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 two 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 -y option is provided on the rndc(1Mtcp) command line, and no key clause is found in a a matching server statement, this default key will be used to authenticate the server's commands and responses.
After the keyword server, the server statement is followed by a string which is the hostname or address for a name server. The statement has a single clause, key . The key name must match the name of a key statement in the file.
The key statement begins with an identifying string, the name of the key. The statement has two clauses. algorithm identifies the encryption algorithm for rndc to use; currently only HMAC-MD5 is supported. This is followed by a secret clause which contains the base-64 encoding of the algorithm's encryption 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 dnssec-keygen(1Mtcp) can be used to generate a random key, or mimencode(1), can be used to generate a base-64 string from known input. mimencode(1) does not ship with BIND 9 but is available on many systems. See the ``EXAMPLES'' section for sample command lines for each.
Host and key names must be quoted using double quotes if they match a keyword, such as having a key named "key".
options {
default-server localhost;
default-key samplekey;
};
server localhost {
key samplekey;
};
key samplekey {
algorithm hmac-md5;
secret "c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
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. The key statement indicates that samplekey uses the HMAC-MD5 algorithm and its secret clause contains the base-64 encoding of the HMAC-MD5 secret enclosed in double quotes.
To generate a random secret with dnssec-keygen(1Mtcp):
$ dnssec-keygen -a hmac-md5 -b 128 -n user rndc
The base-64 string will appear in two files, Krndc.+157.+{random}.key and Krndc.+157.+{random}.private . After extracting the key to be placed in the rndc.conf and named.conf(4tcp) key statements, the .key and .private files can be removed.
To generate a secret from known input with mimencode(1):
$ echo "known plaintext for a secret" | mimencode