NetBIOS name NetBIOS name resolutionresolution

Name resolutionName resolution NetBIOS name resolution:

mapping NetBIOS name to an IP address review of name syntax: machine name: \\

mname <= 15 digits, and share name: \sname <= 12 digits (DOS 8)

NetBIOS name can be seen in network dialog, registry and using nbtstat -n

ARP - Address Resolution Protocol IP address to MAC address resolution ARP cache keeps table with IP and MAC

addresses You can see it using arp -a ARP cache aging (2 minutes) can be setup

NetBIOS over TCP/IP NetBIOS over TCP/IP node typesnode types

b-node: broadcast of the name asking for IP p-node: peer-to-peer using NBNS such as

WINS m-node: mix of b and p, defaults to b-node,

if fails uses p-node resolution h-node: hybrid of b and p, defaults to p-

node, if fails uses b-node resolution Microsoft enhanced b-node: loads

LMHOSTS in local cache when TCP/IP starts. If fails to resolve then starts broadcast query

NetBIOS over TCP/IP in Windows is NetBT

B-node: resolving names B-node: resolving names locallylocally

ARP

Local address cache

AA

B-nodebroadcast

BB CC

A: a command like NET USE K: \\Al200\temp is issued and the local address cache is checked to see if the IP is already thereB: if not found in cache a name query broadcast is sent to the subnet asking for the destination IP numberC: the broadcast is received by all machines that start to check if their names match the one broadcasted. The machine that matches prepares a query response using the ARP to obtain the MAC address of the machine requesting the name resolu- tion. As soon as this happens a NetBIOS connection exists.

Enhanced B-node: resolving Enhanced B-node: resolving remote NetBIOS namesremote NetBIOS names

Local address cacheAA

routerrouter

B-nodebroadcast

BB ARP

LMHOSTSCC

DDA: a command like NET USE K: \\Al200\temp is issued and the local address cache is checked to see if the IP is already thereB: if not found in cache a name query broadcast is sent to the subnet asking for the destination IP numberC: if fails the LMHOSTS table is searched and name is resolvedD: routing table is checked for destination, or ARP issues request for gateway address (normally in the local cache)E: response is sent as soon as ARP resolves MAC address

EE

Resolving NetBIOS names Resolving NetBIOS names with NBNSwith NBNS

Local address cache

AA B-nodebroadcast

BBARP

CC

A: a command like NET USE K: \\Al200\temp is issued and the local address cache is checked to see if the IP is already thereB: if not found in cache a name query broadcast is sent or the NBNS is searched for the name and name is resolvedC: as soon as name is resolved ARP is used to determine the hardware address

Name resolution orderName resolution order Depending of what is selected

HOSTS DNS WINS (if selected) broadcast LMHOSTS (if checked in WINS, before broadcast) DNS again

You can change this in the registry HKEY_LOCAL_MACHINE\System\

CurrentControlSet\Services\TCPIP\Service Provider

You will see: HostsPriority , DNSPriority, NBTPriority the lowest values are checked first

Introduction to NET Introduction to NET commandscommands

NET HELP and NET command /HELP (see) NET USER let you see, add, modify and delete users NET ACCOUNTS changes to the entire user database NET GROUP and NET LOCALGROUP (see WEBTEACH) NET COMPUTER let you add or delete a computer to

domain NET CONFIG WORSKSTATION and SERVER (see

AL200) NET STATISTICS WORSTATION and SERVER NET VIEW let you see shares (see AL200) NET USE to connect to a share (see lpt4 share) NET SHARE shares a resource NET START / STOP start /stop network services (

example) NET SEND name message sends a message