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Connecting to Objects in the Global Catalog


In the tutorial article "LDAP Bind: Establishing a Connection to the Directory" was described how to connect to a directory object in a script in general. On this page, we want to focus on connections to objects in the global catalog. Please remember: There is only read access to the global catalog, and only a subset of the attributes is provided there.

 

Global Catalog Bind using the user ID the script is run with
Global Catalog Bind using special credentials
Global Catalog Bind over LDAP SSL
Global Catalog Bind when the own domain name / forest is unknown



Global Catalog Bind using the user ID the script is run with


We use a normal Bind operation where the LDAP path name is changed, so that the TCP-Port-Nummer 3268 is used. This works for the function GetObject and also with OpenDSObject.

Set obj = GetObject("LDAP://server.cerrotorre.de:3268/cn=Philipp,ou=Accounts,dc=cerrotorre,dc=de") WScript.Echo obj.name Set ou = GetObject("LDAP://server.cerrotorre.de:3268/ou=Accounts,dc=cerrotorre,dc=de") For Each obj In ou WScript.Echo obj.name Next

Prerequisite, of course, is that the regarding server 'server.cerrotorre.de' has been set up as a global catalog.

Here's an easier option that utilizes a special form of the pathname, where the term 'LDAP' is simply replaced by 'GC'. So the special port number 3268 can be omitted:

Set ou = GetObject("GC://server.cerrotorre.de/ou=Accounts,dc=firma,dc=de") For Each obj In ou WScript.Echo obj.name Next

A Serverless Binding can be run also when you are in Active Directory environments. Then a global catalog will automatically be searched by DNS:

Set ou = GetObject("GC://ou=Accounts,dc=cerrotorre,dc=de") For Each obj In ou WScript.Echo obj.name Next

Global Catalog Bind using special credentials


The common method of binding to the directory always works when a logged on user wants to access objects of his own domain respectively his own Active Directory forest. However, it might quite often be necessary to access a directory service where you are not an currently authenticated user. In that case, the bind variation OpenDSObject allows to pass the username and password and thus the logon to e.g. foreign forests is possible.

Set dso = GetObject("LDAP:") Set ou = dso.OpenDSObject("LDAP://controller.cerrotorre.de:3268/ou=test,dc=cerrotorre,dc=de", "administrator", "P@ssw0rd", 1) For Each obj In ou WScript.Echo obj.name Next 'andere Variante: Set dso = GetObject("LDAP:") Set ou = dso.OpenDSObject("GC://controller.cerrotorre.de/ou=test,dc=cerrotorre,dc=de", "administrator", "P@ssw0rd", 1) For Each obj In ou WScript.Echo obj.name Next 'Serverless Binding Set dso = GetObject("LDAP:") Set ou = dso.OpenDSObject("GC://ou=test,dc=cerrotorre,dc=de", "administrator", "P@ssw0rd", 1) For Each obj In ou WScript.Echo obj.name Next

In this example the OU object of the domain company.com is accessed by logging on the server 'controller.domain.com' with the username 'administrator' and password 'P@ssw0rd'. The last parameter (1) acts as a logon-flag, ensuring a secure Kerberos logon.


ADSI Reference in MSDN: OpenDSObject()

The username of an AD logon can be given in the following way:


Pure logon name e.g. 'administrator', for this, the logon-flag needs to be set to '1' (secure logon)
NetBIOS logon name e.g. 'DOMAIN\administrator'
User principal name e.g. 'administrator@domain.com'
Distinguished name e.g. 'cn=administrator,cn=users,dc=domain,dc=com', for this, the logon-flag needs to be set to '0' (clear text logon).

The logon flag determines the type of access. Important are the two values '0' (for encrypted logon in clear text) and '1' (for secure logon via Kerberos or NTLM). Of course, a secure logon should be preferred to clear text logon. However, situations may arise when an insecure clear text logon is needed. Especially when using a bind operation to logon to other directory services like Novell eDirectory or OpenLDAP systems, the logon-flag must be set to '0'. In order to avoid a disclosure of the password from the net, the use of LDAP-SSL is recommended - then the whole traffic of the LDAP protocol is encrypted.


Microsoft explanations of the logon flag in MSDN


The server name can be left out in the LDAP pathname of Active Directory environments and it is automatically bind to an accessible domain controller of the own domain. Also, username and password can be provided as NULL string (''), then the logon data of the own user is used automatically. This possibility might be useless if using the bind option for the logon to another forest DC - thus, server and logon data have to be indicated accordingly.

 


Global Catalog Bind over LDAP SSL


You can also use LDAP-SSL to connect to the global catalog. Simply use the TCP-Port-Nummer 3269 (instead of 3268) to initiate the connection. However, this is working only if a valid SSL certificate was installed on the server before.

Set obj = GetObject("LDAP://server.cerrotorre.de:3269/cn=Philipp,ou=Accounts,dc=cerrotorre,dc=de") WScript.Echo obj.name Set ou = GetObject("LDAP://server.cerrotorre.de:3269/ou=Accounts,dc=cerrotorre,dc=de") For Each obj In ou WScript.Echo obj.name Next

Global Catalog Bind without knowing the own Domain / Forest name


In many cases you want to develop scripts that run in different Active Directory environments. Think about a script that e.g. displays any information about certain objects within the own domain or is responsible for specific changes. In order that this script runs in any domains, you could let pass the domain name as parameter. But it is more sophisticated to automatically identify the current domain name by querying the Active Directory itself through severless binding.

The relevant information can be read in a special directory entry, available on every domain controller: the rootDSE (Root Directory Service Entry).

You can read here the distinguished name of your own domain from the attribute 'defaultNamingContext' and make an LDAP pathname right away with which the desired domain objects can be accessed.

Set rootDSE = GetObject("LDAP://rootDSE") domainDN = rootDSE.Get("defaultNamingContext") set domain = GetObject("GC://" & domainDN) For Each obj In domain WScript.Echo obj.name Next

The next example shows how to detect the name of the root domain in the own forest. You can use the ADSSystemInfo COM object for this - the returned DNS name has to be converted to an LDAP-Pfad:

Set aoi = CreateObject("ADSystemInfo") rootDNS = aoi.ForestDNSName rootDN = "DC=" & Replace(rootDNS, ".", ",DC=") set domain = GetObject("GC://" &rootDN) For Each obj In domain WScript.Echo obj.name Next

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