Differences Between dhcptags and inittab
The inittab file contains more information than the dhcptags file and it uses a different syntax.
A sample dhcptags entry is:
33 StaticRt - IPList Static_Routes
where 33 is the numeric code that is passed in the
DHCP packet, StaticRt is the option name, IPList indicates the expected data is a list of IP addresses, and Static_Routes is a more descriptive name.
The inittab file consists of one-line records that
describe each option. The format is similar to the format that defines symbols
in dhcptab. The following table describes the syntax of
the inittab.
Table 6–3 DHCP
inittab File Syntax
|
Option
|
Description
|
|
option-name
|
Name of the option. The option name must be unique within its option category,
and not overlap with other option names in the Standard, Site, and Vendor
categories. For example, you cannot have two Site options with the same name,
and you should not create a Site option with the same name as a Standard option.
|
|
category
|
Identifies the namespace in which the option belongs. Must be one of Standard,
Site, Vendor, Field, or Internal.
|
|
code
|
Identifies the option when it is sent over the network. In most cases, the
code uniquely identifies the option, without a category. However, in the
case of internal categories like Field or Internal, a code might be used for
other purposes and thus might not be globally unique. The code should be
unique within the option's category, and not overlap with codes in the Standard
and Site fields.
|
|
type
|
Describes the data associated with this option. Valid types are IP, Ascii,
Octet, Boolean, Unumber8, Unumber16, Unumber32, Unumber64, Snumber8, Snumber16,
Snumber32, and Snumber64. For numbers, an initial U or S indicates that the
number is unsigned or signed, and the digits at the end indicate the amount
of bits in the number. The type is not case sensitive.
|
|
granularity
|
Describes how many units of data make up a whole value for this option.
|
|
maximum
|
Describes how many whole values are allowed for this option. 0 indicates
an infinite number.
|
|
consumers
|
Describes which programs can use this information.
This should be set to sdmi, where:
s – snoop
d – in.dhcpd
m – dhcpmgr
i – dhcpinfo
|
A sample inittab entry is:
StaticRt Standard, 33, IP, 2, 0, sdmi
This entry describes an option named StaticRt, which
is in the Standard category and is option code 33. The expected data is a
potentially infinite number of pairs of IP addresses because the type is IP, granularity is 2, and maximum is infinite
(0). The consumers of this option are sdmi: snoop, in.dhcpd, dhcpmgr,
and dhcpinfo.
