Droms R. The DHCP handbook

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The finger server option lists addresses of finger protocol (see RFC 1288) servers

that are available to the client. If more than one address is in the list, the finger

servers are listed in order of preference. The length must be a multiple of 4; if

s finger servers are in the option, the length is

4s.

WWW server

Option code: 72

Length: n

Data: list of IP addresses

The WWW server option lists addresses of World Wide Web (HTTP; see RFC 1945)

servers that are available to the client. If more than one address is in the list, the

WWW servers are listed in order of preference. The length must be a multiple of 4; if

s WWW servers are in the option, the length is

4s.

NNTP server

Option code: 71

Length: n

Data: list of IP addresses

The NNTP server option lists addresses of Network News Transport Protocol (NNTP;

see RFC 977), or NetNews, servers that are available to the client. If more than one

address is in the list, the NNTP servers are listed in order of preference. The length

must be a multiple of 4; if s NNTP servers are in the option, the length is

4s.

IRC server

Option code: 74

Length: n

Data: list of IP addresses

The IRC server option lists addresses of Internet Relay Chat (IRC; see RFC 1459)

servers that are available to the client. If more than one address is in the list, the

IRC servers are listed in order of preference. The length must be a multiple of 4; if

s IRC servers are in the option, the length is

4s.

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X Window System Options

Two options—X Window System Font Server and X Window System Display

Manager—provide information to the client about X Window System resources.

X Window System Font Server

Option code: 48

Length: n

Data: list of IP addresses

The X Window System Font Server option lists addresses of font servers that are

available to the client. If more than one address is in the list, the font servers are

listed in order of preference. The length must be a multiple of 4; if s font servers are

in the list, the length is

4s.

X Window System Display Manager

Option code: 49

Length: n

Data: list of IP addresses

The X Window System Display Manager option lists systems that are running the X

display manager that are available to the client. If more than one address is in the

list, the display manager systems are listed in order of preference. The length must

be a multiple of 4; if s display manager systems are in the list, the length is

4s.

mobile IP home agent

Option code: 68

Length: 0 no agents are available

n length of list

Data: list of IP addresses

The mobile IP home agent option is used with the mobile IP protocol (see RFC

2002). The option lists addresses of home agents available to the client. If the length

0, no home agents are available. Otherwise, the length must be a multiple of 4; if

s home agents exist, the length is

4s.

NIS and NIS+ Options

The four options described next pass information to the client about the local

deployment of NIS, NIS+.

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NIS server addresses

Option code: 41

Length: n

Data: list of IP addresses

This option contains a list of IP addresses of NIS servers. If more than one address is

in the list, the servers are listed in order of preference. The length must be a multiple

of 4; if s servers are in the list, the length is 4s.

NIS domain

Option code: 40

Length: n

Data: NIS domain

This option gives the client its NIS domain. The name in each option is a string that

is not terminated with a null character.

NIS+ server addresses

Option code: 65

Length: n

Data: list of IP addresses

This option contains addresses of the NIS+ version 2 servers. If more than one

address is in the list, the servers are listed in order of preference. The length must be

a multiple of 4; if s servers are in the list, the length is 4s.

NIS+ domain

Option code: 64

Length: n

Data: NIS+ domain

This option gives the client its NIS+ domain. The name in each option is a string

that is not terminated with a null character.

NetBIOS over TCP/IP Options

The options described in the following sections inform the client about the use of

NetBIOS over TCP/IP, as described in RFC 1001 and RFC 1002.

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NetBIOS address over TCP/IP name servers (WINS)

Option code: 44

Length: n

Data: list of IP addresses

The NetBIOS address over TCP/IP name servers option lists the addresses of

Windows Internet Naming Service (WINS) servers that are available to the client. If

more than one address is in the list, the servers are listed in order of preference. The

length must be a multiple of 4; if s servers are in the list, the length is 4s.

NetBIOS address over TCP/IP datagram distribution server

Option code: 45

Length: n

Data: list of IP addresses

The NetBIOS address over TCP/IP datagram distribution (NBDD) server option lists

the addresses of NBDD servers that are available to the client. If more than one

address is in the list, the servers are listed in order of preference. The length must be

a multiple of 4; if s servers are in the list, the length is 4s.

NetBIOS address over TCP/IP node type

Option code: 46

Length: 1

Data: 1 B-node: Broadcast—no WINS

2 P-node: Peer—WINS only

4 M-node: Mixed—broadcast, then WINS

8 H-node: Hybrid—WINS, then broadcast

The NetBIOS address over TCP/IP node type option specifies the type of node to

which the client should configure itself. The data in the option encodes the node

type.

NetBIOS address over TCP/IP scope

Option code: 47

Length: n

Data: NetBIOS over TCP/IP scope

The NetBIOS address over TCP/IP scope option specifies the NetBIOS over TCP/IP

scope for the client. The scope is encoded as a string of characters, which must be

selected according to the restrictions in RFC 1002, RFC 1002, and RFC 1035. The

resulting character string is not terminated with a null character.

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StreetTalk Options

Two options—StreetTalk server and StreetTalk Directory Assistance server—

give information on StreetTalk servers that are available to the client.

StreetTalk server

Option code: 75

Length: n

Data: list of IP addresses

The StreetTalk server option lists the addresses of StreetTalk servers for the client.

If more than one address is in the list, the servers are listed in order of preference.

The length must be a multiple of 4; if s servers are in the list, the length is

4s.

StreetTalk Directory Assistance server

Option code: 76

Length: n

Data: list of IP addresses

The StreetTalk Directory Assistance server option lists the addresses of server

StreetTalk Directory Assistance (STDA) servers that are available to the client. If more

than one address is in the list, the servers are listed in order of preference. The

length must be a multiple of 4; if s servers are in the list, the length is

4s.

NDS Options

The three options described in the following sections inform the client about the use

of NetWare Directory Services (NDS). These options are defined in RFC 2241.

NDS servers

Option code: 85

Length: n

Data: list of IP addresses

The NDS servers option lists the addresses of NDS servers that are available to the

client. If more than one address is in the list, the servers are listed in order of prefer-

ence. The length must be a multiple of 4; if s servers are in the list, the length is

4s.

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NDS Tree Name

Option code: 86

Length: n

Data: UTF-8-byte string

The NDS Tree Name option provides the name of the NDS tree that is available to the

client. The names of NDS trees are normally specified as 16-bit Unicode strings.

When carried in an

NDS Tree Name option, an NDS tree name is encoded using UTF-

8 (UCS Transformation Format-8). The resulting byte string is not terminated with a

null character.

NOTE

ISO/IEC 10646-1 defines a multi-octet character set called the Universal Character Set (UCS),

which incorporates the characters from most of the writing systems that exist today. UCS also

defines an encoding that represents each of those characters as a 16-bit number. A string

composed of these 16-bit UCS values is called a UCS string.

The UCS standard also defines UTF-8 encoding, which represents 7-bit ASCII values in a single

byte and then uses multibyte values to represent other characters from the Unicode Standard.

UTF-8 is useful because text that uses simple 7-bit values is left unchanged when converted to

UTF-8, providing backward compatibility.

NDS context

Option code: 87

Length: n

Data: UTF-8-byte string

The NDS context option gives the initial NDS context for the client. NDS contexts

are normally specified as 16-bit Unicode strings. When carried in an

NDS context

option, an NDS context is encoded by using UTF-8. The resulting byte string is not

terminated with a null character.

NOTE

Because of restrictions in the DHCP option format in which the length field is encoded as a

single byte, a DHCP option can carry only 255 data bytes. However, an NDS context name

can be longer than 255 bytes. To accommodate longer NDS context names, the sender splits

the context name among multiple occurrences of the NDS context option. The receiver then

concatenates the data fields of the NDS context options to reconstruct the complete NDS

context name.

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NetWare/IP Options

Two options—NetWare/IP Domain Name and NetWare/IP Domain Name—provide

information about the client’s configuration for NetWare/IP. These options are

defined in RFC 2242.

NetWare/IP Domain Name

Option code: 62

Length: n

Data: n characters

The NetWare/IP Domain Name option provides the name of the NetWare/IP domain

for the client. The name is a string of characters that is not terminated with a null

character.

NetWare/IP Information

Option code: 63

Length: n

Data: NetWare/IP information

The NetWare/IP Information option carries additional NetWare/IP information for

the client.

NetWare/IP Suboptions

The data area of the

NetWare/IP Information option is composed of one or more

suboptions. The suboptions are encoded in the same way as DHCP options; each

suboption includes a suboption code, a length, and the data.

The first four suboptions define how the NetWare/IP information is carried. The

NetWare/IP Information option must include one of these suboptions as the first

suboption in the option’s information area.

The remaining suboptions carry the NetWare/IP configuration information itself.

NWIP_DOES_NOT_EXIST

Suboption code: 1

Length: 0

Data: N/A

The NWIP_DOES_NOT_EXIST suboption indicates that the DHCP server does not have

NetWare/IP information for the client.

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NWIP_EXIST_IN_OPTIONS_AREA

Suboption code: 2

Length: 0

Data: N/A

If this suboption is present, it indicates that all the NetWare/IP Information option

information is contained in the

options area of the DHCP message.

NWIP_EXIST_BUT_TOO_BIG

Suboption code: 4

Length: 0

Data: N/A

The NWIP_EXIST_BUT_TOO_BIG suboption indicates that the DHCP server has

NetWare/IP configuration information for the client, but the server cannot fit the

information in the DHCP message.

NWIP_EXIST_IN_SNAME_FILE

Suboption code: 3

Length: 0

Data: N/A

The NetWare/IP configuration information is in the sname field and, if necessary, in

the

file field in the fixed-format section of the DHCP message. If this method of

transmitting the NetWare/IP configuration information is used, the

NetWare/IP

Information option appears in the options section, and it contains only the

NWIP_EXIST_IN_SNAME_FILE suboption. The sname and file fields then contain

(optionally) a

NetWare/IP Domain Name option and a NetWare/IP Information

option. The NetWare/IP Information option in the sname and file fields contains

the NetWare/IP information in the suboptions described later in this section, but it

does not include one of these first four suboptions.

NSQ_BROADCAST

Suboption code: 5

Length: 1

Data: 0 client should not use a NetWare Nearest Server Query

1 client should use a NetWare Nearest Server Query

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NSQ_BROADCAST specifies whether the client should use a NetWare Nearest Server

Query to locate a NetWare/IP server.

PREFERRED_DSS

Suboption code: 6

Length: n

Data: list of IP addresses

PREFERRED_DSS lists the addresses of NetWare Domain SAP/RIP Service (DSS) servers.

The maximum number of addresses carried in the

PREFERRED_DSS suboption is five.

The length must be a multiple of 4; if s servers are in the list, the

length field is 4s.

NEAREST_NWIP_SERVER

Suboption code: 7

Length: n

Data: list of IP addresses

NEAREST_NWIP_SERVER lists the addresses of the nearest NetWare/IP servers. The

maximum number of addresses carried in the

NEAREST_NWIP_SERVER suboption is

five. The length must be a multiple of 4; if s servers are in the list, the

length field

is 4s.

AUTORETRIES

Suboption code: 8

Length: 1

Data: 1 byte

AUTORETRIES specifies the number of times a client should attempt to contact a DSS

server initially. The number of retries is encoded as an unsigned 1-byte integer.

AUTORETRY_SECS

Suboption code: 9

Length: 1

Data: 1 byte

AUTORETRY_SECS specifies the number of seconds a client should wait between

attempts to contact a DSS server. The number of seconds is encoded as an unsigned

1-byte integer.

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NWIP_1_1

Suboption code: 10

Length: 0

Data: 0 client should not use NetWare/IP version 1.1 compatibility

1 client should use NetWare/IP version 1.1 compatibility

NWIP_1_1 specifies whether the client should employ NetWare/IP version 1.1 compat-

ibility to contact a NetWare/IP version 1.1 server.

PRIMARY_DSS

Suboption code: 11

Length: 4

Data: IP address

PRIMARY_DSS specifies the address of the primary DSS server for the client.

SLP Options

Two options—SLP Directory Agent Option and SLP Directory Agent Option—

provide information about the client’s configuration for Service Location Protocol

(SLP; see RFC 2608). These options are described in RFC 2610.

SLP Directory Agent Option

Option code: 78

Length: n; 1 + 4 bytes for each address

Data: mandatory flag, IP addresses

The SLP Directory Agent Option option gives the client a list of IP addresses for

SLP servers. The

mandatory flag controls the client’s use of multicast discovery to

locate SLP servers.

SLP Directory Agent Option

Option code: 79

Length: n; 1 + number of bytes in data field

Data: mandatory flag, list of SLP scopes

The SLP Directory Agent Option option gives the client a comma-delimited list of

the scopes that the client’s SLP agent should use. The

mandatory flag controls

whether the list of scopes in this option should override any scopes that are manu-

ally configured in the client.

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