452 lines
18 KiB
Groff
452 lines
18 KiB
Groff
.\" dhcp-options.5
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.\"
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.\" Copyright (c) 1995, 1996, 1997 The Internet Software Consortium.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of The Internet Software Consortium nor the names
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.\" of its contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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.\" CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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.\" CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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.\" ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" This software has been written for the Internet Software Consortium
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.\" by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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.\" Enterprises. To learn more about the Internet Software Consortium,
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.\" see ``http://www.isc.org/isc''. To learn more about Vixie
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.\" Enterprises, see ``http://www.vix.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 string
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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 domain-name
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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 domain-name "isc.org";
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.fi
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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 data-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, seperated by colons. For example:
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.nf
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.sp 1
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option client-identifier "CLIENT-FOO";
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or
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option client-identifier 43:4c:49:45:54:2d:46:4f:4f;
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.fi
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.PP
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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 which
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are not listed by name may be defined by the name option-\fInnn\fR,
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where \fInnn\fI is the decimal number of the option code. These
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options may be followed either by a string, enclosed in quotes, or by
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a series of octets, expressed as two-digit hexadecimal numbers seperated
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by colons. For example:
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.PP
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.nf
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option option-133 "my-option-133-text";
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option option-129 1:54:c9:2b:47;
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.fi
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.PP
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Because dhcpd does not know the format of these undefined option codes,
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no checking is done to ensure the correctness of the entered data.
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.PP
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The standard options are:
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.PP
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\fBoption subnet-mask\fR \fIip-address\fR\fB;\fR
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.PP
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The subnet mask option specifies the client's subnet mask as per RFC
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950. If no subnet mask option is provided anywhere in scope, as a
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last resort dhcpd will use the subnet mask from the subnet declaration
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for the network on which an address is being assigned. However,
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.I any
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subnet-mask option declaration that is in scope for the address being
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assigned will override the subnet mask specified in the subnet
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declaration.
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.PP
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\fBoption time-offset\fR \fIint32\fR\fB;\fR
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.PP
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The time-offset option specifies the offset of the client's subnet in
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seconds from Coordinated Universal Time (UTC).
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.PP
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\fBoption routers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The routers option specifies a list of IP addresses for routers on the
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client's subnet. Routers should be listed in order of preference.
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.PP
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\fBoption time-servers\fR \fIip-address [, \fIip-address\fR ... ]\fB;\fR
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.PP
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The time-server option specifies a list of RFC 868 time servers
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available to the client. Servers should be listed in order of
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preference.
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.PP
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\fBoption\fR \fBien116-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ];
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.PP
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The ien116-name-servers option specifies a list of IEN 116 name servers
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available to the client. Servers should be listed in order of
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preference.
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.PP
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\fBoption\fR \fBdomain-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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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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.PP
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\fBoption\fR \fBlog-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The log-server option specifies a list of MIT-LCS UDP log servers
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available to the client. Servers should be listed in order of
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preference.
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.PP
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\fBoption\fR \fBcookie-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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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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.PP
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\fBoption\fR \fBlpr-servers\fR \fIip-address \fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The LPR server option specifies a list of RFC 1179 line printer
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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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.PP
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\fBoption\fR \fBimpress-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The impress-server option specifies a list of Imagen Impress servers
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available to the client. Servers should be listed in order of
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preference.
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.PP
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\fBoption\fR \fBresource-location-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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This option specifies a list of RFC 887 Resource Location
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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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.PP
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\fBoption\fR \fBhost-name\fR \fIstring\fR\fB;\fR
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.PP
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This option specifies the name of the client. The name may or may
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not be qualified with the local domain name (it is preferable to use
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the domain-name option to specify the domain name). See RFC 1035 for
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character set restrictions.
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.PP
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\fBoption\fR \fBboot-size\fR \fIuint16\fR\fB;\fR
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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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.PP
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\fBoption\fR \fBmerit-dump\fR \fIstring\fR\fB;\fR
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.PP
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This option specifies the path-name of a file to which the client's
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core image should be dumped in the event the client crashes. The
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path is formatted as a character string consisting of characters from
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the NVT ASCII character set.
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.PP
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\fBoption\fR \fBdomain-name\fR \fIstring\fR\fB;\fR
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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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.PP
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\fBoption\fR \fBswap-server\fR \fIip-address\fR\fB;\fR
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.PP
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This specifies the IP address of the client's swap server.
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.PP
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\fBoption\fR \fBroot-path\fR \fIstring\fB;\fR\fR
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.PP
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This option specifies the path-name that contains the client's root
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disk. The path is formatted as a character string consisting of
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characters from the NVT ASCII character set.
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.PP
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\fBoption\fR \fBip-forwarding\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether the client should configure its IP
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layer for packet forwarding. A value of 0 means disable IP
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forwarding, and a value of 1 means enable IP forwarding.
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.PP
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\fBoption\fR \fBnon-local-source-routing\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether the client should configure its IP
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layer to allow forwarding of datagrams with non-local source routes
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(see Section 3.3.5 of [4] for a discussion of this topic). A value
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of 0 means disallow forwarding of such datagrams, and a value of 1
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means allow forwarding.
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.PP
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\fBoption\fR \fBpolicy-filter\fR \fIip-address ip-address\fR [\fB,\fR \fIip-address ip-address\fR ... ]\fB;\fR
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.PP
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This option specifies policy filters for non-local source routing.
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The filters consist of a list of IP addresses and masks which specify
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destination/mask pairs with which to filter incoming source routes.
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.PP
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Any source routed datagram whose next-hop address does not match one
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of the filters should be discarded by the client.
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.PP
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See STD 3 (RFC1122) for further information.
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.PP
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\fBoption\fR \fBmax-dgram-reassembly\fR \fIuint16\fR\fB;\fR
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.PP
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This option specifies the maximum size datagram that the client
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should be prepared to reassemble. The minimum value legal value is
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576.
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.PP
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\fBoption\fR \fBdefault-ip-ttl\fR \fIuint8;\fR
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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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.PP
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\fBoption\fR \fBpath-mtu-aging-timeout\fR \fIuint32\fR\fB;\fR
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.PP
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This option specifies the timeout (in seconds) to use when aging Path
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MTU values discovered by the mechanism defined in RFC 1191.
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.PP
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\fBoption\fR \fBpath-mtu-plateau-table\fR \fIuint16\fR [\fB,\fR \fIuint16\fR ... ]\fB;\fR
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.PP
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This option specifies a table of MTU sizes to use when performing
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Path MTU Discovery as defined in RFC 1191. The table is formatted as
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a list of 16-bit unsigned integers, ordered from smallest to largest.
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The minimum MTU value cannot be smaller than 68.
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.PP
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\fBoption\fR \fBinterface-mtu\fR \fIuint16\fR\fB;\fR
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.PP
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This option specifies the MTU to use on this interface. The minimum
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legal value for the MTU is 68.
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.PP
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\fBoption\fR \fBall-subnets-local\fR \fIflag\fR\fB;\fR
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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 1 indicates that all subnets share
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the same MTU. A value of 0 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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.PP
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\fBoption\fR \fBbroadcast-address\fR \fIip-address\fR\fB;\fR
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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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.PP
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\fBoption\fR \fBperform-mask-discovery\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether or not the client should perform subnet
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mask discovery using ICMP. A value of 0 indicates that the client
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should not perform mask discovery. A value of 1 means that the
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client should perform mask discovery.
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.PP
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\fBoption\fR \fBmask-supplier\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether or not the client should respond to
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subnet mask requests using ICMP. A value of 0 indicates that the
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client should not respond. A value of 1 means that the client should
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respond.
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.PP
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\fBoption\fR \fBrouter-discovery\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether or not the client should solicit
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routers using the Router Discovery mechanism defined in RFC 1256.
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A value of 0 indicates that the client should not perform
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router discovery. A value of 1 means that the client should perform
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router discovery.
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.PP
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\fBoption\fR \fBrouter-solicitation-address\fR \fIip-address\fR\fB;\fR
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.PP
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This option specifies the address to which the client should transmit
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router solicitation requests.
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.PP
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\fBoption\fR \fBstatic-routes\fR \fIip-address ip-address\fR [\fB,\fR \fIip-address ip-address\fR ... ]\fB;\fR
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.PP
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This option specifies a list of static routes that the client should
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install in its routing cache. If multiple routes to the same
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destination are specified, they are listed in descending order of
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priority.
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.PP
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The routes consist of a list of IP address pairs. The first address
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is the destination address, and the second address is the router for
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the destination.
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.PP
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The default route (0.0.0.0) is an illegal destination for a static
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route. To specify the default route, use the
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.B routers
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option.
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.PP
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\fBoption\fR \fBtrailer-encapsulation\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether or not the client should negotiate the
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use of trailers (RFC 893 [14]) when using the ARP protocol. A value
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of 0 indicates that the client should not attempt to use trailers. A
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value of 1 means that the client should attempt to use trailers.
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.PP
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\fBoption\fR \fBarp-cache-timeout\fR \fIuint32\fR\fB;\fR
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.PP
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This option specifies the timeout in seconds for ARP cache entries.
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.PP
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\fBoption\fR \fBieee802-3-encapsulation\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies whether or not the client should use Ethernet
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Version 2 (RFC 894) or IEEE 802.3 (RFC 1042) encapsulation if the
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interface is an Ethernet. A value of 0 indicates that the client
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should use RFC 894 encapsulation. A value of 1 means that the client
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should use RFC 1042 encapsulation.
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.PP
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\fBoption\fR \fBdefault-tcp-ttl\fR \fIuint8\fR\fB;\fR
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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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.PP
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\fBoption\fR \fBtcp-keepalive-interval\fR \fIuint32\fR\fB;\fR
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.PP
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This option specifies the interval (in seconds) that the client TCP
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should wait before sending a keepalive message on a TCP connection.
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The time is specified as a 32-bit unsigned integer. A value of zero
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indicates that the client should not generate keepalive messages on
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connections unless specifically requested by an application.
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.PP
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\fBoption\fR \fBtcp-keepalive-garbage\fR \fIflag\fR\fB;\fR
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.PP
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This option specifies the whether or not the client should send TCP
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keepalive messages with a octet of garbage for compatibility with
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older implementations. A value of 0 indicates that a garbage octet
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should not be sent. A value of 1 indicates that a garbage octet
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should be sent.
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.PP
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\fBoption\fR \fBnis-domain\fR \fIstring\fR\fB;\fR
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.PP
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This option specifies the name of the client's NIS (Sun Network
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Information Services) domain. The domain is formatted as a character
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string consisting of characters from the NVT ASCII character set.
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.PP
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\fBoption\fR \fBnis-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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This option specifies a list of IP addresses indicating NIS servers
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available to the client. Servers should be listed in order of
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preference.
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.PP
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\fBoption\fR \fBntp-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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This option specifies a list of IP addresses indicating NTP (RFC 1035)
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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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.PP
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\fBoption\fR \fBnetbios-name-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The NetBIOS name server (NBNS) option specifies a list of RFC
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1001/1002 NBNS name servers listed in order of preference.
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.PP
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\fBoption\fR \fBnetbios-dd-server\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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The NetBIOS datagram distribution server (NBDD) option specifies a
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list of RFC 1001/1002 NBDD servers listed in order of preference.
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.PP
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\fBoption\fR \fBnetbios-node-type\fR \fIuint8\fR\fB;\fR
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.PP
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|
The NetBIOS node type option allows NetBIOS over TCP/IP clients which
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are configurable to be configured as described in RFC 1001/1002. The
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value is specified as a single octet which identifies the client type.
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A value of 1 corresponds to a NetBIOS B-node; a value of 2 corresponds
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to a P-node; a value of 4 corresponds to an M-node; a value of 8
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corresponds to an H-node.
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.PP
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\fBoption\fR \fBnetbios-scope\fR \fIstring\fR\fB;\fR
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.PP
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The NetBIOS scope option specifies the NetBIOS over TCP/IP scope
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parameter for the client as specified in RFC 1001/1002. See RFC1001,
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RFC1002, and RFC1035 for character-set restrictions.
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.PP
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|
\fBoption\fR \fBfont-servers\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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.PP
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This option specifies a list of X Window System Font servers available
|
|
to the client. Servers should be listed in order of preference.
|
|
.PP
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|
\fBoption\fR \fBx-display-manager\fR \fIip-address\fR [\fB,\fR \fIip-address\fR ... ]\fB;\fR
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|
.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.
|
|
.PP
|
|
\fBoption\fR \fBdhcp-client-identifier\fR \fIdata-string\fR\fB;\fR
|
|
.PP
|
|
This option can be used to specify the a DHCP client identifier in a
|
|
host declaration, so that dhcpd can find the host record by matching
|
|
against the client identifier.
|
|
.SH SEE ALSO
|
|
dhcpd.conf(5), dhcpd.leases(5), dhclient.conf(5), dhcpd(8),
|
|
dhclient(8), RFC2132, RFC2131.
|
|
.SH AUTHOR
|
|
.B dhcpd(8)
|
|
was written by Ted Lemon <mellon@vix.com>
|
|
under a contract with Vixie Labs. Funding
|
|
for this project was provided by the Internet Software Corporation.
|
|
Information about the Internet Software Consortium can be found at
|
|
.B http://www.isc.org/isc.
|