man Pages(4): File Formats

dhcptab(4)

NAME | DESCRIPTION | EXAMPLES | FILES | SEE ALSO

NAME

dhcptab- DHCP configuration parameter table

DESCRIPTION

The dhcptab macro table allows network administrators to organize groups of configuration parameters as macro definitions, which can then be further used in the definition of other useful macros. These macros can be configured such that the DHCP server will return their values to DHCP and BOOTP clients.

The preferred method of managing the dhcptab macro table is through the use of the dhtadm(1M) utility. The syntax described in the balance of this manual page is intended for informational purposes.

Syntax of the dhcptab Table

The syntax of the dhcptab table is as follows:

Comments begin with the cross-hatch (#) character in the first position on the line and end with a carriage return. Lines can be continued by escaping the carriage return character with a backslash (Teri) character.

dhcptab records contain three (3) fields:

Name Type Value

The fields are defined as follows:

Name

This field identifies the record and is used as the search key into the dhcptab table. A Name must consist of ASCII characters. If the record is of type Macro, then the length is limited to 64 characters. If the record is of type Symbol, then the length is limited to 8 characters.

Type

This field specifies the type of record. Currently, there are only two legal values for Type:

m (Macro): This record is a DHCP macro definition.
s (Symbol): 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 macro type, the value will consist of a series of symbol=value pairs, separated by the colon (:) character. For the symbol 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 fields describing the characteristics of a symbol are as follows:

Context Code Type Granularity Maximum

These fields are defined as follows:

Context

This field defines the context in which the symbol definition is to be used. It can have three values:

Extend: This symbol defines a standard option, codes from 77-127. The use of this symbol type is for adding new standard options added since the release of the dhcp server.
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.

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. 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. Granularity and Miximum values have no meaning 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 granularity of 1, 2, 4, and 8 octets.
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).

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 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

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:

Macro records can be specified in the Macro field in dhcp network databases (see dhcp_network(4)), which will bind particular macro definitions to specific IP addresses.

If present, four macro definitions are consulted by the DHCP server to determine the options that are returned to the requesting client:

Client Class Network IP Address Client Identifier

These macros are processed as follows:

Client Class: A macro called by the ASCII representation of the client class is searched for in the dhcptab. If found, then 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 example, 10.0.0.0) is searched for in the dhcptab. If found, then 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 is specified in the dhcp network database for the 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 database 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, 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 specified in the client identifier macro. This 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.

Internal Symbol Names

The following table maps the available internal symbol names to RFC-2132 options:

`Symbol`	`Code`	`Description`
`Subnet`	`1`	Subnet Mask, dotted Internet address (IP).
`UTCoffst`	`2`	Coordinated Universal time offset (seconds).
`Router`	`3`	List of Routers, IP.
`Timeserv`	`4`	List of RFC-868 servers, IP.
`IEN116ns`	`5`	List of IEN 116 name servers, IP.
`DNSserv`	`6`	List of DNS name servers, IP.
`Logserv`	`7`	List of MIT-LCS UDP log servers, IP.
`Cookie`	`8`	List of RFC-865 cookie servers, IP.
`Lprserv`	`9`	List of RFC-1179 line printer servers, IP.
`Impress`	`10`	List of Imagen Impress servers, IP.
`Resource`	`11`	List of RFC-887 resource location servers, IP.
`Hostname`	`12`	Client's hostname, value from hosts database.
`Bootsize`	`13`	Number of 512 octet blocks in boot image, NUMBER.
`Dumpfile`	`14`	Path where core image should be dumped, ASCII.
`DNSdmain`	`15`	DNS domain name, ASCII.
`Swapserv`	`16`	Client's swap server, IP.
`Rootpath`	`17`	Client's Root path, ASCII.
`ExtendP`	`18`	Extensions path, ASCII.
`IpFwdF`	`19`	IP Forwarding Enable/Disable, NUMBER.
`NLrouteF`	`20`	Non-local Source Routing, NUMBER.
`PFilter`	`21`	Policy Filter, IP,IP.
`MaxIpSiz`	`22`	Maximum datagram Reassembly Size, NUMBER.
`IpTTL`	`23`	Default IP Time to Live, (1=<x<=255), NUMBER.
`PathTO`	`24`	RFC-1191 Path MTU Aging Timeout, NUMBER.
`PathTbl`	`25`	RFC-1191 Path MTU Plateau Table, NUMBER.
`MTU`	`26`	Interface MTU, x>=68, NUMBER.
`SameMtuF`	`27`	All Subnets are Local, NUMBER.
`Broadcst`	`28`	Broadcast Address, IP.
`MaskDscF`	`29`	Perform Mask Discovery, NUMBER.
`MaskSupF`	`30`	Mask Supplier, NUMBER.
`RDiscvyF`	`31`	Perform Router Discovery, NUMBER.
`RSolictS`	`32`	Router Solicitation Address, IP.
`StaticRt`	`33`	Static Route, Double IP (network router).
`TrailerF`	`34`	Trailer Encapsulation, NUMBER.
`ArpTimeO`	`35`	ARP Cache Time out, NUMBER.
`EthEncap`	`36`	Ethernet Encapsulation, NUMBER.
`TcpTTL`	`37`	TCP Default Time to Live, NUMBER.
`TcpKaInt`	`38`	TCP Keepalive Interval, NUMBER.
`TcpKaGbF`	`39`	TCP Keepalive Garbage, NUMBER.
`NISdmain`	`40`	NIS Domain name, ASCII.
`NISservs`	`41`	List of NIS servers, IP.
`NTPservs`	`42`	List of NTP servers, IP.
`NetBNms`	`44`	List of NetBIOS Name servers, IP.
`NetBDsts`	`45`	List of NetBIOS Distribution servers, IP.
`NetBNdT`	`46`	NetBIOS Node type (1=B-node, 2=P, 4=M, 8=H)
`NetBScop`	`47`	NetBIOS scope, ASCII.
`XFontSrv`	`48`	List of X Window Font servers, IP.
`XDispMgr`	`49`	List of X Window Display managers, IP.
`LeaseTim`	`51`	Lease Time Policy, (-1 = PERM), NUMBER.
`Message`	`56`	Message to be displayed on client, ASCII.
`T1Time`	`58`	Renewal (T1) time, NUMBER.
`T2Time`	`59`	Rebinding (T2) time, NUMBER.
`NW_dmain`	`62`	NetWare/IP Domain Name, ASCII.
`NWIPOpts`	`63`	NetWare/IP Options, OCTET (unknown type).
`NIS+dom`	`64`	NIS+ Domain name, ASCII.
`NIS+serv`	`65`	NIS+ servers, IP.
`TFTPsrvN`	`66`	TFTP server hostname, ASCII.
`OptBootF`	`67`	Optional Bootfile path, ASCII.
`MblIPAgt`	`68`	Mobile IP Home Agent, IP.
`SMTPserv`	`69`	Simple Mail Transport Protocol Server, IP.
`POP3serv`	`70`	Post Office Protocol (POP3) Server, IP.
`NNTPserv`	`71`	Network News Transport Proto. (NNTP) Server, IP.
`WWWservs`	`72`	Default WorldWideWeb Server, IP.
`Fingersv`	`73`	Default Finger Server, IP.
`IRCservs`	`74`	Internet Relay Chat Server, IP.
`STservs`	`75`	StreetTalk Server, IP.
`STDAservs`	`76`	StreetTalk Directory Assist. Server, IP.
`BootFile`	`N/A`	File to Boot, ASCII.
`BootSrvA`	`N/A`	Boot Server, IP.
`BootSrvN`	`N/A`	Boot Server Hostname, ASCII.
`LeaseNeg`	`N/A`	Lease is Negotiable Flag, (Present=`TRUE`)
`Include`	`N/A`	Include listed macro values in this macro.

EXAMPLES

Example 1 An example `dhcptab` file.

Below is an example dhcptab file, illustrating the concepts described above:

#
# PCNFS vendor options. First define them, then use them in
# our Client Class macro definition to establish proper context.
#
# SolarNet framework servers. Note that this symbol is valid for two
# client classes,  "SUNW.PCNFS.5.1" and "SUNW.PCNFSPRO.1.1".
SNadmfw s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,1,ASCII,1,0
# PCNFS servers. Note that two client classes are specified for
# this symbol.
Pcnfsd s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,2,IP,1,0
# NFS Read and Write sizes. Unsigned shorts.
SNnfsRd s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,4,NUMBER,2,1
SNnfsWr s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,5,NUMBER,2,1
# NFS Timout in 1/10's of a second. An unsigned short.
SNnfsTim s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,6,NUMBER,2,1
# NFS Retries, an unsigned short.
SNnfsTry s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,7,NUMBER,2,1
# PC-Admin login script file.
SNClogin s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,8,ASCII,1,0
# PC-Admin logout script file.
SNClgout s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,9,ASCII,1,0
# PC-Admin script server.
SNCserv s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,10,IP,1,0
# Path to PC-Admin scripts on server.
SNCpath s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,11,ASCII,1,0
# PC-Admin Boot script file.
SNCboot s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,12,ASCII,1,0
# Timezone (TZ)
SN_TZ s Vendor=SUNW.PCNFS.5.1.1 SUNW.PCNFSPRO.1.1,13,ASCII,1,0
# Site specific option.
SiteTest s Site,128,IP,1,1
# PCNFS client class. This option will automatically be returned
# to clients specifying "SUNW.PCNFS.5.1.1" as their Client Class.
# Predefined, Site, or vendor symbols can be used in this definition.
# However, note that vendor symbols used here whose Client Class does not
# match will be omitted in the response to the client.
SUNW.PCNFS.5.1.1 m :SNadmfw="doppelbock pilsner": \
   :Pcnfsd=10.0.5.26 10.0.5.5 10.0.4.1: :SNnfsRd=1024:SNnfsWr=8192: \
   :SNnfsTim=56:SNnfsTry=6: :Impress=10.0.0.254:
# Set the locale. EST's offset is 18000 seconds. Note also the use
# of the SN_TZ (which will overwrite UTCoffst for SUNW.PCNFS.5.1.1 and
# SUNW.PCNFSPRO.1.1 clients).
Locale m :UTCoffst=18000:SN_TZ="EST5EDT":
# Netbios node type is broadcast (1).
NetBIOS m :NetBNms=10.0.5.1 10.0.4.1:NetBNdT=0x1: \
   :NetBDsts=10.0.5.5 10.0.5.6 10.0.4.2: :NetBScop="NB.This.Is.A.Nis.DOMAIN":
# This macro includes the definitions for Locale and NetBIOS.
# Lease is renegotiable, and the maximum lease a client can request
# is 2 hours (7200 seconds)
#
# Note that this macro definition includes the SUNW.PCNFS.5.1.1 and
# SUNW.PCNFSPRO.1.1 Vendor symbol for SolarNet login script file name.
# Only those clients whose Client Class is SUNW.PCNFS.5.1.1 or
# SUNW.PCNFSPRO.1.1 will see this value.
5netnis m :Subnet=255.255.255.0:Router=10.0.5.26 10.0.5.27: \
   :Include=Locale:SNCpath="/opt/SUNWpcnet/1.5/site/pcnfs": \
   :SNCboot="boot.snc":SNCserv=10.0.5.26:Timeserv=10.0.5.5: \
   :NISdmain="This.Is.A.Nis.DOMAIN":NISservs=10.0.5.210: \
   :Message="NIS client, Welcometo the 5 net.": \
   :SiteTest=1.0.0.0:LeaseTim=7200:LeaseNeg:Include=NetBIOS: \
   :SNClogin="login.snc":
# This macro defines a short lease - only 5 minutes! Note the use
# of the pcnfsd vendor option here. Note also that the server will
# return the client's hostname by consulting the hosts database for
# the value.
15netnis m :Subnet=255.255.255.0:Router=10.0.15.226: \
   :Include=Locale:SNCpath="/opt/solarnet":SNCboot="site.snc": \
   :SNCserv=10.0.15.226:Timeserv=10.0.5.5: \
   :NISdmain="Another.Nis.Domain.COM":NISservs=10.0.15.6: \
   :Message="NIS client, Welcome to the 15 net.": \
   :LeaseTim=300:LeaseNeg:Pcnfsd=10.0.15.226:Hostname: 
5netdns m :Subnet=255.255.255.0:Router=10.0.5.26 10.0.5.26: \
	  :SNCserv=10.0.5.26:SNCpath="/opt/SUNWpcnet/site/pcnfs": \
   :SNCboot="boot.snc":Include=Locale:Timeserv=10.0.5.5: \
	  :DNSdmain="East.Sun.COM":DNSserv=10.0.15.6 15.0.1.15: \
   :Message="DNS client, Welcome to the 5 net.":LeaseNeg:
# This macro is named by a client's client identifier. Its options
# will be combined with those of the Client Class macro
# and per network macro, if defined. Regardless of where this client
# boots, these options will follow it!
010800C0EE0E4C m :Impress=10.0.20.55:

FILES

/var/dhcp/dhcptab: file or NIS+ table.