dhcp_inittab(4)

NAME | SYNOPSIS | DESCRIPTION | USAGE | EXAMPLES | FILES | ATTRIBUTES | SEE ALSO

NAME

dhcp_inittab- information repository for DHCP options

SYNOPSIS

/etc/dhcp/inittab

DESCRIPTION

DHCP options are network configuration parameters passed from DHCP servers to DHCP clients when a client machine uses DHCP. Since many DHCP-related commands must parse and understand these DHCP options, this file serves as a central location where information about these options may be obtained.

The dhcp_inittab file provides three general pieces of information:

• It provides a mnemonic alias for each option number. For instance, option 12 is aliased to the name "Hostname". This is useful for DHCP-related programs which require human interaction, such as dhcpinfo(1).

• It provides information about the syntax for each option. This includes information such as the type of the value, for example, whether it is a 16-bit integer or an IP address.

• It provides the policy for what options are visible to which DHCP-related programs.

Each DHCP option belongs to a certain category, which roughly defines the scope of the option; for instance, an option may only be understood by certain hosts within a given site, or it may be globally understood by all DHCP clients and servers. The following categories are defined; the category names are not case-sensitive:

STANDARD

All client and server DHCP implementations agree on the semantics. These are administered by the Internet Assigned Numbers Authority ("IANA"). These options are numbered from 1 to 127.

SITE

Within a specific site, all client and server implementations agree on the semantics. However, at another site the type and meaning of the option may be quite different. These options are numbered from 128 to 254.

VENDOR

Each vendor may define 254 options unique to that vendor. The vendor is identified within a DHCP packet by the "Vendor Class" option, number 60. An option with a specific numeric identifier belonging to one vendor will, in general, have a type and semantics different from that of a different vendor. Vendor options are "super-encapsulated" into the vendor field number 43, as defined in RFC 2132.

FIELD

This category allows the fixed fields within a DHCP packet to be aliased to a mnemonic name for use with dhcpinfo(1).

INTERNAL

This category is internal to the Solaris DHCP implementation and will not be further defined.

USAGE

Data entries are written one per line and have seven fields; each entry provides information for one option. Each field is separated by a comma, except for the first and second, which are separated by whitespace (as defined in isspace(3C)). An entry cannot be continued onto another line. Blank lines and those whose first non-whitespace character is '#' are ignored.

The fields, in order, are:

• Mnemonic Identifier

  The Mnemonic Identifier is a user-friendly alias for the option number; it is not case sensitive. This field must be per-category unique and should be unique across all categories. The option names in the STANDARD, SITE, and VENDOR spaces should not overlap, or the behavior will be undefined.

• Category (scope)

  The Category field is one of STANDARD, SITE, VENDOR, FIELD, or INTERNAL and identifies the scope in which the option falls.

• Option Number

  The Option Number is the number of this option when it is in a DHCP packet. This field should be per-category unique and the STANDARD and SITE fields should not have overlapping code fields or the behavior is undefined.

• Data Type

  Data Type is one of the follow values, which is not case sensitive:

  Ascii

  A printable character string

  Octet

  An array of bytes

  Unumber8

  An 8-bit unsigned integer

  Snumber8

  An 8-bit signed integer

  Unumber16

  A 16-bit unsigned integer

  Snumber16

  A 16-bit signed integer

  Unumber32

  A 32-bit unsigned integer

  Snumber32

  A 32-bit signed integer

  Unumber64

  A 64-bit unsigned integer

  Snumber64

  A 64-bit signed integer

  Ip

  An IP address

  The data type field describes an indivisible unit of the option payload, using one of the values listed above.

• Granularity

  The Granularity field describes how many "indivisible units" in the option payload make up a whole value or item for this option.

• Maximum Number Of Items

• Visibility

  The Visibility field specifies which DHCP-related programs make use of this information, and should always be defined as "sdmi" for newly added options.

EXAMPLES

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Example 1 Altering the dhcp_inittab File




In general, the dhcp_inittab file should only be altered to add either a DHCP STANDARD option or SITE option. For instance:

ipPairs    SITE, 132, IP, 2, 0, sdmi

describes an option named ipPairs, that is in the SITE category. That is, it is defined by each individual site, and is option code 132, which is of type IP Address, consisting of a potentially infinite number of pairs of IP addresses.

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FILES

• /etc/dhcp/inittab

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWcsr
Interface Stability	Unstable

SEE ALSO

dhcpinfo(1),dhcpagent(1M),attributes(5)

Alexander, S., and R. Droms, RFC 2132, DHCP Options and BOOTP Vendor Extensions, Network Working Group, March 1997.

Droms, R., RFC 2131, Dynamic Host Configuration Protocol, Network Working Group, March 1997.

SunOS 5.8  Last Revised 7 Jun1999

NAME | SYNOPSIS | DESCRIPTION | USAGE | EXAMPLES | FILES | ATTRIBUTES | SEE ALSO