• 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 O
  • Index P
  • Index Q
  • Index R
  • Index S
  • Index SYMBOL
  • Index T
  • Index U
  • Index V
  • Index W
  • Index X
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  • Preface
  • Previous Section Next Section

    Limitations of Classic NT Security

    The first questions you may ask when hunkering down to study Active Directory is, "What is it?" and "Why have it?" This section answers the second question. The remainder of the chapter answers the first.

    Account administration in a classic NT network is hampered by many limitations. The most important of these limitations are the following:

    • Restricted SAM size

    • Multiple logon IDs

    • Single point of failure at the primary domain controller

    • Poor operational performance

    • Poor replication performance

    • Lack of management granularity

    • The fact that security databases differ between servers and domain controllers

    • Nontransitive trust relationships

    I'm going to discuss each of these limitations to show exactly how they hinder classic NT operations. This also helps to understand why certain decisions were made in the design of Active Directory.

    Restricted Account Database Size

    Security accounts in classic NT are stored in the Security Account Manager database, called the SAM for short. The SAM is a flat-file database consisting of a set of Groups and a set of Users. Computer accounts are also included in the SAM as a special form of user account.

    SAM Database Structure

    Ordinarily, you cannot view the contents of the SAM database because the Registry only permits access by the System account. If you want to take a peek inside, you can set the Registry permissions to give your account or the Administrators group Read access. Actual data is encrypted and stored in binary format, but you can view the structure. Figure 6.1 shows an example.

    Figure 6.1. SAM database viewed by the Registry Editor after changing security permissions.


    The total number of users, computers, and groups in classic NT is limited because the SAM cannot grow above a certain size. This is due to restrictions on overall Registry size called the Registry size limit (RSL). The RSL permits the Registry to grow to a maximum of 80 percent of paged pool memory. Paged pool memory has a ceiling of 192MB in NT and 470MB in Windows 2000 and Windows Server 2003.

    Memory Pool Registry Settings

    Memory used by the kernel in all Windows server products is divided between non-paged pool memory and paged pool memory. You can view settings for the memory pools in the following Registry key:

    HKLM | System | CurrentControlSet | Control | Session Manager | 
    graphics/ccc.gifMemory Management

    The default values are zero, indicating that the system calculates them dynamically. You should not change any values without specific direction from Microsoft Product Support Services.

    In modern Windows, the RSL is adjusted automatically when the Registry is about to exceed the current RSL setting. The RSL can also be adjusted from the User Interface (UI) using the Computer Management console as follows:

    1. Launch the Computer Management console by entering COMPMGMT.MSC from the Run window.

    2. Right-click the Computer Management icon and select PROPERTIES from the flyout menu.

    3. Select the Advanced tab.

    4. Click Performance Options.

    5. Under Virtual Memory, click Change. This opens the Virtual Memory window.

    6. Put a new value in the Maximum Registry Size field.

    The SAM is only one component of the Registry, so its size is restricted still further. A classic SAM has enough room for about 40,000 users if you count the groups you'll need to manage them. Practical limits on replication and user management reduces this number considerably, although I know of at least one company that has in excess of 60,000 users in a single classic NT domain.

    Single Point of Failure

    The PDC is the only server that has read/write access to the SAM in a classic NT domain. If the PDC crashes or the telecommunications link to it goes down, you cannot make any changes to the domain constituents. You cannot add new users to a group. You cannot join computers to the domain. Users can still log on via a backup domain controller (BDC) but they cannot change their passwords.

    To correct this problem, an administrator must promote a BDC to PDC somewhere in the domain. If the promoted BDC doesn't have the horsepower of the original PDC, worldwide performance suffers. A worse situation occurs if the WAN connection that connects the PDC to the rest of the domain goes down. In this situation, you don't dare promote a BDC because when the WAN connection returns, you'll have two PDCs with slightly different security database contents. This forces you to make a Solomon-like decision to keep one PDC and kill the other. In short, you have the makings of a real disaster.

    Poor Operational Performance

    The single PDC in a classic NT domain also imposes practical limits on daily operations. Assume, for example, that you are an administrator of a global NT network with 30,000 users. You are stationed in Omaha but the PDC for the master security domain is in Boston. You open User Manager for Domains to add a new user. User Manager pulls the account database from the SAM on the PDC, not a local BDC. Depending on the speed of the intervening WAN links, it can take a long, long time to scan through a big SAM. Administrators in large NT domains learn to use command-line utilities to avoid this irritation.

    Poor Replication Performance

    The hub-and-spoke replication model of classic NT imposes operational limits beyond the problem with limited SAM size. A large network with many BDCs imposes a great deal of load on the PDC to keep the databases replicated. By default, replication occurs when 200 updates accumulate every seven minutes or at a random interval between one and seven minutes. If you don't want to wait for replication to carry an update to a remote BDC, you must use Server Manager to force replication. This means opening still another tool and waiting another period of time.

    SAM Database Differs Between Servers and Domain Controllers

    The SAM database has a different structure on a classic domain controller than on a regular server. For this reason, a classic NT server cannot be promoted directly to domain controller or demoted from a domain controller down to a server. You must reinstall the operating system completely to change the server's security role.

    Lack of Management Granularity

    A major weakness in the flat-file SAM structure is its inability to support hierarchical management. Administrators wield supreme power in a domain. A few BuiltIn groups such as Account Admins and Server Operators have specially tailored privileges, but there is no provision for localizing admin rights or creating new groups with a different set of limited rights. Third-party tools are available to overcome this lack of management granularity, but they carry their own replication and management baggage along with a hefty price tag.

    Nontransitive Trust Relationships

    Of all the limitations in classic NT, the ugliest is the inability to link domains together seamlessly while maintaining separate administrative roles.

    Classic domains are linked by trust relationships. Domain controllers in trust-ing domains perform pass-through authentications to check the credentials of users from trust-ed domains. These trust relationships are based on entries in the NT Security database called LSA Secrets. (LSA stands for Local Security Authority.) A pair of LSA Secrets, one in each SAM database, links the two domains together.

    Classic trust relationships can only operate in one direction. You can add complementary pairs of trusts to get the appearance of two-way authentication, but the two trusts operate independently.

    Worse yet, classic trusts cannot extend beyond the two domains that form the trust endpoints. For instance, if Domain A trusts Domain B and Domain B trusts Domain C, then Domain A does not trust Domain C, or vice versa. This forces large NT systems to have many interlocking trusts. You know when you walk into the operations center of a big NT shop because there's butcher paper on the walls with circles and arrows going everywhere.

    Multiple Logon IDs

    In an ideal universe, a single network logon account would provide access to all server-based applications. In the past, application designers have been reluctant to base their authentication services on the classic NT logon mechanism. Part of this reluctance was due to the inscrutable set of security APIs that Microsoft provided. Designers were also put off by the inflexible nature of the SAM.

    This means trying to achieve true single sign-on under NT has been very difficult. This forces users to memorize passwords for many different applications as well as their network logon. Because users often select the same password for different applications, the entire security system becomes as secure as the most vulnerable interface.

    Improvements Made by Active Directory

    Now that I've listed the litany of sins in classic NT, let's take a quick look at what Active Directory does to resolve them:

    • The Active Directory account database in Windows Server 2003 can hold a billion objects. This resolves scalability concerns.

    • Multiple domain controllers can host read/write copies of Active Directory, eliminating the problems with a single point of failure and poor operational performance.

    • The Active Directory replication engine can be tuned to make best use of available bandwidth. This reduces WAN traffic.

    • A modern Windows server (Windows 2000 or Windows Server 2003) can be promoted to a domain controller and demoted back to a member server without the need to reinstall the operating system.

    • Active Directory can be configured with as many branches as needed to localize and compartmentalize administrative functions.

    • Active Directory domains still use "trusts" as an operational model but the trusts now give full, two-way access to resources and are fully transitive between domains.

    • The presence of a truly world-class directory service in Windows has sparked renewed interest among application developers in achieving single sign-on. Microsoft has helped encourage this interest by simplifying the security access methods and greatly expanding the access interfaces.

    So, now we know what we're leaving behind. Let's move on to see what we're getting. The next section describes what goes into a directory service.

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