NAME

       rndc.conf - rndc configuration file

SYNOPSIS

       rndc.conf

DESCRIPTION

       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 is 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 is
       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 is used to connect. The
       default-source-address and default-source-address-v6 clauses 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 are used instead of the server name. Each address can  take
       an  optional  port. If an source-address or source-address-v6 is supplied, it is used to specify the IPv4
       and IPv6 source address, 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.

EXAMPLE

          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 by default uses the  server  at  localhost  (127.0.0.1)  and  the  key  called
       "samplekey".  Commands to the localhost server 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 connects to the 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, is 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

NAME SERVER CONFIGURATION

       The name server must be configured to accept rndc connections and to recognize the key specified  in  the
       rndc.conf file, using the controls statement in named.conf. See the sections on the controls statement in
       the BIND 9 Administrator Reference Manual for details.

SEE ALSO

       rndc(8), rndc-confgen(8), mmencode(1), BIND 9 Administrator Reference Manual.

AUTHOR

       Internet Systems Consortium

COPYRIGHT

       2025, Internet Systems Consortium

9.20.10-1ubuntu1-Ubuntu                            2025-06-06                                       RNDC.CONF(5)