table 17.1, “List of standard DHCPv4 options” below. The third line specifies option code, which must match one of the values from that list. Line 4 specifies option space, which must always be set to "dhcp4" as these are standard DHCPv4 options. For other option spaces, including custom option spaces, see Section 17.2.6, “Nested DHCPv4 options (custom option spaces)”. The fifth line specifies the format in which the data will be entered: use of CSV (comma separated values) is recommended. The sixth line gives the actual value to be sent to clients. Data is specified as a normal text, with values separated by commas if more than one value is allowed.
Options can also be configured as hexadecimal values. If csv-format is set to false, option data must be specified as a hex string. The following commands configure the domain-name-servers option for all subnets with the following addresses: 192.0.3.1 and 192.0.3.2. Note that csv-format is set to false.
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "domain-name-servers"
>config set Dhcp4/option-data[0]/code 6
>config set Dhcp4/option-data[0]/space "dhcp4"
>config set Dhcp4/option-data[0]/csv-format false
>config set Dhcp4/option-data[0]/data "C0 00 03 01 C0 00 03 02"
>config commit
It is possible to override options on a per-subnet basis. If clients connected to most of your subnets are expected to get the same values of a given option, you should use global options: you can then override specific values for a small number of subnets. On the other hand, if you use different values in each subnet, it does not make sense to specify global option values (Dhcp4/option-data), rather you should set only subnet-specific values (Dhcp4/subnet[X]/option-data[Y]).
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 Dhcp4/subnet4[0]/option-data
>config set Dhcp4/subnet4[0]/option-data[0]/name "domain-name-servers"
>config set Dhcp4/subnet4[0]/option-data[0]/code 6
>config set Dhcp4/subnet4[0]/option-data[0]/space "dhcp4"
>config set Dhcp4/subnet4[0]/option-data[0]/csv-format true
>config set Dhcp4/subnet4[0]/option-data[0]/data "192.0.2.3"
>config commit
In a future version of Kea, it will not be necessary to specify the option code, space and csv-format fields as they will be set automatically.
Below is a list of currently supported standard DHCPv4 options. The "Name" and "Code" are the values that should be used as a name in the option-data structures. "Type" designates the format of the data: the meanings of the various types is given in Table 17.2, “List of standard DHCP option types”.
Some options are designated as arrays, which means that more than one value is allowed in such an option. For example the option time-servers allows the specification of more than one IPv4 address, so allowing clients to obtain the the addresses of multiple NTP servers.
Name | Code | Type | Array? |
---|---|---|---|
subnet-mask | 1 | ipv4-address | false |
time-offset | 2 | uint32 | false |
routers | 3 | ipv4-address | true |
time-servers | 4 | ipv4-address | true |
name-servers | 5 | ipv4-address | false |
domain-name-servers | 6 | ipv4-address | true |
log-servers | 7 | ipv4-address | true |
cookie-servers | 8 | ipv4-address | true |
lpr-servers | 9 | ipv4-address | true |
impress-servers | 10 | ipv4-address | true |
resource-location-servers | 11 | ipv4-address | true |
host-name | 12 | string | false |
boot-size | 13 | uint16 | false |
merit-dump | 14 | string | false |
domain-name | 15 | fqdn | false |
swap-server | 16 | ipv4-address | false |
root-path | 17 | string | false |
extensions-path | 18 | string | false |
ip-forwarding | 19 | boolean | false |
non-local-source-routing | 20 | boolean | false |
policy-filter | 21 | ipv4-address | true |
max-dgram-reassembly | 22 | uint16 | false |
default-ip-ttl | 23 | uint8 | false |
path-mtu-aging-timeout | 24 | uint32 | false |
path-mtu-plateau-table | 25 | uint16 | true |
interface-mtu | 26 | uint16 | false |
all-subnets-local | 27 | boolean | false |
broadcast-address | 28 | ipv4-address | false |
perform-mask-discovery | 29 | boolean | false |
mask-supplier | 30 | boolean | false |
router-discovery | 31 | boolean | false |
router-solicitation-address | 32 | ipv4-address | false |
static-routes | 33 | ipv4-address | true |
trailer-encapsulation | 34 | boolean | false |
arp-cache-timeout | 35 | uint32 | false |
ieee802-3-encapsulation | 36 | boolean | false |
default-tcp-ttl | 37 | uint8 | false |
tcp-keepalive-internal | 38 | uint32 | false |
tcp-keepalive-garbage | 39 | boolean | false |
nis-domain | 40 | string | false |
nis-servers | 41 | ipv4-address | true |
ntp-servers | 42 | ipv4-address | true |
vendor-encapsulated-options | 43 | empty | false |
netbios-name-servers | 44 | ipv4-address | true |
netbios-dd-server | 45 | ipv4-address | true |
netbios-node-type | 46 | uint8 | false |
netbios-scope | 47 | string | false |
font-servers | 48 | ipv4-address | true |
x-display-manager | 49 | ipv4-address | true |
dhcp-requested-address | 50 | ipv4-address | false |
dhcp-option-overload | 52 | uint8 | false |
dhcp-message | 56 | string | false |
dhcp-max-message-size | 57 | uint16 | false |
vendor-class-identifier | 60 | binary | false |
nwip-domain-name | 62 | string | false |
nwip-suboptions | 63 | binary | false |
user-class | 77 | binary | false |
fqdn | 81 | record | false |
dhcp-agent-options | 82 | empty | false |
authenticate | 90 | binary | false |
client-last-transaction-time | 91 | uint32 | false |
associated-ip | 92 | ipv4-address | true |
subnet-selection | 118 | ipv4-address | false |
domain-search | 119 | binary | false |
vivco-suboptions | 124 | binary | false |
vivso-suboptions | 125 | binary | false |
Name | Meaning |
---|---|
binary | An arbitrary string of bytes, specified as a set of hexadecimal digits. |
boolean | Boolean value with allowed values true or false |
empty | No value, data is carried in suboptions |
fqdn | Fully qualified domain name (e.g. www.example.com) |
ipv4-address | IPv4 address in the usual dotted-decimal notation (e.g. 192.0.2.1) |
ipv6-address | IPv6 address in the usual colon notation (e.g. 2001:db8::1) |
record | Structured data that may comprise any types (except "record" and "empty") |
string | Any text |
uint8 | 8 bit unsigned integer with allowed values 0 to 255 |
uint16 | 16 bit unsinged integer with allowed values 0 to 65535 |
uint32 | 32 bit unsigned integer with allowed values 0 to 4294967295 |
It is also possible to define options other than the standard ones. Assume that we want to define a new DHCPv4 option called "foo" which will have code 222 and will convey a single unsigned 32 bit integer value. We can define such an option by using the following commands:
>config add Dhcp4/option-def
>config set Dhcp4/option-def[0]/name "foo"
>config set Dhcp4/option-def[0]/code 222
>config set Dhcp4/option-def[0]/type "uint32"
>config set Dhcp4/option-def[0]/array false
>config set Dhcp4/option-def[0]/record-types ""
>config set Dhcp4/option-def[0]/space "dhcp4"
>config set Dhcp4/option-def[0]/encapsulate ""
>config commit
The "false" value of the "array" parameter determines that the option does NOT comprise an array of "uint32" values but rather a single value. Two other parameters have been left blank: "record-types" and "encapsulate". The former specifies the comma separated list of option data fields if the option comprises a record of data fields. The "record-fields" value should be non-empty if the "type" is set to "record". Otherwise it must be left blank. The latter parameter specifies the name of the option space being encapsulated by the particular option. If the particular option does not encapsulate any option space it should be left blank. Note that the above set of comments define the format of the new option and do not set its values.
In the current release the default values are not propagated to the parser when the new configuration is being set. Therefore, all parameters must be specified at all times, even if their values are left blank.
Once the new option format is defined, its value is set in the same way as for a standard option. For example the following commands set a global value that applies to all subnets.
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "foo"
>config set Dhcp4/option-data[0]/code 222
>config set Dhcp4/option-data[0]/space "dhcp4"
>config set Dhcp4/option-data[0]/csv-format true
>config set Dhcp4/option-data[0]/data "12345"
>config commit
New options can take more complex forms than simple use of primitives (uint8, string, ipv4-address etc): it is possible to define an option comprising a number of existing primitives.
Assume we want to define a new option that will consist of an IPv4 address, followed by unsigned 16 bit integer, followed by a text string. Such an option could be defined in the following way:
>config add Dhcp4/option-def
>config set Dhcp4/option-def[0]/name "bar"
>config set Dhcp4/option-def[0]/code 223
>config set Dhcp4/option-def[0]/space "dhcp4"
>config set Dhcp4/option-def[0]/type "record"
>config set Dhcp4/option-def[0]/array false
>config set Dhcp4/option-def[0]/record-types "ipv4-address, uint16, string"
>config set Dhcp4/option-def[0]/encapsulate ""
The "type" is set to "record" to indicate that the option contains multiple values of different types. These types are given as a comma-separated list in the "record-types" field and should be those listed in Table 17.2, “List of standard DHCP option types”.
The values of the option are set as follows:
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "bar"
>config set Dhcp4/option-data[0]/space "dhcp4"
>config set Dhcp4/option-data[0]/code 223
>config set Dhcp4/option-data[0]/csv-format true
>config set Dhcp4/option-data[0]/data "192.0.2.100, 123, Hello World"
>config commit
"csv-format" is set "true" to indicate that the "data" field comprises a command-separated list of values. The values in the "data" must correspond to the types set in the "record-types" field of the option definition.
Currently there are three option spaces defined: dhcp4 (to be used in DHCPv4 daemon) and dhcp6 (for the DHCPv6 daemon); there is also vendor-encapsulated-options-space, which is empty by default, but options can be defined in it. Those options are called vendor-specific information options. The following examples show how to define an option "foo" with code 1 that consists of an IPv4 address, an unsigned 16 bit integer and a string. The "foo" option is conveyed in a vendor specific information option.
The first step is to define the format of the option:
>config add Dhcp4/option-def
>config set Dhcp4/option-def[0]/name "foo"
>config set Dhcp4/option-def[0]/code 1
>config set Dhcp4/option-def[0]/space "vendor-encapsulated-options-space"
>config set Dhcp4/option-def[0]/type "record"
>config set Dhcp4/option-def[0]/array false
>config set Dhcp4/option-def[0]/record-types "ipv4-address, uint16, string"
>config set Dhcp4/option-def[0]/encapsulates ""
>config commit
(Note that the option space is set to "vendor-encapsulated-options-space".) Once the option format is defined, the next step is to define actual values for that option:
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "foo"
>config set Dhcp4/option-data[0]/space "vendor-encapsulated-options-space"
>config set Dhcp4/option-data[0]/code 1
>config set Dhcp4/option-data[0]/csv-format true
>config set Dhcp4/option-data[0]/data "192.0.2.3, 123, Hello World"
>config commit
We also set up a dummy value for vendor-opts, the option that conveys our sub-option "foo". This is required else the option will not be included in messages sent to the client.
>config add Dhcp4/option-data
>config set Dhcp4/option-data[1]/name "vendor-encapsulated-options"
>config set Dhcp4/option-data[1]/space "dhcp4"
>config set Dhcp4/option-data[1]/code 43
>config set Dhcp4/option-data[1]/csv-format false
>config set Dhcp4/option-data[1]/data ""
>config commit
With this version of BIND 10, the "vendor-encapsulated-options" option must be specified in the configuration although it has no configurable parameters. If it is not specified, the server will assume that it is not configured and will not send it to a client. In the future there will be no need to include this option in the configuration.
It is sometimes useful to define completely new option space. This is the case when user creates new option in the standard option space ("dhcp4 or "dhcp6") and wants this option to convey sub-options. Thanks to being in the separate space, sub-option codes will have a separate numbering scheme and may overlap with codes of standard options.
Note that creation of a new option space when defining sub-options for a standard option is not required, because it is created by default if the standard option is meant to convey any sub-options (see Section 17.2.5, “DHCPv4 vendor specific options”).
Assume that we want to have a DHCPv4 option called "container" with code 222 that conveys two sub-options with codes 1 and 2. First we need to define the new sub-options:
>config add Dhcp4/option-def
>config set Dhcp4/option-def[0]/name "subopt1"
>config set Dhcp4/option-def[0]/code 1
>config set Dhcp4/option-def[0]/space "isc"
>config set Dhcp4/option-def[0]/type "ipv4-address"
>config set Dhcp4/option-def[0]/record-types ""
>config set Dhcp4/option-def[0]/array false
>config set Dhcp4/option-def[0]/encapsulate ""
>config commit
>config add Dhcp4/option-def
>config set Dhcp4/option-def[1]/name "subopt2"
>config set Dhcp4/option-def[1]/code 2
>config set Dhcp4/option-def[1]/space "isc"
>config set Dhcp4/option-def[1]/type "string"
>config set Dhcp4/option-def[1]/record-types ""
>config set Dhcp4/option-def[1]/array false
>config set Dhcp4/option-def[1]/encapsulate ""
>config commit
Note that we have defined the options to belong to a new option space (in this case, "isc").
The next step is to define a regular DHCPv4 option with our desired code and specify that it should include options from the new option space:
>add Dhcp4/option-def
>set Dhcp4/option-def[2]/name "container"
>set Dhcp4/option-def[2]/code 222
>set Dhcp4/option-def[2]/space "dhcp4"
>set Dhcp4/option-def[2]/type "empty"
>set Dhcp4/option-def[2]/array false
>set Dhcp4/option-def[2]/record-types ""
>set Dhcp4/option-def[2]/encapsulate "isc"
>commit
The name of the option space in which the sub-options are defined is set in the "encapsulate" field. The "type" field is set to "empty" to indicate that this option does not carry any data other than sub-options.
Finally, we can set values for the new options:
>config add Dhcp4/option-data
>config set Dhcp4/option-data[0]/name "subopt1"
>config set Dhcp4/option-data[0]/space "isc"
>config set Dhcp4/option-data[0]/code 1
>config set Dhcp4/option-data[0]/csv-format true
>config set Dhcp4/option-data[0]/data "192.0.2.3"
>config commit
>
config add Dhcp4/option-data
>config set Dhcp4/option-data[1]/name "subopt2"
>config set Dhcp4/option-data[1]/space "isc"
>config set Dhcp4/option-data[1]/code 2
>config set Dhcp4/option-data[1]/csv-format true
>config set Dhcp4/option-data[1]/data "Hello world"
>config commit
>
config add Dhcp4/option-data
>config set Dhcp4/option-data[2]/name "container"
>config set Dhcp4/option-data[2]/space "dhcp4"
>config set Dhcp4/option-data[2]/code 222
>config set Dhcp4/option-data[2]/csv-format true
>config set Dhcp4/option-data[2]/data ""
>config commit
Even though the "container" option does not carry any data except sub-options, the "data" field must be explictly set to an empty value. This is required because in the current version of BIND 10 DHCP, the default configuration values are not propagated to the configuration parsers: if the "data" is not set the parser will assume that this parameter is not specified and an error will be reported.
Note that it is possible to create an option which carries some data in addition to the sub-options defined in the encapsulated option space. For example, if the "container" option from the previous example was required to carry an uint16 value as well as the sub-options, the "type" value would have to be set to "uint16" in the option definition. (Such an option would then have the following data structure: DHCP header, uint16 value, sub-options.) The value specified with the "data" parameter - which should be a valid integer enclosed in quotes, e.g. "123" - would then be assigned to the uint16 field in the "container" option.
The DHCPv4 protocol uses a "server identifier" for clients to be able to discriminate between several servers present on the same link: this value is an IPv4 address of the server. When started for the first time, the DHCPv4 server will choose one of its IPv4 addresses as its server-id, and store the chosen value to a file. That file will be read by the server and the contained value used whenever the server is subsequently started.
It is unlikely that this parameter should ever need to be changed. However, if such a need arises, stop the server, edit the file and restart the server. (The file is named b10-dhcp4-serverid and by default is stored in the "var" subdirectory of the directory in which BIND 10 is installed. This can be changed when BIND 10 is built by using "--localstatedir" on the "configure" command line.) The file is a text file that should contain an IPv4 address. Spaces are ignored, and no extra characters are allowed in this file.
The following standards and draft standards are currently supported:
These are the current limitations of the DHCPv4 server software. Most of them are reflections of the current stage of development and should be treated as “not implemented yet”, rather than actual limitations.
On startup, the DHCPv4 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 Dhcp4/renew-timer
Dhcp4/renew-timer 1000 integer (default) >config set Dhcp4/renew-timer 1001
>config commit
[1] The server comes with an in-memory database ("memfile") configured as the default database. This is used for internal testing and is not supported. In addition, it does not store lease information on disk: lease information will be lost if the server is restarted.
Table of Contents
b10-dhcp6 is the BIND 10 DHCPv6 server and, like other parts of BIND 10, is configured through the bindctl program.
After starting BIND 10 and starting bindctl, the first step in configuring the server is to add b10-dhcp6 to the list of running BIND 10 services.
>config add Init/components b10-dhcp6
>config set Init/components/b10-dhcp6/kind dispensable
>config commit
To remove b10-dhcp6 from the set of running services, the b10-dhcp4 is removed from list of Init components:
>config remove Init/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.
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/ list (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/option-data [] list (default)
Dhcp6/lease-database/type "memfile" string (default)
Dhcp6/lease-database/name "" string (default)
Dhcp6/lease-database/user "" string (default)
Dhcp6/lease-database/host "" string (default)
Dhcp6/lease-database/password "" string (default)
Dhcp6/subnet6/ list
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.
With this version of BIND 10, there are a number of known limitations and problems in the DHCPv6 server. See Section 18.5, “DHCPv6 Server Limitations”.
All leases issued by the server are stored in the lease database. Currently, the only supported database is MySQL [2], and so the server must be configured to access the correct database with the appropriate credentials.
Database access information must be configured for the DHCPv6 server, even if it has already been configured for the DHCPv4 server. The servers store their information independently, so each server can use a separate database or both servers can use the same database.
Database configuration is controlled through the Dhcp6/lease-database parameters. The type of the database must be set to MySQL (although the string entered is "mysql"):
> config set Dhcp6/lease-database/type "mysql"
Next, the name of the database is to hold the leases must be set: this is the name used when the lease database was created (see Section 16.1.3, “Create MySQL Database and BIND 10 User”).
> config set Dhcp6/lease-database/name "database-name
"
If the database is located on a different system to the DHCPv6 server, the database host name must also be specified (although note that this configuration may have a severe impact on server performance):
> config set Dhcp6/lease-database/host "remote-host-name
"
The usual state of affairs will be to have the database on the same machine as the DHCPv6 server. In this case, set the value to the empty string (this is the default):
> config set Dhcp6/lease-database/host ""
Finally, the credentials of the account under which the server will access the database should be set:
>config set Dhcp6/lease-database/user "
>user-name
"config set Dhcp6/lease-database/password "
password
"
If there is no password to the account, set the password to the empty string "". (This is also the default.)
The password is echoed when entered and is stored in clear text in the BIND 10 configuration database. Improved password security will be added in a future version of BIND 10 DHCP
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 command 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 the "min-max" notation.
One of the major features of DHCPv6 server is to provide configuration options to clients. Although there are several options that require special behavior, most options are sent by the server only if the client explicitly requested them. The following example shows how to configure DNS servers, which is one of the most frequently used options. Numbers in the first column are added for easier reference and will not appear on screen. Options specified in this way are considered global and apply to all configured subnets.
1. >config add Dhcp6/option-data
2. >config set Dhcp6/option-data[0]/name "dns-servers"
3. >config set Dhcp6/option-data[0]/code 23
4. >config set Dhcp6/option-data[0]/space "dhcp6"
5. >config set Dhcp6/option-data[0]/csv-format true
6. >config set Dhcp6/option-data[0]/data "2001:db8::cafe, 2001:db8::babe"
7. >config commit
The first line creates new entry in option-data table. It contains information on all global options that the server is supposed to configure in all subnets. The second line specifies option name. For a complete list of currently supported names, see Table 18.1, “List of standard DHCPv6 options” below. The third line specifies option code, which must match one of the values from that list. Line 4 specifies option space, which must always be set to "dhcp6" as these are standard DHCPv6 options. For other name spaces, including custom option spaces, see Section 18.2.6, “Nested DHCPv6 options (custom option spaces)”. The fifth line specifies the format in which the data will be entered: use of CSV (comma separated values) is recommended. The sixth line gives the actual value to be sent to clients. Data is specified as a normal text, with values separated by commas if more than one value is allowed.
Options can also be configured as hexadecimal values. If csv-format is set to false, the option data must be specified as a string of hexadecimal numbers. The following commands configure the DNS-SERVERS option for all subnets with the following addresses: 2001:db8:1::cafe and 2001:db8:1::babe.
>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]/space "dhcp6"
>config set Dhcp6/option-data[0]/csv-format false
>config set Dhcp6/option-data[0]/data "2001 0DB8 0001 0000 0000 0000
0000 CAFE 2001 0DB8 0001 0000 0000 0000 0000 BABE"
>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, the whole string should be entered on the same line.)
It is possible to override options on a per-subnet basis. If clients connected to most of your subnets are expected to get the same values of a given option, you should use global options: you can then override specific values for a small number of subnets. On the other hand, if you use different values in each subnet, it does not make sense to specify global option values (Dhcp6/option-data), rather you should set only subnet-specific values (Dhcp6/subnet[X]/option-data[Y]).
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]/space "dhcp6"
>config set Dhcp6/subnet6[0]/option-data[0]/csv-format true
>config set Dhcp6/subnet6[0]/option-data[0]/data "2001:db8:1::3"
>config commit
In future versions of BIND 10 DHCP, it will not be necessary to specify option code, space and csv-format fields, as those fields will be set automatically.
Below is a list of currently supported standard DHCPv6 options. The "Name" and "Code" are the values that should be used as a name in the option-data structures. "Type" designates the format of the data: the meanings of the various types is given in Table 17.2, “List of standard DHCP option types”.
Some options are designated as arrays, which means that more than one value is allowed in such an option. For example the option dns-servers allows the specification of more than one IPv6 address, so allowing clients to obtain the the addresses of multiple DNS servers.
Name | Code | Type | Array? |
---|---|---|---|
preference | 7 | uint8 | false |
sip-server-dns | 21 | fqdn | true |
sip-server-addr | 22 | ipv6-address | true |
dns-servers | 23 | ipv6-address | true |
domain-search | 24 | fqdn | true |
nis-servers | 27 | ipv6-address | true |
nisp-servers | 28 | ipv6-address | true |
nis-domain-name | 29 | fqdn | true |
nisp-domain-name | 30 | fqdn | true |
sntp-servers | 31 | ipv6-address | true |
information-refresh-time | 32 | uint32 | false |
bcmcs-server-dns | 33 | fqdn | true |
bcmcs-server-addr | 34 | ipv6-address | true |
geoconf-civic | 36 | record | false |
remote-id | 37 | record | false |
subscriber-id | 38 | binary | false |
client-fqdn | 39 | record | false |
pana-agent | 40 | ipv6-address | true |
new-posix-timezone | 41 | string | false |
new-tzdb-timezone | 42 | string | false |
ero | 43 | uint16 | true |
lq-query | 44 | record | false |
client-data | 45 | empty | false |
clt-time | 46 | uint32 | false |
lq-relay-data | 47 | record | false |
lq-client-link | 48 | ipv6-address | true |
It is also possible to define options other than the standard ones. Assume that we want to define a new DHCPv6 option called "foo" which will have code 100 and will convey a single unsigned 32 bit integer value. We can define such an option by using the following commands:
>config add Dhcp6/option-def
>config set Dhcp6/option-def[0]/name "foo"
>config set Dhcp6/option-def[0]/code 100
>config set Dhcp6/option-def[0]/type "uint32"
>config set Dhcp6/option-def[0]/array false
>config set Dhcp6/option-def[0]/record-types ""
>config set Dhcp6/option-def[0]/space "dhcp6"
>config set Dhcp6/option-def[0]/encapsulate ""
>config commit
The "false" value of the "array" parameter determines that the option does NOT comprise an array of "uint32" values but rather a single value. Two other parameters have been left blank: "record-types" and "encapsulate". The former specifies the comma separated list of option data fields if the option comprises a record of data fields. The "record-fields" value should be non-empty if the "type" is set to "record". Otherwise it must be left blank. The latter parameter specifies the name of the option space being encapsulated by the particular option. If the particular option does not encapsulate any option space it should be left blank. Note that the above set of comments define the format of the new option and do not set its values.
Once the new option format is defined, its value is set in the same way as for a standard option. For example the following commands set a global value that applies to all subnets.
>config add Dhcp6/option-data
>config set Dhcp6/option-data[0]/name "foo"
>config set Dhcp6/option-data[0]/code 100
>config set Dhcp6/option-data[0]/space "dhcp6"
>config set Dhcp6/option-data[0]/csv-format true
>config set Dhcp6/option-data[0]/data "12345"
>config commit
New options can take more complex forms than simple use of primitives (uint8, string, ipv6-address etc): it is possible to define an option comprising a number of existing primitives.
Assume we want to define a new option that will consist of an IPv6 address, followed by unsigned 16 bit integer, followed by a text string. Such an option could be defined in the following way:
>config add Dhcp6/option-def
>config set Dhcp6/option-def[0]/name "bar"
>config set Dhcp6/option-def[0]/code 101
>config set Dhcp6/option-def[0]/space "dhcp6"
>config set Dhcp6/option-def[0]/type "record"
>config set Dhcp6/option-def[0]/array false
>config set Dhcp6/option-def[0]/record-types "ipv6-address, uint16, string"
>config set Dhcp6/option-def[0]/encapsulate ""
The "type" is set to "record" to indicate that the option contains multiple values of different types. These types are given as a comma-separated list in the "record-types" field and should be those listed in Table 17.2, “List of standard DHCP option types”.
The values of the option are set as follows:
>config add Dhcp6/option-data
>config set Dhcp6/option-data[0]/name "bar"
>config set Dhcp6/option-data[0]/space "dhcp6"
>config set Dhcp6/option-data[0]/code 101
>config set Dhcp6/option-data[0]/csv-format true
>config set Dhcp6/option-data[0]/data "2001:db8:1::10, 123, Hello World"
>config commit
"csv-format" is set "true" to indicate that the "data" field comprises a command-separated list of values. The values in the "data" must correspond to the types set in the "record-types" field of the option definition.
Currently there are three option spaces defined: dhcp4 (to be used in DHCPv4 daemon) and dhcp6 (for the DHCPv6 daemon); there is also vendor-opts-space, which is empty by default, but options can be defined in it. Those options are called vendor-specific information options. The following examples show how to define an option "foo" with code 1 that consists of an IPv6 address, an unsigned 16 bit integer and a string. The "foo" option is conveyed in a vendor specific information option. This option comprises a single uint32 value that is set to "12345". The sub-option "foo" follows the data field holding this value.
>config add Dhcp6/option-def
>config set Dhcp6/option-def[0]/name "foo"
>config set Dhcp6/option-def[0]/code 1
>config set Dhcp6/option-def[0]/space "vendor-opts-space"
>config set Dhcp6/option-def[0]/type "record"
>config set Dhcp6/option-def[0]/array false
>config set Dhcp6/option-def[0]/record-types "ipv6-address, uint16, string"
>config set Dhcp6/option-def[0]/encapsulates ""
>config commit
(Note that the option space is set to "vendor-opts-space".) Once the option format is defined, the next step is to define actual values for that option:
>config add Dhcp6/option-data
>config set Dhcp6/option-data[0]/name "foo"
>config set Dhcp6/option-data[0]/space "vendor-opts-space"
>config set Dhcp6/option-data[0]/code 1
>config set Dhcp6/option-data[0]/csv-format true
>config set Dhcp6/option-data[0]/data "2001:db8:1::10, 123, Hello World"
>config commit
We should also define values for the vendor-opts, that will convey our option foo.
>config add Dhcp6/option-data
>config set Dhcp6/option-data[1]/name "vendor-opts"
>config set Dhcp6/option-data[1]/space "dhcp6"
>config set Dhcp6/option-data[1]/code 17
>config set Dhcp6/option-data[1]/csv-format true
>config set Dhcp6/option-data[1]/data "12345"
>config commit
It is sometimes useful to define completely new option spaces. This is useful if the user wants his new option to convey sub-options that use separate numbering scheme, for example sub-options with codes 1 and 2. Those option codes conflict with standard DHCPv6 options, so a separate option space must be defined.
Note that it is not required to create new option space when defining sub-options for a standard option because it is by default created if the standard option is meant to convey any sub-options (see Section 18.2.5, “DHCPv6 vendor specific options”).
Assume that we want to have a DHCPv6 option called "container" with code 102 that conveys two sub-options with codes 1 and 2. First we need to define the new sub-options:
>config add Dhcp6/option-def
>config set Dhcp6/option-def[0]/name "subopt1"
>config set Dhcp6/option-def[0]/code 1
>config set Dhcp6/option-def[0]/space "isc"
>config set Dhcp6/option-def[0]/type "ipv6-address"
>config set Dhcp6/option-def[0]/record-types ""
>config set Dhcp6/option-def[0]/array false
>config set Dhcp6/option-def[0]/encapsulate ""
>config commit
>>
config add Dhcp6/option-def
>config set Dhcp6/option-def[1]/name "subopt2"
>config set Dhcp6/option-def[1]/code 2
>config set Dhcp6/option-def[1]/space "isc"
>config set Dhcp6/option-def[1]/type "string"
>config set Dhcp6/option-def[1]/record-types ""
>config set Dhcp6/option-def[1]/array false
>config set Dhcp6/option-def[1]/encapsulate ""
>config commit
Note that we have defined the options to belong to a new option space (in this case, "isc").
The next step is to define a regular DHCPv6 option and specify that it should include options from the isc option space:
>config add Dhcp6/option-def
>config set Dhcp6/option-def[2]/name "container"
>config set Dhcp6/option-def[2]/code 102
>config set Dhcp6/option-def[2]/space "dhcp6"
>config set Dhcp6/option-def[2]/type "empty"
>config set Dhcp6/option-def[2]/array false
>config set Dhcp6/option-def[2]/record-types ""
>config set Dhcp6/option-def[2]/encapsulate "isc"
>config commit
The name of the option space in which the sub-options are defined is set in the "encapsulate" field. The "type" field is set to "empty" which imposes that this option does not carry any data other than sub-options.
Finally, we can set values for the new options:
>config add Dhcp6/option-data
>config set Dhcp6/option-data[0]/name "subopt1"
>config set Dhcp6/option-data[0]/space "isc"
>config set Dhcp6/option-data[0]/code 1
>config set Dhcp6/option-data[0]/csv-format true
>config set Dhcp6/option-data[0]/data "2001:db8::abcd"
>config commit
>>
config add Dhcp6/option-data
>config set Dhcp6/option-data[1]/name "subopt2"
>config set Dhcp6/option-data[1]/space "isc"
>config set Dhcp6/option-data[1]/code 2
>config set Dhcp6/option-data[1]/csv-format true
>config set Dhcp6/option-data[1]/data "Hello world"
>config commit
>>
config add Dhcp6/option-data
>config set Dhcp6/option-data[2]/name "container"
>config set Dhcp6/option-data[2]/space "dhcp6"
>config set Dhcp6/option-data[2]/code 102
>config set Dhcp6/option-data[2]/csv-format true
>config set Dhcp6/option-data[2]/data ""
>config commit
Even though the "container" option does not carry any data except sub-options, the "data" field must be explictly set to an empty value. This is required because in the current version of BIND 10 DHCP, the default configuration values are not propagated to the configuration parsers: if the "data" is not set the parser will assume that this parameter is not specified and an error will be reported.
Note that it is possible to create an option which carries some data in addition to the sub-options defined in the encapsulated option space. For example, if the "container" option from the previous example was required to carry an uint16 value as well as the sub-options, the "type" value would have to be set to "uint16" in the option definition. (Such an option would then have the following data structure: DHCP header, uint16 value, sub-options.) The value specified with the "data" parameter - which should be a valid integer enclosed in quotes, e.g. "123" - would then be assigned to the uint16 field in the "container" option.
The DHCPv6 server may receive requests from local (connected to the same subnet as the server) and remote (connecting via relays) clients.
Currently relayed DHCPv6 traffic is not supported. The server will only respond to local DHCPv6 requests - see Section 18.5, “DHCPv6 Server Limitations”
As it may have many subnet configurations defined, it must select appropriate subnet for a given request. To do this, the server first checks if there is only one subnet defined and source of the packet is link-local. If this is the case, the server assumes that the only subnet defined is local and client is indeed connected to it. This check simplifies small deployments.
If there are two or more subnets defined, the server can not assume which of those (if any) subnets are local. Therefore an optional "interface" parameter is available within a subnet definition to designate that a given subnet is local, i.e. reachable directly over specified interface. For example the server that is intended to serve a local subnet over eth0 may be configured as follows:
>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 set Dhcp6/subnet6[1]/interface "eth0"
>config commit
The DHCPv6 protocol uses a "server identifier" (also known as a DUID) for clients to be able to discriminate between several servers present on the same link. There are several types of DUIDs defined, but RFC 3315 instructs servers to use DUID-LLT if possible. This format consists of a link-layer (MAC) address and a timestamp. When started for the first time, the DHCPv6 server will automatically generate such a DUID and store the chosen value to a file. That file is read by the server and the contained value used whenever the server is subsequently started.
It is unlikely that this parameter should ever need to be changed. However, if such a need arises, stop the server, edit the file and restart the server. (The file is named b10-dhcp6-serverid and by default is stored in the "var" subdirectory of the directory in which BIND 10 is installed. This can be changed when BIND 10 is built by using "--localstatedir" on the "configure" command line.) The file is a text file that contains double digit hexadecimal values separated by colons. This format is similar to typical MAC address format. Spaces are ignored. No extra characters are allowed in this file.
The following standards and draft standards are currently supported:
These are the current limitations and known problems with 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.
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
[2] The server comes with an in-memory database ("memfile") configured as the default database. This is used for internal testing and is not supported. In addition, it does not store lease information on disk: lease information will be lost if the server is restarted.
Table of Contents
libdhcp++ is a common library written in C++ that handles many DHCP-related tasks, including:
While this library is currently used by BIND 10 DHCP, it is designed to be a portable, universal library, useful for any kind of DHCP-related software.
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.
The b10-stats process is started by b10-init. 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
},
"Init": {
"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
}
}
Table of Contents
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.
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).
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 both “*” and “Resolver”, the resolver module — and all libraries it uses — 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”).
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):
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.
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:
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.
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”.
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.
The destination is the type of output. It can be one of:
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 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.
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 — if a ".1" file exists, it is renamed ".2", etc.)
If this is 0, no maximum file size is used.
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 “*”.
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:
The date and time at which the message was generated.
The severity of the message.
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).
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 (http://bind10.isc.org/docs/bind10-messages.html) from which more information can be obtained.
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.