Appendix B:
NetBT (NetBIOS over TCP) Configuration Parameters
Introduction
All of the NetBT parameters are registry values located
under one of two different subkeys of HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services:
T
NetBT\Parameters
T
NetBT\Adapters\<Adapter Name>, in which <Adapter Name>
refers the subkey for a network adapter that NetBT is bound to, such as Lance01.
Values under the latter key(s) are specific to each adapter.
If the system is configured via DHCP, then a change in parameters will take
effect if the command ipconfig /renew is issued in a command shell. Otherwise,
a reboot of the system is required for a change in any of these parameters to
take effect.
Standard Parameters Configurable from the Registry Editor
The following parameters are installed with default values
by the NCPA during the installation of the TCP/IP components. They may be modified
using the Registry Editor (regedt32.exe).
BcastNameQueryCount
Key: Netbt\Parameters
Value
Type: REG_DWORD - Count
Valid
Range: 1 to 0xFFFF
Default:
3
Description: This value determines
the number of times NetBT broadcasts a query for a given name without receiving
a response.
BcastQueryTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 100 to 0xFFFFFFFF
Default:
0x2ee ( 750 decimal)
Description: This value determines
the time interval between successive broadcast name queries for the same name.
CacheTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 60000 to 0xFFFFFFFF
Default:
0x927c0 ( 600000 milliseconds
= 10 minutes)
Description: This value determines
the time interval that names are cached in the remote name table.
NameServerPort
Key: Netbt\Parameters
Value
Type: REG_DWORD - UDP port
number
Valid
Range: 0 - 0xFFFF
Default:
0x89
Description:
This parameter determines
the destination port number to which NetBT will send name service related packets,
such as name queries and name
registrations,
to WINS. The Microsoft WINS Server listens on port 0x89. NetBIOS name servers
from other vendors may listen on different ports.
NameSrvQueryCount
Key: Netbt\Parameters
Value
Type: REG_DWORD - Count
Valid
Range: 0 - 0xFFFF
Default:
3
Description: This value determines
the number of times NetBT sends a query to a WINS server for a given name without
receiving a response.
NameSrvQueryTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 100 - 0xFFFFFFFF
Default: 1500 (1.5 seconds)
Description: This value determines
the time interval between successive name queries to WINS for a given name.
SessionKeepAlive
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 60,000 - 0xFFFFFFFF
Default:
3,600,000 (1 hour)
Description: This value determines
the time interval between keepalive transmissions on a session. Setting the value
to 0xFFFFFFF disables keepalives.
Size/Small/Medium/Large
Key: Netbt\Parameters
Value
Type: REG_DWORD
Valid
Range: 1, 2, 3 (Small, Medium,
Large)
Default:
1 (Small)
Description: This value determines
the size of the name tables used to store local and remote names. In general,
a setting of Small is adequate. If the system is acting as a proxy nameserver,
then the value is automatically set to Large to increase the size of the name
cache hash table. Hash table buckets are sized as follows:
Small: 16=============== Medium: 128=============== Large: 256
Optional Parameters Configurable from the Registry Editor
These parameters normally do not exist in the registry.
They may be created to modify the default behavior of the NetBT protocol driver.
BroadcastAddress
Key: Netbt\Parameters
Value
Type: REG_DWORD - Four
byte, little-endian encoded IP address
Valid
Range: 0 - 0xFFFFFFFF
Default:
The ones-broadcast
address for each network.
Description: This parameter can
be used to force NetBT to use a specific address for all broadcast name related
packets. By default, NetBT uses the ones-broadcast address appropriate for each
net (i.e., for a network of 10.101.0.0 with a subnet mask of 255.255.0.0, the
subnet broadcast address would be 10.101.255.255). This parameter would be set,
for example, if the network uses the zeros-broadcast address (set using the UseZeroBroadcast
TCP/IP parameter). The appropriate subnet broadcast address would then be 10.101.0.0
in the example above. This parameter would then be set to 0x0b650000. Note that
this parameter is global and will be used on all subnets that NetBT is bound to.
EnableProxyRegCheck
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range: 0 or 1 (False or
True)
Default:
0 (False)
Description: If this parameter
is set to 1 (True), then the proxy name server will send a negative response to
a broadcast name registration if the name is already registered with WINS or is
in the proxy-s local name cache with a different IP address. The hazard of enabling
this feature is that it prevents a system from changing its IP address as long
as WINS has a mapping for the name. For this reason, it is disabled by default.
InitialRefreshTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 960000 - 0xFFFFFFF
Default:
960000 (16 minutes)
Description:
This parameter specifies
the initial refresh time-out used by NetBT during name registration. NetBT tries
to contact the WINS servers at 1/8th of this time interval when it is first registering
names. When it receives a successful registration response, that response will
contain the new refresh interval to use.
LmhostsTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 1000 - 0xFFFFFFFF
Default:
6000 (6 seconds)
Description: This parameter specifies
the time-out value for LMHOSTS and DNS name queries. The timer has a granularity
of the time-out value, so the actual time-out could be as much as twice the value.
MaxDgramBuffering
Key: Netbt\Parameters
Value
Type: REG_DWORD - Count
of bytes
Valid
Range: 0 - 0xFFFFFFFF
Default:
0x20000 (128 Kb)
Description: This parameter specifies
the maximum amount of memory that NetBT will dynamically allocate for all outstanding
datagram sends. Once this limit is reached, further sends will fail due to insufficient
resources.
NodeType
Key: Netbt\Parameters
Value
Type: REG_DWORD - Number
Valid
Range: 1,2,4,8 (b-node,
p-node, m-node, h-node)
Default:
1 or 8 based on the
WINS server configuration
Description:
This parameter determines
what methods NetBT will use to register and resolve names. A b-node system uses
broadcasts. A p-node system uses only point-to-point name queries to a name server
(WINS). An m-node system broadcasts first, then queries the name server. An h-node
system queries the name server first, then broadcasts. Resolution via LMHOSTS
and/or DNS, if enabled, will follow these methods. If this key is present it will
override the DhcpNodeType key. If neither key is present, the system defaults
to b-node if there are no WINS servers configured for the client. The system defaults
to h-node if there is at least one WINS server configured.
RandomAdapter
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range: 0 or 1 (False or
True)
Default:
0 (False)
Description: This parameter applies
to a multihomed host only. If it is set to 1 (True), then NetBT will randomly
choose the IP address to put in a name query response from all of its bound interfaces.
Usually, the response contains the address of the interface that the query arrived
on. This feature would be used by a server with two interfaces on the same network
for load balancing.
RefreshOpCode
Key: Netbt\Parameters
Value
Type: REG_DWORD - Number
Valid
Range: 8, 9
Default:
8
Description: This parameter forces
NetBT to use a specific opcode in name refresh packets. The specification for
the NetBT protocol is somewhat ambiguous in this area. Although the default of
8 used by Microsoft implementations appears to be the intended value, some other
implementations, such as those by Ungermann-Bass, use the value 9. Two implementations
must use the same opcode to interoperate.
SingleResponse
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range:
0 or 1 (False or True)
Default: 0 (False)
Description: This parameter applies
to a multihomed host only. If this parameter is set to 1 (True), then NBT will
only supply the IP address from one of its bound interfaces in name query responses.
By default, the addresses of all bound interfaces are included.
WinsDownTimeout
Key: Netbt\Parameters
Value
Type: REG_DWORD - Time
in milliseconds
Valid
Range: 1000 - 0xFFFFFFFF
Default:
15,000 ( 15 seconds)
Description: This parameter determines
the amount of time NetBT will wait before again trying to use WINS after it fails
to contact any WINS server. This feature primarily allows computers that are temporarily
disconnected from the network, such as laptops, to proceed through boot processing
without waiting to time-out out each WINS name registration or query individually.
Parameters Configurable from the NCPA
The following parameters can be set via the NCPA. There
should be no need to configure them directly.
EnableDns
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range: 0 or 1 (False or
True)
Default:
0 (False)
Description: If this value is
set to 1 (True), then NetBT will query the DNS for names that cannot be resolved
by WINS, broadcast, or the LMHOSTS file.
EnableLmhosts
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range: 0 or 1 (False or
True)
Default:
1 (True)
Description:
If this value is set
to 1 (True), then NetBT will search the LMHOSTS file, if it exists, for names
that cannot be resolved by WINS or broadcast. By default there is no LMHOSTS file
database directory (specified by Tcpip\Parameters\DatabasePath), so no action
will be taken. This value is written by the Advanced TCP/IP Configuration dialog
box of the NCPA.
EnableProxy
Key: Netbt\Parameters
Value
Type: REG_DWORD - Boolean
Valid
Range: 0 or 1 (False or
True)
Default:
0 (False)
Description: If this value is
set to 1 (True), then the system will act as a proxy name server for the networks
to which NetBT is bound. A proxy name server answers broadcast queries for names
that it has resolved through WINS. A proxy nameserver allows a network of b-node
implementations to connect to servers on other subnets that are registered with
WINS.
NameServer
Key: Netbt\Adapters\<Adapter
Name>
Value
Type: REG_SZ - Dotted decimal
IP address (i.e. 10.101.1.200)
Valid
Range: Any valid IP address
Default: blank ( no address
)
Description: This parameter specifies
the IP address of the primary WINS server. If this parameter contains a valid
value, it overrides the DHCP parameter of the same name.
NameServerBackup
Key: Netbt\Adapters\<Adapter
Name>
Value
Type: REG_SZ - Dotted decimal
IP address (i.e. 10.101.1.200)
Valid
Range: Any valid IP address.
Default: blank (no address)
Description: This parameter specifies
the IP address of the secondary WINS server. If this parameter contains a valid
value, it overrides the DHCP parameter of the same name.
ScopeId
Key: Netbt\Parameters
Value
Type: REG_SZ - Character
string
Valid
Range: Any valid DNS domain
name consisting of two dot-separated parts, or a ?*¦.
Default: None
Description: This parameter specifies
the NetBIOS name scope for the node. This value must not begin with a period.
If this parameter contains a valid value, it will override the DHCP parameter
of the same name. A blank value (empty string) will be ignored. Setting this parameter
to the value ?*¦ indicates a null scope and will override the DHCP parameter.
Non-Configurable
Parameters
The following parameters are created and used internally
by the NetBT components. They should never be modified using the Registry Editor.
They are listed here for reference only.
DhcpNameServer
Key: Netbt\Adapters\<Adapter
Name>
Value
Type: REG_SZ - Dotted decimal
IP address (i.e. 10.101.1.200)
Valid
Range: Any valid IP address
Default: None
Description: This parameter specifies
the IP address of the primary WINS server. It is written by the DHCP client service,
if enabled. A valid NameServer value will override this parameter.
DhcpNameServerBackup
Key: Netbt\Adapters\<Adapter
Name>
Value
Type: REG_SZ - Dotted decimal
IP address (i.e. 10.101.1.200)
Valid
Range: Any valid IP address
Default: None
Description: This parameter specifies
the IP address of the secondary WINS server. It is written by the DHCP client
service, if enabled. A valid NameServerBackup value will override this parameter.
DhcpNodeType
Key: Netbt\Parameters
Value
Type: REG_DWORD - Number
Valid
Range: 1 - 8
Default:
1
Description: This parameter specifies
the NetBT node type. It is written by the DHCP client service, if enabled. A valid
NodeType value will override this parameter. See the entry for NodeType for a
complete description.
DhcpScopeId
Key: Netbt\Parameters
Value
Type: REG_SZ - Character
string
Valid
Range:
a dot separated name
string such as ?microsoft.com¦
Default:
None
Description:
This parameter specifies
the NetBIOS name scope for the node. It is written by the DHCP client service,
if enabled. This value must not begin with a period. See the entry for ScopeId
for more information.
NbProvider
Key: Netbt\Parameters
Value
Type: REG_SZ - Character
string
Valid
Range: _tcp
Default: _tcp
Description: This parameter is
used internally by the RPC component. The default value should not be changed.
TransportBindName
Key: Netbt\Parameters
Value
Type: REG_SZ - Character
string
Valid
Range: N/A
Default:
\Device\
Description:
This parameter is
used internally during product development. The default value should not be changed.