1643 lines
55 KiB
Groff
1643 lines
55 KiB
Groff
.\" $Id: dhcp-options.5,v 1.1 2007/11/12 23:16:08 dcantrel Exp $
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.\"
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.\" Copyright (c) 2004-2007 by Internet Systems Consortium, Inc. ("ISC")
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.\" Copyright (c) 1996-2003 by Internet Software Consortium
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.\" Internet Systems Consortium, Inc.
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.\" 950 Charter Street
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.\" Redwood City, CA 94063
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.\" <info@isc.org>
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.\" http://www.isc.org/
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.\"
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.\" This software has been written for Internet Systems Consortium
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.\" by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
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.\" To learn more about Internet Systems Consortium, see
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.\" ``http://www.isc.org/''. To learn more about Vixie Enterprises,
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.\" see ``http://www.vix.com''. To learn more about Nominum, Inc., see
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.\" ``http://www.nominum.com''.
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.TH dhcpd-options 5
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.SH NAME
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dhcp-options - Dynamic Host Configuration Protocol options
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.SH DESCRIPTION
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The Dynamic Host Configuration protocol allows the client to receive
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.B options
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from the DHCP server describing the network configuration and various
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services that are available on the network. When configuring
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.B dhcpd(8)
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or
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.B dhclient(8) ,
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options must often be declared. The syntax for declaring options,
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and the names and formats of the options that can be declared, are
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documented here.
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.SH REFERENCE: OPTION STATEMENTS
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.PP
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DHCP \fIoption\fR statements always start with the \fIoption\fR
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keyword, followed by an option name, followed by option data. The
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option names and data formats are described below. It is not
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necessary to exhaustively specify all DHCP options - only those
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options which are needed by clients must be specified.
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.PP
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Option data comes in a variety of formats, as defined below:
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.PP
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The
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.B ip-address
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data type can be entered either as an explicit IP
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address (e.g., 239.254.197.10) or as a domain name (e.g.,
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haagen.isc.org). When entering a domain name, be sure that that
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domain name resolves to a single IP address.
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.PP
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The
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.B int32
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data type specifies a signed 32-bit integer. The
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.B uint32
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data type specifies an unsigned 32-bit integer. The
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.B int16
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and
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.B uint16
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data types specify signed and unsigned 16-bit integers. The
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.B int8
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and
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.B uint8
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data types specify signed and unsigned 8-bit integers.
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Unsigned 8-bit integers are also sometimes referred to as octets.
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.PP
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The
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.B text
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data type specifies an NVT ASCII string, which must be
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enclosed in double quotes - for example, to specify a root-path
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option, the syntax would be
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.nf
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.sp 1
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option root-path "10.0.1.4:/var/tmp/rootfs";
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.fi
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.PP
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The
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.B domain-name
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data type specifies a domain name, which must not
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enclosed in double quotes. This data type is not used for any
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existing DHCP options. The domain name is stored just as if it were
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a text option.
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.PP
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The
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.B domain-list
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data type specifies a list of domain names, a space between each name and
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the entire string enclosed in double quotes. These types of data are used
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for the domain-search option for example, and encodes an RFC1035 compressed
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DNS label list on the wire.
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.PP
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The
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.B flag
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data type specifies a boolean value. Booleans can be either true or
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false (or on or off, if that makes more sense to you).
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.PP
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The
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.B string
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data type specifies either an NVT ASCII string
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enclosed in double quotes, or a series of octets specified in
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hexadecimal, separated by colons. For example:
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.nf
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.sp 1
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option dhcp-client-identifier "CLIENT-FOO";
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or
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option dhcp-client-identifier 43:4c:49:45:54:2d:46:4f:4f;
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.fi
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.SH SETTING OPTION VALUES USING EXPRESSIONS
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Sometimes it's helpful to be able to set the value of a DHCP option
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based on some value that the client has sent. To do this, you can
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use expression evaluation. The
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.B dhcp-eval(5)
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manual page describes how to write expressions. To assign the result
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of an evaluation to an option, define the option as follows:
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.nf
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.sp 1
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\fBoption \fImy-option \fB= \fIexpression \fB;\fR
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.fi
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.PP
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For example:
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.nf
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.sp 1
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option hostname = binary-to-ascii (16, 8, "-",
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substring (hardware, 1, 6));
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.fi
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.SH STANDARD DHCP OPTIONS
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The documentation for the various options mentioned below is taken
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from the latest IETF draft document on DHCP options. Options not
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listed below may not yet be implemented, but it is possible to use
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such options by defining them in the configuration file. Please see
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the DEFINING NEW OPTIONS heading later in this document for more
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information.
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.PP
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Some of the options documented here are automatically generated by
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the DHCP server or by clients, and cannot be configured by the user.
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The value of such an option can be used in the configuration file of
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the receiving DHCP protocol agent (server or client), for example in
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conditional expressions. However, the value of the option cannot be
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used in the configuration file of the sending agent, because the value
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is determined only \fIafter\fR the configuration file has been
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processed. In the following documentation, such options will be shown
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as "not user configurable"
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.PP
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The standard options are:
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.PP
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.B option \fBall-subnets-local\fR \fIflag\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies whether or not the client may assume that all
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subnets of the IP network to which the client is connected use the
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same MTU as the subnet of that network to which the client is
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directly connected. A value of true indicates that all subnets share
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the same MTU. A value of false means that the client should assume that
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some subnets of the directly connected network may have smaller MTUs.
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.RE
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.PP
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.B option \fBarp-cache-timeout\fR \fIuint32\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the timeout in seconds for ARP cache entries.
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.RE
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.PP
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.B option \fBbcms-controller-address\fR \fIip-address\fR [\fB,\fR
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\fIip-address\fR... ]\fB;\fR
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.RS 0.25i
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.PP
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This option configures a list of IPv4 addresses for use as Broadcast and
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Multicast Controller Servers ("BCMS").
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.RE
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.PP
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.B option \fBbootfile-name\fR \fItext\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used to identify a bootstrap file. If supported by the
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client, it should have the same effect as the \fBfilename\fR
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declaration. BOOTP clients are unlikely to support this option. Some
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DHCP clients will support it, and others actually require it.
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.RE
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.PP
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.B option \fBboot-size\fR \fIuint16\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the length in 512-octet blocks of the default
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boot image for the client.
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.RE
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.PP
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.B option \fBbroadcast-address\fR \fIip-address\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the broadcast address in use on the client's
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subnet. Legal values for broadcast addresses are specified in
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section 3.2.1.3 of STD 3 (RFC1122).
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.RE
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.PP
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.B option \fBcookie-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
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]\fB;\fR
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.RS 0.25i
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.PP
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The cookie server option specifies a list of RFC 865 cookie
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servers available to the client. Servers should be listed in order
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of preference.
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.RE
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.PP
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.B option \fBdefault-ip-ttl\fR \fIuint8;\fR
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.RS 0.25i
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.PP
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This option specifies the default time-to-live that the client should
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use on outgoing datagrams.
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.RE
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.PP
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.B option \fBdefault-tcp-ttl\fR \fIuint8\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the default TTL that the client should use when
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sending TCP segments. The minimum value is 1.
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.RE
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.PP
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.B option \fBdefault-url\fR \fIstring\fR\fB;\fR
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.RS 0.25i
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.PP
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The format and meaning of this option is not described in any standards
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document, but is claimed to be in use by Apple Computer. It is not known
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what clients may reasonably do if supplied with this option. Use at your
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own risk.
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.RE
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.PP
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.B option \fBdhcp-client-identifier\fR \fIstring\fR\fB;\fR
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.RS 0.25i
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.PP
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This option can be used to specify a DHCP client identifier in a
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host declaration, so that dhcpd can find the host record by matching
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against the client identifier.
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.PP
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Please be aware that some DHCP clients, when configured with client
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identifiers that are ASCII text, will prepend a zero to the ASCII
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text. So you may need to write:
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.nf
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option dhcp-client-identifier "\\0foo";
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rather than:
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option dhcp-client-identifier "foo";
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.fi
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.RE
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.PP
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.B option \fBdhcp-lease-time\fR \fIuint32\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used in a client request (DHCPDISCOVER or DHCPREQUEST)
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to allow the client to request a lease time for the IP address. In a
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server reply (DHCPOFFER), a DHCP server uses this option to specify
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the lease time it is willing to offer.
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.PP
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This option is not directly user configurable in the server; refer to the
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\fImax-lease-time\fR and \fIdefault-lease-time\fR server options in
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.B dhcpd.conf(5).
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.RE
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.PP
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.B option \fBdhcp-max-message-size\fR \fIuint16\fR\fB;\fR
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.RS 0.25i
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.PP
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This option, when sent by the client, specifies the maximum size of
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any response that the server sends to the client. When specified on
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the server, if the client did not send a dhcp-max-message-size option,
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the size specified on the server is used. This works for BOOTP as
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well as DHCP responses.
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.RE
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.PP
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.B option \fBdhcp-message\fR \fItext\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used by a DHCP server to provide an error message to a
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DHCP client in a DHCPNAK message in the event of a failure. A client
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may use this option in a DHCPDECLINE message to indicate why the
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client declined the offered parameters.
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.PP
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This option is not user configurable.
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.RE
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.PP
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.B option \fBdhcp-message-type\fR \fIuint8\fR\fB;\fR
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.RS 0.25i
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.PP
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This option, sent by both client and server, specifies the type of DHCP
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message contained in the DHCP packet. Possible values (taken directly from
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RFC2132) are:
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.PP
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.nf
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1 DHCPDISCOVER
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2 DHCPOFFER
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3 DHCPREQUEST
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4 DHCPDECLINE
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5 DHCPACK
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6 DHCPNAK
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7 DHCPRELEASE
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8 DHCPINFORM
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.fi
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.PP
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This option is not user configurable.
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.PP
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.RE
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.B option \fBdhcp-option-overload\fR \fIuint8\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used to indicate that the DHCP 'sname' or 'file'
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fields are being overloaded by using them to carry DHCP options. A
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DHCP server inserts this option if the returned parameters will
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exceed the usual space allotted for options.
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.PP
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If this option is present, the client interprets the specified
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additional fields after it concludes interpretation of the standard
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option fields.
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.PP
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Legal values for this option are:
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.PP
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.nf
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1 the 'file' field is used to hold options
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2 the 'sname' field is used to hold options
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3 both fields are used to hold options
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.fi
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.PP
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This option is not user configurable.
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.PP
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.RE
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.PP
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.B option \fBdhcp-parameter-request-list\fR \fIuint16\fR\fB;\fR
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.RS 0.25i
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.PP
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This option, when sent by the client, specifies which options the
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client wishes the server to return. Normally, in the ISC DHCP
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client, this is done using the \fIrequest\fR statement. If this
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option is not specified by the client, the DHCP server will normally
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return every option that is valid in scope and that fits into the
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reply. When this option is specified on the server, the server
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returns the specified options. This can be used to force a client to
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take options that it hasn't requested, and it can also be used to
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tailor the response of the DHCP server for clients that may need a
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more limited set of options than those the server would normally
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return.
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.RE
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.PP
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.B option \fBdhcp-rebinding-time\fR \fIuint32\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the number of seconds from the time a client gets
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an address until the client transitions to the REBINDING state.
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.PP
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This option is not user configurable.
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.PP
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.RE
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.PP
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.B option \fBdhcp-renewal-time\fR \fIuint32\fR\fB;\fR
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.RS 0.25i
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.PP
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This option specifies the number of seconds from the time a client gets
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an address until the client transitions to the RENEWING state.
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.PP
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This option is not user configurable.
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.PP
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.RE
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.PP
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.B option \fBdhcp-requested-address\fR \fIip-address\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used by the client in a DHCPDISCOVER to
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request that a particular IP address be assigned.
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.PP
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This option is not user configurable.
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.PP
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.RE
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.PP
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.B option \fBdhcp-server-identifier\fR \fIip-address\fR\fB;\fR
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.RS 0.25i
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.PP
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This option is used in DHCPOFFER and DHCPREQUEST messages, and may
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optionally be included in the DHCPACK and DHCPNAK messages. DHCP
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servers include this option in the DHCPOFFER in order to allow the
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client to distinguish between lease offers. DHCP clients use the
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contents of the 'server identifier' field as the destination address
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for any DHCP messages unicast to the DHCP server. DHCP clients also
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indicate which of several lease offers is being accepted by including
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this option in a DHCPREQUEST message.
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.PP
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The value of this option is the IP address of the server.
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.PP
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This option is not directly user configurable. See the
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\fIserver-identifier\fR server option in
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.B \fIdhcpd.conf(5).
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.PP
|
|
.RE
|
|
.PP
|
|
.B option \fBdomain-name\fR \fItext\fR\fB;\fR
|
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.RS 0.25i
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.PP
|
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This option specifies the domain name that client should use when
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resolving hostnames via the Domain Name System.
|
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.RE
|
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.PP
|
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.B option \fBdomain-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
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]\fB;\fR
|
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.RS 0.25i
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.PP
|
|
The domain-name-servers option specifies a list of Domain Name System
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(STD 13, RFC 1035) name servers available to the client. Servers
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should be listed in order of preference.
|
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.RE
|
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.PP
|
|
.B option \fBdomain-search\fR \fIstring\fR\fB;\fR
|
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.RS 0.25i
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.PP
|
|
The domain-search option specifies a 'search list' of Domain Names to be
|
|
used by the client to locate not-fully-qualified domain names. The difference
|
|
between this option and historic use of the domain-name option for the same
|
|
ends is that this option is encoded in RFC1035 compressed labels on the wire.
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|
.RE
|
|
.PP
|
|
.B option \fBextensions-path\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
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|
.PP
|
|
This option specifies the name of a file containing additional options
|
|
to be interpreted according to the DHCP option format as specified in
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|
RFC2132.
|
|
.RE
|
|
.PP
|
|
.B option \fBfinger-server\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The Finger server option specifies a list of Finger servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBfont-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of X Window System Font servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBhost-name\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the name of the client. The name may or may
|
|
not be qualified with the local domain name (it is preferable to use
|
|
the domain-name option to specify the domain name). See RFC 1035 for
|
|
character set restrictions. This option is only honored by
|
|
.B dhclient-script(8)
|
|
if the hostname for the client machine is not set.
|
|
.RE
|
|
.PP
|
|
.B option \fBieee802-3-encapsulation\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should use Ethernet
|
|
Version 2 (RFC 894) or IEEE 802.3 (RFC 1042) encapsulation if the
|
|
interface is an Ethernet. A value of false indicates that the client
|
|
should use RFC 894 encapsulation. A value of true means that the client
|
|
should use RFC 1042 encapsulation.
|
|
.RE
|
|
.PP
|
|
.B option \fBien116-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
];
|
|
.RS 0.25i
|
|
.PP
|
|
The ien116-name-servers option specifies a list of IEN 116 name servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBimpress-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The impress-server option specifies a list of Imagen Impress servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBinterface-mtu\fR \fIuint16\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the MTU to use on this interface. The minimum
|
|
legal value for the MTU is 68.
|
|
.RE
|
|
.PP
|
|
.B option \fBip-forwarding\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether the client should configure its IP
|
|
layer for packet forwarding. A value of false means disable IP
|
|
forwarding, and a value of true means enable IP forwarding.
|
|
.RE
|
|
.PP
|
|
.B option \fBirc-server\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The IRC server option specifies a list of IRC servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBlog-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The log-server option specifies a list of MIT-LCS UDP log servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBlpr-servers\fR \fIip-address \fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The LPR server option specifies a list of RFC 1179 line printer
|
|
servers available to the client. Servers should be listed in order
|
|
of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBmask-supplier\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should respond to
|
|
subnet mask requests using ICMP. A value of false indicates that the
|
|
client should not respond. A value of true means that the client should
|
|
respond.
|
|
.RE
|
|
.PP
|
|
.B option \fBmax-dgram-reassembly\fR \fIuint16\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the maximum size datagram that the client
|
|
should be prepared to reassemble. The minimum legal value is
|
|
576.
|
|
.RE
|
|
.PP
|
|
.B option \fBmerit-dump\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the path-name of a file to which the client's
|
|
core image should be dumped in the event the client crashes. The
|
|
path is formatted as a character string consisting of characters from
|
|
the NVT ASCII character set.
|
|
.RE
|
|
.PP
|
|
.B option \fBmobile-ip-home-agent\fR \fIip-address\fR [\fB,\fR \fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of IP addresses indicating mobile IP
|
|
home agents available to the client. Agents should be listed in
|
|
order of preference, although normally there will be only one such
|
|
agent.
|
|
.RE
|
|
.PP
|
|
.B option \fBnds-context\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The nds-context option specifies the name of the initial Netware
|
|
Directory Service for an NDS client.
|
|
.RE
|
|
.PP
|
|
.B option \fBnds-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The nds-servers option specifies a list of IP addresses of NDS servers.
|
|
.RE
|
|
.PP
|
|
.B option \fBnds-tree-name\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The nds-tree-name option specifies NDS tree name that the NDS client
|
|
should use.
|
|
.RE
|
|
.PP
|
|
.B option \fBnetbios-dd-server\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The NetBIOS datagram distribution server (NBDD) option specifies a
|
|
list of RFC 1001/1002 NBDD servers listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBnetbios-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The NetBIOS name server (NBNS) option specifies a list of RFC
|
|
1001/1002 NBNS name servers listed in order of preference. NetBIOS
|
|
Name Service is currently more commonly referred to as WINS. WINS
|
|
servers can be specified using the netbios-name-servers option.
|
|
.RE
|
|
.PP
|
|
.B option \fBnetbios-node-type\fR \fIuint8\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The NetBIOS node type option allows NetBIOS over TCP/IP clients which
|
|
are configurable to be configured as described in RFC 1001/1002. The
|
|
value is specified as a single octet which identifies the client type.
|
|
.PP
|
|
Possible node types are:
|
|
.PP
|
|
.TP 5
|
|
.I 1
|
|
B-node: Broadcast - no WINS
|
|
.TP
|
|
.I 2
|
|
P-node: Peer - WINS only
|
|
.TP
|
|
.I 4
|
|
M-node: Mixed - broadcast, then WINS
|
|
.TP
|
|
.I 8
|
|
H-node: Hybrid - WINS, then broadcast
|
|
.RE
|
|
.PP
|
|
.B option \fBnetbios-scope\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The NetBIOS scope option specifies the NetBIOS over TCP/IP scope
|
|
parameter for the client as specified in RFC 1001/1002. See RFC1001,
|
|
RFC1002, and RFC1035 for character-set restrictions.
|
|
.RE
|
|
.PP
|
|
.B option \fBnetinfo-server-address\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The \fBnetinfo-server-address\fR option has not been described in any
|
|
RFC, but has been allocated (and is claimed to be in use) by Apple
|
|
Computers. It's hard to say if the above is the correct format, or
|
|
what clients might be expected to do if values were configured. Use
|
|
at your own risk.
|
|
.RE
|
|
.PP
|
|
.B option \fBnetinfo-server-tag\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The \fBnetinfo-server-tag\fR option has not been described in any
|
|
RFC, but has been allocated (and is claimed to be in use) by Apple
|
|
Computers. It's hard to say if the above is the correct format,
|
|
or what clients might be expected to do if values were configured. Use
|
|
at your own risk.
|
|
.RE
|
|
.PP
|
|
.B option \fBnis-domain\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the name of the client's NIS (Sun Network
|
|
Information Services) domain. The domain is formatted as a character
|
|
string consisting of characters from the NVT ASCII character set.
|
|
.RE
|
|
.PP
|
|
.B option \fBnis-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of IP addresses indicating NIS servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBnisplus-domain\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the name of the client's NIS+ domain. The
|
|
domain is formatted as a character string consisting of characters
|
|
from the NVT ASCII character set.
|
|
.RE
|
|
.PP
|
|
.B option \fBnisplus-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of IP addresses indicating NIS+ servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBnntp-server\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The NNTP server option specifies a list of NNTP servesr available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBnon-local-source-routing\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether the client should configure its IP
|
|
layer to allow forwarding of datagrams with non-local source routes
|
|
(see Section 3.3.5 of [4] for a discussion of this topic). A value
|
|
of false means disallow forwarding of such datagrams, and a value of true
|
|
means allow forwarding.
|
|
.RE
|
|
.PP
|
|
.B option \fBntp-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of IP addresses indicating NTP (RFC 1035)
|
|
servers available to the client. Servers should be listed in order
|
|
of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip-domain\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The name of the NetWare/IP domain that a NetWare/IP client should
|
|
use.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip-suboptions\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
A sequence of suboptions for NetWare/IP clients - see RFC2242 for
|
|
details. Normally this option is set by specifying specific
|
|
NetWare/IP suboptions - see the NETWARE/IP SUBOPTIONS section for more
|
|
information.
|
|
.RE
|
|
.PP
|
|
.B option \fBpath-mtu-aging-timeout\fR \fIuint32\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the timeout (in seconds) to use when aging Path
|
|
MTU values discovered by the mechanism defined in RFC 1191.
|
|
.RE
|
|
.PP
|
|
.B option \fBpath-mtu-plateau-table\fR \fIuint16\fR [\fB,\fR \fIuint16\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a table of MTU sizes to use when performing
|
|
Path MTU Discovery as defined in RFC 1191. The table is formatted as
|
|
a list of 16-bit unsigned integers, ordered from smallest to largest.
|
|
The minimum MTU value cannot be smaller than 68.
|
|
.RE
|
|
.PP
|
|
.B option \fBperform-mask-discovery\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should perform subnet
|
|
mask discovery using ICMP. A value of false indicates that the client
|
|
should not perform mask discovery. A value of true means that the
|
|
client should perform mask discovery.
|
|
.RE
|
|
.PP
|
|
.nf
|
|
.B option \fBpolicy-filter\fR \fIip-address ip-address\fR
|
|
[\fB,\fR \fIip-address ip-address\fR...]\fB;\fR
|
|
.RE
|
|
.fi
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies policy filters for non-local source routing.
|
|
The filters consist of a list of IP addresses and masks which specify
|
|
destination/mask pairs with which to filter incoming source routes.
|
|
.PP
|
|
Any source routed datagram whose next-hop address does not match one
|
|
of the filters should be discarded by the client.
|
|
.PP
|
|
See STD 3 (RFC1122) for further information.
|
|
.RE
|
|
.PP
|
|
.B option \fBpop-server\fR \fIip-address\fR [\fB,\fR \fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The POP3 server option specifies a list of POP3 servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBresource-location-servers\fR \fIip-address\fR
|
|
[\fB, \fR\fIip-address\fR...]\fB;\fR
|
|
.fi
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of RFC 887 Resource Location
|
|
servers available to the client. Servers should be listed in order
|
|
of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBroot-path\fR \fItext\fB;\fR\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the path-name that contains the client's root
|
|
disk. The path is formatted as a character string consisting of
|
|
characters from the NVT ASCII character set.
|
|
.RE
|
|
.PP
|
|
.B option \fBrouter-discovery\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should solicit
|
|
routers using the Router Discovery mechanism defined in RFC 1256.
|
|
A value of false indicates that the client should not perform
|
|
router discovery. A value of true means that the client should perform
|
|
router discovery.
|
|
.RE
|
|
.PP
|
|
.B option \fBrouter-solicitation-address\fR \fIip-address\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the address to which the client should transmit
|
|
router solicitation requests.
|
|
.RE
|
|
.PP
|
|
.B option routers \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The routers option specifies a list of IP addresses for routers on the
|
|
client's subnet. Routers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option slp-directory-agent \fIboolean ip-address
|
|
[\fB,\fR \fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies two things: the IP addresses of one or more
|
|
Service Location Protocol Directory Agents, and whether the use of
|
|
these addresses is mandatory. If the initial boolean value is true,
|
|
the SLP agent should just use the IP addresses given. If the value
|
|
is false, the SLP agent may additionally do active or passive
|
|
multicast discovery of SLP agents (see RFC2165 for details).
|
|
.PP
|
|
Please note that in this option and the slp-service-scope option, the
|
|
term "SLP Agent" is being used to refer to a Service Location Protocol
|
|
agent running on a machine that is being configured using the DHCP
|
|
protocol.
|
|
.PP
|
|
Also, please be aware that some companies may refer to SLP as NDS.
|
|
If you have an NDS directory agent whose address you need to
|
|
configure, the slp-directory-agent option should work.
|
|
.RE
|
|
.PP
|
|
.B option slp-service-scope \fIboolean text\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The Service Location Protocol Service Scope Option specifies two
|
|
things: a list of service scopes for SLP, and whether the use of this
|
|
list is mandatory. If the initial boolean value is true, the SLP
|
|
agent should only use the list of scopes provided in this option;
|
|
otherwise, it may use its own static configuration in preference to
|
|
the list provided in this option.
|
|
.PP
|
|
The text string should be a comma-separated list of scopes that the
|
|
SLP agent should use. It may be omitted, in which case the SLP Agent
|
|
will use the aggregated list of scopes of all directory agents known
|
|
to the SLP agent.
|
|
.RE
|
|
.PP
|
|
.B option \fBsmtp-server\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The SMTP server option specifies a list of SMTP servers available to
|
|
the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.nf
|
|
.B option \fBstatic-routes\fR \fIip-address ip-address\fR
|
|
[\fB,\fR \fIip-address ip-address\fR...]\fB;\fR
|
|
.fi
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of static routes that the client should
|
|
install in its routing cache. If multiple routes to the same
|
|
destination are specified, they are listed in descending order of
|
|
priority.
|
|
.PP
|
|
The routes consist of a list of IP address pairs. The first address
|
|
is the destination address, and the second address is the router for
|
|
the destination.
|
|
.PP
|
|
The default route (0.0.0.0) is an illegal destination for a static
|
|
route. To specify the default route, use the
|
|
.B routers
|
|
option. Also, please note that this option is not intended for
|
|
classless IP routing - it does not include a subnet mask. Since
|
|
classless IP routing is now the most widely deployed routing standard,
|
|
this option is virtually useless, and is not implemented by any of the
|
|
popular DHCP clients, for example the Microsoft DHCP client.
|
|
.PP
|
|
NOTE to @PRODUCTNAME@ dhclient users:
|
|
.br
|
|
dhclient-script interprets trailing 0 octets of the target
|
|
as indicating the subnet class of the route - so for this
|
|
static-routes value:
|
|
.br
|
|
option static-routes 172.0.0.0 172.16.2.254,
|
|
.br
|
|
192.168.0.0 192.168.2.254;
|
|
.br
|
|
dhclient-script will create routes:
|
|
.br
|
|
172/8 via 172.16.2.254 dev $interface
|
|
.br
|
|
192.168/16 via 192.168.2.254 dev $interface
|
|
.br
|
|
which slightly increases the usefulness of the static-routes option.
|
|
.RE
|
|
.PP
|
|
.nf
|
|
.B option \fBstreettalk-directory-assistance-server\fR \fIip-address\fR
|
|
[\fB,\fR \fIip-address\fR...]\fB;\fR
|
|
.fi
|
|
.RS 0.25i
|
|
.PP
|
|
The StreetTalk Directory Assistance (STDA) server option specifies a
|
|
list of STDA servers available to the client. Servers should be
|
|
listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBstreettalk-server\fR \fIip-address\fR [\fB,\fR \fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The StreetTalk server option specifies a list of StreetTalk servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option subnet-mask \fIip-address\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The subnet mask option specifies the client's subnet mask as per RFC
|
|
950. If no subnet mask option is provided anywhere in scope, as a
|
|
last resort dhcpd will use the subnet mask from the subnet declaration
|
|
for the network on which an address is being assigned. However,
|
|
.I any
|
|
subnet-mask option declaration that is in scope for the address being
|
|
assigned will override the subnet mask specified in the subnet
|
|
declaration.
|
|
.RE
|
|
.PP
|
|
.B option \fBsubnet-selection\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
Sent by the client if an address is required in a subnet other than the one
|
|
that would normally be selected (based on the relaying address of the
|
|
connected subnet the request is obtained from). See RFC3011. Note that the
|
|
option number used by this server is 118; this has not always been the
|
|
defined number, and some clients may use a different value. Use of this
|
|
option should be regarded as slightly experimental!
|
|
.RE
|
|
.PP
|
|
This option is not user configurable in the server.
|
|
.PP
|
|
.PP
|
|
.B option \fBswap-server\fR \fIip-address\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This specifies the IP address of the client's swap server.
|
|
.RE
|
|
.PP
|
|
.B option \fBtcp-keepalive-garbage\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should send TCP
|
|
keepalive messages with an octet of garbage for compatibility with
|
|
older implementations. A value of false indicates that a garbage octet
|
|
should not be sent. A value of true indicates that a garbage octet
|
|
should be sent.
|
|
.RE
|
|
.PP
|
|
.B option \fBtcp-keepalive-interval\fR \fIuint32\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies the interval (in seconds) that the client TCP
|
|
should wait before sending a keepalive message on a TCP connection.
|
|
The time is specified as a 32-bit unsigned integer. A value of zero
|
|
indicates that the client should not generate keepalive messages on
|
|
connections unless specifically requested by an application.
|
|
.RE
|
|
.PP
|
|
.B option \fBtftp-server-name\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option is used to identify a TFTP server and, if supported by the
|
|
client, should have the same effect as the \fBserver-name\fR
|
|
declaration. BOOTP clients are unlikely to support this option.
|
|
Some DHCP clients will support it, and others actually require it.
|
|
.RE
|
|
.PP
|
|
.B option time-offset \fIint32\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The time-offset option specifies the offset of the client's subnet in
|
|
seconds from Coordinated Universal Time (UTC).
|
|
.RE
|
|
.PP
|
|
.B option time-servers \fIip-address\fR [, \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The time-server option specifies a list of RFC 868 time servers
|
|
available to the client. Servers should be listed in order of
|
|
preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBtrailer-encapsulation\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies whether or not the client should negotiate the
|
|
use of trailers (RFC 893 [14]) when using the ARP protocol. A value
|
|
of false indicates that the client should not attempt to use trailers. A
|
|
value of true means that the client should attempt to use trailers.
|
|
.RE
|
|
.PP
|
|
.B option \fBuap-servers\fR \fItext\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of URLs, each pointing to a user
|
|
authentication service that is capable of processing authentication
|
|
requests encapsulated in the User Authentication Protocol (UAP). UAP
|
|
servers can accept either HTTP 1.1 or SSLv3 connections. If the list
|
|
includes a URL that does not contain a port component, the normal
|
|
default port is assumed (i.e., port 80 for http and port 443 for
|
|
https). If the list includes a URL that does not contain a path
|
|
component, the path /uap is assumed. If more than one URL is
|
|
specified in this list, the URLs are separated by spaces.
|
|
.RE
|
|
.PP
|
|
.B option \fBuser-class\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option is used by some DHCP clients as a way for users to
|
|
specify identifying information to the client. This can be used in a
|
|
similar way to the vendor-class-identifier option, but the value of
|
|
the option is specified by the user, not the vendor. Most recent
|
|
DHCP clients have a way in the user interface to specify the value for
|
|
this identifier, usually as a text string.
|
|
.RE
|
|
.PP
|
|
.B option \fBvendor-class-identifier\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option is used by some DHCP clients to identify the vendor
|
|
type and possibly the configuration of a DHCP client. The information
|
|
is a string of bytes whose contents are specific to the vendor and are
|
|
not specified in a standard. To see what vendor class identifier
|
|
clients are sending, you can write the following in your DHCP server
|
|
configuration file:
|
|
.nf
|
|
.PP
|
|
set vendor-string = option vendor-class-identifier;
|
|
.fi
|
|
.PP
|
|
This will result in all entries in the DHCP server lease database file
|
|
for clients that sent vendor-class-identifier options having a set
|
|
statement that looks something like this:
|
|
.nf
|
|
.PP
|
|
set vendor-string = "SUNW.Ultra-5_10";
|
|
.fi
|
|
.PP
|
|
The vendor-class-identifier option is normally used by the DHCP server
|
|
to determine the options that are returned in the
|
|
.B vendor-encapsulated-options
|
|
option. Please see the VENDOR ENCAPSULATED OPTIONS section later in this
|
|
manual page for further information.
|
|
.RE
|
|
.PP
|
|
.B option \fBvendor-encapsulated-options\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The \fBvendor-encapsulated-options\fR option can contain either a
|
|
single vendor-specific value or one or more vendor-specific
|
|
suboptions. This option is not normally specified in the DHCP server
|
|
configuration file - instead, a vendor class is defined for each
|
|
vendor, vendor class suboptions are defined, values for those
|
|
suboptions are defined, and the DHCP server makes up a response on
|
|
that basis.
|
|
.PP
|
|
Some default behaviours for well-known DHCP client vendors (currently,
|
|
the Microsoft Windows 2000 DHCP client) are configured automatically,
|
|
but otherwise this must be configured manually - see the VENDOR
|
|
ENCAPSULATED OPTIONS section later in this manual page for details.
|
|
.RE
|
|
.PP
|
|
.B option \fBwww-server\fR \fIip-address\fR [\fB,\fR
|
|
\fIip-address\fR... ]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The WWW server option specifies a list of WWW servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.RE
|
|
.PP
|
|
.B option \fBx-display-manager\fR \fIip-address\fR [\fB,\fR \fIip-address\fR...
|
|
]\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This option specifies a list of systems that are running the X Window
|
|
System Display Manager and are available to the client. Addresses
|
|
should be listed in order of preference.
|
|
.RE
|
|
.SH RELAY AGENT INFORMATION OPTION
|
|
An IETF draft, draft-ietf-dhc-agent-options-11.txt, defines a series
|
|
of encapsulated options that a relay agent can add to a DHCP packet
|
|
when relaying it to the DHCP server. The server can then make
|
|
address allocation decisions (or whatever other decisions it wants)
|
|
based on these options. The server also returns these options in any
|
|
replies it sends through the relay agent, so that the relay agent can
|
|
use the information in these options for delivery or accounting
|
|
purposes.
|
|
.PP
|
|
The current draft defines two options. To reference
|
|
these options in the dhcp server, specify the option space name,
|
|
"agent", followed by a period, followed by the option name. It is
|
|
not normally useful to define values for these options in the server,
|
|
although it is permissible. These options are not supported in the
|
|
client.
|
|
.PP
|
|
.B option \fBagent.circuit-id\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The circuit-id suboption encodes an agent-local identifier of the
|
|
circuit from which a DHCP client-to-server packet was received. It is
|
|
intended for use by agents in relaying DHCP responses back to the
|
|
proper circuit. The format of this option is currently defined to be
|
|
vendor-dependent, and will probably remain that way, although the
|
|
current draft allows for for the possibility of standardizing the
|
|
format in the future.
|
|
.RE
|
|
.PP
|
|
.B option \fBagent.remote-id\fR \fIstring\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The remote-id suboption encodes information about the remote host end
|
|
of a circuit. Examples of what it might contain include caller ID
|
|
information, username information, remote ATM address, cable modem ID,
|
|
and similar things. In principal, the meaning is not well-specified,
|
|
and it should generally be assumed to be an opaque object that is
|
|
administratively guaranteed to be unique to a particular remote end of
|
|
a circuit.
|
|
.RE
|
|
.PP
|
|
.B option \fBagent.DOCSIS-device-class\fR \fIuint32\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The DOCSIS-device-class suboption is intended to convey information about
|
|
the host endpoint, hardware, and software, that either the host operating
|
|
system or the DHCP server may not otherwise be aware of (but the relay is
|
|
able to distinguish). This is implemented as a 32-bit field (4 octets),
|
|
each bit representing a flag describing the host in one of these ways.
|
|
So far, only bit zero (being the least significant bit) is defined in
|
|
RFC3256. If this bit is set to one, the host is considered a CPE
|
|
Controlled Cable Modem (CCCM). All other bits are reserved.
|
|
.RE
|
|
.PP
|
|
.B option \fBagent.link-selection\fR \fIip-address\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
The link-selection suboption is provided by relay agents to inform servers
|
|
what subnet the client is actually attached to. This is useful in those
|
|
cases where the giaddr (where responses must be sent to the relay agent)
|
|
is not on the same subnet as the client. When this option is present in
|
|
a packet from a relay agent, the DHCP server will use its contents to find
|
|
a subnet declared in configuration, and from here take one step further
|
|
backwards to any shared-network the subnet may be defined within...the
|
|
client may be given any address within that shared network, as normally
|
|
appropriate.
|
|
.RE
|
|
.SH THE CLIENT FQDN SUBOPTIONS
|
|
The Client FQDN option, currently defined in the Internet Draft
|
|
draft-ietf-dhc-fqdn-option-00.txt is not a standard yet, but is in
|
|
sufficiently wide use already that we have implemented it. Due to
|
|
the complexity of the option format, we have implemented it as a
|
|
suboption space rather than a single option. In general this
|
|
option should not be configured by the user - instead it should be
|
|
used as part of an automatic DNS update system.
|
|
.PP
|
|
.B option fqdn.no-client-update \fIflag\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
When the client sends this, if it is true, it means the client will not
|
|
attempt to update its A record. When sent by the server to the client,
|
|
it means that the client \fIshould not\fR update its own A record.
|
|
.RE
|
|
.PP
|
|
.B option fqdn.server-update \fIflag\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
When the client sends this to the server, it is requesting that the server
|
|
update its A record. When sent by the server, it means that the server
|
|
has updated (or is about to update) the client's A record.
|
|
.RE
|
|
.PP
|
|
.B option fqdn.encoded \fIflag\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
If true, this indicates that the domain name included in the option is
|
|
encoded in DNS wire format, rather than as plain ASCII text. The client
|
|
normally sets this to false if it doesn't support DNS wire format in the
|
|
FQDN option. The server should always send back the same value that the
|
|
client sent. When this value is set on the configuration side, it controls
|
|
the format in which the \fIfqdn.fqdn\fR suboption is encoded.
|
|
.RE
|
|
.PP
|
|
.B option fqdn.rcode1 \fIflag\fB;
|
|
.PP
|
|
.B option fqdn.rcode2 \fIflag\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
These options specify the result of the updates of the A and PTR records,
|
|
respectively, and are only sent by the DHCP server to the DHCP client.
|
|
The values of these fields are those defined in the DNS protocol specification.
|
|
.RE
|
|
.PP
|
|
.B option fqdn.fqdn \fItext\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
Specifies the domain name that the client wishes to use. This can be a
|
|
fully-qualified domain name, or a single label. If there is no trailing
|
|
'.' character in the name, it is not fully-qualified, and the server will
|
|
generally update that name in some locally-defined domain.
|
|
.RE
|
|
.PP
|
|
.B option fqdn.hostname \fI--never set--\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
This option should never be set, but it can be read back using the \fBoption\fR
|
|
and \fBconfig-option\fR operators in an expression, in which case it returns
|
|
the first label in the \fBfqdn.fqdn\fR suboption - for example, if
|
|
the value of \fBfqdn.fqdn\fR is "foo.example.com.", then \fBfqdn.hostname\fR
|
|
will be "foo".
|
|
.RE
|
|
.PP
|
|
.B option fqdn.domainname \fI--never set--\fB;
|
|
.RS 0.25i
|
|
.PP
|
|
This option should never be set, but it can be read back using the \fBoption\fR
|
|
and \fBconfig-option\fR operators in an expression, in which case it returns
|
|
all labels after the first label in the \fBfqdn.fqdn\fR suboption - for
|
|
example, if the value of \fBfqdn.fqdn\fR is "foo.example.com.",
|
|
then \fBfqdn.hostname\fR will be "example.com.". If this suboption value
|
|
is not set, it means that an unqualified name was sent in the fqdn option,
|
|
or that no fqdn option was sent at all.
|
|
.RE
|
|
.PP
|
|
If you wish to use any of these suboptions, we strongly recommend that you
|
|
refer to the Client FQDN option draft (or standard, when it becomes a
|
|
standard) - the documentation here is sketchy and incomplete in comparison,
|
|
and is just intended for reference by people who already understand the
|
|
Client FQDN option specification.
|
|
.SH THE NETWARE/IP SUBOPTIONS
|
|
RFC2242 defines a set of encapsulated options for Novell NetWare/IP
|
|
clients. To use these options in the dhcp server, specify the option
|
|
space name, "nwip", followed by a period, followed by the option name.
|
|
The following options can be specified:
|
|
.PP
|
|
.B option \fBnwip.nsq-broadcast\fR \fIflag\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
If true, the client should use the NetWare Nearest Server Query to
|
|
locate a NetWare/IP server. The behaviour of the Novell client if
|
|
this suboption is false, or is not present, is not specified.
|
|
.PP
|
|
.RE
|
|
.B option \fBnwip.preferred-dss\fR \fIip-address\fR [\fB,\fR \fIip-address\fR... ]\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This suboption specifies a list of up to five IP addresses, each of
|
|
which should be the IP address of a NetWare Domain SAP/RIP server
|
|
(DSS).
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip.nearest-nwip-server\fR \fI\fIip-address\fR
|
|
[\fB,\fR \fIip-address\fR...]\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
This suboption specifies a list of up to five IP addresses, each of
|
|
which should be the IP address of a Nearest NetWare IP server.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip.autoretries\fR \fIuint8\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
Specifies the number of times that a NetWare/IP client should attempt
|
|
to communicate with a given DSS server at startup.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip.autoretry-secs\fR \fIuint8\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
Specifies the number of seconds that a Netware/IP client should wait
|
|
between retries when attempting to establish communications with a DSS
|
|
server at startup.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip.nwip-1-1\fR \fIuint8\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
If true, the NetWare/IP client should support NetWare/IP version 1.1
|
|
compatibility. This is only needed if the client will be contacting
|
|
Netware/IP version 1.1 servers.
|
|
.RE
|
|
.PP
|
|
.B option \fBnwip.primary-dss\fR \fIip-address\fR\fB;\fR
|
|
.RS 0.25i
|
|
.PP
|
|
Specifies the IP address of the Primary Domain SAP/RIP Service server
|
|
(DSS) for this NetWare/IP domain. The NetWare/IP administration
|
|
utility uses this value as Primary DSS server when configuring a
|
|
secondary DSS server.
|
|
.RE
|
|
.SH DEFINING NEW OPTIONS
|
|
The Internet Systems Consortium DHCP client and server provide the
|
|
capability to define new options. Each DHCP option has a name, a
|
|
code, and a structure. The name is used by you to refer to the
|
|
option. The code is a number, used by the DHCP server and client to
|
|
refer to an option. The structure describes what the contents of an
|
|
option looks like.
|
|
.PP
|
|
To define a new option, you need to choose a name for it that is not
|
|
in use for some other option - for example, you can't use "host-name"
|
|
because the DHCP protocol already defines a host-name option, which is
|
|
documented earlier in this manual page. If an option name doesn't
|
|
appear in this manual page, you can use it, but it's probably a good
|
|
idea to put some kind of unique string at the beginning so you can be
|
|
sure that future options don't take your name. For example, you
|
|
might define an option, "local-host-name", feeling some confidence
|
|
that no official DHCP option name will ever start with "local".
|
|
.PP
|
|
Once you have chosen a name, you must choose a code. All codes between
|
|
224 and 254 are reserved as 'site-local' DHCP options, so you can pick
|
|
any one of these for your site (not for your product/application). In
|
|
RFC3942, site-local space was moved from starting at 128 to starting at
|
|
224. In practice, some vendors have interpreted the protocol rather
|
|
loosely and have used option code values greater than 128 themselves.
|
|
There's no real way to avoid this problem, and it was thought to be
|
|
unlikely to cause too much trouble in practice. If you come across
|
|
a vendor-documented option code in either the new or old site-local
|
|
spaces, please contact your vendor and inform them about rfc3942.
|
|
.PP
|
|
The structure of an option is simply the format in which the option
|
|
data appears. The ISC DHCP server currently supports a few simple
|
|
types, like integers, booleans, strings and IP addresses, and it also
|
|
supports the ability to define arrays of single types or arrays of
|
|
fixed sequences of types.
|
|
.PP
|
|
New options are declared as follows:
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.I definition
|
|
.B ;
|
|
.PP
|
|
The values of
|
|
.I new-name
|
|
and
|
|
.I new-code
|
|
should be the name you have chosen for the new option and the code you
|
|
have chosen. The
|
|
.I definition
|
|
should be the definition of the structure of the option.
|
|
.PP
|
|
The following simple option type definitions are supported:
|
|
.PP
|
|
.B BOOLEAN
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.B boolean
|
|
.B ;
|
|
.PP
|
|
An option of type boolean is a flag with a value of either on or off
|
|
(or true or false). So an example use of the boolean type would be:
|
|
.nf
|
|
|
|
option use-zephyr code 180 = boolean;
|
|
option use-zephyr on;
|
|
|
|
.fi
|
|
.B INTEGER
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.I sign
|
|
.B integer
|
|
.I width
|
|
.B ;
|
|
.PP
|
|
The \fIsign\fR token should either be blank, \fIunsigned\fR
|
|
or \fIsigned\fR. The width can be either 8, 16 or 32, and refers to
|
|
the number of bits in the integer. So for example, the following two
|
|
lines show a definition of the sql-connection-max option and its use:
|
|
.nf
|
|
|
|
option sql-connection-max code 192 = unsigned integer 16;
|
|
option sql-connection-max 1536;
|
|
|
|
.fi
|
|
.B IP-ADDRESS
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.B ip-address
|
|
.B ;
|
|
.PP
|
|
An option whose structure is an IP address can be expressed either as
|
|
a domain name or as a dotted quad. So the following is an example use
|
|
of the ip-address type:
|
|
.nf
|
|
|
|
option sql-server-address code 193 = ip-address;
|
|
option sql-server-address sql.example.com;
|
|
|
|
.fi
|
|
.PP
|
|
.B TEXT
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.B text
|
|
.B ;
|
|
.PP
|
|
An option whose type is text will encode an ASCII text string. For
|
|
example:
|
|
.nf
|
|
|
|
option sql-default-connection-name code 194 = text;
|
|
option sql-default-connection-name "PRODZA";
|
|
|
|
.fi
|
|
.PP
|
|
.B DATA STRING
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.B string
|
|
.B ;
|
|
.PP
|
|
An option whose type is a data string is essentially just a collection
|
|
of bytes, and can be specified either as quoted text, like the text
|
|
type, or as a list of hexadecimal contents separated by colons whose
|
|
values must be between 0 and FF. For example:
|
|
.nf
|
|
|
|
option sql-identification-token code 195 = string;
|
|
option sql-identification-token 17:23:19:a6:42:ea:99:7c:22;
|
|
|
|
.fi
|
|
.PP
|
|
.B ENCAPSULATION
|
|
.PP
|
|
.B option
|
|
.I new-name
|
|
.B code
|
|
.I new-code
|
|
.B =
|
|
.B encapsulate
|
|
.I identifier
|
|
.B ;
|
|
.PP
|
|
An option whose type is \fBencapsulate\fR will encapsulate the
|
|
contents of the option space specified in \fIidentifier\fR. Examples
|
|
of encapsulated options in the DHCP protocol as it currently exists
|
|
include the vendor-encapsulated-options option, the netware-suboptions
|
|
option and the relay-agent-information option.
|
|
.nf
|
|
|
|
option space local;
|
|
option local.demo code 1 = text;
|
|
option local-encapsulation code 197 = encapsulate local;
|
|
option local.demo "demo";
|
|
|
|
.fi
|
|
.PP
|
|
.B ARRAYS
|
|
.PP
|
|
Options can contain arrays of any of the above types except for the
|
|
text and data string types, which aren't currently supported in
|
|
arrays. An example of an array definition is as follows:
|
|
.nf
|
|
|
|
option kerberos-servers code 200 = array of ip-address;
|
|
option kerberos-servers 10.20.10.1, 10.20.11.1;
|
|
|
|
.fi
|
|
.B RECORDS
|
|
.PP
|
|
Options can also contain data structures consisting of a sequence of
|
|
data types, which is sometimes called a record type. For example:
|
|
.nf
|
|
|
|
option contrived-001 code 201 = { boolean, integer 32, text };
|
|
option contrived-001 on 1772 "contrivance";
|
|
|
|
.fi
|
|
It's also possible to have options that are arrays of records, for
|
|
example:
|
|
.nf
|
|
|
|
option new-static-routes code 201 = array of {
|
|
ip-address, ip-address, ip-address, integer 8 };
|
|
option static-routes
|
|
10.0.0.0 255.255.255.0 net-0-rtr.example.com 1,
|
|
10.0.1.0 255.255.255.0 net-1-rtr.example.com 1,
|
|
10.2.0.0 255.255.224.0 net-2-0-rtr.example.com 3;
|
|
|
|
.fi
|
|
.SH VENDOR ENCAPSULATED OPTIONS
|
|
The DHCP protocol defines the \fB vendor-encapsulated-options\fR
|
|
option, which allows vendors to define their own options that will be
|
|
sent encapsulated in a standard DHCP option. The format of the
|
|
.B vendor-encapsulated-options
|
|
option is either a series of bytes whose format is not specified, or
|
|
a sequence of options, each of which consists of a single-byte
|
|
vendor-specific option code, followed by a single-byte length,
|
|
followed by as many bytes of data as are specified in the length (the
|
|
length does not include itself or the option code).
|
|
.PP
|
|
The value of this option can be set in one of two ways. The first
|
|
way is to simply specify the data directly, using a text string or a
|
|
colon-separated list of hexadecimal values. For example:
|
|
.PP
|
|
.nf
|
|
option vendor-encapsulated-options
|
|
2:4:AC:11:41:1:
|
|
3:12:73:75:6e:64:68:63:70:2d:73:65:72:76:65:72:31:37:2d:31:
|
|
4:12:2f:65:78:70:6f:72:74:2f:72:6f:6f:74:2f:69:38:36:70:63;
|
|
.fi
|
|
.PP
|
|
The second way of setting the value of this option is to have the DHCP
|
|
server generate a vendor-specific option buffer. To do this, you
|
|
must do four things: define an option space, define some options in
|
|
that option space, provide values for them, and specify that that
|
|
option space should be used to generate the
|
|
.B vendor-encapsulated-options
|
|
option.
|
|
.PP
|
|
To define a new option space in which vendor options can be stored,
|
|
use the \fRoption space\fP statement:
|
|
.PP
|
|
.B option
|
|
.B space
|
|
.I name
|
|
.B [ [ code width
|
|
.I number
|
|
.B ] [ length width
|
|
.I number
|
|
.B ] [ hash size
|
|
.I number
|
|
.B ] ] ;
|
|
.PP
|
|
Where the numbers following \fBcode width\fR, \fBlength width\fR,
|
|
and \fBhash size\fR respectively identify the number of bytes used to
|
|
describe option codes, option lengths, and the size in buckets of the
|
|
hash tables to hold options in this space.
|
|
.PP
|
|
The code and length widths are used in DHCP protocol - you must configure
|
|
these numbers to match the applicable option space you are configuring.
|
|
They each default to 1. Valid values for code widths are 1, 2 or 4.
|
|
Valid values for length widths are 1 or 2.
|
|
.PP
|
|
The hash size defaults depend upon the \fBcode width\fR selected, and
|
|
may be 254 or 1009. Valid values range between 1 and 65535. Note
|
|
that the higher you configure this value, the more memory will be used. It
|
|
is considered good practice to configure a value that is slightly larger
|
|
than the estimated number of options you plan to configure within the
|
|
space. Due to limitations in previous versions of ISC DHCP (up to and
|
|
including DHCP 3.0.*), this value was fixed at 9973.
|
|
.PP
|
|
The name can then be used in option definitions, as described earlier in
|
|
this document. For example:
|
|
.nf
|
|
|
|
option space SUNW code width 1 length width 1 hash size 3;
|
|
option SUNW.server-address code 2 = ip-address;
|
|
option SUNW.server-name code 3 = text;
|
|
option SUNW.root-path code 4 = text;
|
|
|
|
.fi
|
|
Once you have defined an option space and the format of some options,
|
|
you can set up scopes that define values for those options, and you
|
|
can say when to use them. For example, suppose you want to handle
|
|
two different classes of clients. Using the option space definition
|
|
shown in the previous example, you can send different option values to
|
|
different clients based on the vendor-class-identifier option that the
|
|
clients send, as follows:
|
|
.PP
|
|
.nf
|
|
class "vendor-classes" {
|
|
match option vendor-class-identifier;
|
|
}
|
|
|
|
option SUNW.server-address 172.17.65.1;
|
|
option SUNW.server-name "sundhcp-server17-1";
|
|
|
|
subclass "vendor-classes" "SUNW.Ultra-5_10" {
|
|
vendor-option-space SUNW;
|
|
option SUNW.root-path "/export/root/sparc";
|
|
}
|
|
|
|
subclass "vendor-classes" "SUNW.i86pc" {
|
|
vendor-option-space SUNW;
|
|
option SUNW.root-path "/export/root/i86pc";
|
|
}
|
|
.fi
|
|
.PP
|
|
As you can see in the preceding example, regular scoping rules apply,
|
|
so you can define values that are global in the global scope, and only
|
|
define values that are specific to a particular class in the local
|
|
scope. The \fBvendor-option-space\fR declaration tells the DHCP
|
|
server to use options in the SUNW option space to construct the
|
|
.B vendor-encapsulated-options
|
|
option.
|
|
.SH SEE ALSO
|
|
dhcpd.conf(5), dhcpd.leases(5), dhclient.conf(5), dhcp-eval(5), dhcpd(8),
|
|
dhclient(8), RFC2132, RFC2131, draft-ietf-dhc-agent-options-??.txt.
|
|
.SH AUTHOR
|
|
The Internet Systems Consortium DHCP Distribution was written by Ted
|
|
Lemon under a contract with Vixie Labs. Funding for
|
|
this project was provided through Internet Systems Consortium.
|
|
Information about Internet Systems Consortium can be found at
|
|
.B http://www.isc.org.
|