ITN 208-01N Mrs. Z. D. Bodwin1 Guide To TCP/IP Chapter 12 TCP/IP, NETBIOS, And WINS.

ITN 208-01N Mrs. Z. D. Bodwin 1

Guide To TCP/IP

Chapter 12TCP/IP, NETBIOS, And WINS


NETBIOS ( an Application Programming Interface)

• Developed by Sytek – 1985

• Later adopted by IBM & Microsoft

• Original NetBIOS -not a protocol; it is an API (Application Programming Interface)– Used to call network resources


NetBios - contd

• Original network protocol for DOS and Windows PCs

• Did not use network addresses

• Interface to NetBios and transport part were later separated

• Used routable protocols like TCP/IP and SPX/IPX


NetBIOS - contd

• TheAPI retained the NetBios name

• The transport protocol was renamed NetBeui (NetBios Enhanced User Interface),

• Chatty – periodically broadcasts names over network so Network Neighborhood can catalog them.


API

• A language and message format used by an application program to communicate with the operating system

• APIs are implemented by writing function calls in the program, which provide the linkage to a specific subroutine for execution.

• API implies that some program module or routine is either already in place or that


API


NetBIOS

• For backward compatibility– Win2K relies on DNS for name resolution. – Active Directory, uses LDAP (Light

Directory Access Protocol)– To share resources with older Windows,

enable NetBIOS – Install & configure NetBEUI (NetBios

Extended User Interface), now called NetBIOS FRAME, (NBF) also


How Windows 2000/ XP, And Windows Server 2003 Work With NetBIOS

• Windows 2000 and later use DNS as the preferred method of resolving names

• Enable NetBIOS name resolution for older versions of Windows

• WINS server• NetBIOS over TCP/IP• Windows Server 2003 DNS services are

compatible with WINS



How does NetBIOS work?

• NetBIOS is a:– Naming convention– a network API– Set of protocols for sharing resources– Can identify computer names, a user, a

process– Applications use resources by using

NetBios names.


How does NetBIOS work?

• When a computer (end node) or a user logs into a NetBios network, it registers and resolves its names– Computer/user registers by sending Name

Registration Request– If name has been claimed

• Challenge• negative Name Registration reply


How NetBios Work?

• 2 types of NetBIOS frames– Datagrams – connectionless traffic. Ex –

announcements– Session – used when reliable connection is

required. Ex: host to host interaction


How does NetBIos work? - contd

• Name Resolution – depends on client configuration & services needed.– Local list – local machine’s cache, LMHost

file, HOST file– Broadcast on subnet– Direct queries to name servers – WINS,

DNS


The Hows…

• Net Resolution by Node Type - computer name based on node type– B-Node (Broadcast) – broadcasts Name

Registration packet locally– Takes ownership if no negative Name Registration

Reply– Releases name when computer /process shuts

down– Can’t use WINS– Default node type for Win2K clients

Node type set by DHCP or in the Registry


Name Resolution

• 1. By Node Type – contd– P-Node (Peer) – uses local WINS server– Unicast :Name Registration Request– Negative/Positive Name Registration reply– Name Release Request; TTL (default-6days_– Multiple WINS all servers will be queried until a

reply is obtained.– Win2K,Win98 – up to 12 WINS server


Name Resolution

• Node Type– M-Node (mixed)– Attempts to use b-mode broadcasts first– Then it contacts WINS server

– H-Node (Hybrid)– P-node first then broadcasts


Node type resolution - contd

• Enhanced B-node– Uses the NetBios name cache, then, the

LMHOST file, then the normal b-node resolution.

– WFW3.11, LAN Manager and Win2K use this enhanced b-node


Name Resolution - contd

• 2. By NetBios Name Cache & LMHosts– LMHosts – plain text file; static list– Found in <windows root>\system 32\

drivers\etc directory– Lists NetBIOS names with associated IP

addresses– Create with plain text editor; syntax;

keywords


Name Resolution - contd

• 3. WINS Name Registration• Wins Servers do not participate in b-node

name resolution. Why?• Unicast; direct communication between

themselves & end nodes• Handle name resolution for p-nodes, m-nodes

an h-nodes• Older WINS clients-one primary, one

secondary WINS servers


Wins - contd

• Win 98 & Win2K – clients can be configured to use 1 primary and 11 secondary

• Name Registration Request Packet:– Positive Name Registration Reply-if name

does not exist in DB– TTL (default 6 days)– Name renewal – half TTL value


WINS - contd

• Wait Acknowledgement (WACK) -if name exists in DB– WINS server acknowledges request w/o

denying it– Contacts registered holder – is name still

being used, server issues negative Name Registration Reply

– If not – sends positive Name Registration Reply


WINS - contd

• Additional features– Demand packets – imperative; nodes must

comply; used during configuration process– Name Conflict Demand packet – node is

informed of conflict and must release name– Name Release Demand packet – node

must remove name from its table


WINS

• Burst Mode – server responds to Name Registration with positive Name Registration Reply.

• Holds off on name conflict resolution

• Issues replies with different TTL. Why?

• Load balancing;

• Queue size – default 500 registrations


Name Resolution - cont

• 4. DNS & HOSTS files• DNS is the preferred method of name resolution for

Windows 2000 and Windows XP• Some applications or clients attempt to resolve

names with the HOSTS file• HOSTS file lists IP name and IP address pairs• UNIX and Linux name resolution order

– Local host– HOSTS file– DNS– NetBIOS


Name Resolution – contd

• DNS naming convention (see your notes on ch. 7)

• HOSTS file – static list of IP names & addresses; same location as LMHosts

• Sometimes used by Telnet & FTP

• No special syntax & keywords


Let us look at LMHOST & HOST files

• Go to your Windows Explorer

• WINNT Folder

• Systems32

• Drivers

• Etc– Note the structure of each file…. Both are

static files.


NetBios over TCP/IP (NetBT or NBT)

• Allows NetBios to use TCP/IP addressing to make it transportable and translatable.

• Uses TCP/UDP ports

137 Name Services

138 Datagram Service

139 Session Services

TCP/UDP ports

NetBios Services


NetBIOS Names & IP Names

• 15-characters; 16th character is service identifier.

• Expressed in Hex; 2-byte hex = one character (range 0x00 thru 0xFF)

• If NetBIOS name shorter than 15, it is padded with blanks (0x20)


Names - contd

• NetBIOS names to be recognized by DNS:– Domain portion has to be added– Scope Identifier added to create NetBios

domain name– Problem? Scope ID is a user string and

adds only one level in the hierarchy• Will not work with Internet domain names


Windows Internet Naming Services(WINS)

• Name resolution software from MS• Runs under WinNT & Win2K• Converts NetBIOS names to IP

addresses• WINS server keeps these names &

addresses in DB; with TTL and version#.

• DB replication among WINS servers


How WINS works?

DNS or WINS

Server


WINS Server

• Does not perform broadcast name registration (b-node)

• DHCP IP address assignment updates WINS database; if will help if both are in the same machine

• At least one 1 secondary WINS in each subnet


Other WINS Configurations

• WINS proxy – to integrate b-node clients with wins-enabled network; to resolve name query broadcasts.

• WINS replication – info sharing– PUSH partner – when server has updated

info since last replication– PULL partner – when server pulls the


WINS configuration

• Integrating WINS & DNS – DNS can use WINS to resolve NetBIOS names.

• Where? – primary or zone root level• How? – configure DNS to point to one or

more WINS servers– Each subdomain has its own Start of Authority

(SOA) with its own zone root DNS– Create a special domain just for NetBIOS clients


Large Network – each DMS can resolve NetBIOS names

ITN 208-01N Mrs. Z. D. Bodwin1 Guide To TCP/IP Chapter 12 TCP/IP, NETBIOS, And WINS.

Documents

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netbios network

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netbios work

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bodwin2 netbios

wins slide