I have group G and user U. The entry for G includes U as a "member" record. The entry for U does not include G as a "memberOf" record. (I am querying the entries programmatically, in C#, and viewing them in Softerra LDAP Browser). Can anybody explain this paradox?
The memberOf attribute is not authoritative. Whether a group is listed there depends on the "Scope" of the group. It will only include:
Universal groups in the same AD forest
Global groups from the same domain as the user
Domain Local groups on the same domain as the server you are reading from (which may or may not be the same domain as the user)
I describe this in a little more detail in an article I wrote, under the heading "Beware of memberOf".
If you need to find groups that memberOf doesn't list, I also wrote an article called Finding all of a user's groups with code samples.
Related
I'm working with a vendor who needs to use LDAP queries to pull information on our Active Directory. The query pulls from the 'members' attribute of the AD Group directly. However it only pulls 8 of the 20+ users in this group. If I look at the group's Members tab, I can see all of the users, and they work without an issue. I switch to the Attributes tab and scroll to the members entry view the values which shows only 8 of the users. The LDAP query only pulls these 8 and not the rest of the users.
How do I fix this so the attribute and members list match without deleting/recreating the group? If I delete and recreate it would take down our production environment.
I've tried removing and re-adding users to the group and it does not fix the issue.
I'm going to guess that this group is the primary group for the users that you don't see in the member attribute. Members don't appear in the member attribute if the group is the primary group. I don't know why this is... blame Microsoft.
To find those users, look at the primaryGroupToken of the group. It will be a number. Then search for users that have that value in their primaryGroupId attribute.
Usually, the primary group is the built-in Domain Users group, which always has a primaryGroupToken of 513. So to find users of that, you would use this LDAP query:
(primaryGroupId=513)
According to the documentation, the primaryGroupId attribute is indexed, so you don't need any other criteria.
If you want to learn more about how memberships work, I wrote an article a while ago about What makes a member a member?
I'm trying to write a filter to get all the users of a given group in Active Directory.
To that end I have the following query
LDAPSearch("DC=test,DC=myorg,DC=com", "(objectClass=user)", 1, "name")
I'm a bit confused as to where I should give the name of the group on which to base the search on. As far as I know you cannot have two groups in AD with the same name.
In general, user objects have an attribute called memberOf that lists DNs of groups that a user is member of. Therefore you can search with a filter like (&(objectClass=user)(memberOf=<DN of requested group>)).
Please note that due to AD design, user's primary group is not included in memberOf attribute. For most users that group would be Domain Users (unless explicitly changed), but if changed, that group will no longer list in memberOf and this query will not find such user.
If I query the AD then for some users the attribute memberOf does not contains any builtin groups. The users with the problem are all moved in a separate OU.
The query is simple:
(&(objectClass=person)(uid=xyz))
But the "Active Directory Users and Computers" tool from Microsoft show this members. Where can be the problem? Is this an access right problem?
There is a notion of a Primary group in AD. The default is usually Domain Users.
This is represented on the user object as an attribute called PrimaryGroupID, and 513 is Domain Users.
There can and must be only one primary group, and to remove the current one, you need to first add another group as a member, to then swap with the primary group ID.
I need to implement nested group membership for generic AD services.
Previously, i was using a specific search-filter ("member:1.2.840.113556.1.4.1941:=") through which using a single search request, i was able to get hold of all group membership through which that user was part of. However, it looks like that search-filter seems to work only for MS AD servers and not for generic AD servers.
So, is anybody aware of any specific search filter which we can send in a search request (applicable to All AD servers), through which i can derive nested group membership via a single search query.
Thanks in advance for your help on this.
"member:1.2.840.113556.1.4.1941" is LDAP_MATCHING_RULE_IN_CHAIN and might very well not be implemented by other LDAP vendors. LDAP Wiki
Edit:
You could do something like this if you want to reurse the groups:
Use the filter:
(&(objectCategory=organizationalPerson)(objectClass=User)(sAMAccountName=YOURUSER)
get "distinguishedName" (this is the user's distinguishedName)
get "memberOf" (this is a collection of distinguishedNames of the groups the user is a member of (minus the primary group in MS Active Directory, which should be "Domain Users"))
Foreach memberOf in the collection: (This is the first level, so there is no need to check if he is there, because he is.)
(&(objectCategory=group)(distinguishedName=THISMEMBEROF))
get "member" (this is a collection of distinguishedNames of group members)
Foreach memberOf in the collection:
This is the second level (the groups within the groups), so first check if the users distinguishedName is present.
(&(objectCategory=group)(distinguishedName=THISMEMBEROF))
get "member" (this is a collection of distinguishedNames of group members)
Foreach memberOf in the collection:
This is the third level (the groups within the groups), so first check if the users distinguishedName is present.
(&(objectCategory=group)(distinguishedName=THISMEMBEROF))
get "member" (this is a collection of distinguishedNames of group members)
etc.
An AD setup I'm using has users that are stored as members of (multiple) security groups.
I am using software that reads the memberof property of a user to work out access permissions.
In AD Explorer I can see the memberof property of the user shows the immediate security groups they belong to say 'Course - English'. It does not show the parents groups, nested up to say 'ALL Students'.
Is there a reason for this or a way of ensuring all nested groups are shown in the memberof property?
If you're on .NET 3.5 and up, you should check out the System.DirectoryServices.AccountManagement (S.DS.AM) namespace. Read all about it here:
Managing Directory Security Principals in the .NET Framework 3.5
MSDN docs on System.DirectoryServices.AccountManagement
Basically, you can define a domain context and easily find users and/or groups in AD:
// set up domain context
PrincipalContext ctx = new PrincipalContext(ContextType.Domain);
// find a user
UserPrincipal user = UserPrincipal.FindByIdentity(ctx, "SomeUserName");
if(user != null)
{
var groups = user.GetAuthorizationGroups();
// enumerate over groups
foreach(GroupPrincipal gp in groups)
{
// do something here....
}
}
The new S.DS.AM makes it really easy to play around with users and groups in AD!
The .GetAuthorizationGroups() method is the only one around that I know of that will do recursive searches, e.g. find groups that a user is member of by virtue of another group. The pre-.NET 3.5 DirectoryServices stuff doesn't do this - you would have to totally roll your own if you need that.
The probable reason that the memberOf attribute does not contain all the nested group information is that the value is computed when the attribute is loaded, as noted in this link:
Be aware that this attribute lists the groups that contain the user in their member attribute—it does not contain the recursive list of nested predecessors. For example, if user O is a member of group C and group B and group B were nested in group A, the memberOf attribute of user O would list group C and group B, but not group A.
This attribute is not stored—it is a computed back-link attribute.
Hence, to support this, your DC would be forced to load all nested groups every time a LDAP query returned the memberOf attribute, which could be a lot of excess work.
Depending on the technology you are using, there are almost certainly better ways to check group membership than loading all groups and listing them all. For example, ADSI has a pre-built function to check if a user is a member of the group.
However, for a pure LDAP solution, you could use the LDAP_MATCHING_RULE_IN_CHAIN as shown in this answer (assuming you have the DN for the user), e.g.,
(member:1.2.840.113556.1.4.1941:=CN=Administrator,OU=Users,DC=fabrikam,DC=com)
Which will get all the groups which Administrator is a member of. Note, however, that this query can be extremely slow. To speed up performance, consider paging results or restricting the search base to only the group you are interested in checking.