OpenLDAP The LDAP server is unavailable

Question

I have been trying to connect to our OpenLDAP server from asp.net for the last four days without success. Just before I pull off my hair, could any one out there have a solution that has worked( ie using c# asp.net to connect to OpenLDAP server). Apparently I can access the ldap server from putty.exe and do a search. Furthermore, I can use the LDAP server for authentication using a local installation of Drupal CMS without any problems - given that I have added the LDAP module. My problem is doing the same in asp.net. The specific details are as follows:

Ldap server is hosted on sun solaries. My development machine is running Win XP Service pack 3. The error shows up when I try to call bind with a username and password that I have used successfully with putty.

    string hostNameAndSSLPort = "ipaddress";
    string userName = "username";
    string password = "password";

    // establish a connection
    LdapConnection connection = new LdapConnection(hostNameAndSSLPort);

    // create an LdapSessionOptions object to configure session
    // settings on the connection.
    LdapSessionOptions options = connection.SessionOptions;

    options.ProtocolVersion = 3;


    options.SecureSocketLayer = true;

    connection.AuthType = AuthType.Basic;

    connection.Credential =
    new NetworkCredential(userName , password );

    try
    {
        connection.Bind();
    }
    catch(Exception e){
         lblSecurity.Text = e.Message;
    }

I have even tried starting TLS using options.StartTransportLayerSecurity(null); before calling bind by the same error persists. What could I be doing wrong? Please help!!!!!!!!

Have you tried it without SSL just to see if you can connect that way? — Kasapo, Jul 16 '12 at 15:37
Also, in this post: http://stackoverflow.com/questions/8904832/using-starttls-with-ldap-from-system-directoryservices it seems they use a DN instead of just a user name... perhaps in their example bindDN is equal to username (uid?), but that could be a place to start. I've also had issues where I had to simply connect to a non-standard port for SSL because of the way LDAP was configured (or some zany firewall rule on the way there...) — Kasapo, Jul 16 '12 at 15:41
Is your certificate for the LDAP server self-signed or is it signed by a Cert Authority? If it's signed by a Cert Authority, is it a public or private one? You may have a chain of trust issue. Also, what specific exception are you getting? — JamieSee, Jul 16 '12 at 16:43

score 3 · Answer 1 · answered Jun 20 '17 at 20:41

I had the same issue. My fix was very similar to the answer above. The issue was the LDAP server was sending back a certificate and the client (our code) wasn't accepting it. So by adding the following line of code, made me celebrate and rip a shirt!

connection.SessionOptions.VerifyServerCertificate = new VerifyServerCertificateCallback((con, cer) => true);

Or in vb terms:

connection.SessionOptions.VerifyServerCertificate = New VerifyServerCertificateCallback(Function(con, cer) True)

score 0 · Answer 2 · edited May 23 '17 at 12:12

0

See this answer for some example code that works. How do I connect to a locally installed OpenLDAP service?

You mention using XP. I believe there is a hot fix that fixes an issue in the TLS implementation of winldap on XP. You'll have to do some searching around the microsoft site for it. I remember it being buried in a technet page somewhere.

Also don't use TLS with .net/winldap. You'll tear your hair out wondering why your web site randomly pegs out the cpu until it is killed. The answer above has an explanation. Just use SSL.

edited May 23 '17 at 12:12

Community

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answered Jul 16 '12 at 18:39

Sam Corder

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I tried tracking the problem and I can see in the autos window that problems start imediately I call new LdapConnection(hostNameAndSSLPort) because when I examine the connection variable within the session options there is already an error + SecurityContext 'connection.SessionOptions.SecurityContext' threw an exception of type 'System.DirectoryServices.Protocols.DirectoryOperationException' object {System.DirectoryServices.Protocols.DirectoryOperationException} in the 'security context' and + SendTimeout – john Jul 17 '12 at 08:52
Thank you all for your taking time to help me. I have equally tried using the full dn without success. As I mention above, the problem starts when I call new connection. However, I have checked that the host is reacheable from the connection.options variable. – john Jul 17 '12 at 09:05

score -1 · Answer 3 · edited May 02 '13 at 12:13

-1

Code like this:

LdapConnection connection = new LdapConnection(new LdapDirectoryIdentifier(this._domain,     Convert.ToInt32(this._port)));
connection.SessionOptions.VerifyServerCertificate = new VerifyServerCertificateCallback((con, cer) => true);
connection.SessionOptions.ProtocolVersion = 3;
connection.AuthType = AuthType.Basic;       
connection.SessionOptions.SecureSocketLayer = true;

edited May 02 '13 at 12:13

Zaheer Ahmed

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answered Oct 22 '12 at 06:00

mayank.karki

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OpenLDAP The LDAP server is unavailable

3 Answers3