Java GSS/Kerberos issue - Autheticating server

[Douglas E. Engert]

Laurence Brockman wrote:

> I can authenticate as that particular principal in the client portion of the
> code that I have written using exactly the same case, etc.
> 
> I have a server and a client portion of code that pass GSS-wrapped kerberos
> tokens through a SOAP connection 

So you are using GSSAPI, and passing the GSSAPI tokens via soap betwen the
clint and server. And the server accepts the authentication.


> and the server is unable to authenticate to
> the KDC using any credentials (Same error) and the client can authenticate

Normally the server does not talk to the KDC at all. SO what is it really
trying to do?

But the GSSAPI Delegation feature can be used be the client to delegate
a credential to the server so the server can act as the client. (The client
gets a new Kerbveros TGT and sends to to the server.) Usefull with ssh
for example where the user is logging in as the user.

> using any credentials.
> 
> Both use the same code:
> 
> LoginContext("confName", new PasswordCallbackClass(....,....));

So where is geting the password?  Does the server think the principal
is that of the user, as the gssapi delegated a TGT to the server?

> lc.login();
> 
> Thc lc.login() on the server portion is failing. The server is runnning on
> my Windows XP devel box and is running as a Tomcat servlet. Any known issues
> with this type of setup?
> 

You can run Ethereal on the box, and watch the network traffic. Ethereal
can format krb5 packets. Very helpfull is cases like this.


Don't know.

> Thanks all the help!
> 
> Laurence
> 
> 
> On 11/30/05, Douglas E. Engert <deengert at anl.gov> wrote:
> 
>>
>>
>>Laurence wrote:
>>
>>
>>>Hey guys, hopefully someone can help me out here.
>>>
>>>I am having a problem with authenticating a user to a KDC (I believe
>>>the MIT reference implementation) using Java (JDK1.5 and JDK1.4)
>>>through GSS.
>>>
>>>Here is the background:
>>>
>>>I have two processes running on one machine (Client and Server).
>>>
>>>1. Client authenticates to kerberos server and logs in, uses the GSS
>>>libraries to create a service ticket for destination server
>>>(Authenticates with principal test/admin at realm.com).
>>>2. Server receives request from client (Through soap transcation).
>>>Generates a login context and tries to authenticate against the
>>>kerberos server using test2/admin at realm.com. Server is returned an
>>>error from the kerberos server (Integrity check on decrypted field
>>>failed (31) - PREAUTH_FAILED).
>>
>>There is a bug in Java related to PREAUTH. (Its fixed in 1.6 I believe.)
>>It has to do with Jave assuming it knows the "salt" to use when generating
>>the key from the password. key = fun(passwrod,salt); The salt is based on
>>user and realm. Jave assumes that the these have not changed since the
>>password was last changed. Windows is also case insensitive but does
>>preserve the case of the salt when changing the password.
>>
>>So if you have moved an AD account from one domain to another or changed
>>the acount name (even the case) and not changed the password  you could
>>have problems.
>>
>>So make sure the case of the principal and the principal is the same
>>as when the password for the acount was last changed.
>>
>>
>>
>>>If I configured the client to use the same username/password I can
>>>authenticate on the client, but no matter what I put in the server it
>>>fails.
>>>
>>>I don't know the kerberos protocol well enough to know if I can even do
>>>this (Having the server contact the KDC after a service ticket has been
>>>issued to the client to authenticate). Is that why I'm getting what
>>>I've read indicates a password error?
>>>
>>>________________________________________________
>>>Kerberos mailing list           Kerberos at mit.edu
>>>https://mailman.mit.edu/mailman/listinfo/kerberos
>>>
>>>
>>
>>--
>>
>>Douglas E. Engert  <DEEngert at anl.gov>
>>Argonne National Laboratory
>>9700 South Cass Avenue
>>Argonne, Illinois  60439
>>(630) 252-5444
>>
> 
> 

-- 

  Douglas E. Engert  <DEEngert at anl.gov>
  Argonne National Laboratory
  9700 South Cass Avenue
  Argonne, Illinois  60439
  (630) 252-5444