How can I get a UserPrincipal for a user in a different domain?

Question

The following code works great for users in my domain (eg, "TESTER" instead of "DEVELOPER"), but I can't figure out how to search higher than the current domain. I tried variation combinations of searches with the PrincipalSearcher class, but I'm not sure how to pass in a search by email address or username to look for other domains within my organization even though they're all in a single forest.

var name = "DEVELOPER\\JULIANI99";
var p = UserPrincipal.FindByIdentity(new PrincipalContext(ContextType.Domain), name);

Answer 1

FindByIdentity doesn't work well for searching a forest.

I tried something like this:

var d = new PrincipalContext(ContextType.Domain, "domain.com:3268", "DC=com");
var p = UserPrincipal.FindByIdentity(d, IdentityType.SamAccountName, username);

But I keep getting an error saying a referral was returned. It might be different for you. The "3268" port tells it to use the global catalog (forest-wide search). The root (which I have as "DC=com") has to be the common across all the domains in your forest. So if all your domains are sub-domains of "domain.com", then you could put "DC=domain,DC=com". But if you have "domain.com" and "otherdomain.com" part of the same AD forest, then that wouldn't work.

FindByIdentity also won't work for searching by email address, so you may just be better off using PrincipalSearcher .

If you get the same referral error I got, you can tell it to follow the referral:

PrincipalSearcher srch = new PrincipalSearcher(User);
((DirectorySearcher) srch.GetUnderlyingSearcher()).ReferralChasing = ReferralChasingOption.All;