DHCP Data Store

All the data used by the Solaris DHCP server is maintained in a data store, which might be stored as plain text files, NIS+ tables, or binary-format files. While configuring the DHCP service, the administrator chooses the type of data store to be used. The section Choosing the Data Store describes the differences between the data stores. Data stores can be converted from one format to another using DHCP Manager or the dhcpconfig command.

You can also move data from one DHCP server's data store to another with export and import utilities that work with the data stores, even if the servers are using different data store formats. The entire content of a data store, or just some of the data within it, can be exported and imported using DHCP Manager or the dhcpconfig command.

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Note –

Any database or file format can be used for DHCP data storage if you want to develop your own code module to provide an interface between Solaris DHCP (server and management tools) and the database. Solaris DHCP Service Developer's Guide contains information for doing this.

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Within the Solaris DHCP data store are two types of tables, the contents of which you can view and manage by using either the DHCP Manager or command-line utilities. The data tables are:

• dhcptab table – Table of configuration information that can be passed to clients.

• DHCP network tables – Tables that contain information about the DHCP and BOOTP clients that reside on the network specified in the table name. For example, the network 134.20.0.0 would have a table whose name includes 134_20_0_0.

The dhcptab Table

The dhcptab table contains all the information that clients can obtain from the DHCP server. The DHCP server scans the dhcptab each time it starts. The file name of the dhcptab varies according to the data store used. For example, the dhcptab created by the NIS+ data store SUNWnisplus is SUNWnisplus1_dhcptab.

The DHCP protocol defines a number of standard items of information that can be passed to clients. These items are referred to as parameters, symbols, or options. Options are defined in the DHCP protocol by numeric codes and text labels, but without values. Some commonly used standard options are shown in the following table.

Table 1–1 Sample DHCP Standard Options

Code	Label	Description
1	Subnet	Subnet mask IP address
3	Router	IP address for router
6	DNSserv	IP address for DNS server
12	Hostname	Text string for client host name
15	DNSdmain	DNS domain name

Some options are automatically assigned values when the administrator provides information during server configuration. The administrator can also explicitly assign values to other options at a later time. Options and their values are passed to the client to provide configuration information. For example, the option/value pair, DNSdmain=Georgia.Peach.COM, sets the client's DNS domain name to Georgia.Peach.COM.

Options can be grouped with other options in containers known as macros, which makes it easier to pass information to a client. Some macros are created automatically during server configuration, and contain options that were assigned values during configuration. Macros can also contain other macros.

The format of the dhcptab table is described in dhcptab(4) man page. In DHCP Manager, all the information shown in the Options and Macros tabs comes from the dhcptab table. See About Options for more information about options, and About Macros for more information about macros.

Note that the dhcptab table should not be edited manually. You should use either the dhtadm command or DHCP Manager to create, delete, or modify options and macros.

DHCP Network Tables

A DHCP network table maps client identifiers to IP addresses and the configuration parameters associated with each address. The format of the network tables is described in the dhcp_network(4) man page. In DHCP Manager, all the information shown in the Addresses tab is acquired from the network tables.