PowerShell Active Directory list all Multi-Valued attributes - powershell

Question

not sure if I'm chaing the wild goose here but as per subject I'd need to get a list of AD attributes, for the user ObjectClass, that are multie valued.
For example the proxyAddresses exchange specific attribute is multi valued where extensionAttribute* only accept a single string.
We use a heavily customized schema and while I could go through each attribute documentation I'd rather get a list of aforementioned attributes via PowerShell.
I've tried using ldp.exe but could not achive desired results and was wondering if there is a way to do this via PowerShell or .Net managed code.
Thanks in advance for any help/pointer.

Answer 1

So you have to query the Schema part of the directory and look for objectClass attributeSchema and attribute isSingleValued (FALSE). The part of the distinguichName wichh is invariant is : CN=Schema,CN=Configuration.
try first with CSV :
csvde -f MultivaluedAttributes.csv -d CN=Schema,CN=Configuration,DC=MySubdomain,DC=MyDomain,DC=com -r "(&(objectclass=attributeSchema)(isSingleValued=FALSE))" -l lDAPDisplayName
Here is the powershell code.
# LDAPSchemaQuery.PS1
try
{
$dn = New-Object System.DirectoryServices.DirectoryEntry ("LDAP://179.22.21.01/CN=Schema,CN=Configuration,DC=MyDomain,DC=MyExt","MyUser", 'MyPassword')
# Query into the Schema
# csvde -f MultivaluedAttributes.csv -d CN=Schema,CN=Configuration,DC=office,DC=coyotesystems,DC=com -r "(&(objectclass=attributeSchema)(isSingleValued=FALSE))" -l lDAPDisplayName
$Rech = new-object System.DirectoryServices.DirectorySearcher($dn)
#$Rech.filter = "(&(objectclass=user)(mail=*)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))"
$Rech.filter = "(&(objectclass=attributeSchema)(isSingleValued=FALSE))"
$Rech.SearchScope = "subtree"
$dumy=$Rech.PropertiesToLoad.Add("lDAPDisplayName")
$adAttributes = $Rech.findall()
foreach ($adAttribute in $adAttributes)
{
$multivaluedAttribute = try{$adAttribute.Properties["lDAPDisplayName"]}catch{""}
$multivaluedAttribute
}
}
catch
{
Write-Verbose "LDAPSchemaQuery : PB with $($adAttribute.Path)"
}