rndc.conf
— rndc configuration file
rndc.conf
rndc.conf
is the configuration file
for rndc, the BIND 9 name server control
utility. This file has a similar structure and syntax to
named.conf
. Statements are enclosed
in braces and terminated with a semi-colon. Clauses in
the statements are also semi-colon terminated. The usual
comment styles are supported:
C style: /* */
C++ style: // to end of line
Unix style: # to end of line
rndc.conf
is much simpler than
named.conf
. The file uses three
statements: an options statement, a server statement
and a key statement.
The options
statement contains five clauses.
The default-server
clause is followed by the
name or address of a name server. This host will be used when
no name server is given as an argument to
rndc. The default-key
clause is followed by the name of a key which is identified by
a key
statement. If no
keyid
is provided on the rndc command line,
and no key
clause is found in a matching
server
statement, this default key will be
used to authenticate the server's commands and responses. The
default-port
clause is followed by the port
to connect to on the remote name server. If no
port
option is provided on the rndc command
line, and no port
clause is found in a
matching server
statement, this default port
will be used to connect.
The default-source-address
and
default-source-address-v6
clauses which
can be used to set the IPv4 and IPv6 source addresses
respectively.
After the server
keyword, the server
statement includes a string which is the hostname or address
for a name server. The statement has three possible clauses:
key
, port
and
addresses
. The key name must match the
name of a key statement in the file. The port number
specifies the port to connect to. If an addresses
clause is supplied these addresses will be used instead of
the server name. Each address can take an optional port.
If an source-address
or source-address-v6
of supplied then these will be used to specify the IPv4 and IPv6
source addresses respectively.
The key
statement begins with an identifying
string, the name of the key. The statement has two clauses.
algorithm
identifies the authentication algorithm
for rndc to use; currently only HMAC-MD5
(for compatibility), HMAC-SHA1, HMAC-SHA224, HMAC-SHA256
(default), HMAC-SHA384 and HMAC-SHA512 are
supported. This is followed by a secret clause which contains
the base-64 encoding of the algorithm's authentication key. The
base-64 string is enclosed in double quotes.
There are two common ways to generate the base-64 string for the secret. The BIND 9 program rndc-confgen can be used to generate a random key, or the mmencode program, also known as mimencode, can be used to generate a base-64 string from known input. mmencode does not ship with BIND 9 but is available on many systems. See the EXAMPLE section for sample command lines for each.
options { default-server localhost; default-key samplekey; };
server localhost { key samplekey; };
server testserver { key testkey; addresses { localhost port 5353; }; };
key samplekey { algorithm hmac-sha256; secret "6FMfj43Osz4lyb24OIe2iGEz9lf1llJO+lz"; };
key testkey { algorithm hmac-sha256; secret "R3HI8P6BKw9ZwXwN3VZKuQ=="; };
In the above example, rndc will by default use the server at localhost (127.0.0.1) and the key called samplekey. Commands to the localhost server will use the samplekey key, which must also be defined in the server's configuration file with the same name and secret. The key statement indicates that samplekey uses the HMAC-SHA256 algorithm and its secret clause contains the base-64 encoding of the HMAC-SHA256 secret enclosed in double quotes.
If rndc -s testserver is used then rndc will connect to server on localhost port 5353 using the key testkey.
To generate a random secret with rndc-confgen:
rndc-confgen
A complete rndc.conf
file, including
the
randomly generated key, will be written to the standard
output. Commented-out key
and
controls
statements for
named.conf
are also printed.
To generate a base-64 secret with mmencode:
echo "known plaintext for a secret" | mmencode
BIND 9.10.2rc1