• Chapter 1. Installing and Configuring Windows Server 2003
  • software development Company Server 2003
  • Chapter 1. Installing and Configuring Windows Server 2003
  • New Features in Windows Server 2003
  • Best Practices
  • Moving Forward
  • Version Comparisons
  • Hardware Recommendations
  • Installation Checklist
  • Functional Overview of Windows Server 2003 Setup
  • Installing Windows Server 2003
  • Post Setup Configurations
  • Functional Description of the Windows Server 2003 Boot Process
  • Correcting Common Setup Problems
  • Chapter 2. Performing Upgrades and Automated Installations
  • New Features in Windows Server 2003
  • NT4 Upgrade Functional Overview
  • Upgrading an NT4 or Windows 2000 Server
  • Automating Windows Server 2003 Deployments
  • Moving Forward
  • Chapter 3. Adding Hardware
  • New Features in Windows Server 2003
  • Functional Description of Windows Server 2003 Architecture
  • Overview of Windows Server 2003 Plug and Play
  • Installing and Configuring Devices
  • Troubleshooting New Devices
  • Moving Forward
  • Chapter 4. Managing NetBIOS Name Resolution
  • New Features in Windows Server 2003
  • Moving Forward
  • Overview of Windows Server 2003 Networking
  • Name Resolution and Network Services
  • Network Diagnostic Utilities
  • Resolving NetBIOS Names Using Broadcasts
  • Resolving NetBIOS Names Using Lmhosts
  • Resolving NetBIOS Names Using WINS
  • Managing WINS
  • Disabling NetBIOS-over-TCP/IP Name Resolution
  • Chapter 5. Managing DNS
  • New Features in Windows Server 2003
  • Configuring a Caching-Only Server
  • Configuring a DNS Server to Use a Forwarder
  • Managing Dynamic DNS
  • Configuring Advanced DNS Server Parameters
  • Examining Zones with Nslookup
  • Command-Line Management of DNS
  • Configuring DHCP to Support DNS
  • Moving Forward
  • Overview of DNS Domain Structure
  • Functional Description of DNS Query Handling
  • Designing DNS Domains
  • Active Directory Integration
  • Configuring DNS Clients
  • Installing and Configuring DNS Servers
  • Configuring Secondary DNS Servers
  • Integrating DNS Zones into Active Directory
  • Chapter 6. Understanding Active Directory Services
  • New Features in Windows Server 2003
  • Active Directory Support Files
  • Active Directory Utilities
  • Bulk Imports and Exports
  • Moving Forward
  • Limitations of Classic NT Security
  • Directory Service Components
  • Brief History of Directory Services
  • X.500 Overview
  • LDAP Information Model
  • LDAP Namespace Structure
  • Active Directory Namespace Structure
  • Active Directory Schema
  • Chapter 7. Managing Active Directory Replication
  • New Features in Windows Server 2003
  • Replication Overview
  • Detailed Replication Transaction Descriptions
  • Designing Site Architectures
  • Configuring Inter-site Replication
  • Controlling Replication Parameters
  • Special Replication Operations
  • Troubleshooting Replication Problems
  • Moving Forward
  • Chapter 8. Designing Windows Server 2003 Domains
  • New Features in Windows Server 2003
  • Design Objectives
  • DNS and Active Directory Namespaces
  • Domain Design Strategies
  • Strategies for OU Design
  • Flexible Single Master Operations
  • Domain Controller Placement
  • Moving Forward
  • Chapter 9. Deploying Windows Server 2003 Domains
  • New Features in Windows Server 2003
  • Preparing for an NT Domain Upgrade
  • In-Place Upgrade of an NT4 Domain
  • In-Place Upgrade of a Windows 2000 Forest
  • Migrating from NT and Windows 2000 Domains to Windows Server 2003
  • Additional Domain Operations
  • Moving Forward
  • Chapter 10. Active Directory Maintenance
  • New Features in Windows Server 2003
  • Loss of a DNS Server
  • Loss of a Domain Controller
  • Loss of Key Replication Components
  • Backing Up the Directory
  • Performing Directory Maintenance
  • Moving Forward
  • Chapter 11. Understanding Network Access Security and Kerberos
  • New Features in Windows Server 2003
  • Windows Server 2003 Security Architecture
  • Security Components
  • Password Security
  • Authentication
  • Analysis of Kerberos Transactions
  • MITv5 Kerberos Interoperability
  • Security Auditing
  • Moving Forward
  • Chapter 12. Managing Group Policies
  • New Features in Windows Server 2003
  • Group Policy Operational Overview
  • Managing Individual Group Policy Types
  • Moving Forward
  • Chapter 13. Managing Active Directory Security
  • New Features in Windows Server 2003
  • Overview of Active Directory Security
  • Using Groups to Manage Active Directory Objects
  • Service Accounts
  • Using the Secondary Logon Service and RunAs
  • Using WMI for Active Directory Event Notification
  • Moving Forward
  • Chapter 14. Configuring Data Storage
  • New Features in Windows Server 2003
  • Functional Description of Windows Server 2003 Data Storage
  • Performing Disk Operations on IA32 Systems
  • Recovering Failed Fault Tolerant Disks
  • Working with GPT Disks
  • Moving Forward
  • Chapter 15. Managing File Systems
  • New Features in Windows Server 2003
  • Overview of Windows Server 2003 File Systems
  • NTFS Attributes
  • Link Tracking Service
  • Reparse Points
  • File System Recovery and Fault Tolerance
  • Quotas
  • File System Operations
  • Moving Forward
  • Chapter 16. Managing Shared Resources
  • New Features in Windows Server 2003
  • Functional Description of Windows Resource Sharing
  • Configuring File Sharing
  • Connecting to Shared Folders
  • Resource Sharing Using the Distributed File System (Dfs)
  • Printer Sharing
  • Configuring Windows Server 2003 Clients to Print
  • Managing Print Services
  • Moving Forward
  • Chapter 17. Managing File Encryption
  • New Features in Windows Server 2003
  • File Encryption Functional Description
  • Certificate Management
  • Encrypted File Recovery
  • Encrypting Server-Based Files
  • EFS File Transactions and WebDAV
  • Special EFS Guidelines
  • EFS Procedures
  • Moving Forward
  • Chapter 18. Managing a Public Key Infrastructure
  • New Features in Windows Server 2003
  • Moving Forward
  • PKI Goals
  • Cryptographic Elements in Windows Server 2003
  • Public/Private Key Services
  • Certificates
  • Certification Authorities
  • Certificate Enrollment
  • Key Archival and Recovery
  • Command-Line PKI Tools
  • Chapter 19. Managing the User Operating Environment
  • New Features in Windows Server 2003
  • Side-by-Side Assemblies
  • User State Migration
  • Managing Folder Redirection
  • Creating and Managing Home Directories
  • Managing Offline Files
  • Managing Servers via Remote Desktop
  • Moving Forward
  • Chapter 20. Managing Remote Access and Internet Routing
  • New Features in Windows Server 2003
  • Configuring a Network Bridge
  • Configuring Virtual Private Network Connections
  • Configuring Internet Authentication Services (IAS)
  • Moving Forward
  • Functional Description of WAN Device Support
  • PPP Authentication
  • NT4 RAS Servers and Active Directory Domains
  • Deploying Smart Cards for Remote Access
  • Installing and Configuring Modems
  • Configuring a Remote Access Server
  • Configuring a Demand-Dial Router
  • Configuring an Internet Gateway Using NAT
  • Chapter 21. Recovering from System Failures
  • New Features in Windows Server 2003
  • Functional Description Ntbackup
  • Backup and Restore Operations
  • Recovering from Blue Screen Stops
  • Using Emergency Management Services (EMS)
  • Using Safe Mode
  • Restoring Functionality with the Last Known Good Configuration
  • Recovery Console
  • Moving Forward
  • Who Should Read This Book
  • Who This Book Is Not For
  • Conventions
  • Acknowledgments
  • About the Author
  • About the Technical Reviewers
  • Index
  • Index A
  • Index B
  • Index C
  • Index D
  • Index E
  • Index F
  • Index G
  • Index H
  • Index I
  • Index J
  • Index K
  • Index L
  • Index M
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  • Index Q
  • Index R
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  • Index SYMBOL
  • Index T
  • Index U
  • Index V
  • Index W
  • Index X
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  • Preface
  • Previous Section Next Section

    LDAP Namespace Structure

    A directory service has two major features. First, it distributes its information base among many different servers. Second, users can access directory information by querying any of those servers. Making this work requires defining a namespace in which each object's location can be quickly determined.

    Common Names

    As we saw in the last section, information in an LDAP database comes in the form of objects. Objects have attributes that describe them. For example, the User object for Tom Jones would have attributes such as Tom's logon name, his password, his phone number, his email address, his department, and so forth.

    When an LDAP client needs to locate information about an object, it submits a query that contains the object's distinguished name (DN) and the attributes the client wants to see. A search for information about Tom Jones could be phrased in a couple of ways:

    • You could search for attributes in Tom's User object. "Give me the Department attribute for cn=Tom Jones,cn=Users,dc=Company,dc=com."

    • You could search for attributes that end up including Tom's object. "Give me all User objects with a Department attribute equal to Finance."

    In either case, LDAP can find Tom's object because the name assigned to the object describes its place in the LDAP namespace.

    Figure 6.6 shows a portion of the LDAP namespace in Active Directory. With one exception, each folder represents a Container object, which in turn holds other objects. The exception is the domain controllers object, which is an Organizational Unit (OU). Domain controllers are placed in an OU so that they can have discrete group policies. Generic Container objects cannot be linked to group policies.

    Figure 6.6. Example LDAP directory hierarchy.

    graphics/06fig06.gif

    The User objects in the diagram have designators that start with CN, meaning Common Name. The CN designator applies to all but a few object types. Active Directory only uses two other object designators (although LDAP defines several). They are as follows:

    • Domain Component (DC). DC objects represent the top of an LDAP tree that uses DNS to define its namespace. Active Directory is an example of such an LDAP tree. The designator for an Active Directory domain with the DNS name Company.com would be dc=Company,dc=com.

    • Organizational Unit (OU). OU objects act as containers that hold other objects. They provide structure to the LDAP namespace. OUs are the only general-purpose container available to administrators in Active Directory. An example OU name would be ou=Accounting.

    Distinguished Names

    A name that includes an object's entire path to the root of the LDAP namespace is called its distinguished name, or DN. An example DN for a user named CSantana whose object is stored in the cn=Users container in a domain named Company.com would be cn=CSantana,cn=Users,dc=Company,dc=com.

    An identifying characteristic of LDAP distinguished names is their little-endian path syntax. As you read from left to right, you travel up the directory tree. This contrasts to file system paths, which run down the tree as you read from left to right.

    Relative Distinguished Names

    An object name without a path, or a partial path, is called a relative distinguished name, or RDN. The common name cn=CSantana is an example of an RDN. So is cn=CSantana,cn=Users. The RDN serves the same purpose as a path fragment in a filename. It is a convenient navigational shortcut.

    Two objects can have the same RDN, but LDAP has a rule that no two objects can have the same DN. This makes sense if you think of the object-oriented nature of the database. Two objects with the same DN would try to occupy the same row in the database table. C'est impossible, as we say in southern New Mexico.

    Case Sensitivity of LDAP Names

    Distinguished names in Active Directory are not case sensitive. In most instances, the case you specify when you enter a value is retained in the object's attribute. This is similar to the way Windows treats filenames. Feel free to mix cases based on your corporate standards or personal aesthetic.

    Typeful Names

    The combination of an object's name and its LDAP designator is called a typeful name. Examples include cn=Administrator and cn=Administrator,cn=Users,dc=Company, dc=com.

    Some applications can parse for delimiters such as periods or semicolons between the elements of a distinguished name. For example, an application may permit you to enter Administrator.Users.Company.com rather than the full typeful name. This is called typeless naming. When entering typeless names, it is important to place the delimiters properly.

    The console-based tools provided by Microsoft use a GUI to navigate the LDAP namespace, so you don't need to worry about interpreting typeful or typeless names right away. But if you want to use many of the support tools that come on the Windows Server 2003 CD or in the Resource Kit, or you want to use scripts to manage Active Directory, you'll need to use typeful naming. After you get the hang of it, rattling off a long typeful name becomes second nature.

    Directory Information Tree

    In LDAP, as in X.500, the servers that host copies of the information base are called Directory Service Agents, or DSAs. A DSA can host all or part of the information base. The portions of the information base form a hierarchy called a Directory Information Tree, or DIT. Figure 6.7 shows an example.

    Figure 6.7. Directory Information Tree.

    graphics/06fig07.gif

    The top of the DIT is occupied by a single object. The class of this object is not defined by the LDAP specification. In Active Directory, the object must come from the object class DomainDNS. Because Active Directory uses DNS to structure its namespace, the DomainDNS object is given a DC designator. For example, the object at the top of the tree in Figure 6.7 would have the distinguished name dc=Company,dc=com.

    Typeless Names and Delimiters

    If you write scripts and you need to allow for periods in object names, precede the period with a backslash. This tells the parser that the period is a special character, not a delimiter. For example, if your user names look like tom.collins, a typeless name in a script would look like this: tom\.collins.Users.Company.com. The same is true for user names that have embedded commas and periods, such as Winston H. Borntothepurple, Jr. An ADSI query for this name would look like this: winston h\. borntothepurple\, jr\.

    Active Directory and DNS Roots

    Active Directory cannot be rooted at the very top of a DNS namespace. The assumption is that many different Active Directory namespaces could share the same root. For this reason, the DomainDNS object at the top of the tree must always have at least two domain component designators.

    An LDAP tree contains branches formed by containers underneath the root container. These containers hold objects that have some relation to each other as defined by the namespace. For instance, in Active Directory, the default container for User objects is cn=Users. For Computer objects, it is cn=Computers. Information about group policies, DNS, Remote Access Services, and so forth go in cn=System. As we'll see when we discuss Active Directory design in Chapter 8, "Designing Windows Server 2003 Domains," administrators have the ability to create Organizational Units (OUs) to contain objects that have similar management or configuration requirements.

    Naming Contexts

    As the number of objects in a DIT grows, the database may get too large to store efficiently on one DSA. Also, an organization might want to use bandwidth more effectively by using a DSA in New York to store information about users in North America and another DSA in Amsterdam to store information about users in Europe.

    Naming Contexts and Partitions

    X.501, "Information TechnologyOpen Systems InterconnectionThe Directory: Models," defines the term naming context as, "A subtree of entries held in a single master DSA." It goes on to describe the process of dividing a tree into multiple naming contexts as partitioning.

    Novell chose to adopt the term partition to define separate pieces of the directory database. In their seminal book, Understanding and Deploying LDAP Directory Services, Tim Howe, Mark Smith, and Gordon Good use the term partition in favor of naming context, although they describe both as meaning the same thing. Microsoft uses the two terms interchangeably.

    The tools that come with the Windows Server 2003 CD and in the Resource Kit favor the term naming context. That is the term I use throughout this book.

    Here is where the distributed nature of an LDAP database comes into play. The Directory Information Base can be separated into parts called naming contexts, or NCs. In Active Directory, each domain represents a separate naming context. Domain controllers in the same domain each have a read/write replica of that Domain naming context. Configuration and Schema objects are stored in their own naming contexts, as are DNS Record objects when using Active Directory Integrated DNS zones.

    When a client submits a query for information about a particular object, the system must determine which DSA hosts the naming context that contains that particular object. It does this using the object's distinguished name and knowledge about the directory topology.

    If a DSA cannot respond to a query using information in the naming contexts it hosts, it sends the client a referral to a DSA hosting the next higher or lower naming context in the tree (depending on the distinguished name of the object in the search). The client then submits the request to a DSA hosting the naming context in the referral. This DSA either responds with the information being requested or a referral to another DSA. This is called walking the tree.

    DSAs that host copies of the same naming context must replicate changes to each other. It's important to keep this in mind as you work with Active Directory servers. If you have separate domains, then clients in one domain must walk the tree to get access to Active Directory objects in another domain. If the domain controllers for the domains are in different locations in the WAN, this can slow performance. Many of the architectural decisions you'll make as you design your system focus on the location, accessibility, and reliability of naming contexts.

    LDAP Searches

    From a client's perspective, LDAP operates like a well-run department store. In a department store, you can sidle up to the fragrance counter and ask, "How much is the Chanel No. 5?" and be sure of getting an immediate reply, especially if you already have your credit card in hand. The same is true of LDAP. When a search request is submitted to a DSA that hosts a copy of the naming context containing the objects involved in the search, the DSA can answer the request immediately.

    But in a department store, what if you ask the fragrance associate, "Where can I find a size 16 chambray shirt that looks like a Tommy Hilfiger design but doesn't cost so darn much?" The associate probably doesn't know, but gives you directions to the Menswear department. You make your way there and ask your question to an associate standing near the slacks. The associate may not know the answer, but gives you directions to the Bargain Menswear department in the basement behind last year's Christmas decorations. You proceed to that area and ask an associate your question again. This time you're either handed a shirt or given an excuse why one isn't available.

    LDAP uses a similar system of referrals to point clients at the DSA that hosts the naming context containing the requested information. These referrals virtually guarantee the success of any lookup so long as the object exists inside the scope of the information base.

    The key point to remember is that LDAP referrals put the burden of searching on the clients. This contrasts to X.500, where all the messy search work is handed over to the DSAs. LDAP is Wal-Mart to the Nordstroms of X.500.

    RootDSE

    When LDAP clients need information from a DSA, they must first bind to the directory service. This authenticates the client and establishes a session for the connection. The client then submits queries for objects and attributes within the directory. This means the client needs to know the security requirements of the DSA along with the structure of the directory service it hosts.

    DSAs "advertise" this information by constructing a special object called RootDSE. The RootDSE object acts like a signpost at a rural intersection. It points the way to various important features in the directory service and gives useful information about the service. LDAP clients use this information to select an authentication mechanism and configure their searches.

    Each DSA constructs its own copy of RootDSE. The information is not replicated between DSAs. RootDSE is like the eye above the pyramid on the back of a dollar bill. It sits apart from the structure but knows all about it. You'll be seeing more about RootDSE later in this book in topics that cover scripting. Querying RootDSE for information about Active Directory rather than hard-coding that information into your scripts is a convenient way to make your scripts portable.

    LDAP Namespace Structure Summary

    Here are the highlights of what you need to remember about the LDAP namespace structure to help you design and administer Active Directory:

    • An object's full path in the LDAP namespace is called its distinguished name. All DNs must be unique.

    • The Directory Information Tree, or DIT, is a distributed LDAP database that can be hosted by more than one server.

    • The DIT is divided into separate units called naming contexts. A domain controller can host more than one naming context.

    • Active Directory uses separate naming contexts to store information about domains in the same DIT.

    • When LDAP clients search for an object, LDAP servers refer the clients to servers that host the naming context containing that object. They do this using shared knowledge about the system topology.

    • Each DSA creates a RootDSE object that describes the content, controls, and security requirements of the directory service. Clients use this information to select an authentication method and to help formulate their search requests.

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