dhcptab(4) File Formats dhcptab(4)NAMEdhcptab - DHCP configuration parameter table
DESCRIPTION
The dhcptab configuration table allows network administrators to orga‐
nize groups of configuration parameters as macro definitions, which can
then be referenced in the definition of other useful macros. These
macros are then used by the DHCP server to return their values to DHCP
and BOOTP clients.
The preferred method of managing the dhcptab is through the use of the
dhcpmgr(1M) or dhtadm(1M) utility. The description of dhcptab entries
included in this manual page is intended for informational purposes
only, and should not be used to manually edit entries.
You can view the contents of the dhcptab using the DHCP manager's tabs
for Macros and Options, or using the dhtadm -P command.
Syntax of dhcptab Entries
The format of a dhcptab table depends on the data store used to main‐
tain it. However, any dhcptab must contain the following fields in each
record:
Name This field identifies the macro or symbol record and is used
as a search key into the dhcptab table. The name of a macro or
symbol must consist of ASCII characters, with the length lim‐
ited to 128 characters. Names can include spaces, except at
the end of the name. The name is not case-sensitive.
Type This field specifies the type of record and is used as a
search key into the dhcptab. Currently, there are only two
legal values for Type:
m This record is a DHCP macro definition.
s This record is a DHCP symbol definition. It is used to
define vendor and site-specific options.
Value This field contains the value for the specified type of
record. For the m type, the value will consist of a series of
symbol=value pairs, separated by the colon (:) character. For
the s type, the value will consist of a series of fields, sep‐
arated by a comma (,), which define a symbol's characteris‐
tics. Once defined, a symbol can be used in macro definitions.
Symbol Characteristics
The Value field of a symbols definition contain the following fields
describing the characteristics of a symbol:
Context This field defines the context in which the symbol defi‐
nition is to be used. It can have one of the following
values:
Site This symbol defines a site-
specific option, codes
128-254.
Vendor=Client Class ... This symbol defines a vendor-
specific option, codes 1-254.
The Vendor context takes
ASCII string arguments which
identify the client class
that this vendor option is
associated with. Multiple
client class names can be
specified, separated by white
space. Only those clients
whose client class matches
one of these values will see
this option. For Sun
machines, the Vendor client
class matches the value
returned by the command uname
-i on the client, with peri‐
ods replacing commas.
Code This field specifies the option code number associated
with this symbol. Valid values are 128-254 for site-spe‐
cific options, and 1-254 for vendor-specific options.
Type This field defines the type of data expected as a value
for this symbol, and is not case-sensitive. Legal values
are:
ASCII NVT ASCII text. Value is enclosed in double-
quotes ("). Granularity setting has no effect
on symbols of this type, since ASCII strings
have a natural granularity of one (1).
BOOLEAN No value is associated with this data type.
Presence of symbols of this type denote bool‐
ean TRUE, whereas absence denotes FALSE.
Granularity and Miximum values have no mean‐
ing for symbols of this type.
IP Dotted decimal form of an Internet address.
Multi-IP address granularity is supported.
NUMBER An unsigned number with a supported granular‐
ity of 1, 2, 4, and 8 octets.
Valid NUMBER types are: UNUMBER8, SNUMBER8,
UNUMBER16, SNUMBER16, UNUMBER32, SNUMBER32,
UNUMBER64, and SNUMBER64. See dhcp_inittab(4)
for details.
OCTET Uninterpreted ASCII representation of binary
data. The client identifier is one example of
an OCTET string. Valid characters are 0-9, a-
f, A-F. One ASCII character represents one
nibble (4 bits), thus two ASCII characters
are needed to represent an 8 bit quantity.
The granularity setting has no effect on sym‐
bols of this type, since OCTET strings have a
natural granularity of one (1).
For example, to encode a sequence of bytes
with decimal values 77, 82, 5, 240, 14, the
option value would be encoded as 4d5205f00e.
A macro which supplies a value for option
code 78, SLP_DA, with a 0 Mandatory byte and
Directory Agents at 192.168.1.5 and
192.168.0.133 would appear in the dhcptab
as:
slpparams
Macro
:SLP_DA=00c0a80105c0a80085:
Granularity This value specifies how many objects of Type define a
single instance of the symbol value. For example, the
static route option is defined to be a variable list of
routes. Each route consists of two IP addresses, so the
Type is defined to be IP, and the data's granularity is
defined to be 2 IP addresses. The granularity field
affects the IP and NUMBER data types.
Maximum This value specifies the maximum items of Granularity
which are permissible in a definition using this symbol.
For example, there can only be one IP address specified
for a subnet mask, so the Maximum number of items in
this case is one (1). A Maximum value of zero (0) means
that a variable number of items is permitted.
The following example defines a site-specific option (symbol) called
MystatRt, of code 130, type IP, and granularity 2, and a Maximum of 0.
This definition corresponds to the internal definition of the static
route option (StaticRt).
MystatRt s Site,130,IP,2,0
The following example demonstrates how a SLP Service Scope symbol
(SLP_SS) with a scope value of happy and mandatory byte set to 0 is
encoded. The first octet of the option is the Mandatory octet, which is
set either to 0 or 1. In this example, it is set to 0 (00). The balance
of the value is the hexidecimal ASCII code numbers representing the
name happy, that is, 6861707079.
SLP_SS=006861707079
Macro Definitions
The following example illustrates a macro defined using the MystatRt
site option symbol just defined:
10netnis m :MystatRt=3.0.0.0 10.0.0.30:
Macros can be specified in the Macro field in DHCP network tables (see
dhcp_network(4)), which will bind particular macro definitions to spe‐
cific IP addresses.
Up to four macro definitions are consulted by the DHCP server to deter‐
mine the options that are returned to the requesting client.
These macros are processed in the following order:
Client Class A macro named using the ASCII representation of
the client class (e.g. SUNW.Ultra-30) is searched
for in the dhcptab. If found, its symbol/value
pairs will be selected for delivery to the client.
This mechanism permits the network administrator
to select configuration parameters to be returned
to all clients of the same class.
Network A macro named by the dotted Internet form of the
network address of the client's network (for exam‐
ple, 10.0.0.0) is searched for in the dhcptab. If
found, its symbol/value pairs will be combined
with those of the Client Class macro. If a symbol
exists in both macros, then the Network macro
value overrides the value defined in the Client
Class macro. This mechanism permits the network
administrator to select configuration parameters
to be returned to all clients on the same network.
IP Address This macro may be named anything, but must be
specified in the DHCP network table for the IP
address record assigned to the requesting client.
If this macro is found in the dhcptab, then its
symbol/value pairs will be combined with those of
the Client Class macro and the Network macro. This
mechanism permits the network administrator to
select configuration parameters to be returned to
clients using a particular IP address. It can also
be used to deliver a macro defined to include
"server-specific" information by including this
macro definition in all DHCP network table entries
owned by a specific server.
Client Identifier A macro named by the ASCII representation of the
client's unique identifier as shown in the DHCP
network table (see dhcp_network(4)). If found, its
symbol/value pairs are combined to the sum of the
Client Class, Network, and IP Address macros. Any
symbol collisions are replaced with those speci‐
fied in the client identifier macro. The client
mechanism permits the network administrator to
select configuration parameters to be returned to
a particular client, regardless of what network
that client is connected to.
Refer to System Administration Guide: IP Services for more information
about macro processing.
Refer to the dhcp_inittab(4) man page for more information about sym‐
bols used in Solaris DHCP.
SEE ALSOdhcpmgr(1M), dhtadm(1M), in.dhcpd(1M), dhcp_inittab(4), dhcp_net‐
work(4), dhcp(5)
System Administration Guide: IP Services
Alexander, S., and R. Droms, DHCP Options and BOOTP Vendor Extensions,
RFC 2132, Silicon Graphics, Inc., Bucknell University, March 1997.
Droms, R., Interoperation Between DHCP and BOOTP, RFC 1534, Bucknell
University, October 1993.
Droms, R., Dynamic Host Configuration Protocol, RFC 2131, Bucknell Uni‐
versity, March 1997.
Wimer, W., Clarifications and Extensions for the Bootstrap Protocol,
RFC 1542, Carnegie Mellon University, October 1993.
SunOS 5.11 15 Mar 2002 dhcptab(4)
