Dynamic Updates from DHCP

[Cricket Liu]

> I apologize in advance if this has already been addressed, I've searched
> around and can't find the answers.
>
> I'm running ISC bind and dhcp and am looking at implementing dhcp updating
> dns with client info instead of using WINS.
>
> We primarily have Windows 2k systems with Solaris back end.  I've found a
> lot of documentation talking about it but how do you actually set it up???
> What is the syntax in the dhcpd.conf or named.conf?

Well, it depends on whether you're using TSIG-signed dynamic updates
or unsigned dynamic updates.  I'll assume you're going to use TSIG.

The named.conf file has a key statement for the TSIG key, and the
zone statements for the forward- and reverse-mapping zones allow
updates signed with that key:

key dhcp-server.foo.example {
	algorithm hmac-md5;
	secret "<base64 secret>";
};

zone "foo.example" {
	type master;
	file "db.foo.example";
	allow-update { key dhcp-server.foo.example; };
};

The dhcpd.conf file tells the DHCP server the name of the forward-
mapping zone, the key to use to sign updates, and some information
about the zone to update:

ddns-domainname "foo.example";
ddns-update-style interim;
ignore client-updates;

key dhcp-server.foo.example. {
        algorithm hmac-md5;
        secret "<base64 secret>";
}

zone foo.example. {
        primary 127.0.0.1;
        key dhcp-server.foo.example.;
}

zone 0.168.192.in-addr.arpa. {
        primary 127.0.0.1;
        key dhcp-server.foo.example.;
}

Note that the syntax of the dhcpd.conf file is similar to, but not
the same as, that of named.conf.  In particular, there's no semicolon
to close the statement.

cricket

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