The other day I needed to know the Active Directory groups a user had assigned.  Not being an operations person, I couldn’t go and use the tools on the server.  I decided there must be an easy way to get this done.  After a bit of searching, I came up with this LinqPad script using some assemblies Microsoft provided.

Assemblies:
System.DirectoryServices
System.DirectoryServices.ActiveDirectory
System.DirectoryServices.AccountManagement
System.DirectoryServices.Protocols

string username = 'hlord'; 
string domain = 'MyDomain'; 

var domainGroups = new List<string>(); 
var domainContext = new PrincipalContext(ContextType.Domain, domain); 
var user = UserPrincipal.FindByIdentity(domainContext, username); 
var authGroups = user.GetAuthorizationGroups();
authGroups.All(g => {
		if (!string.IsNullOrEmpty(g.Name) && !domainGroups.Contains(g.Name))
			domainGroups.Add(g.Name);
		return true;
	});

domainGroups.Sort();
domainGroups.Dump();

LinqPad File: LDAP – User Groups.linq