&author.jht; &author.jerry; &author.dbannon; &person.gd; LDAP updates There are many who approach MS Windows networking with incredible misconceptions. That's okay, because it gives the rest of us plenty of opportunity to be of assistance. Those who really want help are well advised to become familiar with information that is already available. domaincontroller You are advised not to tackle this section without having first understood and mastered some basics. MS Windows networking is not particularly forgiving of misconfiguration. Users of MS Windows networking are likely to complain of persistent niggles that may be caused by a broken network configuration. To a great many people, however, MS Windows networking starts with a domain controller that in some magical way is expected to solve all network operational ills. The Example Domain Illustration shows a typical MS Windows domain security network environment. Workstations A, B, and C are representative of many physical MS Windows network clients.

domain

From the Samba mailing list we can readily identify many common networking issues. If you are not clear on the following subjects, then it will do much good to read the sections of this HOWTO that deal with it. These are the most common causes of MS Windows networking problems: Basic TCP/IP configuration. NetBIOS name resolution. Authentication configuration. User and group configuration. Basic file and directory permission control in UNIX/Linux. Understanding how MS Windows clients interoperate in a network environment. Do not be put off; on the surface of it MS Windows networking seems so simple that anyone can do it. In fact, it is not a good idea to set up an MS Windows network with inadequate training and preparation. But let's get our first indelible principle out of the way: It is perfectly okay to make mistakes! In the right place and at the right time, mistakes are the essence of learning. It is very much not okay to make mistakes that cause loss of productivity and impose an avoidable financial burden on an organization. Where is the right place to make mistakes? Only out of harms way. If you are going to make mistakes, then please do it on a test network, away from users, and in such a way as to not inflict pain on others. Do your learning on a test network. domain security What is the key benefit of Microsoft Domain Security? single sign-onSSO trust account domainsecurityprotocols In a word, single sign-on, or SSO for short. To many, this is the Holy Grail of MS Windows NT and beyond networking. SSO allows users in a well-designed network to log onto any workstation that is a member of the domain that contains their user account (or in a domain that has an appropriate trust relationship with the domain they are visiting) and they will be able to log onto the network and access resources (shares, files, and printers) as if they are sitting at their home (personal) workstation. This is a feature of the domain security protocols. SID RID relative identifierRID security identifierSID access control The benefits of domain security are available to those sites that deploy a Samba PDC. A domain provides a unique network security identifier (SID). Domain user and group security identifiers are comprised of the network SID plus a relative identifier (RID) that is unique to the account. User and group SIDs (the network SID plus the RID) can be used to create access control lists (ACLs) attached to network resources to provide organizational access control. UNIX systems recognize only local security identifiers. SID A SID represents a security context. For example, every Windows machine has local accounts within the security context of the local machine which has a unique SID. Every domain (NT4, ADS, Samba) contains accounts that exist within the domain security context which is defined by the domain SID. SID RID A domain member server will have a SID that differs from the domain SID. The domain member server can be configured to regard all domain users as local users. It can also be configured to recognize domain users and groups as non-local. SIDs are persistent. A typical domain of user SID looks like this: S-1-5-21-726309263-4128913605-1168186429 Every account (user, group, machine, trust, etc.) is assigned a RID. This is done automatically as an account is created. Samba produces the RID algorithmically. The UNIX operating system uses a separate name space for user and group identifiers (the UID and GID) but Windows allocates the RID from a single name space. A Windows user and a Windows group can not have the same RID. Just as the UNIX user root has the UID=0, the Windows Administrator has the well-known RID=500. The RID is catenated to the Windows domain SID, so Administrator account for a domain that has the above SID will have the user SID S-1-5-21-726309263-4128913605-1168186429-500 The result is that every account in the Windows networking world has a globally unique security identifier. domainmember machine account domaintrust account Network clients of an MS Windows domain security environment must be domain members to be able to gain access to the advanced features provided. Domain membership involves more than just setting the workgroup name to the domain name. It requires the creation of a domain trust account for the workstation (called a machine account). Refer to Domain Membership for more information. The following functionalities are an overview of some of the features in the Samba-4 release: accountbackend Samba-4 supports the use of a choice of backends that may be used in which user, group and machine accounts may be stored, but only when acting as a classic (NT4) domain controller, but not when it is acting as an Active Directory Domain Controller. LDAP replicated distributed scalability reliability An LDAP passdb backend confers the benefit that the account backend can be distributed and replicated, which is of great value because it confers scalability and provides a high degree of reliability. This may be used when Samba-4 is acting as an classic (NT4-like) domain controller, but not when it is acting as an Active Directory Domain Controller. interdomaintrustaccount trust accountinterdomain interoperability Windows NT4 domain trusts. Samba-4 supports workstation and server (machine) trust accounts. It also supports Windows NT4 style interdomain trust accounts, which further assists in network scalability and interoperability, but only when itself is an classic (NT4-like) domain controller. NetBIOS raw SMB active directory domainmember server domaincontroller networkbrowsing Operation without NetBIOS over TCP/IP, rather using the raw SMB over TCP/IP. Note, this is feasible only when operating as a Microsoft active directory domain member server. When acting as a Samba classic (NT4-like) domain controller the use of NetBIOS is necessary to provide network browsing support. WINS TCP port session services Samba-4 provides NetBIOS name services (WINS), NetBIOS over TCP/IP (TCP port 139) session services, SMB over TCP/IP (TCP port 445) session services, and Microsoft compatible ONC DCE RPC services (TCP port 135) services. kerberos active directory Acting as a Windows 2000 active directory domain controller (i.e., Kerberos and Active Directory). MMC SVRTOOLS.EXE Microsoft management consoleMMC The Windows 200x/XP Microsoft Management Console (MMC) can be used to manage a Samba-4 server, when it is an Active Directory Domain Controller. When acting as a classic (NT4) domain controller, you can use only the MS Windows NT4 Domain Server Manager and the MS Windows NT4 Domain User Manager. Both are part of the SVRTOOLS.EXE package mentioned later. The following functionalities are not provided by Samba-4: SAM replication SAM replication with Windows NT4 domain controllers (i.e., a Samba PDC and a Windows NT BDC, or vice versa). This means Samba cannot operate as a BDC when the PDC is Microsoft-based Windows NT PDC. Samba-4 can not participate in replication of account data to Windows PDCs and BDCs. groupmapping Samba-3 implements group mapping between Windows NT groups and UNIX groups (this is really quite complicated to explain in a short space). This is discussed more fully in Group Mapping: MS Windows and UNIX. machine trust account trust accountmachine machine account Samba-4, like an MS Windows NT4 PDC or a Windows 200x Active Directory, needs to store user and Machine Trust Account information in a suitable backend data-store. Refer to MS Windows Workstation/Server Machine Trust Accounts. A complete discussion of account database backends can be found in Account Information Databases. single sign-onSSO SSO active directory authentication validation password uniqueness password history When network administrators are asked to describe the benefits of Windows NT4 and active directory networking the most often mentioned feature is that of single sign-on (SSO). Many companies have implemented SSO solutions. The mode of implementation of a single sign-on solution is an important factor in the practice of networking in general, and is critical in respect of Windows networking. A company may have a wide variety of information systems, each of which requires a form of user authentication and validation, thus it is not uncommon that users may need to remember more than ten login IDs and passwords. This problem is compounded when the password for each system must be changed at regular intervals, and particularly so where password uniqueness and history limits are applied. management overheads There is a broadly held perception that SSO is the answer to the problem of users having to deal with too many information system access credentials (username/password pairs). Many elaborate schemes have been devised to make it possible to deliver a user-friendly SSO solution. The trouble is that if this implementation is not done correctly, the site may end up paying dearly by way of complexity and management overheads. Simply put, many SSO solutions are an administrative nightmare. identity management authentication system SSO SSO implementations utilize centralization of all user account information. Depending on environmental complexity and the age of the systems over which a SSO solution is implemented, it may not be possible to change the solution architecture so as to accommodate a new identity management and user authentication system. Many SSO solutions involving legacy systems consist of a new super-structure that handles authentication on behalf of the user. The software that gets layered over the old system may simply implement a proxy authentication system. This means that the addition of SSO increases over-all information systems complexity. Ideally, the implementation of SSO should reduce complexity and reduce administative overheads. centralized identity management identity managementcentralized centralizedauthentication legacy systems access control The initial goal of many network administrators is often to create and use a centralized identity management system. It is often assumed that such a centralized system will use a single authentication infrastructure that can be used by all information systems. The Microsoft Windows NT4 security domain architecture and the Micrsoft active directory service are often put forward as the ideal foundation for such a system. It is conceptually simple to install an external authentication agent on each of the disparate infromation systems that can then use the Microsoft (NT4 domain or ads service) for user authentication and access control. The wonderful dream of a single centralized authentication service is commonly broken when realities are realized. The problem with legacy systems is often the inability to externalize the authentication and access control system it uses because its implementation will be excessively invasive from a re-engineering perspective, or because application software has built-in dependencies on particular elements of the way user authentication and access control were designed and built. meta-directory credentials disparate information systems management procedures work-flow protocol rights privileges provisioned Over the past decade an industry has been developed around the various methods that have been built to get around the key limitations of legacy information technology systems. One approach that is often used involves the use of a meta-directory. The meta-directory stores user credentials for all disparate information systems in the format that is particular to each system. An elaborate set of management procedures is coupled with a rigidly enforced work-flow protocol for managing user rights and privileges within the maze of systems that are provisioned by the new infrastructure makes possible user access to all systems using a single set of user credentials. Organization for the Advancement of Structured Information StandardsOASIS Security Assertion Markup LanguageSAML Federated Identity ManagementFIM secure access The Organization for the Advancement of Structured Information Standards (OASIS) has developed the Security Assertion Markup Language (SAML), a structured method for communication of authentication information. The over-all umbrella name for the technologies and methods that deploy SAML is called Federated Identity Management (FIM). FIM depends on each system in the complex maze of disparate information systems to authenticate their respective users and vouch for secure access to the services each provides. Simple Object Access ProtocolSOAP federated organizations Liberty Alliance federated-identity SAML documents can be wrapped in a Simple Object Access Protocol (SOAP) message for the computer-to-computer communications needed for Web services. Or they may be passed between Web servers of federated organizations that share live services. The Liberty Alliance, an industry group formed to promote federated-identity standards, has adopted SAML 1.1 as part of its application framework. Microsoft and IBM have proposed an alternative specification called WS-Security. Some believe that the competing technologies and methods may converge when the SAML 2.0 standard is introduced. A few Web access-management products support SAML today, but implementation of the technology mostly requires customization to integrate applications and develop user interfaces. In a nutshell, that is why FIM is a big and growing industry. interoperability ADS LDAP GSSAPI general security service application programming interfaceGSSAPI Ignoring the bigger picture, which is beyond the scope of this book, the migration of all user and group management to a centralized system is a step in the right direction. It is essential for interoperability reasons to locate the identity management system data in a directory such as Microsoft Active Directory Service (ADS), or any proprietary or open source system that provides a standard protocol for information access (such as LDAP) and that can be coupled with a flexible array of authentication mechanisms (such as kerberos) that use the protocols that are defined by the various general security service application programming interface (GSSAPI) services. OpenLDAP ADS authentication agents A growing number of companies provide authentication agents for disparate legacy platforms to permit the use of LDAP systems. Thus the use of OpenLDAP, the dominant open source software implementation of the light weight directory access protocol standard. This fact, means that by providing support in Samba for the use of LDAP and Microsoft ADS make Samba a highly scalable and forward reaching organizational networking technology. ADS LDAP authentication architecture ntlm_auth SQUID FIM Microsoft ADS provides purely proprietary services that, with limitation, can be extended to provide a centralized authentication infrastructure. Samba plus LDAP provides a similar opportunity for extension of a centralized authentication architecture, but it is the fact that the Samba Team are pro-active in introducing the extension of authentication services, using LDAP or otherwise, to applications such as SQUID (the open source proxy server) through tools such as the ntlm_auth utility, that does much to create sustainable choice and competition in the FIM market place. LDAP OpenLDAP identity information Primary domain control, if it is to be scalable to meet the needs of large sites, must therefore be capable of using LDAP. The rapid adoption of OpenLDAP, and Samba configurations that use it, is ample proof that the era of the directory has started. Samba-3 does not demand the use of LDAP, but the demand for a mechanism by which user and group identity information can be distributed makes it an an unavoidable option. BDC LDAP e-Directory At this time, the use of Samba based BDCs, necessitates the use of either the Samba-4 Active Directory Domain controller or, for classic (NT4-like)domains an LDAP backend. The most commonly used LDAP implementation used by Samba sites is OpenLDAP. It is possible to use any standards compliant LDAP server. Those known to work includes those manufactured by: IBM, CA, Novell (e-Directory), and others. domain control Over the years, public perceptions of what domain control really is has taken on an almost mystical nature. Before we branch into a brief overview of domain control, there are three basic types of domain controllers. NT4 style Primary Domain Controller NT4 style Backup Domain Controller ADS Domain Controller PDC powerful networkperformance domainmemberserver The Primary Domain Controller or PDC plays an important role in MS Windows NT4. In Windows 200x domain control architecture, this role is held by domain controllers. Folklore dictates that because of its role in the MS Windows network, the domain controller should be the most powerful and most capable machine in the network. As strange as it may seem to say this here, good overall network performance dictates that the entire infrastructure needs to be balanced. It is advisable to invest more in standalone (domain member) servers than in the domain controllers. SAM BDC authenticatior synchronization FSMO Flexible Single Master OperatorFSMO Security Account ManagerSAM In the case of MS Windows NT4-style domains, it is the PDC that initiates a new domain control database. This forms a part of the Windows registry called the Security Account Manager (SAM). It plays a key part in NT4-type domain user authentication and in synchronization of the domain authentication database with BDCs. With Active Directory domains, while some servers may be a Flexible Single Master Operator (FSMO) role owner (and therefore hold the monopoly for certain operations), it is in general a distributed, multi-master replicated directory. backend database registry Samba-4 can use a backend database that holds the same type of data as the NT4-style SAM database (one of the registry files). For BDC/BDC operations in a classic domain, this functionality can be implemented using an LDAP-based user and machine account backend. The Samba-4 Active Directory Domain controller implements the required storage internally.See also Account Information Databases. BDC PDC WINS authentication netlogon name lookup The Backup Domain Controller or BDC plays a key role in servicing network authentication requests. The BDC is biased to answer logon requests in preference to the PDC. On a network segment that has a BDC and a PDC, the BDC will most likely service network logon requests. The PDC will answer network logon requests when the BDC is too busy (high load). When a user logs onto a Windows domain member client the workstation will query the network to locate the nearest network logon server. Where a WINS server is used, this is done via a query to the WINS server. If a netlogon server can not be found from the WINS query, or in the absence of a WINS server, the workstation will perform a NetBIOS name lookup via a mailslot broadcast over the UDP broadcast protocol. This means that the netlogon server that the windows client will use is influenced by a number of variables, thus there is no simple determinant of whether a PDC or a BDC will serve a particular logon authentication request. promote demote A Windows NT4 BDC can be promoted to a PDC. If the PDC is online at the time that a BDC is promoted to PDC, the previous PDC is automatically demoted to a BDC. With Samba-3, this is not an automatic operation; the PDC and BDC must be manually configured, and other appropriate changes also need to be made. domaincontrollerconvert With MS Windows NT4, a decision is made at installation to determine what type of machine the server will be. It is possible to promote a BDC to a PDC, and vice versa. The only method Microsoft provide to convert a Windows NT4 domain controller to a domain member server or a standalone server is to reinstall it. The install time choices offered are: Primary Domain Controller &smbmdash; the one that seeds the domain SAM. Backup Domain Controller &smbmdash; one that obtains a copy of the domain SAM. Domain Member Server &smbmdash; one that has no copy of the domain SAM; rather it obtains authentication from a domain controller for all access controls. Standalone Server &smbmdash; one that plays no part in SAM synchronization, has its own authentication database, and plays no role in domain security. domaincontrolrole native member Samba-3 servers can readily be converted to and from domain controller roles through simple changes to the &smb.conf; file. Samba-3 is capable of acting fully as a native member of a Windows 200x server Active Directory domain. convertdomain member server For the sake of providing a complete picture, MS Windows 2000 domain control configuration is done after the server has been installed. Please refer to Microsoft documentation for the procedures that should be followed to convert a domain member server to or from a domain control, and to install or remove active directory service support. replicationSAM SAMreplication New to Samba-3 is the ability to function fully as an MS Windows NT4-style domain controller, excluding the SAM replication components. However, please be aware that Samba-3 also supports the MS Windows 200x domain control protocols. standalone workgroup member security There are two ways that MS Windows machines may interact with each other, with other servers, and with domain controllers: either as standalone systems, more commonly called workgroup members, or as full participants in a security system, more commonly called domain members. workgroup workgroupmembership machine trust account It should be noted that workgroup membership involves no special configuration other than the machine being configured so the network configuration has a commonly used name for its workgroup entry. It is not uncommon for the name WORKGROUP to be used for this. With this mode of configuration, there are no Machine Trust Accounts, and any concept of membership as such is limited to the fact that all machines appear in the network neighborhood to be logically grouped together. Again, just to be clear: workgroup mode does not involve security machine accounts. domain membership machine trust accountpassword trigger Domain member machines have a machine trust account in the domain accounts database. A special procedure must be followed on each machine to effect domain membership. This procedure, which can be done only by the local machine Administrator account, creates the domain machine account (if it does not exist), and then initializes that account. When the client first logs onto the domain, a machine trust account password change will be automatically triggered. domain member When Samba is configured as a domain controller, secure network operation demands that all MS Windows NT4/200x/XP Professional clients should be configured as domain members. If a machine is not made a member of the domain, then it will operate like a workgroup (standalone) machine. Please refer to Domain Membership, for information regarding domain membership. The following are necessary for configuring Samba-3 as an MS Windows NT4-style PDC for MS Windows NT4/200x/XP clients: Configuration of basic TCP/IP and MS Windows networking. Correct designation of the server role (user). Consistent configuration of name resolution.See Network Browsing, and Integrating MS Windows Networks with Samba. Domain logons for Windows NT4/200x/XP Professional clients. Configuration of roaming profiles or explicit configuration to force local profile usage. Configuration of network/system policies. Adding and managing domain user accounts. Configuring MS Windows NT4/2000 Professional and Windows XP Professional client machines to become domain members. roaming profiles account policies Roaming profiles and system/network policies are advanced network administration topics that are covered in Desktop Profile Management and System and Account Policies of this document. However, these are not necessarily specific to a Samba PDC as much as they are related to Windows NT networking concepts. A domain controller is an SMB/CIFS server that: NetBIOSbrooadcast WINS UDP DNS active directory Registers and advertises itself as a domain controller (through NetBIOS broadcasts as well as by way of name registrations either by Mailslot Broadcasts over UDP broadcast, to a WINS server over UDP unicast, or via DNS and Active Directory). NETLOGON LanMan logon service Provides the NETLOGON service. (This is actually a collection of services that runs over multiple protocols. These include the LanMan logon service, the Netlogon service, the Local Security Account service, and variations of them.) Provides a share called NETLOGON. domainmasterbrowser localmasterbrowser DMB LMB browse list It is rather easy to configure Samba to provide these. Each Samba domain controller must provide the NETLOGON service that Samba calls the functionality (after the name of the parameter in the &smb.conf; file). Additionally, one server in a Samba-3 domain must advertise itself as the domain master browser.See Network Browsing. This causes the PDC to claim a domain-specific NetBIOS name that identifies it as a DMB for its given domain or workgroup. Local master browsers (LMBs) in the same domain or workgroup on broadcast-isolated subnets then ask for a complete copy of the browse list for the whole wide-area network. Browser clients then contact their LMB, and will receive the domain-wide browse list instead of just the list for their broadcast-isolated subnet. The first step in creating a working Samba PDC is to understand the parameters necessary in &smb.conf;. An example &smb.conf; for acting as a PDC can be found in the smb.conf file for an example PDC. BELERIAND &example.workgroup; tdbsam user yes \\%N\profiles\%U H: \\homeserver\%U\winprofile logon.cmd /var/lib/samba/netlogon yes ntadmin /var/lib/samba/profiles no 0600 0700 The basic options shown in this example are explained as follows: passdb backend groupaccount smbpasswd tdbsam ldapsam guest default accounts This contains all the user and group account information. Acceptable values for a PDC are: smbpasswd, tdbsam, and ldapsam. The guest entry provides default accounts and is included by default; there is no need to add it explicitly. passdb backend distributed smbpasswd tdbsam Where use of BDCs is intended, the only logical choice is to use LDAP so the passdb backend can be distributed. The tdbsam and smbpasswd files cannot effectively be distributed and therefore should not be used. Domain Control Parameters networklogon The parameters domain logons parameter is the key parameter indicating domain control and network logon support. Environment Parameters logon path logon home logon drive logon script The parameters logon path, logon home, logon drive, and logon script are environment support settings that help to facilitate client logon operations and that help to provide automated control facilities to ease network management overheads. Please refer to the man page information for these parameters. NETLOGON Share NETLOGON logon processing domain logon domain membership group policy NTConfig.POL The NETLOGON share plays a central role in domain logon and domain membership support. This share is provided on all Microsoft domain controllers. It is used to provide logon scripts, to store group policy files (NTConfig.POL), as well as to locate other common tools that may be needed for logon processing. This is an essential share on a domain controller. PROFILE Share desktop profile VFS fake_permissions profile This share is used to store user desktop profiles. Each user must have a directory at the root of this share. This directory must be write-enabled for the user and must be globally read-enabled. Samba-3 has a VFS module called fake_permissions that may be installed on this share. This will allow a Samba administrator to make the directory read-only to everyone. Of course this is useful only after the profile has been properly created. The above parameters make for a full set of functionality that may define the server's mode of operation. The following &smb.conf; parameters are the essentials alone: BELERIAND &example.workgroup; Yes User The additional parameters shown in the longer listing in this section just make for a more complete explanation. active directory Samba-4 is also available as an Active Directory server. It can truly function as an Active Directory PDC. The protocols for some of the functionality of Active Directory domain controllers has been implemented. domain controllers active directory classic domain support To be sure, Samba-4 is also designed to provide most of the functionality that Microsoft Windows NT4-style domain controllers have. Samba-4 does not have all the capabilities of Windows NT4, but it does have a number of features that Windows NT4 domain controllers do not have. We call it a classic domain controller for this reason, as in short, Samba-4 when acting in this mode is not NT4, and the Active Directory Domain Control aspect is a distinct capability. domain logon The subject of network or domain logons is discussed here because it forms an integral part of the essential functionality that is provided by a domain controller. domain logon All domain controllers must run the netlogon service (domain logons in Samba). One domain controller must be configured without the parameter (the PDC); on all BDCs set the parameter No. Yes (omit on PDC, No on BDCs) Network Logon Service /var/lib/samba/netlogon Yes No Windows Home editions To be completely clear: If you want MS Windows Home Editions to integrate with your MS Windows NT4 or Active Directory domain security, understand it cannot be done. The only option is to purchase the upgrade from MS Windows Home Edition to a MS Windows Professional edition. MS Windows Home Editions do not have the ability to join any type of domain security facility. Unlike MS Windows 9x/Me, MS Windows Home Edition deliberatly lacks the ability to log onto a network. Now that this has been said, please do not ask the mailing list or email any of the Samba Team members with your questions asking how to make this work. It can't be done. If it can be done, then to do so would violate your software license agreement with Microsoft, and we recommend that you do not do that. security mode user-mode security share-mode security There are a few comments to make in order to tie up some loose ends. There has been much debate over the issue of whether it is okay to configure Samba as a domain controller that operates with security mode other than user-mode. The only security mode that will not work due to technical reasons is share-mode security. Domain and server mode security are really just a variation on SMB user-level security. DOMAIN<1C> DOMAIN<1B> DMB PDC NetBIOS name domain controller election Actually, this issue is also closely tied to the debate on whether Samba must be the DMB for its workgroup when operating as a domain controller. In a pure Microsoft Windows NT domain, the PDC wins the election to be the DMB, and then registers the DOMAIN<1B> NetBIOS name. This is not the name used by Windows clients to locate the domain controller, all domain controllers register the DOMAIN<1C> name and Windows clients locate a network logon server by seraching for the DOMAIN<1C> name. A DMB is a Domain Master Browser &smbmdash; see The Network Browsing Chapter, Configuring WORKGROUP Browsing; Microsoft PDCs expect to win the election to become the DMB, if it loses that election it will report a continuous and rapid sequence of warning messages to its Windows event logger complaining that it has lost the election to become a DMB. For this reason, in networks where a Samba server is the PDC it is wise to configure the Samba domain controller as the DMB. DOMAIN<1D> synchronization domain control browse list management networklogonservice SMB/CIFS servers that register the DOMAIN<1C> name do so because they provide the network logon service. Server that register the DOMAIN<1B> name are DMBs &smbmdash; meaning that they are responsible for browse list synchronization across all machines that have registered the DOMAIN<1D> name. The later are LMBs that have the responsibility to listen to all NetBIOS name registrations that occur locally to their own network segment. The network logon service (NETLOGON) is germane to domain control and has nothing to do with network browsing and browse list management. The 1C and 1B/1D name services are orthogonal to each other. Now back to the issue of configuring a Samba domain controller to use a mode other than user. If a Samba host is configured to use another SMB server or domain controller in order to validate user connection requests, it is a fact that some other machine on the network (the ) knows more about the user than the Samba host. About 99 percent of the time, this other host is a domain controller. Now to operate in domain mode security, the parameter must be set to the name of the Windows NT domain (which already has a domain controller). If the domain does not already have a domain controller, you do not yet have a domain. Configuring a Samba box as a domain controller for a domain that already by definition has a PDC is asking for trouble. Therefore, you should always configure the Samba domain controller to be the DMB for its domain and set user. This is the only officially supported mode of operation. BSD FreeBSD /etc/passwd A machine account, typically stored in /etc/passwd, takes the form of the machine name with a $ appended. Some BSD systems will not create a user with a $ in the name. Recent versions of FreeBSD have removed this limitation, but older releases are still in common use. vipw The problem is only in the program used to make the entry. Once made, it works perfectly. Create a user without the $. Then use vipw to edit the entry, adding the $. Or create the whole entry with vipw if you like; make sure you use a unique user login ID. The machine account must have the exact name that the workstation has. The UNIX tool vipw is a common tool for directly editing the /etc/passwd file. The use of vipw will ensure that shadow files (where used) will remain current with the passwd file. This is important for security reasons. join domain I get told, `You already have a connection to the Domain....' or `Cannot join domain, the credentials supplied conflict with an existing set...' when creating a Machine Trust Account. This happens if you try to create a Machine Trust Account from the machine itself and already have a connection (e.g., mapped drive) to a share (or IPC$) on the Samba PDC. The following command will remove all network drive connections: &dosprompt;net use * /d This will break all network connections. Further, if the machine is already a member of a workgroup that is the same name as the domain you are joining (bad idea), you will get this message. Change the workgroup name to something else &smbmdash; it does not matter what &smbmdash; reboot, and try again. I joined the domain successfully but after upgrading to a newer version of the Samba code I get the message, `The system cannot log you on (C000019B). Please try again or consult your system administrator when attempting to logon.' SID This occurs when the domain SID stored in the secrets.tdb database is changed. The most common cause of a change in domain SID is when the domain name and/or the server name (NetBIOS name) is changed. The only way to correct the problem is to restore the original domain SID or remove the domain client from the domain and rejoin. The domain SID may be reset using either the net or rpcclient utilities. To reset or change the domain SID you can use the net command as follows: &rootprompt;net getlocalsid 'OLDNAME' &rootprompt;net setlocalsid 'SID' Workstation Machine Trust Accounts work only with the domain (or network) SID. If this SID changes, domain members (workstations) will not be able to log onto the domain. The original domain SID can be recovered from the secrets.tdb file. The alternative is to visit each workstation to rejoin it to the domain. When I try to join the domain I get the message, "The machine account for this computer either does not exist or is not accessible." What's wrong? This problem is caused by the PDC not having a suitable Machine Trust Account. If you are using the method to create accounts, then this would indicate that it has not worked. Ensure the domain admin user system is working. Alternately, if you are creating account entries manually, then they have not been created correctly. Make sure that you have the entry correct for the Machine Trust Account in smbpasswd file on the Samba PDC. If you added the account using an editor rather than using the smbpasswd utility, make sure that the account name is the machine NetBIOS name with a $ appended to it (i.e., computer_name$). There must be an entry in both the POSIX UNIX system account backend as well as in the SambaSAMAccount backend. The default backend for Samba-3 (i.e., the parameter passdb backend is not specified in the &smb.conf; file, or if specified is set to smbpasswd, are respectively the /etc/passwd and /etc/samba/smbpasswd (or /usr/local/samba/lib/private/smbpasswd if compiled using Samba Team default settings). The use of the /etc/passwd can be overridden by alternative settings in the NSS /etc/nsswitch.conf file. Some people have also reported that inconsistent subnet masks between the Samba server and the NT client can cause this problem. Make sure that these are consistent for both client and server. When I attempt to log in to a Samba domain from a NT4/W200x workstation, I get a message about my account being disabled. Enable the user accounts with smbpasswd -e username . This is normally done as an account is created. Until a few minutes after Samba has started, clients get the error `Domain Controller Unavailable' A domain controller has to announce its role on the network. This usually takes a while. Be patient for up to 15 minutes, then try again. schannel signing After successfully joining the domain, user logons fail with one of two messages: one to the effect that the domain controller cannot be found; the other claims that the account does not exist in the domain or that the password is incorrect. This may be due to incompatible settings between the Windows client and the Samba-3 server for schannel (secure channel) settings or smb signing settings. Check your Samba settings for client schannel, server schannel, client signing, server signing by executing: testparm -v | grep channel and looking for the value of these parameters. Also use the MMC &smbmdash; Local Security Settings. This tool is available from the Control Panel. The Policy settings are found in the Local Policies/Security Options area and are prefixed by Secure Channel:..., and Digitally sign.... It is important that these be set consistently with the Samba-3 server settings.