LDAP connection - server is not operational

Question

User1151108763 posted

Hello, I am trying to connect to the LDAP server and my goal is to change user password through the application. My working application is hosted inside the domain and the following code works fine to change password.

using (PrincipalContext principalContext = new PrincipalContext
(ContextType.Domain, DomainName, DomainDN, ContextOptions.Negotiate, AdminUserName, AdminUserPassword))
{
UserPrincipal userPrincipal = UserPrincipal.FindByIdentity(principalContext, IdentityType.SamAccountName, userName);
dnuser = userPrincipal.DistinguishedName;
currentdc = principalContext.ConnectedServer;
DirectoryEntry directoryEntry = (DirectoryEntry)userPrincipal.GetUnderlyingObject();
userPrincipal.ChangePassword(oldPassword, newPassword);

userPrincipal.Dispose();

}

Now I need to move the application to a new server which is outside the domain (DMZ server) of the DC. So I am having to use LDAP connection over SSL. I am trying to connect to the LDAP server with the following code but getting error "The server is not operational" on the line deSearch.FindOne().

string ldapString = "LDAP://123.45.678.123:636/DC=mydomain,DC=com";

DirectoryEntry de = new DirectoryEntry(ldapString, adminUser, adminPass, AuthenticationTypes.Secure);
//DirectoryEntry de = new DirectoryEntry(ldapString, adminUser, adminPass);
DirectorySearcher deSearch = new DirectorySearcher(de) { SearchRoot = de, Filter = "(&(objectCategory=user)(cn=" + "xar22" + "))" };

var directoryEntry = deSearch.FindOne();

Can someone please help me understanding what I am doing wrong?

Thanks!

Answer 1

User1724605321 posted

Hi sAMAccount ,

That error may occur when hostname or IP address listed in the Server path is not correct, or that an LDAP server is not listening on that address , or connection is not correct . You can refer to below links for potential solution :

https://stackoverflow.com/questions/28608542/how-to-get-a-directoryentry-from-ldap-over-ssl 

https://stackoverflow.com/questions/54987776/ldap-connection-error-the-server-is-not-operational-when-connecting-to-port

Best Regards,

Nan  Yu

Answer 2

User1151108763 posted

I did Test-NetConnection ldap.domain.com -Port 636. That gave successful ping. So I am guessing the server ip address is correct (I am using IP address instead of the host name). I do not have any cert installed on the application server. Does it need to have some cert?

Answer 3

User1724605321 posted

Hi sAMAccount ,

Do you try to use name instead of ip ?

Best Regards,
Nan Yu