Guide to TCP/IP, Third Edition. Chapter 12: TCP/IP, NetBIOS, and WINS

Transcription

1 Guide to TCP/IP, Third Edition Chapter 12: TCP/IP, NetBIOS, and WINS

2 Objectives Discuss the history of NetBIOS Understand what NetBIOS is and its limitations Understand the role of NetBIOS in Windows 2000 and higher operating systems Understand the significance of NetBIOS over TCP/IP on your network Understand how NetBIOS works TCP/IP, NetBIOS, and WINS 2

3 Objectives (continued) Explore NetBIOS names, including structure and types Explore the various ways of registering and resolving NetBIOS names Understand naming conventions associated with NetBIOS over TCP/IP Understand how NetBIOS names must change to work with DNS name resolution TCP/IP, NetBIOS, and WINS 3

4 Objectives (continued) Set up a WINS server for your network Integrate WINS services with DNS Troubleshoot WINS and NetBIOS errors with commonly used tools TCP/IP, NetBIOS, and WINS 4

5 History of NetBIOS NetBIOS Developed by Sytek in 1983 Adopted by IBM and Microsoft for naming network resources on small peer-to-peer networks Original was an Application Programming Interface (API) used to call network resources NetBIOS Extended User Interface (NetBEUI) Extension of NetBIOS TCP/IP, NetBIOS, and WINS 5

6 What is NetBIOS (and Why Do I care) NetBIOS operates by Maintaining a list of unique names assigned to network resources Providing the services to establish, defend, and resolve these names Carrying the needed communications between applications that make use of these network resources TCP/IP, NetBIOS, and WINS 6

7 How Windows 2000, Windows XP, and Windows Server 2003 Work with Windows 2000 NetBIOS First Microsoft operating system to use DNS When upgrading servers to Windows 2000 Server or Windows Server 2003 Determine if you will still need to support NetBIOS names on your network If uncertain if your network requires NetBIOS support You can use the WINS performance monitor counter TCP/IP, NetBIOS, and WINS 7

8 NetBIOS and TCP/IP Using DNS Only Preferred form of networking in an all-windows 2000 and/or Windows XP environment Direct hosting of the (SMB) protocol Using NBF Only To deliberately restrict resource sharing only to the local network segment Bind Windows File and Print Sharing to NBF, but not to TCP/IP TCP/IP, NetBIOS, and WINS 8

9 Combining TCP/IP and NetBIOS NetBT or NBT NetBIOS over TCP/IP NetBIOS names Can be resolved by any of several combinations of methods Default configuration for Windows 2000 and Windows XP machines Have both NetBT and NBF enabled TCP/IP, NetBIOS, and WINS 9

10 TCP/IP, NetBIOS, and WINS 10

11 How Does NetBIOS Work? NetBIOS Takes advantage of simple naming, address handling, and message formatting conventions Supports connectionless datagrams as well as connection-oriented session frames Supports simple name registration and challenge mechanisms TCP/IP, NetBIOS, and WINS 11

12 NetBIOS Traffic Consists of NetBIOS frames of one of two types Datagrams or session frames NetBIOS sessions Used in situations that require a reliable connection When NetBIOS is run over TCP/IP as NetBT Datagrams are carried in UDP packets and session frames are carried in TCP packets TCP/IP, NetBIOS, and WINS 12

13 How Does NetBIOS Work? Registering and Challenging NetBIOS Names Registration Process of asserting that a name exists and belongs to a particular computer, user, process, or group Categories of name resolution methods Look up in a list of names on the local machine Broadcast queries on the local subnet Direct queries to name servers TCP/IP, NetBIOS, and WINS 13

14 Other NetBIOS Services Name services The most important NetBIOS services NetBIOS datagram and session services Used by applications such as Applications such as the Network Browser, LAN Manager TCP/IP, NetBIOS, and WINS 14

15 TCP/IP, NetBIOS, and WINS 15

16 NetBIOS Names Based on User name during logon Information configured for the specific computer in the Network applet in Control Panel NetBIOS names are of two general types Unique names and group names Unique names Resolve to a single address TCP/IP, NetBIOS, and WINS 16

17 Structure of NetBIOS Names Group names May resolve to multiple addresses NetBIOS names 16 characters long, divided into two parts First 15 characters are the name itself Last character is a code describing the class of resource to which the name belongs TCP/IP, NetBIOS, and WINS 17

18 TCP/IP, NetBIOS, and WINS 18

19 TCP/IP, NetBIOS, and WINS 19

20 NetBIOS Scope Identifier NetBIOS Provides the NetBIOS scope identifier Scope identifier Adds a character string to end of the name, separated from rest of name by a period (.) NetBIOS scope Identifies a logical community of network hosts DHCP scope Identifies a range of IP addresses that a DHCP server can assign to clients TCP/IP, NetBIOS, and WINS 20

21 NetBIOS Name Registration and Resolution NetBIOS names are registered and resolved using Node type NetBIOS name cache and the LMHOSTS file WINS servers configured as NetBIOS Name Servers DNS and the HOSTS file TCP/IP, NetBIOS, and WINS 21

22 Name Resolution Regimes by Node Type Four basic types of NetBIOS nodes Broadcast node (b-node) Peer node (p-node) Mixed node (m-node) Hybrid node (h-node) TCP/IP, NetBIOS, and WINS 22

23 NetBIOS Name Cache and LMHOSTS NetBIOS name cache File Temporary file that resides in memory, pairing NetBIOS names and IP addresses Names in the NetBIOS name cache Times out after 10 minutes, by default LMHOSTS file Plain text file that resides in the <windows root>\system32\drivers\etc directory TCP/IP, NetBIOS, and WINS 23

24 WINS Name Registration and WINS servers Resolution NetBIOS Name Servers that set up and maintain database of NetBIOS names and their associated IP addresses Do not participate in broadcast or b-node name registration and resolution WINS servers Support a special name registration regime called burst mode TCP/IP, NetBIOS, and WINS 24

25 DNS and The HOSTS File Preferred configuration for Windows 2000 and Windows XP clients Is to use DNS for name resolution HOSTS file Static list of IP name and address pairs, located in the <windowsroot>\system32\driver\etc directory TCP/IP, NetBIOS, and WINS 25

26 NetBIOS Over TCP/IP To coexist with TCP/IP, NetBIOS had to accommodate TCP/IP s conventions NetBIOS scope identifier was added as a sort of analog of the TCP/IP domain Set of steps created to make NetBIOS names and commands transportable over a TCP/IP connection TCP/IP, NetBIOS, and WINS 26

27 TCP/IP, NetBIOS, and WINS 27

28 NetBIOS and DNS Name Resolution To convert NetBIOS name into name that is recognizable and routable by DNS NetBIOS name had to become a usable host name Domain portion of the name had to be added TCP/IP, NetBIOS, and WINS 28

29 Creating a Usable Host Name from a NetBIOS name NetBIOS Name Has to be restated in a way that replaces any characters not recognizable by DNS DNS names must be printable In the ASCII code set None of these characters is printable TCP/IP, NetBIOS, and WINS 29

30 TCP/IP, NetBIOS, and WINS 30

31 Converting an Encoded NetBIOS Name to a Fully Qualified Domain Name To convert the (translated) NetBIOS name into a fully qualified domain name (FQDN) Domain portion of name has to be added as well NetBIOS scope identifier User-configurable string Adds only one level of hierarchy Internet domain names Regulated and restricted Conform to a deeper and rigorously enforced hierarchy TCP/IP, NetBIOS, and WINS 31

32 TCP/IP, NetBIOS, and WINS 32

33 WINS Servers WINS A server service Runs under Windows NT Server, Windows 2000 Server, or Windows Server 2003 WINS server Registers NetBIOS names and IP addresses Can be configured to return the IP address associated with a resource name or The NetBIOS names associated with an IP address TCP/IP, NetBIOS, and WINS 33

34 Different WINS Configurations WINS servers Can be deployed in several different ways to meet the needs of different networks Netsh command-line tool in Windows Server 2003 Helpful for WINS servers over WAN links to better manage slower network connections TCP/IP, NetBIOS, and WINS 34

35 Different WINS Configurations (continued) Administrator-level access to the WINS server allows you to Check server statistics Check the database and version numbers for consistency Mark records for eventual deletion (called tombstoning the records) Remove old records (scavenge the database) TCP/IP, NetBIOS, and WINS 35

36 WINS Proxy WINS clients Available for recent versions of DOS, OS/2, and all versions of Windows Available for Linux and UNIX machines running Samba You can configure any Windows 2000, Windows Server 2003, or Windows XP computer to Be a WINS proxy by setting the Enable Proxy parameter in the Registry to 1 TCP/IP, NetBIOS, and WINS 36

37 TCP/IP, NetBIOS, and WINS 37

38 Integrating WINS and DNS The Microsoft DNS server implementation (MS DNS) Can be configured to use WINS to resolve NetBIOS names in the primary or root zone domain MS DNS Cannot resolve NetBIOS names that are not direct children of the zone root or primary DNS domain TCP/IP, NetBIOS, and WINS 38

39 TCP/IP, NetBIOS, and WINS 39

40 TCP/IP, NetBIOS, and WINS 40

41 Reverse DNS Lookup for NetBIOS Names MS DNS servers in the in-addr.arpa domain Provide reverse lookup MS DNS servers in the reverse look-up zone root Can be configured to use WINS-R to find NetBIOS resources associated with an IP address WINS server Uses a NetBIOS Adapter Status Query to find the name(s) associated with a given IP address TCP/IP, NetBIOS, and WINS 41

42 Windows Server 2003 WINS Improvements Two improvements in WINS have been added to Windows Server 2003 Filtering records Accepting replication partners With improved filtering and search functions You locate records by showing only the records fitting the criteria you specify TCP/IP, NetBIOS, and WINS 42

43 Troubleshooting WINS and NetBIOS Errors in Windows name resolution fall into two broad categories Outright failure Degradation of service Accumulation of several instances of degradation Seldom leads to outright failure of the service TCP/IP, NetBIOS, and WINS 43

44 NBTSTAT Command-line program that returns statistics on NetBIOS A fast way to check the status of a particular NetBIOS host, or Get a quick snapshot of NetBIOS name resolution activity on the local network segment TCP/IP, NetBIOS, and WINS 44

45 WINS and DNS Consoles WINS Console Can search for active registrants by name or owner DNS Console in Windows 2000 and Windows Server 2003 More geared to monitoring and system diagnostics than the WINS server WINS operating parameters Are stored in a Management Information Base (MIB) TCP/IP, NetBIOS, and WINS 45

46 Typical Errors in NetBIOS and WINS Misconfiguration of end nodes due to user error Incorrect network logon due to user error Wrong node type due to user error or misconfigured DHCP Timeouts set too low to allow for network latency Unwanted traffic due to misconfiguration of end nodes and/or servers, or client/server topology TCP/IP, NetBIOS, and WINS 46

47 Security Flaw in NetBIOS Security Bulletin MS Details flaw in NetBIOS that could result in disclosure of information from your computer Operating systems are affected Windows NT 4.0 Windows NT 4.0 Terminal Server Edition Windows 2000 Windows XP Windows Server 2003 TCP/IP, NetBIOS, and WINS 47

48 Summary NetBIOS Native Windows approach to networking NetBIOS and NetBEUI (NBF) Use a flat namespace and are inherently nonroutable NetBIOS name can be resolved in three ways Look it up in a locally held list Ask the server (WINS, DNS, or Samba), or Ask the whole local network segment TCP/IP, NetBIOS, and WINS 48

49 Summary (continued) NetBIOS and WINS services Typically used in a mixed-network environment Windows networking clients or end nodes Can be configured to use one of four basic regimes of name registration and resolution WINS servers Are like DNS servers designed to serve only the NetBIOS namespace TCP/IP, NetBIOS, and WINS 49