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Network Working Group
Request for Comments: 1002 March, 1987




PROTOCOL STANDARD FOR A NetBIOS SERVICE
ON A TCP/UDP TRANSPORT:
DETAILED SPECIFICATIONS




ABSTRACT

This RFC defines a proposed standard protocol to support NetBIOS
services in a TCP/IP environment. Both local network and internet
operation are supported. Various node types are defined to accommodate
local and internet topologies and to allow operation with or without the
use of IP broadcast.

This RFC gives the detailed specifications of the NetBIOS-over-TCP
packets, protocols, and defined constants and variables. A more general
overview is found in a companion RFC, "Protocol Standard For a NetBIOS
Service on a TCP/UDP Transport: Concepts and Methods".





























NetBIOS Working Group [Page 1]

RFC 1002 March 1987


TABLE OF CONTENTS


1. STATUS OF THIS MEMO 4

2. ACKNOWLEDGEMENTS 4

3. INTRODUCTION 5

4. PACKET DESCRIPTIONS 5
4.1 NAME FORMAT 5
4.2 NAME SERVICE PACKETS 7
4.2.1 GENERAL FORMAT OF NAME SERVICE PACKETS 7
4.2.1.1 HEADER 8
4.2.1.2 QUESTION SECTION 10
4.2.1.3 RESOURCE RECORD 11
4.2.2 NAME REGISTRATION REQUEST 13
4.2.3 NAME OVERWRITE REQUEST & DEMAND 14
4.2.4 NAME REFRESH REQUEST 15
4.2.5 POSITIVE NAME REGISTRATION RESPONSE 16
4.2.6 NEGATIVE NAME REGISTRATION RESPONSE 16
4.2.7 END-NODE CHALLENGE REGISTRATION RESPONSE 17
4.2.8 NAME CONFLICT DEMAND 18
4.2.9 NAME RELEASE REQUEST & DEMAND 19
4.2.10 POSITIVE NAME RELEASE RESPONSE 20
4.2.11 NEGATIVE NAME RELEASE RESPONSE 20
4.2.12 NAME QUERY REQUEST 21
4.2.13 POSITIVE NAME QUERY RESPONSE 22
4.2.14 NEGATIVE NAME QUERY RESPONSE 23
4.2.15 REDIRECT NAME QUERY RESPONSE 24
4.2.16 WAIT FOR ACKNOWLEDGEMENT (WACK) RESPONSE 25
4.2.17 NODE STATUS REQUEST 26
4.2.18 NODE STATUS RESPONSE 27
4.3 SESSION SERVICE PACKETS 29
4.3.1 GENERAL FORMAT OF SESSION PACKETS 29
4.3.2 SESSION REQUEST PACKET 30
4.3.3 POSITIVE SESSION RESPONSE PACKET 31
4.3.4 NEGATIVE SESSION RESPONSE PACKET 31
4.3.5 SESSION RETARGET RESPONSE PACKET 31
4.3.6 SESSION MESSAGE PACKET 32
4.3.7 SESSION KEEP ALIVE PACKET 32
4.4 DATAGRAM SERVICE PACKETS 32
4.4.1 NetBIOS DATAGRAM HEADER 32
4.4.2 DIRECT_UNIQUE, DIRECT_GROUP, & BROADCAST DATAGRAM 33
4.4.3 DATAGRAM ERROR PACKET 34
4.4.4 DATAGRAM QUERY REQUEST 34
4.4.5 DATAGRAM POSITIVE AND NEGATIVE QUERY RESPONSE 34

5. PROTOCOL DESCRIPTIONS 35
5.1 NAME SERVICE PROTOCOLS 35
5.1.1 B-NODE ACTIVITY 35



NetBIOS Working Group [Page 2]

RFC 1002 March 1987


5.1.1.1 B-NODE ADD NAME 35
5.1.1.2 B-NODE ADD_GROUP NAME 37
5.1.1.3 B-NODE FIND_NAME 37
5.1.1.4 B NODE NAME RELEASE 38
5.1.1.5 B-NODE INCOMING PACKET PROCESSING 39
5.1.2 P-NODE ACTIVITY 42
5.1.2.1 P-NODE ADD_NAME 42
5.1.2.2 P-NODE ADD GROUP NAME 45
5.1.2.3 P-NODE FIND NAME 45
5.1.2.4 P-NODE DELETE_NAME 46
5.1.2.5 P-NODE INCOMING PACKET PROCESSING 47
5.1.2.6 P-NODE TIMER INITIATED PROCESSING 49
5.1.3 M-NODE ACTIVITY 50
5.1.3.1 M-NODE ADD NAME 50
5.1.3.2 M-NODE ADD GROUP NAME 54
5.1.3.3 M-NODE FIND NAME 55
5.1.3.4 M-NODE DELETE NAME 56
5.1.3.5 M-NODE INCOMING PACKET PROCESSING 58
5.1.3.6 M-NODE TIMER INITIATED PROCESSING 60
5.1.4 NBNS ACTIVITY 60
5.1.4.1 NBNS INCOMING PACKET PROCESSING 61
5.1.4.2 NBNS TIMER INITIATED PROCESSING 66
5.2 SESSION SERVICE PROTOCOLS 67
5.2.1 SESSION ESTABLISHMENT PROTOCOLS 67
5.2.1.1 USER REQUEST PROCESSING 67
5.2.1.2 RECEIVED PACKET PROCESSING 71
5.2.2 SESSION DATA TRANSFER PROTOCOLS 72
5.2.2.1 USER REQUEST PROCESSING 72
5.2.2.2 RECEIVED PACKET PROCESSING 72
5.2.2.3 PROCESSING INITIATED BY TIMER 73
5.2.3 SESSION TERMINATION PROTOCOLS 73
5.2.3.1 USER REQUEST PROCESSING 73
5.2.3.2 RECEPTION INDICATION PROCESSING 73
5.3 NetBIOS DATAGRAM SERVICE PROTOCOLS 74
5.3.1 B NODE TRANSMISSION OF NetBIOS DATAGRAMS 74
5.3.2 P AND M NODE TRANSMISSION OF NetBIOS DATAGRAMS 76
5.3.3 RECEPTION OF NetBIOS DATAGRAMS BY ALL NODES 78
5.3.4 PROTOCOLS FOR THE NBDD 80

6. DEFINED CONSTANTS AND VARIABLES 83

REFERENCES 85












NetBIOS Working Group [Page 3]

RFC 1002 March 1987


PROTOCOL STANDARD FOR A NetBIOS SERVICE
ON A TCP/UDP TRANSPORT:
DETAILED SPECIFICATIONS


1. STATUS OF THIS MEMO

This RFC specifies a proposed standard for the DARPA Internet
community. Since this topic is new to the Internet community,
discussions and suggestions are specifically requested.

Please send written comments to:

Karl Auerbach
Epilogue Technology Corporation
P.O. Box 5432
Redwood City, CA 94063

Please send online comments to:

Avnish Aggarwal
Internet: [email protected]
Usenet: ucbvax!mtxinu!excelan!avnish

Distribution of this memorandum is unlimited.

2. ACKNOWLEDGEMENTS

This RFC has been developed under the auspices of the Internet
Activities Board.

The following individuals have contributed to the development of
this RFC:

Avnish Aggarwal Arvind Agrawal Lorenzo Aguilar
Geoffrey Arnold Karl Auerbach K. Ramesh Babu
Keith Ball Amatzia Ben-Artzi Vint Cerf
Richard Cherry David Crocker Steve Deering
Greg Ennis Steve Holmgren Jay Israel
David Kaufman Lee LaBarre James Lau
Dan Lynch Gaylord Miyata David Stevens
Steve Thomas Ishan Wu

The system proposed by this RFC does not reflect any existing
Netbios-over-TCP implementation. However, the design
incorporates considerable knowledge obtained from prior
implementations. Special thanks goes to the following
organizations which have provided this invaluable information:

CMC/Syros Excelan Sytek Ungermann-Bass




NetBIOS Working Group [Page 4]

RFC 1002 March 1987


3. INTRODUCTION

This RFC contains the detailed packet formats and protocol
specifications for NetBIOS-over-TCP. This RFC is a companion to
RFC 1001, "Protocol Standard For a NetBIOS Service on a TCP/UDP
Transport: Concepts and Methods" [1].

4. PACKET DESCRIPTIONS

Bit and byte ordering are defined by the most recent version of
"Assigned Numbers" [2].

4.1. NAME FORMAT

The NetBIOS name representation in all NetBIOS packets (for NAME,
SESSION, and DATAGRAM services) is defined in the Domain Name
Service RFC 883[3] as "compressed" name messages. This format is
called "second-level encoding" in the section entitled
"Representation of NetBIOS Names" in the Concepts and Methods
document.

For ease of description, the first two paragraphs from page 31,
the section titled "Domain name representation and compression",
of RFC 883 are replicated here:

Domain names messages are expressed in terms of a sequence
of labels. Each label is represented as a one octet length
field followed by that number of octets. Since every domain
name ends with the null label of the root, a compressed
domain name is terminated by a length byte of zero. The
high order two bits of the length field must be zero, and
the remaining six bits of the length field limit the label
to 63 octets or less.

To simplify implementations, the total length of label
octets and label length octets that make up a domain name is
restricted to 255 octets or less.

The following is the uncompressed representation of the NetBIOS name
"FRED ", which is the 4 ASCII characters, F, R, E, D, followed by 12
space characters (0x20). This name has the SCOPE_ID: "NETBIOS.COM"

EGFCEFEECACACACACACACACACACACACA.NETBIOS.COM

This uncompressed representation of names is called "first-level
encoding" in the section entitled "Representation of NetBIOS Names"
in the Concepts and Methods document.

The following is a pictographic representation of the compressed
representation of the previous uncompressed Domain Name
representation.



NetBIOS Working Group [Page 5]

RFC 1002 March 1987


1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x20 | E (0x45) | G (0x47) | F (0x46) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| C (0x43) | E (0x45) | F (0x46) | E (0x45) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| E (0x45) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x41) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x41) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x41) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x41) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x41) | C (0x43) | A (0x41) | C (0x43) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0X41) | 0x07 | N (0x4E) | E (0x45) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T (0x54) | B (0x42) | I (0x49) | O (0x4F) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| S (0x53) | 0x03 | C (0x43) | O (0x4F) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| M (0x4D) | 0x00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Each section of a domain name is called a label [7 (page 31)]. A
label can be a maximum of 63 bytes. The first byte of a label in
compressed representation is the number of bytes in the label. For
the above example, the first 0x20 is the number of bytes in the
left-most label, EGFCEFEECACACACACACACACACACACACA, of the domain
name. The bytes following the label length count are the characters
of the label. The following labels are in sequence after the first
label, which is the encoded NetBIOS name, until a zero (0x00) length
count. The zero length count represents the root label, which is
always null.

A label length count is actually a 6-bit field in the label length
field. The most significant 2 bits of the field, bits 7 and 6, are
flags allowing an escape from the above compressed representation.
If bits 7 and 6 are both set (11), the following 14 bits are an
offset pointer into the full message to the actual label string from
another domain name that belongs in this name. This label pointer
allows for a further compression of a domain name in a packet.

NetBIOS implementations can only use label string pointers in Name
Service packets. They cannot be used in Session or Datagram Service
packets.




NetBIOS Working Group [Page 6]

RFC 1002 March 1987


The other two possible values for bits 7 and 6 (01 and 10) of a label
length field are reserved for future use by RFC 883[2 (page 32)].


Note that the first octet of a compressed name must contain one of
the following bit patterns. (An "x" indicates a bit whose value may
be either 0 or 1.):

00100000 - Netbios name, length must be 32 (decimal)
11xxxxxx - Label string pointer
10xxxxxx - Reserved
01xxxxxx - Reserved

4.2. NAME SERVICE PACKETS

4.2.1. GENERAL FORMAT OF NAME SERVICE PACKETS

The NetBIOS Name Service packets follow the packet structure defined
in the Domain Name Service (DNS) RFC 883 [7 (pg 26-31)]. The
structures are compatible with the existing DNS packet formats,
however, additional types and codes have been added to work with
NetBIOS.

If Name Service packets are sent over a TCP connection they are
preceded by a 16 bit unsigned integer representing the length of the
Name Service packet.

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ ------ ------- +
| HEADER |
+ ------ ------- +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION ENTRIES /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ ANSWER RESOURCE RECORDS /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ AUTHORITY RESOURCE RECORDS /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ ADDITIONAL RESOURCE RECORDS /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



NetBIOS Working Group [Page 7]

RFC 1002 March 1987


4.2.1.1. HEADER

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID | OPCODE | NM_FLAGS | RCODE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QDCOUNT | ANCOUNT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NSCOUNT | ARCOUNT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Field Description

NAME_TRN_ID Transaction ID for Name Service Transaction.
Requestor places a unique value for each active
transaction. Responder puts NAME_TRN_ID value
from request packet in response packet.

OPCODE Packet type code, see table below.

NM_FLAGS Flags for operation, see table below.

RCODE Result codes of request. Table of RCODE values
for each response packet below.

QDCOUNT Unsigned 16 bit integer specifying the number of
entries in the question section of a Name

Service packet. Always zero (0) for responses.
Must be non-zero for all NetBIOS Name requests.

ANCOUNT Unsigned 16 bit integer specifying the number of
resource records in the answer section of a Name
Service packet.

NSCOUNT Unsigned 16 bit integer specifying the number of
resource records in the authority section of a
Name Service packet.

ARCOUNT Unsigned 16 bit integer specifying the number of
resource records in the additional records
section of a Name Service packet.

The OPCODE field is defined as:

0 1 2 3 4
+---+---+---+---+---+
| R | OPCODE |
+---+---+---+---+---+




NetBIOS Working Group [Page 8]

RFC 1002 March 1987


Symbol Bit(s) Description

OPCODE 1-4 Operation specifier:
0 = query
5 = registration
6 = release
7 = WACK
8 = refresh

R 0 RESPONSE flag:
if bit == 0 then request packet
if bit == 1 then response packet.

The NM_FLAGS field is defined as:


0 1 2 3 4 5 6
+---+---+---+---+---+---+---+
|AA |TC |RD |RA | 0 | 0 | B |
+---+---+---+---+---+---+---+

Symbol Bit(s) Description

B 6 Broadcast Flag.
= 1: packet was broadcast or multicast
= 0: unicast

RA 3 Recursion Available Flag.

Only valid in responses from a NetBIOS Name
Server -- must be zero in all other
responses.

If one (1) then the NBNS supports recursive
query, registration, and release.

If zero (0) then the end-node must iterate
for query and challenge for registration.

RD 2 Recursion Desired Flag.

May only be set on a request to a NetBIOS
Name Server.

The NBNS will copy its state into the
response packet.

If one (1) the NBNS will iterate on the
query, registration, or release.

TC 1 Truncation Flag.



NetBIOS Working Group [Page 9]

RFC 1002 March 1987


Set if this message was truncated because the
datagram carrying it would be greater than
576 bytes in length. Use TCP to get the
information from the NetBIOS Name Server.

AA 0 Authoritative Answer flag.

Must be zero (0) if R flag of OPCODE is zero
(0).

If R flag is one (1) then if AA is one (1)
then the node responding is an authority for
the domain name.

End nodes responding to queries always set
this bit in responses.

4.2.1.2. QUESTION SECTION

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QUESTION_TYPE | QUESTION_CLASS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Field Description

QUESTION_NAME The compressed name representation of the
NetBIOS name for the request.

QUESTION_TYPE The type of request. The values for this field
are specified for each request.

QUESTION_CLASS The class of the request. The values for this
field are specified for each request.

QUESTION_TYPE is defined as:

Symbol Value Description:

NB 0x0020 NetBIOS general Name Service Resource Record
NBSTAT 0x0021 NetBIOS NODE STATUS Resource Record (See NODE
STATUS REQUEST)

QUESTION_CLASS is defined as:




NetBIOS Working Group [Page 10]

RFC 1002 March 1987


Symbol Value Description:

IN 0x0001 Internet class

4.2.1.3. RESOURCE RECORD

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RR_TYPE | RR_CLASS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDLENGTH | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
/ /
/ RDATA /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Field Description

RR_NAME The compressed name representation of the
NetBIOS name corresponding to this resource
record.

RR_TYPE Resource record type code

RR_CLASS Resource record class code

TTL The Time To Live of a the resource record's
name.

RDLENGTH Unsigned 16 bit integer that specifies the
number of bytes in the RDATA field.

RDATA RR_CLASS and RR_TYPE dependent field. Contains
the resource information for the NetBIOS name.

RESOURCE RECORD RR_TYPE field definitions:

Symbol Value Description:

A 0x0001 IP address Resource Record (See REDIRECT NAME
QUERY RESPONSE)
NS 0x0002 Name Server Resource Record (See REDIRECT



NetBIOS Working Group [Page 11]

RFC 1002 March 1987


NAME QUERY RESPONSE)
NULL 0x000A NULL Resource Record (See WAIT FOR
ACKNOWLEDGEMENT RESPONSE)
NB 0x0020 NetBIOS general Name Service Resource Record
(See NB_FLAGS and NB_ADDRESS, below)
NBSTAT 0x0021 NetBIOS NODE STATUS Resource Record (See NODE
STATUS RESPONSE)

RESOURCE RECORD RR_CLASS field definitions:

Symbol Value Description:

IN 0x0001 Internet class

NB_FLAGS field of the RESOURCE RECORD RDATA field for RR_TYPE of
"NB":

1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| G | ONT | RESERVED |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

Symbol Bit(s) Description:

RESERVED 3-15 Reserved for future use. Must be zero (0).
ONT 1,2 Owner Node Type:
00 = B node
01 = P node
10 = M node
11 = Reserved for future use
For registration requests this is the
claimant's type.
For responses this is the actual owner's
type.

G 0 Group Name Flag.
If one (1) then the RR_NAME is a GROUP
NetBIOS name.
If zero (0) then the RR_NAME is a UNIQUE
NetBIOS name.

The NB_ADDRESS field of the RESOURCE RECORD RDATA field for
RR_TYPE of "NB" is the IP address of the name's owner.










NetBIOS Working Group [Page 12]

RFC 1002 March 1987


4.2.2. NAME REGISTRATION REQUEST

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x5 |0|0|1|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Since the RR_NAME is the same name as the QUESTION_NAME, the
RR_NAME representation must use pointers to the QUESTION_NAME
name's labels to guarantee the length of the datagram is less
than the maximum 576 bytes. See section above on name formats
and also page 31 and 32 of RFC 883, Domain Names - Implementation
and Specification, for a complete description of compressed name
label pointers.















NetBIOS Working Group [Page 13]

RFC 1002 March 1987


4.2.3. NAME OVERWRITE REQUEST & DEMAND

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x5 |0|0|0|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+























NetBIOS Working Group [Page 14]

RFC 1002 March 1987


4.2.4. NAME REFRESH REQUEST

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x9 |0|0|0|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+























NetBIOS Working Group [Page 15]

RFC 1002 March 1987


4.2.5. POSITIVE NAME REGISTRATION RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x5 |1|0|1|1|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.6. NEGATIVE NAME REGISTRATION RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x5 |1|0|1|1|0 0|0| RCODE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





NetBIOS Working Group [Page 16]

RFC 1002 March 1987


RCODE field values:

Symbol Value Description:

FMT_ERR 0x1 Format Error. Request was invalidly
formatted.
SRV_ERR 0x2 Server failure. Problem with NBNS, cannot
process name.
IMP_ERR 0x4 Unsupported request error. Allowable only
for challenging NBNS when gets an Update type
registration request.
RFS_ERR 0x5 Refused error. For policy reasons server
will not register this name from this host.
ACT_ERR 0x6 Active error. Name is owned by another node.
CFT_ERR 0x7 Name in conflict error. A UNIQUE name is
owned by more than one node.

4.2.7. END-NODE CHALLENGE REGISTRATION RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x5 |1|0|1|0|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+













NetBIOS Working Group [Page 17]

RFC 1002 March 1987


4.2.8. NAME CONFLICT DEMAND

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x5 |1|0|1|1|0 0|0| 0x7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00000000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 |0|ONT|0| 0x000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00000000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This packet is identical to a NEGATIVE NAME REGISTRATION RESPONSE
with RCODE = CFT_ERR.



























NetBIOS Working Group [Page 18]

RFC 1002 March 1987


4.2.9. NAME RELEASE REQUEST & DEMAND

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x6 |0|0|0|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00000000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Since the RR_NAME is the same name as the QUESTION_NAME, the
RR_NAME representation must use label string pointers to the
QUESTION_NAME labels to guarantee the length of the datagram is
less than the maximum 576 bytes. This is the same condition as
with the NAME REGISTRATION REQUEST.

















NetBIOS Working Group [Page 19]

RFC 1002 March 1987


4.2.10. POSITIVE NAME RELEASE RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x6 |1|0|0|0|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.11. NEGATIVE NAME RELEASE RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x6 |1|0|0|0|0 0|0| RCODE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0006 | NB_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





NetBIOS Working Group [Page 20]

RFC 1002 March 1987


RCODE field values:

Symbol Value Description:

FMT_ERR 0x1 Format Error. Request was invalidly
formatted.

SRV_ERR 0x2 Server failure. Problem with NBNS, cannot
process name.

RFS_ERR 0x5 Refused error. For policy reasons server
will not release this name from this host.

ACT_ERR 0x6 Active error. Name is owned by another node.
Only that node may release it. A NetBIOS
Name Server can optionally allow a node to
release a name it does not own. This would
facilitate detection of inactive names for
nodes that went down silently.

4.2.12. NAME QUERY REQUEST

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x0 |0|0|1|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
















NetBIOS Working Group [Page 21]

RFC 1002 March 1987


4.2.13. POSITIVE NAME QUERY RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x0 |1|T|1|?|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDLENGTH | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
/ ADDR_ENTRY ARRAY /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The ADDR_ENTRY ARRAY a sequence of zero or more ADDR_ENTRY
records. Each ADDR_ENTRY record represents an owner of a name.
For group names there may be multiple entries. However, the list
may be incomplete due to packet size limitations. Bit 22, "T",
will be set to indicate truncated data.

Each ADDR_ENTRY has the following format:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_FLAGS | NB_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NB_ADDRESS (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+













NetBIOS Working Group [Page 22]

RFC 1002 March 1987


4.2.14. NEGATIVE NAME QUERY RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x0 |1|0|1|?|0 0|0| RCODE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NULL (0x000A) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00000000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

RCODE field values:

Symbol Value Description

FMT_ERR 0x1 Format Error. Request was invalidly
formatted.
SRV_ERR 0x2 Server failure. Problem with NBNS, cannot
process name.
NAM_ERR 0x3 Name Error. The name requested does not
exist.
IMP_ERR 0x4 Unsupported request error. Allowable only
for challenging NBNS when gets an Update type
registration request.
RFS_ERR 0x5 Refused error. For policy reasons server
will not register this name from this host.
















NetBIOS Working Group [Page 23]

RFC 1002 March 1987


4.2.15. REDIRECT NAME QUERY RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x0 |0|0|1|0|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NS (0x0002) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDLENGTH | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
/ NSD_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A (0x0001) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0004 | NSD_IP_ADDR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NSD_IP_ADDR, continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

An end node responding to a NAME QUERY REQUEST always responds
with the AA and RA bits set for both the NEGATIVE and POSITIVE
NAME QUERY RESPONSE packets. An end node never sends a REDIRECT
NAME QUERY RESPONSE packet.









NetBIOS Working Group [Page 24]

RFC 1002 March 1987


When the requestor receives the REDIRECT NAME QUERY RESPONSE it
must reiterate the NAME QUERY REQUEST to the NBNS specified by
the NSD_IP_ADDR field of the A type RESOURCE RECORD in the
ADDITIONAL section of the response packet. This is an optional
packet for the NBNS.

The NSD_NAME and the RR_NAME in the ADDITIONAL section of the
response packet are the same name. Space can be optimized if
label string pointers are used in the RR_NAME which point to the
labels in the NSD_NAME.

The RR_NAME in the AUTHORITY section is the name of the domain
the NBNS called by NSD_NAME has authority over.

4.2.16. WAIT FOR ACKNOWLEDGEMENT (WACK) RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x7 |1|0|0|0|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NULL (0x0020) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0002 | OPCODE | NM_FLAGS | 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


















NetBIOS Working Group [Page 25]

RFC 1002 March 1987


The NAME_TRN_ID of the WACK RESPONSE packet is the same
NAME_TRN_ID of the request that the NBNS is telling the requestor
to wait longer to complete. The RR_NAME is the name from the
request, if any. If no name is available from the request then
it is a null name, single byte of zero.

The TTL field of the ResourceRecord is the new time to wait, in
seconds, for the request to complete. The RDATA field contains
the OPCODE and NM_FLAGS of the request.

A TTL value of 0 means that the NBNS can not estimate the time it
may take to complete a response.

4.2.17. NODE STATUS REQUEST

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |0| 0x0 |0|0|0|0|0 0|B| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0001 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ QUESTION_NAME /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NBSTAT (0x0021) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
























NetBIOS Working Group [Page 26]

RFC 1002 March 1987


4.2.18. NODE STATUS RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TRN_ID |1| 0x0 |1|0|0|0|0 0|0| 0x0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0000 | 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ RR_NAME /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NBSTAT (0x0021) | IN (0x0001) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00000000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RDLENGTH | NUM_NAMES | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ +
/ NODE_NAME ARRAY /
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
/ STATISTICS /
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The NODE_NAME ARRAY is an array of zero or more NUM_NAMES entries
of NODE_NAME records. Each NODE_NAME entry represents an active
name in the same NetBIOS scope as the requesting name in the
local name table of the responder. RR_NAME is the requesting
name.















NetBIOS Working Group [Page 27]

RFC 1002 March 1987


NODE_NAME Entry:

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+--- ---+
| |
+--- NETBIOS FORMAT NAME ---+
| |
+--- ---+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The NAME_FLAGS field:

1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| G | ONT |DRG|CNF|ACT|PRM| RESERVED |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

The NAME_FLAGS field is defined as:

Symbol Bit(s) Description:

RESERVED 7-15 Reserved for future use. Must be zero (0).
PRM 6 Permanent Name Flag. If one (1) then entry
is for the permanent node name. Flag is zero
(0) for all other names.
ACT 5 Active Name Flag. All entries have this flag
set to one (1).
CNF 4 Conflict Flag. If one (1) then name on this
node is in conflict.
DRG 3 Deregister Flag. If one (1) then this name
is in the process of being deleted.
ONT 1,2 Owner Node Type:
00 = B node
01 = P node
10 = M node
11 = Reserved for future use
G 0 Group Name Flag.
If one (1) then the name is a GROUP NetBIOS
name.
If zero (0) then it is a UNIQUE NetBIOS name.







NetBIOS Working Group [Page 28]

RFC 1002 March 1987


STATISTICS Field of the NODE STATUS RESPONSE:

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UNIT_ID (Unique unit ID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UNIT_ID,continued | JUMPERS | TEST_RESULT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VERSION_NUMBER | PERIOD_OF_STATISTICS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_OF_CRCs | NUMBER_ALIGNMENT_ERRORS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_OF_COLLISIONS | NUMBER_SEND_ABORTS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_GOOD_SENDS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_GOOD_RECEIVES |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_RETRANSMITS | NUMBER_NO_RESOURCE_CONDITIONS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NUMBER_FREE_COMMAND_BLOCKS | TOTAL_NUMBER_COMMAND_BLOCKS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MAX_TOTAL_NUMBER_COMMAND_BLOCKS| NUMBER_PENDING_SESSIONS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAX_NUMBER_PENDING_SESSIONS | MAX_TOTAL_SESSIONS_POSSIBLE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SESSION_DATA_PACKET_SIZE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.3. SESSION SERVICE PACKETS

4.3.1. GENERAL FORMAT OF SESSION PACKETS

All session service messages are sent over a TCP connection.

All session packets are of the following general structure:

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ TRAILER (Packet Type Dependent) /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The TYPE, FLAGS, and LENGTH fields are present in every session
packet.




NetBIOS Working Group [Page 29]

RFC 1002 March 1987


The LENGTH field is the number of bytes following the LENGTH
field. In other words, LENGTH is the combined size of the
TRAILER field(s). For example, the POSITIVE SESSION RESPONSE
packet always has a LENGTH field value of zero (0000) while the
RETARGET SESSION RESPONSE always has a LENGTH field value of six
(0006).

One of the bits of the FLAGS field acts as an additional, high-
order bit for the LENGTH field. Thus the cumulative size of the
trailer field(s) may range from 0 to 128K bytes.

Session Packet Types (in hexidecimal):

00 - SESSION MESSAGE
81 - SESSION REQUEST
82 - POSITIVE SESSION RESPONSE
83 - NEGATIVE SESSION RESPONSE
84 - RETARGET SESSION RESPONSE
85 - SESSION KEEP ALIVE

Bit definitions of the FLAGS field:

0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | E |
+---+---+---+---+---+---+---+---+

Symbol Bit(s) Description

E 7 Length extension, used as an additional,
high-order bit on the LENGTH field.

RESERVED 0-6 Reserved, must be zero (0)

4.3.2. SESSION REQUEST PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ CALLED NAME /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ CALLING NAME /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





NetBIOS Working Group [Page 30]

RFC 1002 March 1987


4.3.3. POSITIVE SESSION RESPONSE PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.3.4. NEGATIVE SESSION RESPONSE PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ERROR_CODE |
+-+-+-+-+-+-+-+-+

NEGATIVE SESSION RESPONSE packet error code values (in
hexidecimal):

80 - Not listening on called name
81 - Not listening for calling name
82 - Called name not present
83 - Called name present, but insufficient resources
8F - Unspecified error

4.3.5. SESSION RETARGET RESPONSE PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RETARGET_IP_ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
















NetBIOS Working Group [Page 31]

RFC 1002 March 1987


4.3.6. SESSION MESSAGE PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ /
/ USER_DATA /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.3.7. SESSION KEEP ALIVE PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | FLAGS | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.4. DATAGRAM SERVICE PACKETS

4.4.1. NetBIOS DATAGRAM HEADER

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSG_TYPE | FLAGS | DGM_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_IP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_PORT | DGM_LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PACKET_OFFSET |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

MSG_TYPE values (in hexidecimal):

10 - DIRECT_UNIQUE DATAGRAM
11 - DIRECT_GROUP DATAGRAM
12 - BROADCAST DATAGRAM
13 - DATAGRAM ERROR
14 - DATAGRAM QUERY REQUEST
15 - DATAGRAM POSITIVE QUERY RESPONSE
16 - DATAGRAM NEGATIVE QUERY RESPONSE







NetBIOS Working Group [Page 32]

RFC 1002 March 1987


Bit definitions of the FLAGS field:

0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| 0 | 0 | 0 | 0 | SNT | F | M |
+---+---+---+---+---+---+---+---+

Symbol Bit(s) Description

M 7 MORE flag, If set then more NetBIOS datagram
fragments follow.

F 6 FIRST packet flag, If set then this is first
(and possibly only) fragment of NetBIOS
datagram

SNT 4,5 Source End-Node type:
00 = B node
01 = P node
10 = M node
11 = NBDD
RESERVED 0-3 Reserved, must be zero (0)

4.4.2. DIRECT_UNIQUE, DIRECT_GROUP, & BROADCAST DATAGRAM

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSG_TYPE | FLAGS | DGM_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_IP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_PORT | DGM_LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PACKET_OFFSET | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
/ SOURCE_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ DESTINATION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ USER_DATA /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



NetBIOS Working Group [Page 33]

RFC 1002 March 1987


4.4.3. DATAGRAM ERROR PACKET

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSG_TYPE | FLAGS | DGM_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_IP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_PORT | ERROR_CODE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

ERROR_CODE values (in hexidecimal):

82 - DESTINATION NAME NOT PRESENT
83 - INVALID SOURCE NAME FORMAT
84 - INVALID DESTINATION NAME FORMAT

4.4.4. DATAGRAM QUERY REQUEST

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSG_TYPE | FLAGS | DGM_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_IP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_PORT | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
/ DESTINATION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.4.5. DATAGRAM POSITIVE AND NEGATIVE QUERY RESPONSE

1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSG_TYPE | FLAGS | DGM_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_IP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOURCE_PORT | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
/ DESTINATION_NAME /
/ /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



NetBIOS Working Group [Page 34]

RFC 1002 March 1987


5. PROTOCOL DESCRIPTIONS

5.1. NAME SERVICE PROTOCOLS

A REQUEST packet is always sent to the well known UDP port -
NAME_SERVICE_UDP_PORT. The destination address is normally
either the IP broadcast address or the address of the NBNS - the
address of the NBNS server it set up at initialization time. In
rare cases, a request packet will be sent to an end node, e.g. a
NAME QUERY REQUEST sent to "challenge" a node.

A RESPONSE packet is always sent to the source UDP port and
source IP address of the request packet.

A DEMAND packet must always be sent to the well known UDP port -
NAME_SERVICE_UDP_PORT. There is no restriction on the target IP
address.

Terms used in this section:

tid - Transaction ID. This is a value composed from
the requestor's IP address and a unique 16 bit
value generated by the originator of the
transaction.

5.1.1. B-NODE ACTIVITY

5.1.1.1. B-NODE ADD NAME

PROCEDURE add_name(newname)

/*
* Host initiated processing for a B node
*/
BEGIN

REPEAT

/* build name service packet */

ONT = B_NODE; /* broadcast node */
G = UNIQUE; /* unique name */
TTL = 0;

broadcast NAME REGISTRATION REQUEST packet;

/*
* remote node(s) will send response packet
* if applicable
*/




NetBIOS Working Group [Page 35]

RFC 1002 March 1987


pause(BCAST_REQ_RETRY_TIMEOUT);

UNTIL response packet is received or
retransmit count has been exceeded

IF no response packet was received THEN
BEGIN /* no response */
/*
* build packet
*/

ONT = B_NODE; /* broadcast node */
G = UNIQUE; /* unique name */
TTL = 0;

/*

* Let other nodes known you have the name
*/

broadcast NAME UPDATE REQUEST packet;
/* name can be added to local name table */
return success;
END /* no response */
ELSE
BEGIN /* got response */

/*
* Match return transaction id
* against tid sent in request
*/

IF NOT response tid = request tid THEN
BEGIN
ignore response packet;
END
ELSE
CASE packet type OF

NEGATIVE NAME REGISTRATION RESPONSE:

return failure; /* name cannot be added */

POSITIVE NAME REGISTRATION RESPONSE:
END-NODE CHALLENGE NAME REGISTRATION RESPONSE:

/*
* B nodes should normally not get this
* response.
*/

ignore packet;



NetBIOS Working Group [Page 36]

RFC 1002 March 1987


END /* case */;
END /* got response */
END /* procedure */

5.1.1.2. B-NODE ADD_GROUP NAME

PROCEDURE add_group_name(newname)

/*
* Host initiated processing for a B node
*/

BEGIN
/*
* same as for a unique name with the
* exception that the group bit (G) must
* be set in the request packets.
*/

...
G = GROUP;
...
...

/*
* broadcast request ...
*/


END

5.1.1.3. B-NODE FIND_NAME

PROCEDURE find_name(name)

/*
* Host initiated processing for a B node
*/

BEGIN

REPEAT
/*
* build packet
*/
ONT = B;
TTL = 0;
G = DONT CARE;

broadcast NAME QUERY REQUEST packet;





NetBIOS Working Group [Page 37]

RFC 1002 March 1987


/*
* a node might send response packet
*/

pause(BCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet received OR
max transmit threshold exceeded

IF no response packet received THEN
return failure;
ELSE
IF NOT response tid = request tid THEN
ignore packet;
ELSE
CASE packet type OF
POSITIVE NAME QUERY RESPONSE:
/*
* Start a timer to detect conflict.
*
* Be prepared to detect conflict if
* any more response packets are received.
*
*/

save response as authoritative response;
start_timer(CONFLICT_TIMER);
return success;

NEGATIVE NAME QUERY RESPONSE:
REDIRECT NAME QUERY RESPONSE:

/*
* B Node should normally not get either
* response.
*/

ignore response packet;

END /* case */
END /* procedure */

5.1.1.4. B NODE NAME RELEASE

PROCEDURE delete_name (name)
BEGIN

REPEAT

/*
* build packet
*/



NetBIOS Working Group [Page 38]

RFC 1002 March 1987


...

/*
* send request
*/

broadcast NAME RELEASE REQUEST packet;

/*
* no response packet expected
*/

pause(BCAST_REQ_RETRY_TIMEOUT);

UNTIL retransmit count has been exceeded
END /* procedure */

5.1.1.5. B-NODE INCOMING PACKET PROCESSING

Following processing is done when broadcast or unicast packets
are received at the NAME_SERVICE_UDP_PORT.

PROCEDURE process_incoming_packet(packet)

/*
* Processing initiated by incoming packets for a B node
*/

BEGIN
/*
* Note: response packets are always sent
* to:
* source IP address of request packet
* source UDP port of request packet
*/

CASE packet type OF

NAME REGISTRATION REQUEST (UNIQUE):
IF name exists in local name table THEN
send NEGATIVE NAME REGISTRATION RESPONSE ;
NAME REGISTRATION REQUEST (GROUP):
IF name exists in local name table THEN
BEGIN
IF local entry is a unique name THEN
send NEGATIVE NAME REGISTRATION RESPONSE ;
END
NAME QUERY REQUEST:
IF name exists in local name table THEN
BEGIN
build response packet;



NetBIOS Working Group [Page 39]

RFC 1002 March 1987


send POSITIVE NAME QUERY RESPONSE;
POSITIVE NAME QUERY RESPONSE:
IF name conflict timer is not active THEN
BEGIN
/*
* timer has expired already... ignore this
* packet
*/

return;
END
ELSE /* timer is active */
IF a response for this name has previously been
received THEN
BEGIN /* existing entry */

/*
* we sent out a request packet, and
* have already received (at least)
* one response
*
* Check if conflict exists.
* If so, send out a conflict packet.
*
* Note: detecting conflict does NOT
* affect any existing sessions.
*
*/

/*
* Check for name conflict.
* See "Name Conflict" in Concepts and Methods
*/
check saved authoritative response against
information in this response packet;
IF conflict detected THEN
BEGIN
unicast NAME CONFLICT DEMAND packet;
IF entry exists in cache THEN
BEGIN
remove entry from cache;
END
END
END /* existing entry */
ELSE
BEGIN
/*
* Note: If this was the first response
* to a name query, it would have been
* handled in the
* find_name() procedure.



NetBIOS Working Group [Page 40]

RFC 1002 March 1987


*/

ignore packet;
END
NAME CONFLICT DEMAND:
IF name exists in local name table THEN
BEGIN
mark name as conflict detected;

/*
* a name in the state "conflict detected"
* does not "logically" exist on that node.
* No further session will be accepted on
* that name.
* No datagrams can be sent against that name.
* Such an entry will not be used for
* purposes of processing incoming request
* packets.
* The only valid user NetBIOS operation
* against such a name is DELETE NAME.
*/
END
NAME RELEASE REQUEST:
IF caching is being done THEN
BEGIN
remove entry from cache;
END
NAME UPDATE REQUEST:
IF caching is being done THEN
BEGIN
IF entry exists in cache already,
update cache;
ELSE IF name is "interesting" THEN
BEGIN
add entry to cache;
END
END

NODE STATUS REQUEST:
IF name exists in local name table THEN
BEGIN
/*
* send only those names that are
* in the same scope as the scope
* field in the request packet
*/

send NODE STATUS RESPONSE;
END
END




NetBIOS Working Group [Page 41]

RFC 1002 March 1987


5.1.2. P-NODE ACTIVITY

All packets sent or received by P nodes are unicast UDP packets.
A P node sends name service requests to the NBNS node that is
specified in the P-node configuration.

5.1.2.1. P-NODE ADD_NAME

PROCEDURE add_name(newname)

/*
* Host initiated processing for a P node
*/

BEGIN

REPEAT
/*
* build packet
*/

ONT = P;
G = UNIQUE;
...

/*
* send request
*/

unicast NAME REGISTRATION REQUEST packet;

/*
* NBNS will send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet is received OR
retransmit count has been exceeded

IF no response packet was received THEN
BEGIN /* no response */
/*
* NBNS is down. Cannot claim name.
*/

return failure; /* name cannot be claimed */
END /* no response */
ELSE



NetBIOS Working Group [Page 42]

RFC 1002 March 1987


BEGIN /* response */
IF NOT response tid = request tid THEN
BEGIN
/* Packet may belong to another transaction */
ignore response packet;
END
ELSE
CASE packet type OF

POSITIVE NAME REGISTRATION RESPONSE:

/*
* name can be added
*/

adjust refresh timeout value, TTL, for this name;
return success; /* name can be added */

NEGATIVE NAME REGISTRATION RESPONSE:
return failure; /* name cannot be added */

END-NODE CHALLENGE REGISTRATION REQUEST:
BEGIN /* end node challenge */

/*
* The response packet has in it the
* address of the presumed owner of the
* name. Challenge that owner.
* If owner either does not
* respond or indicates that he no longer
* owns the name, claim the name.
* Otherwise, the name cannot be claimed.
*
*/

REPEAT
/*
* build packet
*/
...

unicast NAME QUERY REQUEST packet to the
address contained in the END NODE
CHALLENGE RESPONSE packet;

/*
* remote node may send response packet
*/

pause(UCAST_REQ_RETRY_TIMEOUT);




NetBIOS Working Group [Page 43]

RFC 1002 March 1987


UNTIL response packet is received or
retransmit count has been exceeded
IF no response packet is received OR
NEGATIVE NAME QUERY RESPONSE packet
received THEN
BEGIN /* update */

/*
* name can be claimed
*/

REPEAT

/*
* build packet
*/
...

unicast NAME UPDATE REQUEST to NBNS;

/*
* NBNS node will send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet is received or
retransmit count has been exceeded
IF no response packet received THEN
BEGIN /* no response */

/*
* name could not be claimed
*/

return failure;
END /* no response */
ELSE
CASE packet type OF
POSITIVE NAME REGISTRATION RESPONSE:
/*
* add name
*/
return success;
NEGATIVE NAME REGISTRATION RESPONSE:

/*
* you lose ...
*/



NetBIOS Working Group [Page 44]

RFC 1002 March 1987


return failure;
END /* case */
END /* update */
ELSE

/*
* received a positive response to the "challenge"
* Remote node still has name
*/

return failure;
END /* end node challenge */
END /* response */
END /* procedure */

5.1.2.2. P-NODE ADD GROUP NAME

PROCEDURE add_group_name(newname)

/*
* Host initiated processing for a P node
*/

BEGIN
/*
* same as for a unique name, except that the
* request packet must indicate that a
* group name claim is being made.
*/

...
G = GROUP;
...

/*
* send packet
*/
...


END

5.1.2.3. P-NODE FIND NAME

PROCEDURE find_name(name)

/*
* Host initiated processing for a P node
*/

BEGIN



NetBIOS Working Group [Page 45]

RFC 1002 March 1987


REPEAT
/*
* build packet
*/

ONT = P;
G = DONT CARE;

unicast NAME QUERY REQUEST packet;

/*
* a NBNS node might send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet received OR
max transmit threshold exceeded

IF no response packet received THEN
return failure;
ELSE
IF NOT response tid = request tid THEN
ignore packet;
ELSE
CASE packet type OF
POSITIVE NAME QUERY RESPONSE:
return success;

REDIRECT NAME QUERY RESPONSE:

/*
* NBNS node wants this end node
* to use some other NBNS node
* to resolve the query.
*/

repeat query with NBNS address
in the response packet;
NEGATIVE NAME QUERY RESPONSE:
return failure;

END /* case */
END /* procedure */

5.1.2.4. P-NODE DELETE_NAME

PROCEDURE delete_name (name)




NetBIOS Working Group [Page 46]

RFC 1002 March 1987


/*
* Host initiated processing for a P node
*/

BEGIN

REPEAT

/*
* build packet
*/
...

/*
* send request
*/

unicast NAME RELEASE REQUEST packet;
IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL retransmit count has been exceeded
or response been received

IF response has been received THEN
CASE packet type OF
POSITIVE NAME RELEASE RESPONSE:
return success;
NEGATIVE NAME RELEASE RESPONSE:

/*
* NBNS does want node to delete this
* name !!!
*/

return failure;
END /* case */
END /* procedure */

5.1.2.5. P-NODE INCOMING PACKET PROCESSING

Processing initiated by reception of packets at a P node

PROCEDURE process_incoming_packet(packet)

/*
* Processing initiated by incoming packets at a P node
*/

BEGIN



NetBIOS Working Group [Page 47]

RFC 1002 March 1987


/*
* always ignore UDP broadcast packets
*/

IF packet was sent as a broadcast THEN
BEGIN
ignore packet;
return;
END
CASE packet type of

NAME CONFLICT DEMAND:
IF name exists in local name table THEN
mark name as in conflict;
return;

NAME QUERY REQUEST:
IF name exists in local name table THEN
BEGIN /* name exists */

/*
* build packet
*/
...

/*
* send response to the IP address and port
* number from which the request was received.
*/

send POSITIVE NAME QUERY RESPONSE ;
return;
END /* exists */
ELSE
BEGIN /* does not exist */

/*
* send response to the requestor
*/

send NEGATIVE NAME QUERY RESPONSE ;
return;
END /* does not exist */
NODE STATUS REQUEST:
/*
* Name of "*" may be used for force node to
* divulge status for administrative purposes
*/
IF name in local name table OR name = "*" THEN
BEGIN
/*



NetBIOS Working Group [Page 48]

RFC 1002 March 1987


* Build response packet and
* send to requestor node
* Send only those names that are
* in the same scope as the scope
* in the request packet.
*/

send NODE STATUS RESPONSE;
END

NAME RELEASE REQUEST:
/*
* This will be received if the NBNS wants to flush the
* name from the local name table, or from the local
* cache.
*/

IF name exists in the local name table THEN
BEGIN
delete name from local name table;
inform user that name has been deleted;
END
ELSE
IF name has been cached locally THEN
BEGIN
remove entry from cache:
END

END /* case */
END /* procedure */

5.1.2.6. P-NODE TIMER INITIATED PROCESSING

Processing initiated by timer expiration.

PROCEDURE timer_expired()
/*
* Processing initiated by the expiration of a timer on a P node
*/
BEGIN
/*
* Send a NAME REFRESH REQUEST for each name which the
* TTL which has expired.
*/
REPEAT
build NAME REFRESH REQUEST packet;
REPEAT
send packet to NBNS;

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);



NetBIOS Working Group [Page 49]

RFC 1002 March 1987


ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet is received or
retransmit count has been exceeded

CASE packet type OF
POSITIVE NAME REGISTRATION RESPONSE:
/* successfully refreshed */
reset TTL timer for this name;

NEGATIVE NAME REGISTRATION RESPONSE:
/*
* refused, can't keep name
* assume in conflict
*/
mark name as in conflict;
END /* case */

UNTIL request sent for all names for which TTL
has expired
END /* procedure */

5.1.3. M-NODE ACTIVITY

M nodes behavior is similar to that of P nodes with the addition
of some B node-like broadcast actions. M node name service
proceeds in two steps:

1.Use broadcast UDP based name service. Depending on the
operation, goto step 2.

2.Use directed UDP name service.

The following code for M nodes is exactly the same as for a P
node, with the exception that broadcast operations are done
before P type operation is attempted.

5.1.3.1. M-NODE ADD NAME

PROCEDURE add_name(newname)

/*
* Host initiated processing for a M node
*/

BEGIN

/*
* check if name exists on the
* broadcast area
*/



NetBIOS Working Group [Page 50]

RFC 1002 March 1987


REPEAT
/* build packet */

....
broadcast NAME REGISTRATION REQUEST packet;
pause(BCAST_REQ_RETRY_TIMEOUT);

UNTIL response packet is received or
retransmit count has been exceeded

IF valid response received THEN
BEGIN
/* cannot claim name */

return failure;
END

/*
* No objections received within the
* broadcast area.
* Send request to name server.
*/

REPEAT
/*
* build packet
*/

ONT = M;
...

unicast NAME REGISTRATION REQUEST packet;

/*
* remote NBNS will send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);

UNTIL response packet is received or
retransmit count has been exceeded

IF no response packet was received THEN
BEGIN /* no response */
/*
* NBNS is down. Cannot claim name.
*/




NetBIOS Working Group [Page 51]

RFC 1002 March 1987


return failure; /* name cannot be claimed */
END /* no response */
ELSE
BEGIN /* response */
IF NOT response tid = request tid THEN
BEGIN
ignore response packet;
END
ELSE
CASE packet type OF
POSITIVE NAME REGISTRATION RESPONSE:

/*
* name can be added
*/

adjust refresh timeout value, TTL;
return success; /* name can be added */

NEGATIVE NAME REGISTRATION RESPONSE:
return failure; /* name cannot be added */

END-NODE CHALLENGE REGISTRATION REQUEST:
BEGIN /* end node challenge */

/*
* The response packet has in it the
* address of the presumed owner of the
* name. Challenge that owner.
* If owner either does not
* respond or indicates that he no longer
* owns the name, claim the name.
* Otherwise, the name cannot be claimed.
*
*/

REPEAT
/*
* build packet
*/
...

/*
* send packet to address contained in the
* response packet
*/

unicast NAME QUERY REQUEST packet;

/*
* remote node may send response packet



NetBIOS Working Group [Page 52]

RFC 1002 March 1987


*/

pause(UCAST_REQ_RETRY_TIMEOUT);

UNTIL response packet is received or
retransmit count has been exceeded
IF no response packet is received THEN
BEGIN /* no response */

/*
* name can be claimed
*/
REPEAT

/*
* build packet
*/
...

unicast NAME UPDATE REQUEST to NBNS;

/*
* NBNS node will send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);

UNTIL response packet is received or
retransmit count has been exceeded
IF no response packet received THEN
BEGIN /* no response */

/*
* name could not be claimed
*/

return failure;
END /* no response */
ELSE
CASE packet type OF
POSITIVE NAME REGISTRATION RESPONSE:
/*
* add name
*/

return success;
NEGATIVE NAME REGISTRATION RESPONSE:




NetBIOS Working Group [Page 53]

RFC 1002 March 1987


/*
* you lose ...
*/

return failure;
END /* case */
END /* no response */
ELSE
IF NOT response tid = request tid THEN
BEGIN
ignore response packet;
END

/*
* received a response to the "challenge"
* packet
*/

CASE packet type OF
POSITIVE NAME QUERY:

/*
* remote node still has name.
*/

return failure;
NEGATIVE NAME QUERY:

/*
* remote node no longer has name
*/

return success;
END /* case */
END /* end node challenge */
END /* case */
END /* response */
END /* procedure */

5.1.3.2. M-NODE ADD GROUP NAME

PROCEDURE add_group_name(newname)

/*
* Host initiated processing for a P node
*/

BEGIN
/*
* same as for a unique name, except that the
* request packet must indicate that a



NetBIOS Working Group [Page 54]

RFC 1002 March 1987


* group name claim is being made.
*/

...
G = GROUP;
...

/*
* send packet
*/
...


END

5.1.3.3. M-NODE FIND NAME

PROCEDURE find_name(name)

/*
* Host initiated processing for a M node
*/

BEGIN
/*
* check if any node on the broadcast
* area has the name
*/

REPEAT
/* build packet */
...

broadcast NAME QUERY REQUEST packet;
pause(BCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet received OR
max transmit threshold exceeded

IF valid response received THEN
BEGIN
save response as authoritative response;
start_timer(CONFLICT_TIMER);
return success;
END

/*
* no valid response on the b'cast segment.
* Try the name server.
*/

REPEAT



NetBIOS Working Group [Page 55]

RFC 1002 March 1987


/*
* build packet
*/

ONT = M;
G = DONT CARE;

unicast NAME QUERY REQUEST packet to NBNS;

/*
* a NBNS node might send response packet
*/

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet received OR
max transmit threshold exceeded

IF no response packet received THEN
return failure;
ELSE
IF NOT response tid = request tid THEN
ignore packet;
ELSE
CASE packet type OF
POSITIVE NAME QUERY RESPONSE:
return success;

REDIRECT NAME QUERY RESPONSE:

/*
* NBNS node wants this end node
* to use some other NBNS node
* to resolve the query.
*/

repeat query with NBNS address
in the response packet;
NEGATIVE NAME QUERY RESPONSE:
return failure;

END /* case */
END /* procedure */

5.1.3.4. M-NODE DELETE NAME

PROCEDURE delete_name (name)

/*



NetBIOS Working Group [Page 56]

RFC 1002 March 1987


* Host initiated processing for a P node
*/

BEGIN
/*
* First, delete name on NBNS
*/

REPEAT

/*
* build packet
*/
...

/*
* send request
*/

unicast NAME RELEASE REQUEST packet to NBNS;

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL retransmit count has been exceeded
or response been received

IF response has been received THEN
CASE packet type OF
POSITIVE NAME RELEASE RESPONSE:
/*
* Deletion of name on b'cast segment is deferred
* until after NBNS has deleted the name
*/

REPEAT
/* build packet */

...
broadcast NAME RELEASE REQUEST;
pause(BCAST_REQ_RETRY_TIMEOUT);
UNTIL rexmt threshold exceeded

return success;
NEGATIVE NAME RELEASE RESPONSE:

/*
* NBNS does want node to delete this
* name
*/



NetBIOS Working Group [Page 57]

RFC 1002 March 1987


return failure;
END /* case */
END /* procedure */

5.1.3.5. M-NODE INCOMING PACKET PROCESSING

Processing initiated by reception of packets at a M node

PROCEDURE process_incoming_packet(packet)

/*
* Processing initiated by incoming packets at a M node
*/

BEGIN
CASE packet type of

NAME CONFLICT DEMAND:
IF name exists in local name table THEN
mark name as in conflict;
return;

NAME QUERY REQUEST:
IF name exists in local name table THEN
BEGIN /* name exists */

/*
* build packet
*/
...

/*
* send response to the IP address and port
* number from which the request was received.
*/

send POSITIVE NAME QUERY RESPONSE ;
return;
END /* exists */
ELSE
BEGIN /* does not exist */

/*
* send response to the requestor
*/

IF request NOT broadcast THEN
/*
* Don't send negative responses to
* queries sent by B nodes
*/



NetBIOS Working Group [Page 58]

RFC 1002 March 1987


send NEGATIVE NAME QUERY RESPONSE ;
return;
END /* does not exist */
NODE STATUS REQUEST:
BEGIN
/*
* Name of "*" may be used for force node to
* divulge status for administrative purposes
*/
IF name in local name table OR name = "*" THEN
/*
* Build response packet and
* send to requestor node
* Send only those names that are
* in the same scope as the scope
* in the request packet.
*/

send NODE STATUS RESPONSE;
END

NAME RELEASE REQUEST:
/*
* This will be received if the NBNS wants to flush the
* name from the local name table, or from the local
* cache.
*/

IF name exists in the local name table THEN
BEGIN
delete name from local name table;
inform user that name has been deleted;
END
ELSE
IF name has been cached locally THEN
BEGIN
remove entry from cache:
END

NAME REGISTRATION REQUEST (UNIQUE):
IF name exists in local name table THEN
send NEGATIVE NAME REGISTRATION RESPONSE ;
NAME REGISTRATION REQUEST (GROUP):
IF name exists in local name table THEN
BEGIN
IF local entry is a unique name THEN
send NEGATIVE NAME REGISTRATION RESPONSE ;
END
END /* case */
END /* procedure */




NetBIOS Working Group [Page 59]

RFC 1002 March 1987


5.1.3.6. M-NODE TIMER INITIATED PROCESSING

Processing initiated by timer expiration:

PROCEDURE timer_expired()
/*
* Processing initiated by the expiration of a timer on a M node
*/
BEGIN
/*
* Send a NAME REFRESH REQUEST for each name which the
* TTL which has expired.
*/
REPEAT
build NAME REFRESH REQUEST packet;
REPEAT
send packet to NBNS;

IF receive a WACK RESPONSE THEN
pause(time from TTL field of response);
ELSE
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response packet is received or
retransmit count has been exceeded

CASE packet type OF
POSITIVE NAME REGISTRATION RESPONSE:
/* successfully refreshed */
reset TTL timer for this name;

NEGATIVE NAME REGISTRATION RESPONSE:
/*
* refused, can't keep name
* assume in conflict
*/
mark name as in conflict;
END /* case */

UNTIL request sent for all names for which TTL
has expired
END /* procedure */

5.1.4. NBNS ACTIVITY

A NBNS node will receive directed packets from P and M nodes.
Reply packets are always sent as directed packets to the source
IP address and UDP port number. Received broadcast packets must
be ignored.






NetBIOS Working Group [Page 60]

RFC 1002 March 1987


5.1.4.1. NBNS INCOMING PACKET PROCESSING

PROCEDURE process_incoming_packet(packet)

/*
* Incoming packet processing on a NS node
*/

BEGIN
IF packet was sent as a broadcast THEN
BEGIN
discard packet;
return;
END
CASE packet type of

NAME REGISTRATION REQUEST (UNIQUE):
IF unique name exists in data base THEN
BEGIN /* unique name exists */
/*
* NBNS node may be a "passive"
* server in that it expects the
* end node to do the challenge
* server. Such a NBNS node is
* called a "non-secure" server.
* A "secure" server will do the
* challenging before it sends
* back a response packet.
*/

IF non-secure THEN
BEGIN
/*
* build response packet
*/
...


/*
* let end node do the challenge
*/

send END-NODE CHALLENGE NAME REGISTRATION
RESPONSE;
return;
END
ELSE
/*
* secure server - do the name
* challenge operation
*/



NetBIOS Working Group [Page 61]

RFC 1002 March 1987


REPEAT
send NAME QUERY REQUEST;
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response has been received or
retransmit count has been exceeded
IF no response was received THEN
BEGIN

/* node down */

update data base - remove entry;
update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END
ELSE
BEGIN /* challenged node replied */
/*
* challenged node replied with
* a response packet
*/

CASE packet type

POSITIVE NAME QUERY RESPONSE:

/*
* name still owned by the
* challenged node
*
* build packet and send response
*/
...


/*
* Note: The NBNS will need to
* keep track (based on transaction id) of
* the IP address and port number
* of the original requestor.
*/

send NEGATIVE NAME REGISTRATION RESPONSE;
return;
NEGATIVE NAME QUERY RESPONSE:

update data base - remove entry;
update data base - add new entry;

/*
* build response packet and send



NetBIOS Working Group [Page 62]

RFC 1002 March 1987


* response
*/
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END /* case */
END /* challenged node replied */
END /* unique name exists in data base */
ELSE
IF group name exists in data base THEN
BEGIN /* group names exists */

/*
* Members of a group name are NOT
* challenged.
* Make the assumption that
* at least some of the group members
* are still alive.
* Refresh mechanism will
* allow the NBNS to detect when all
* members of a group no longer use that
* name
*/

send NEGATIVE NAME REGISTRATION RESPONSE;
END /* group name exists */
ELSE
BEGIN /* name does not exist */

/*
* Name does not exist in data base
*
* This code applies to both non-secure
* and secure server.
*/

update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END

NAME QUERY REQUEST:
IF name exists in data base THEN
BEGIN
/*
* build response packet and send to
* requestor
*/
...

send POSITIVE NAME QUERY RESPONSE;
return;



NetBIOS Working Group [Page 63]

RFC 1002 March 1987


ELSE
BEGIN
/*
* build response packet and send to
* requestor
*/
...

send NEGATIVE NAME QUERY RESPONSE;
return;
END

NAME REGISTRATION REQUEST (GROUP):
IF name exists in data base THEN
BEGIN
IF local entry is a unique name THEN
BEGIN /* local is unique */

IF non-secure THEN
BEGIN
send END-NODE CHALLENGE NAME
REGISTRATION RESPONSE;
return;
END

REPEAT
send NAME QUERY REQUEST;
pause(UCAST_REQ_RETRY_TIMEOUT);
UNTIL response received or
retransmit count exceeded
IF no response received or
NEGATIVE NAME QUERY RESPONSE
received THEN
BEGIN
update data base - remove entry;
update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END
ELSE
BEGIN
/*
* name still being held
* by challenged node
*/

send NEGATIVE NAME REGISTRATION RESPONSE;
END
END /* local is unique */
ELSE
BEGIN /* local is group */



NetBIOS Working Group [Page 64]

RFC 1002 March 1987


/*
* existing entry is a group name
*/

update data base - remove entry;
update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END /* local is group */
END /* names exists */
ELSE
BEGIN /* does not exist */

/* name does not exist in data base */

update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
return;
END /* does not exist */

NAME RELEASE REQUEST:

/*
* secure server may choose to disallow
* a node from deleting a name
*/

update data base - remove entry;
send POSITIVE NAME RELEASE RESPONSE;
return;

NAME UPDATE REQUEST:

/*
* End-node completed a successful challenge,
* no update database
*/

IF secure server THEN
send NEGATIVE NAME REGISTRATION RESPONSE;
ELSE
BEGIN /* new entry */
IF entry already exists THEN
update data base - remove entry;
update data base - add new entry;
send POSITIVE NAME REGISTRATION RESPONSE;
start_timer(TTL);
END

NAME REFRESH REQUEST:
check for consistency;



NetBIOS Working Group [Page 65]

RFC 1002 March 1987


IF node not allowed to have name THEN
BEGIN

/*
* tell end node that it can't have name
*/
send NEGATIVE NAME REGISTRATION RESPONSE;
END
ELSE
BEGIN

/*
* send confirmation response to the
* end node.
*/
send POSITIVE NAME REGISTRATION;
start_timer(TTL);
END
return;
END /* case */
END /* procedure */

5.1.4.2. NBNS TIMER INITIATED PROCESSING

A NS node uses timers to flush out entries from the data base.
Each entry in the data base is removed when its timer expires.
This time value is a multiple of the refresh TTL established when
the name was registered.

PROCEDURE timer_expired()

/*
* processing initiated by expiration of TTL for a given name
*/

BEGIN
/*
* NBNS can (optionally) ensure
* that the node is actually down
* by sending a NODE STATUS REQUEST.
* If such a request is sent, and
* no response is received, it can
* be assumed that the node is down.
*/
remove entry from data base;
END









NetBIOS Working Group [Page 66]

RFC 1002 March 1987


5.2. SESSION SERVICE PROTOCOLS

The following are variables and should be configurable by the
NetBIOS user. The default values of these variables is found in
"Defined Constants and Variables" in the Detailed
Specification.):

- SSN_RETRY_COUNT - The maximum number TCP connection attempts
allowable per a single NetBIOS call request.

- SSN_CLOSE_TIMEOUT is the time period to wait when closing the
NetBIOS session before killing the TCP connection if session
sends are outstanding.

The following are Defined Constants for the NetBIOS Session
Service. (See "Defined Constants and Variables" in the Detailed
Specification for the value of these constants):

- SSN_SRVC_TCP_PORT - is the globally well-known TCP port
allocated for the NetBIOS Session Service. The service accepts
TCP connections on this port to establish NetBIOS Sessions.
The TCP connection established to this port by the caller is
initially used for the exchange of NetBIOS control information.
The actual NetBIOS data connection may also pass through this
port or, through the retargetting facility, through another
port.

5.2.1. SESSION ESTABLISHMENT PROTOCOLS

5.2.1.1. USER REQUEST PROCESSING

PROCEDURE listen(listening name, caller name)
/*
* User initiated processing for B, P and M nodes
*
* This procedure assumes that an incoming session will be
* retargetted here by a session server.
*/
BEGIN
Do TCP listen; /* Returns TCP port used */
Register listen with Session Service, give names and
TCP port;

Wait for TCP connection to open; /* Incoming call */

Read SESSION REQUEST packet from connection

Process session request (see section on
processing initiated by the reception of session
service packets);




NetBIOS Working Group [Page 67]

RFC 1002 March 1987


Inform Session Service that NetBIOS listen is complete;

IF session established THEN
return success and session information to user;
ELSE
return failure;
END /* procedure */

PROCEDURE call(calling name, called name)
/*
* user initiated processing for B, P and M nodes
*/

/*
* This algorithm assumes that the called name is a unique name.
* If the called name is a group name, the call() procedure
* needs to cycle through the members of the group
* until either (retry_count == SSN_RETRY_COUNT) or
* the list has been exhausted.
*/
BEGIN
retry_count = 0;
retarget = FALSE; /* TRUE: caller is being retargetted */
name_query = TRUE; /* TRUE: caller must begin again with */
/* name query. */

REPEAT
IF name_query THEN
BEGIN
do name discovery, returns IP address;
TCP port = SSN_SRVC_TCP_PORT;

IF name discovery fails THEN
return failure;
ELSE
name_query = FALSE;
END

/*
* now have IP address and TCP port of
* remote party.
*/

establish TCP connection with remote party, use an
ephemeral port as source TCP port;
IF connection refused THEN
BEGIN
IF retarget THEN
BEGIN
/* retry */
retarget = FALSE;



NetBIOS Working Group [Page 68]

RFC 1002 March 1987



use original IP address and TCP port;
goto LOOP;
END

/* retry for just missed TCP listen */

pause(SESSION_RETRY_TIMER);
establish TCP connection, again use ephemeral
port as source TCP port;

IF connection refused OR
connection timed out THEN
return failure;
END
ELSE
IF connection timed out THEN
BEGIN
IF retarget THEN
BEGIN
/* retry */
retarget = FALSE;
use original IP address and TCP port;
goto LOOP;
END
ELSE
BEGIN
/*
* incorrect name discovery was done,
* try again
*/

inform name discovery process of
possible error;
name_query = TRUE;
goto LOOP;
END
END

/*
* TCP connection has been established
*/

wait for session response packet;
CASE packet type OF

POSITIVE SESSION RESPONSE:
return success and session established
information;

NEGATIVE SESSION RESPONSE:
BEGIN



NetBIOS Working Group [Page 69]

RFC 1002 March 1987


CASE error OF
NOT LISTENING ON CALLED NAME:
NOT LISTENING FOR CALLING NAME:
BEGIN
kill TCP connection;
return failure;
END

CALLED NAME NOT PRESENT:
BEGIN
/*
* called name does not exist on
* remote node
*/

inform name discovery procedure
of possible error;

IF this is a P or M node THEN
BEGIN
/*
* Inform NetBIOS Name Server
* it has returned incorrect
* information.
*/
send NAME RELEASE REQUEST for called
name and IP address to
NetBIOS Name Server;
END
/* retry from beginning */
retarget = FALSE;
name_query = TRUE;
goto LOOP;
END /* called name not present */
END /* case */
END /* negative response */

RETARGET SESSION RESPONSE:
BEGIN
close TCP connection;
extract IP address and TCP port from
response;
retarget = TRUE;
END /* retarget response */
END /* case */

LOOP: retry_count = retry_count + 1;

UNTIL (retry_count > SSN_RETRY_COUNT);
return failure;
END /* procedure */



NetBIOS Working Group [Page 70]

RFC 1002 March 1987


5.2.1.2. RECEIVED PACKET PROCESSING

These are packets received on a TCP connection before a session
has been established. The listen routines attached to a NetBIOS
user process need not implement the RETARGET response section.
The user process version, separate from a shared Session Service,
need only accept (POSITIVE SESSION RESPONSE) or reject (NEGATIVE
SESSION RESPONSE) a session request.

PROCEDURE session_packet(packet)
/*
* processing initiated by receipt of a session service
* packet for a session in the session establishment phase.
* Assumes the TCP connection has been accepted.
*/
BEGIN
CASE packet type

SESSION REQUEST:
BEGIN
IF called name does not exist on node THEN
BEGIN
send NEGATIVE SESSION RESPONSE with CALLED
NAME NOT PRESENT error code;
close TCP connection;
END

Search for a listen with CALLING NAME for CALLED
NAME;
IF matching listen is found THEN
BEGIN
IF port of listener process is port TCP
connection is on THEN
BEGIN
send POSITIVE SESSION RESPONSE;

Hand off connection to client process
and/or inform user session is
established;
END
ELSE
BEGIN
send RETARGET SESSION RESPONSE with
listener's IP address and
TCP port;
close TCP connection;
END
END
ELSE
BEGIN
/* no matching listen pending */



NetBIOS Working Group [Page 71]

RFC 1002 March 1987


send NEGATIVE SESSION RESPONSE with either
NOT LISTENING ON CALLED NAME or NOT
LISTENING FOR CALLING NAME error
code;
close TCP connection;
END
END /* session request */
END /* case */
END /* procedure */

5.2.2. SESSION DATA TRANSFER PROTOCOLS

5.2.2.1. USER REQUEST PROCESSING

PROCEDURE send_message(user_message)
BEGIN
build SESSION MESSAGE header;
send SESSION MESSAGE header;
send user_message;
reset and restart keep-alive timer;
IF send fails THEN
BEGIN
/*
* TCP connection has failed */
*/
close NetBIOS session;
inform user that session is lost;
return failure;
END
ELSE
return success;
END

5.2.2.2. RECEIVED PACKET PROCESSING

These are packets received after a session has been established.

PROCEDURE session_packet(packet)
/*
* processing initiated by receipt of a session service
* packet for a session in the data transfer phase.
*/
BEGIN
CASE packet type OF

SESSION MESSAGE:
BEGIN
process message header;
read in user data;
reset and restart keep-alive timer;
deliver data to user;



NetBIOS Working Group [Page 72]

RFC 1002 March 1987


END /* session message */

SESSION KEEP ALIVE:
discard packet;

END /* case */
END /* procedure */

5.2.2.3. PROCESSING INITIATED BY TIMER

PROCEDURE session_ka_timer()
/*
* processing initiated when session keep alive timer expires
*/
BEGIN
send SESSION KEEP ALIVE, if configured;
IF send fails THEN
BEGIN
/* remote node, or path to it, is down */

abort TCP connection;
close NetBIOS session;
inform user that session is lost;
return;
END
END /* procedure */

5.2.3. SESSION TERMINATION PROTOCOLS

5.2.3.1. USER REQUEST PROCESSING

PROCEDURE close_session()

/* initiated by a user request to close a session */

BEGIN
close gracefully the TCP connection;

WAIT for the connection to close or SSN_CLOSE_TIMEOUT
to expire;

IF time out expired THEN
abort TCP connection;
END /* procedure */

5.2.3.2. RECEPTION INDICATION PROCESSING

PROCEDURE close_indication()
/*
* initiated by a TCP indication of a close request from
* the remote connection partner.



NetBIOS Working Group [Page 73]

RFC 1002 March 1987


*/
BEGIN
close gracefully TCP connection;

close NetBIOS session;

inform user session closed by remote partner;
END /* procedure */

5.3. NetBIOS DATAGRAM SERVICE PROTOCOLS

The following are GLOBAL variables and should be NetBIOS user
configurable:

- SCOPE_ID: the non-leaf section of the domain name preceded by a
'.' which represents the domain of the NetBIOS scope for the
NetBIOS name. The following protocol description only supports
single scope operation.

- MAX_DATAGRAM_LENGTH: the maximum length of an IP datagram. The
minimal maximum length defined in for IP is 576 bytes. This
value is used when determining whether to fragment a NetBIOS
datagram. Implementations are expected to be capable of
receiving unfragmented NetBIOS datagrams up to their maximum
size.

- BROADCAST_ADDRESS: the IP address B-nodes use to send datagrams
with group name destinations and broadcast datagrams. The
default is the IP broadcast address for a single IP network.


The following are Defined Constants for the NetBIOS Datagram
Service:

- DGM_SRVC_UDP_PORT: the globally well-known UDP port allocated
where the NetBIOS Datagram Service receives UDP packets. See
section 6, "Defined Constants", for its value.

5.3.1. B NODE TRANSMISSION OF NetBIOS DATAGRAMS

PROCEDURE send_datagram(data, source, destination, broadcast)

/*
* user initiated processing on B node
*/

BEGIN
group = FALSE;

do name discovery on destination name, returns name type and
IP address;



NetBIOS Working Group [Page 74]

RFC 1002 March 1987


IF name type is group name THEN
BEGIN
group = TRUE;
END

/*
* build datagram service UDP packet;
*/
convert source and destination NetBIOS names into
half-ASCII, biased encoded name;
SOURCE_NAME = cat(source, SCOPE_ID);
SOURCE_IP = this nodes IP address;
SOURCE_PORT = DGM_SRVC_UDP_PORT;

IF NetBIOS broadcast THEN
BEGIN
DESTINATION_NAME = cat("*", SCOPE_ID)
END
ELSE
BEGIN
DESTINATION_NAME = cat(destination, SCOPE_ID)
END

MSG_TYPE = select_one_from_set
{BROADCAST, DIRECT_UNIQUE, DIRECT_GROUP}
DGM_ID = next transaction id for Datagrams;
DGM_LENGTH = length of data + length of second level encoded
source and destination names;

IF (length of the NetBIOS Datagram, including UDP and
IP headers, > MAX_DATAGRAM_LENGTH) THEN
BEGIN
/*
* fragment NetBIOS datagram into 2 UDP packets
*/
Put names into 1st UDP packet and any data that fits
after names;
Set MORE and FIRST bits in 1st UDP packet's FLAGS;
OFFSET in 1st UDP = 0;

Replicate NetBIOS Datagram header from 1st UDP packet
into 2nd UDP packet;
Put rest of data in 2nd UDP packet;
Clear MORE and FIRST bits in 2nd UDP packet's FLAGS;
OFFSET in 2nd UDP = DGM_LENGTH - number of name and
data bytes in 1st UDP;
END
BEGIN
/*
* Only need one UDP packet
*/



NetBIOS Working Group [Page 75]

RFC 1002 March 1987


USER_DATA = data;
Clear MORE bit and set FIRST bit in FLAGS;
OFFSET = 0;
END

IF (group == TRUE) OR (NetBIOS broadcast) THEN
BEGIN
send UDP packet(s) to BROADCAST_ADDRESS;
END
ELSE
BEGIN
send UDP packet(s) to IP address returned by name
discovery;
END
END /* procedure */

5.3.2. P AND M NODE TRANSMISSION OF NetBIOS DATAGRAMS

PROCEDURE send_datagram(data, source, destination, broadcast)

/*
* User initiated processing on P and M node.
*
* This processing is the same as for B nodes except for
* sending broadcast and multicast NetBIOS datagrams.
*/

BEGIN
group = FALSE;

do name discovery on destination name, returns name type
and IP address;
IF name type is group name THEN
BEGIN
group = TRUE;
END

/*
* build datagram service UDP packet;
*/
convert source and destination NetBIOS names into
half-ASCII, biased encoded name;
SOURCE_NAME = cat(source, SCOPE_ID);
SOURCE_IP = this nodes IP address;
SOURCE_PORT = DGM_SRVC_UDP_PORT;

IF NetBIOS broadcast THEN
BEGIN
DESTINATION_NAME = cat("*", SCOPE_ID)
END
ELSE



NetBIOS Working Group [Page 76]

RFC 1002 March 1987


BEGIN
DESTINATION_NAME = cat(destination, SCOPE_ID)
END

MSG_TYPE = select_one_from_set
{BROADCAST, DIRECT_UNIQUE, DIRECT_GROUP}
DGM_ID = next transaction id for Datagrams;
DGM_LENGTH = length of data + length of second level encoded
source and destination names;

IF (length of the NetBIOS Datagram, including UDP and
IP headers, > MAX_DATAGRAM_LENGTH) THEN
BEGIN
/*
* fragment NetBIOS datagram into 2 UDP packets
*/
Put names into 1st UDP packet and any data that fits
after names;
Set MORE and FIRST bits in 1st UDP packet's FLAGS;

OFFSET in 1st UDP = 0;

Replicate NetBIOS Datagram header from 1st UDP packet
into 2nd UDP packet;
Put rest of data in 2nd UDP packet;
Clear MORE and FIRST bits in 2nd UDP packet's FLAGS;
OFFSET in 2nd UDP = DGM_LENGTH - number of name and
data bytes in 1st UDP;
END
BEGIN
/*
* Only need one UDP packet
*/
USER_DATA = data;
Clear MORE bit and set FIRST bit in FLAGS;
OFFSET = 0;
END

IF (group == TRUE) OR (NetBIOS broadcast) THEN
BEGIN
/*
* Sending of following query is optional.
* Node may send datagram to NBDD immediately
* but NBDD may discard the datagram.
*/
send DATAGRAM QUERY REQUEST to NBDD;
IF response is POSITIVE QUERY RESPONSE THEN
send UDP packet(s) to NBDD Server IP address;
ELSE
BEGIN
get list of destination nodes from NBNS;



NetBIOS Working Group [Page 77]

RFC 1002 March 1987


FOR EACH node in list
BEGIN
send UDP packet(s) to this node's
IP address;
END
END
END
ELSE
BEGIN
send UDP packet(s) to IP address returned by name
discovery;
END /* procedure */

5.3.3. RECEPTION OF NetBIOS DATAGRAMS BY ALL NODES

The following algorithm discards out of order NetBIOS Datagram
fragments. An implementation which reassembles out of order
NetBIOS Datagram fragments conforms to this specification. The
fragment discard timer is initialized to the value FRAGMENT_TO.
This value should be user configurable. The default value is
given in Section 6, "Defined Constants and Variables".

PROCEDURE datagram_packet(packet)

/*
* processing initiated by datagram packet reception
* on B, P and M nodes
*/
BEGIN
/*
* if this node is a P node, ignore
* broadcast packets.
*/

IF this is a P node AND incoming packet is
a broadcast packet THEN
BEGIN
discard packet;
END

CASE packet type OF

DATAGRAM SERVICE:
BEGIN
IF FIRST bit in FLAGS is set THEN
BEGIN
IF MORE bit in FLAGS is set THEN
BEGIN
Save 1st UDP packet of the Datagram;
Set this Datagram's fragment discard
timer to FRAGMENT_TO;



NetBIOS Working Group [Page 78]

RFC 1002 March 1987


return;
END
ELSE
Datagram is composed of a single
UDP packet;
END
ELSE
BEGIN
/* Have the second fragment of a Datagram */

Search for 1st fragment by source IP address
and DGM_ID;
IF found 1st fragment THEN
Process both UDP packets;
ELSE
BEGIN
discard 2nd fragment UDP packet;
return;
END
END

IF DESTINATION_NAME is '*' THEN
BEGIN
/* NetBIOS broadcast */

deliver USER_DATA from UDP packet(s) to all
outstanding receive broadcast
datagram requests;
return;
END
ELSE
BEGIN /* non-broadcast */
/* Datagram for Unique or Group Name */

IF DESTINATION_NAME is not present in the
local name table THEN
BEGIN
/* destination not present */
build DATAGRAM ERROR packet, clear
FIRST and MORE bit, put in
this nodes IP and PORT, set
ERROR_CODE;
send DATAGRAM ERROR packet to
source IP address and port
of UDP;
discard UDP packet(s);
return;
END
ELSE
BEGIN /* good */
/*



NetBIOS Working Group [Page 79]

RFC 1002 March 1987


* Replicate received NetBIOS datagram for
* each recipient
*/
FOR EACH pending NetBIOS user's receive
datagram operation
BEGIN
IF source name of operation
matches destination name
of packet THEN
BEGIN
deliver USER_DATA from UDP
packet(s);
END
END /* for each */
return;
END /* good */
END /* non-broadcast */
END /* datagram service */

DATAGRAM ERROR:
BEGIN
/*
* name service returned incorrect information
*/

inform local name service that incorrect
information was provided;

IF this is a P or M node THEN
BEGIN
/*
* tell NetBIOS Name Server that it may
* have given incorrect information
*/

send NAME RELEASE REQUEST with name
and incorrect IP address to NetBIOS
Name Server;
END
END /* datagram error */

END /* case */
END

5.3.4. PROTOCOLS FOR THE NBDD

The key to NetBIOS Datagram forwarding service is the packet
delivered to the destination end node must have the same NetBIOS
header as if the source end node sent the packet directly to the
destination end node. Consequently, the NBDD does not reassemble
NetBIOS Datagrams. It forwards the UDP packet as is.



NetBIOS Working Group [Page 80]

RFC 1002 March 1987


PROCEDURE datagram_packet(packet)

/*
* processing initiated by a incoming datagram service
* packet on a NBDD node.
*/

BEGIN
CASE packet type OF

DATAGRAM SERVICE:
BEGIN
IF packet was sent as a directed
NetBIOS datagram THEN
BEGIN
/*
* provide group forwarding service
*
* Forward datagram to each member of the
* group. Can forward via:
* 1) get list of group members and send
* the DATAGRAM SERVICE packet unicast
* to each
* 2) use Group Multicast, if available
* 3) combination of 1) and 2)
*/

...

END

ELSE
BEGIN
/*
* provide broadcast forwarding service
*
* Forward datagram to every node in the
* NetBIOS scope. Can forward via:
* 1) get list of group members and send
* the DATAGRAM SERVICE packet unicast
* to each
* 2) use Group Multicast, if available
* 3) combination of 1) and 2)
*/

...

END
END /* datagram service */

DATAGRAM ERROR:



NetBIOS Working Group [Page 81]

RFC 1002 March 1987


BEGIN
/*
* Should never receive these because Datagrams
* forwarded have source end node IP address and
* port in NetBIOS header.
*/

send DELETE NAME REQUEST with incorrect name and
IP address to NetBIOS Name Server;

END /* datagram error */

DATAGRAM QUERY REQUEST:
BEGIN
IF can send packet to DESTINATION_NAME THEN
BEGIN
/*
* NBDD is able to relay Datagrams for
* this name
*/

send POSITIVE DATAGRAM QUERY RESPONSE to
REQUEST source IP address and UDP port
with request's DGM_ID;
END
ELSE
BEGIN
/*
* NBDD is NOT able to relay Datagrams for
* this name
*/

send NEGATIVE DATAGRAM QUERY RESPONSE to
REQUEST source IP address and UDP port

with request's DGM_ID;
END
END /* datagram query request */

END /* case */
END /* procedure */













NetBIOS Working Group [Page 82]

RFC 1002 March 1987


6. DEFINED CONSTANTS AND VARIABLES

GENERAL:

SCOPE_ID The name of the NetBIOS scope.

This is expressed as a character
string meeting the requirements of
the domain name system and without
a leading or trailing "dot".

An implementation may elect to make
this a single global value for the
node or allow it to be specified
with each separate NetBIOS name
(thus permitting cross-scope
references.)

BROADCAST_ADDRESS An IP address composed of the
nodes's network and subnetwork
numbers with all remaining bits set
to one.

I.e. "Specific subnet" broadcast
addressing according to section 2.3
of RFC 950.

BCAST_REQ_RETRY_TIMEOUT 250 milliseconds.
An adaptive timer may be used.

BCAST_REQ_RETRY_COUNT 3

UCAST_REQ_RETRY_TIMEOUT 5 seconds
An adaptive timer may be used.

UCAST_REQ_RETRY_COUNT 3

MAX_DATAGRAM_LENGTH 576 bytes (default)



NAME SERVICE:

REFRESH_TIMER Negotiated with NBNS for each name.

CONFLICT_TIMER 1 second
Implementations may chose a longer
value.


NAME_SERVICE_TCP_PORT 137 (decimal)



NetBIOS Working Group [Page 83]

RFC 1002 March 1987


NAME_SERVICE_UDP_PORT 137 (decimal)

INFINITE_TTL 0


SESSION SERVICE:

SSN_SRVC_TCP_PORT 139 (decimal)

SSN_RETRY_COUNT 4 (default)
Re-configurable by user.

SSN_CLOSE_TIMEOUT 30 seconds (default)
Re-configurable by user.

SSN_KEEP_ALIVE_TIMEOUT 60 seconds, recommended, may be set to
a higher value.
(Session keep-alives are used only
if configured.)

DATAGRAM SERVICE:

DGM_SRVC_UDP_PORT 138 (decimal)

FRAGMENT_TO 2 seconds (default)





























NetBIOS Working Group [Page 84]

RFC 1002 March 1987


REFERENCES



[1] "Protocol Standard For a NetBIOS Service on a TCP/UDP
Transport: Concepts and Methods", RFC 1001, March 1987.

[2] J. Reynolds, J. Postel, "Assigned Numbers", RFC 990, November
1986.

[3] P. Mockapetris, "Domain Names - Implementation and
Specification", RFC 883, November 1983.










































NetBIOS Working Group [Page 85]


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