option

title: "option" date: 2019-09-20T19:00:00+02:00 draft: false

option

Name

option - configures a DHCP option

Description

The option plugin can be used to configure one or more DHCP options for clients requesting them. It provides some common names for well-known options but can also be used to configure custom DHCP options. See examples for more information. The option plugin may be used multiple times per server-block.

Syntax

option NAME VALUE...

• NAME is the well-known name of the option. See below for a list of supported names
• VALUE one or more values for the option. The actual format of the value depends on the option name.

option {
    NAME VALUE
    ...
}

The option plugin allows multiple DHCP options to be configured at once by using a {} block add adding multiple NAME/VALUE pairs (one per line).

Custom Options

Since the list of option names supported by this plugin is limited it is also possible to configure any DHCP option by specifying it the one-byte option code as the name (prefixed with 0x) and specify the payload as an hex encoded string. For example, the following is equal to option router 10.1.0.1:

option 0x03 0x0100010a

The option code and the required payload encoding can be looked up in the RFC defining the option you want to use.

Examples

10.1.0.1/24 {
    option router 10.1.0.1 10.1.0.2
    option nameserver 10.1.0.1 10.1.0.2
}

The next example has the same effect as the above one but this time using only one option directive

10.1.0.1/24 {
    option {
        router 10.1.0.1 10.1.0.2
        nameserver 10.1.0.1 10.1.0.2
    }
}

Supported Names

This plugin supports all options that are defined in the option package of NextDHCP so the below list might not be complete. Refer to the option package documentation for a list of all options.

router

Configures default gateways. Expects one or more IP addresses.

option router 10.1.0.1 10.1.0.2

nameserver

Configures the DNS servers. Expects one or more IP addresses.

option nameserver 8.8.8.8 1.1.1.1

ntp-server

Configures the time servers to use by clients. Expectes on or more IP addresses.

option ntp-server 1.2.3.4 10.1.1.1

broadcast-address

The boardcast address of the local network. Expects an IP address

option broadcast-address 192.168.0.255

netmask

Configures the netmask of the local network. Expects the mask to be in IP address format.

option netmask 255.255.255.0

hostname

Configures the hostname that should be used by the client

option hostname myhostname

domain-name

Configures the domain-name that should be used by the client.

option domain-name nextdhcp.io

tftp-server-name

This option is used to identify a TFTP server. (Option 66).

option tftp-server-name tftp.nextdhcp.io

tftp-server-addr

This option sets the TFTP server address (150). Note that RFC5859 defines this option with a higher priority than the tftp-server-name (66) option.

filename

The filename that should be loaded during PXE / network boot. (Option 67)

option filename pxe.0