dhcptab(4)
NAME
dhcptab - DHCP configuration parameter table
DESCRIPTION
The dhcptab configuration table allows network administra-
tors to organize 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 descrip-
tion 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 maintain it. However, any dhcptab must contain the fol-
lowing 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 char-
acters, with the length limited 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, separated by a comma (,), which
define a symbol's characteristics. Once defined, a
symbol can be used in macro definitions.
Symbol Characteristics
The Value field of a symbols definition contain the follow-
ing fields describing the characteristics of a symbol:
Context
This field defines the context in which the symbol
definition is to be used. It can have one of the fol-
lowing 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. Mul-
tiple 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 Ven-
dor client class matches the value returned by
the command uname -i on the client, with periods
replacing commas.
Code This field specifies the option code number associated
with this symbol. Valid values are 128-254 for site-
specific 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 boolean
TRUE, whereas absence denotes FALSE. Granular-
ity and Miximum values have no meaning for sym-
bols of this type.
IP Dotted decimal form of an Internet address.
Multi-IP address granularity is supported.
NUMBER
An unsigned number with a supported granularity
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 symbols 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 granular-
ity 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 sym-
bol. 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 per-
mitted.
The following example defines a site-specific option (sym-
bol) 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 specific IP addresses.
Up to four macro definitions are consulted by the DHCP
server to determine 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 configura-
tion parameters to be returned to all clients of the
same class.
Network
A macro named by the dotted Internet form of the net-
work address of the client's network (for example,
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 mechan-
ism permits the network administrator to select confi-
guration parameters to be returned to all clients on
the same network.
IP Address
This macro may be named anything, but must be speci-
fied 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 particu-
lar 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 net-
work 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 sym-
bol collisions are replaced with those specified in
the client identifier macro. The client mechanism per-
mits 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 symbols used in Solaris DHCP.
SEE ALSO
dhcpmgr(1M), dhtadm(1M), in.dhcpd(1M), dhcp_inittab(4),
dhcp_network(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 University, March 1997.
Wimer, W., Clarifications and Extensions for the Bootstrap
Protocol, RFC 1542, Carnegie Mellon University, October
1993.
Man(1) output converted with
man2html