Kerberos con Java

Question

provo ad accedere a kerberos kdc da Java. Ma Java lancia un'eccezione. Sembra che l'accesso abbia esito positivo, ma qualcosa è arresto login. Non so perché? Qualcuno ha una soluzione per questo problema? Qui è la mia uscita del sistema Java:

Debug is true storeKey false useTicketCache true useKeyTab false doNotPrompt false ticketCache is null isInitiator true KeyTab is null refreshKrb5Config is true principal is null tryFirstPass is false useFirstPass is false storePass is false clearPass is false 
Refreshing Kerberos configuration 
Acquire TGT from Cache 
Principal is null 
null credentials from Ticket Cache 
       [Krb5LoginModule] user entered username: kadirb 

principal is kadirb@EXAMPLE.COM 
Commit Succeeded 

Exception in thread "main" java.lang.Error: GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER) 
     at KerberosTicketRetriever$TicketCreatorAction.run(KerberosTicketRetriever.java:76) 
     at java.security.AccessController.doPrivileged(Native Method) 
     at javax.security.auth.Subject.doAsPrivileged(Subject.java:473) 
     at KerberosTicketRetriever.retrieveTicket(KerberosTicketRetriever.java:179) 
     at KerberosTicketRetriever.main(KerberosTicketRetriever.java:188) 
Caused by: GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER) 
     at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:710) 
     at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:248) 
     at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:179) 
     at KerberosTicketRetriever$TicketCreatorAction.createTicket(KerberosTicketRetriever.java:105) 
     at KerberosTicketRetriever$TicketCreatorAction.run(KerberosTicketRetriever.java:72) 
     ... 4 more 
Caused by: KrbException: Server not found in Kerberos database (7) - LOOKING_UP_SERVER 
     at sun.security.krb5.KrbTgsRep.<init>(KrbTgsRep.java:73) 
     at sun.security.krb5.KrbTgsReq.getReply(KrbTgsReq.java:192) 
     at sun.security.krb5.KrbTgsReq.sendAndGetCreds(KrbTgsReq.java:203) 
     at sun.security.krb5.internal.CredentialsUtil.serviceCreds(CredentialsUtil.java:311) 
     at sun.security.krb5.internal.CredentialsUtil.acquireServiceCreds(CredentialsUtil.java:115) 
     at sun.security.krb5.Credentials.acquireServiceCreds(Credentials.java:442) 
     at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:641) 
     ... 8 more 
Caused by: KrbException: Identifier doesn't match expected value (906) 
     at sun.security.krb5.internal.KDCRep.init(KDCRep.java:143) 
     at sun.security.krb5.internal.TGSRep.init(TGSRep.java:66) 
     at sun.security.krb5.internal.TGSRep.<init>(TGSRep.java:61) 
     at sun.security.krb5.KrbTgsRep.<init>(KrbTgsRep.java:55) 
     ... 14 more 
Disconnected from the target VM, address: '127.0.0.1:51126', transport: 'socket' 

Process finished with exit code 1 

E il mio codice Java:

import com.sun.security.auth.callback.DialogCallbackHandler; 
import org.ietf.jgss.*; 
import sun.misc.BASE64Encoder; 
import javax.security.auth.Subject; 
import javax.security.auth.login.LoginContext; 
import javax.security.auth.login.LoginException; 
import java.io.*; 
import java.security.Principal; 
import java.security.PrivilegedAction; 
import java.util.Set; 

/** 
* Tool to retrieve a kerberos ticket. This one will not be stored in the windows ticket cache. 
*/ 
public final class KerberosTicketRetriever 
{ 
private final static Oid KERB_V5_OID; 
private final static Oid KRB5_PRINCIPAL_NAME_OID; 

static { 
    try 
    { 
     KERB_V5_OID = new Oid("1.2.840.113554.1.2.2"); 
     KRB5_PRINCIPAL_NAME_OID = new Oid("1.2.840.113554.1.2.2.1"); 

    } catch (final GSSException ex) 
    { 
     throw new Error(ex); 
    } 
} 

/** 
* Not to be instanciated 
*/ 
private KerberosTicketRetriever() {}; 

/** 
* 
*/ 
private static class TicketCreatorAction implements PrivilegedAction 
{ 
    final String userPrincipal; 
    final String applicationPrincipal; 

    private StringBuffer outputBuffer; 

    /** 
    * 
    * @param userPrincipal p.ex. <tt>MuelleHA@MYFIRM.COM</tt> 
    * @param applicationPrincipal p.ex. <tt>HTTP/webserver.myfirm.com</tt> 
    */ 
    private TicketCreatorAction(final String userPrincipal, final String applicationPrincipal) 
    { 
     this.userPrincipal = userPrincipal; 
     this.applicationPrincipal = applicationPrincipal; 
    } 

    private void setOutputBuffer(final StringBuffer newOutputBuffer) 
    { 
     outputBuffer = newOutputBuffer; 
    } 

    /** 
    * Only calls {@link #createTicket()} 
    * @return <tt>null</tt> 
    */ 
    public Object run() 
    { 
     try 
     { 
      createTicket(); 
     } 
     catch (final GSSException ex) 
     { 
      throw new Error(ex); 
     } 

     return null; 
    } 

    /** 
    * 
    * @throws GSSException 
    */ 
    private void createTicket() throws GSSException 
    { 
     final GSSManager manager = GSSManager.getInstance(); 
     final GSSName clientName = manager.createName(userPrincipal, KRB5_PRINCIPAL_NAME_OID); 
     final GSSCredential clientCred = manager.createCredential(clientName, 
       8 * 3600, 
       KERB_V5_OID, 
       GSSCredential.INITIATE_ONLY); 

     final GSSName serverName = manager.createName(applicationPrincipal, KRB5_PRINCIPAL_NAME_OID); 

     final GSSContext context = manager.createContext(serverName, 
       KERB_V5_OID, 
       clientCred, 
       GSSContext.DEFAULT_LIFETIME); 
     context.requestMutualAuth(true); 
     context.requestConf(false); 
     context.requestInteg(true); 

     final byte[] outToken = context.initSecContext(new byte[0], 0, 0); 

     if (outputBuffer !=null) 
     { 
      outputBuffer.append(String.format("Src Name: %s\n", context.getSrcName())); 
      outputBuffer.append(String.format("Target : %s\n", context.getTargName())); 
      outputBuffer.append(new BASE64Encoder().encode(outToken)); 
      outputBuffer.append("\n"); 
     } 

     context.dispose(); 
    } 
} 

/** 
* 
* @param realm p.ex. <tt>MYFIRM.COM</tt> 
* @param kdc p.ex. <tt>kerbserver.myfirm.com</tt> 
* @param applicationPrincipal cf. {@link #TicketCreatorAction(String, String)} 
* @throws GSSException 
* @throws LoginException 
*/ 
static public String retrieveTicket(
     final String realm, 
     final String kdc, 
     final String applicationPrincipal) 
     throws GSSException, LoginException 
{ 

    // create the jass-config-file 
    final File jaasConfFile; 
    try 
    { 
     jaasConfFile = File.createTempFile("jaas.conf", null); 
     final PrintStream bos = new PrintStream(new FileOutputStream(jaasConfFile)); 
     bos.print(String.format(
       "Krb5LoginContext { com.sun.security.auth.module.Krb5LoginModule required refreshKrb5Config=true useTicketCache=true debug=true ; };" 
     )); 
     bos.close(); 
     jaasConfFile.deleteOnExit(); 
    } 
    catch (final IOException ex) 
    { 
     throw new IOError(ex); 
    } 

    // set the properties 
    System.setProperty("java.security.krb5.realm", realm); 
    System.setProperty("java.security.krb5.kdc", kdc); 
    System.setProperty("java.security.auth.login.config",jaasConfFile.getAbsolutePath()); 

    // get the Subject(), i.e. the current user under Windows 
    final Subject subject = new Subject(); 
    final LoginContext lc = new LoginContext("Krb5LoginContext", subject, new DialogCallbackHandler()); 
    try { 
     lc.login(); 
    } catch (LoginException e) { 
     e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. 
     //e = Client not found in Kerberos database (6) - CLIENT_NOT_FOUND 
     System.exit(0); 
    } 

    // extract our principal 
    final Set<Principal> principalSet = subject.getPrincipals(); 
    if (principalSet.size() != 1) 
     throw new AssertionError("No or several principals: " + principalSet); 
    final Principal userPrincipal = principalSet.iterator().next(); 

    // now try to execute the SampleAction as the authenticated Subject 
    // action.run() without doAsPrivileged leads to 
    // No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt) 
    final TicketCreatorAction action = new TicketCreatorAction(userPrincipal.getName(), applicationPrincipal); 
    final StringBuffer outputBuffer = new StringBuffer(); 
    action.setOutputBuffer(outputBuffer); 
    Subject.doAsPrivileged(lc.getSubject(), action, null); 

    return outputBuffer.toString(); 
} 

public static void main (final String args[]) throws Throwable 
{ 
    final String ticket = retrieveTicket("EXAMPLE.COM", "EXAMPLE.COM", "HTTP/webserver.myfirm.com"); 
    System.out.println(ticket); 
} 
} 

Answer 1

non ho la prova il codice, ma leggendo StackTrace Credo che il problema è con il dominio KDC. Come documentation says:

regno difetto ed il KDC per quel livello sono indicati nella Kerberos krb5.conf

Tipicamente KDC regno in krb5.conf è kdc. Esempio da installazione di Fedora di default:

[realms] 
EXAMPLE.COM = { 
kdc = kerberos.example.com 
admin_server = kerberos.example.com 
} 

mi sembra ovvio che si dovrebbe cambiare il dominio kdc con nome di dominio, non il nome Realm:

final String ticket = retrieveTicket("EXAMPLE.COM", "localhost", "HTTP/webserver.myfirm.com"); 

Si sta utilizzando Kerberos sulla macchina locale, si potrebbe desiderare di aggiungi l'opzione dns_lookup_kdc = false al tuo krb5.conf