dhcp_inittab(4) File Formats dhcp_inittab(4)
dhcp_inittab - information repository for DHCP options
The /etc/dhcp/inittab file contains information about the Dynamic Host Configuration Protocol (DHCP) options, which are network configura-
tion 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:
o A mnemonic alias, or symbol name, for each option number. For instance, option 12 is aliased to the name Hostname. This is useful for
DHCP-related programs that require human interaction, such as dhcpinfo(1).
o 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.
o The policy for what options are visible to which DHCP-related programs.
The dhcp_inittab file can only be changed upon system upgrade. Only additions of SITE options (or changes to same) will be preserved dur-
The VENDOR options defined here are intended for use by the Solaris DHCP client and DHCP management tools. The SUNW vendor space is owned
by Sun, and changes are likely during upgrade. If you need to configure the Solaris DHCP server to support the vendor options of a differ-
ent client, see dhcptab(4) for details.
Each DHCP option belongs to a certain category, which roughly defines the scope of the option; for instance, an option may only be under-
stood 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. The dhcp_inittab file only contains Sun vendor options. Define non-Sun vendor options
in the dhcptab file.
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.
DHCP inittab Format
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:
o 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. See Mnemonic Identifiers for Options section of this man page for descriptions of the option names.
o Category (scope)
The Category field is one of STANDARD, SITE, VENDOR, FIELD, or INTERNAL and identifies the scope in which the option falls.
o 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.
o Data Type
Data Type is one of the following values, which are not case sensitive:
Ascii A printable character string
Bool Has no value. Scope limited to category limited to INTERNAL. Presence of an option of this type within a Solaris con-
figuration file represents TRUE, absence represents FALSE.
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.
The Granularity field describes how many "indivisible units" in the option payload make up a whole value or item for this option. The
value must be greater than zero(0) for any data type other than Bool, in which case it must be zero(0).
o Maximum Number Of Items
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
of zero(0) means that a variable number of items is permitted.
The Visibility field specifies which DHCP-related programs make use of this information, and should always be defined as "sdmi" for
newly added options.
Mnemonic Identifiers for Options
The following table maps the mnemonic identifiers used in Solaris DHCP to RFC 2132 options:
Symbol Code Description
Subnet 1 Subnet Mask, dotted Internet
UTCoffst 2 Coordinated Universal time offset
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,
Cookie 8 List of RFC-865 cookie servers, IP.
Lprserv 9 List of RFC-1179 line printer
Impress 10 List of Imagen Impress servers, IP.
Resource 11 List of RFC-887 resource location
Hostname 12 Client's hostname, value from hosts
Bootsize 13 Number of 512 octet blocks in boot
Dumpfile 14 Path where core image should be
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, NUM-
NLrouteF 20 Non-local Source Routing, NUMBER.
PFilter 21 Policy Filter, IP.
MaxIpSiz 22 Maximum datagram Reassembly Size,
IpTTL 23 Default IP Time to Live,
PathTO 24 RFC-1191 Path MTU Aging Timeout,
PathTbl 25 RFC-1191 Path MTU Plateau Table,
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
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
NetBNdT 46 NetBIOS Node type (1=B-node, 2=P,
NetBScop 47 NetBIOS scope, ASCII.
XFontSrv 48 List of X Window Font servers, IP.
XDispMgr 49 List of X Window Display managers,
LeaseTim 51 Lease Time Policy, (-1 = PERM),
Message 56 Message to be displayed on client,
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
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
POP3serv 70 Post Office Protocol (POP3) Server,
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.
UserClas 77 User class information, ASCII.
SLP_DA 78 Directory agent, OCTET.
SLP_SS 79 Service scope, OCTET.
AgentOpt 82 Agent circuit ID, OCTET.
FQDN 89 Fully Qualified Domain Name, OCTET.
PXEarch 93 Client system architecture, NUMBER.
PXEnii 94 Client Network Device Interface,
PXEcid 97 UUID/GUID-based client indentifier,
BootFile N/A File to Boot, ASCII.
BootPath N/A Boot path prefix to apply to
client's requested boot file,
BootSrvA N/A Boot Server, IP.
BootSrvN N/A Boot Server Hostname, ASCII.
EchoVC N/A Echo Vendor Class Identifier Flag,
LeaseNeg N/A Lease is Negotiable Flag,
Include N/A Include listed macro values in this
Example 1: Altering the DHCP inittab File
In general, the DHCP inittab file should only be altered to add SITE options. If other options are added, they will not be automatically
carried forward when the system is upgraded. 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.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Availability |SUNWcsr |
|Interface Stability |Evolving |
dhcpinfo(1),dhcpagent(1M), isspace(3C), dhcptab(4), attributes(5), dhcp(5), dhcp_modules(5)
System Administration Guide: IP Services
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 5.10 7 Jun 2001 dhcp_inittab(4)