Laurence Brockman wrote:
Tried that already too and received:
GSSException: GSSException: No valid credentials provided (Mechanism level:
Failed to find any Kerberos Key)
Then you have to get the key into the keytab. This is the way a server works,
It does not try and get a ticket.
Figure 2 provides a sample login configuration entry for a server
application. With this configuration, the secret key from the keytab
is used to authenticate the principal "nfs/bar.foo.com" and both the TGT
obtained from the Kerberos KDC and the secret key are stored in the Subject's
private credentials set. The stored key may be used later to validate a
service
ticket sent by a client (See the section on Java GSS-API.)
SampleServer {
com.sun.security.auth.module.Krb5LoginModule
required useKeyTab=true storeKey=true principal="nfs/bar.foo.com"
};
There should be an option above to set the file name. If not, it will use the
default which is owned by root, and something like /etc/krb5.keytab or
/etc/krb5/krb5.keytab. (If you server is not run as root, then it should have
its
own keytab.) (If the KDC is a windows AD, then the Microsoft ktpass can be used
to create the key, and a keytab, that can be copied to your server.)
Also note well that the <serevice>@<host> is used GSS, and is changed
to a principal <service>/<host>@<realm>
GSSName serverName = manager.createName("[EMAIL PROTECTED]",
GSSName.NT_HOSTBASED_SERVICE);
The Kerberos V5 mechanism would map this name to the Kerberos specific
form nfs/[EMAIL PROTECTED] where FOO.COM is the realm of the principal.
This principal represents the service nfs running on the host machine
bar.foo.com.
If I don't setup the Kerberos stuff before calling that GSSCredentials I get
that error (See code below).
GSSManager manager = GSSManager.getInstance();
Oid kerberos = new Oid("1.2.840.113554.1.2.2");
GSSName serverGSSName = manager.createName(this.serverName, null);
GSSCredential serverGSSCreds = manager.createCredential(serverGSSName,
GSSCredential.INDEFINITE_LIFETIME,
kerberos, GSSCredential.ACCEPT_ONLY);
this.serverGSSContext = manager.createContext(serverGSSCreds);
this.serverName = "another/admin" (The principal that I want to authenticate
as).
No. See the above about the gss name to principal mapping. Its not the admin.
You need to ge the keytab.
Thanks for all the help!
Laurence
On 11/30/05, Douglas E. Engert <[EMAIL PROTECTED]> wrote:
Laurence Brockman wrote:
On 11/30/05, Douglas E. Engert <[EMAIL PROTECTED]> wrote:
So you are using GSSAPI, and passing the GSSAPI tokens via soap betwen
the
clint and server. And the server accepts the authentication.
Prior to the server even looking at the packet from the client, it needs
to
contact the kerberos server to get it's own credentials (GSS Uses these
underlying credentials when communicating with the client).
No.
See:
http://java.sun.com/j2se/1.4.2/docs/guide/security/jgss/single-signon.html
Credential acquisition on the server side occurs as follows:
GSSCredential serverCreds =
manager.createCredential(serverName,
GSSCredential.INDEFINITE_LIFETIME,
desiredMechs,
GSSCredential.ACCEPT_ONLY);
The behavior is similar to the client case, except that the kind of
credential
requested is one that can accept incoming requests (i.e., a server
credential).
Moreover, servers are typically long lived and like to request a longer
lifetime
for the credentials such as the INDEFINITE_LIFETIME shown here. The
Kerberos V5
mechanism element stored is an instance of a subclass of
javax.security.auth.kerberos.KerberosKey containing the secret key of
the server.
This step can be an expensive one, and applications generally acquire a
reference
at initialization time to all the credentials they expect to use during
their
lifetime.
There is an example of the server side later on, with gs name of "
[EMAIL PROTECTED]"
which when handled by the Kerberos would turn in into principal
"nfs/[EMAIL PROTECTED]"
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?
I'm refering to the kerberos server that granted the service ticket to
the
client. My server will need to talk to that server to get it's shared
key at
some point otherwise it will not be able to verify the ticket the client
is
sending.
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?
The principal is manually submitted and the password is returned from
the
callback class (The call back class is instiated in such a way that it
has
the password stored on the object and when the method responsible for
returning the password is called on the callback class it returns that
password (1234567890 in our case). This is the same process that is used
on
my client and it works no problem (Using the same commands, same
principals
and same variables).
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.
Yup, this will be the next step.
Don't know.
Thanks all the help!
Laurence
On 11/30/05, Douglas E. Engert <[EMAIL PROTECTED]> 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/[EMAIL PROTECTED]).
2. Server receives request from client (Through soap transcation).
Generates a login context and tries to authenticate against the
kerberos server using test2/[EMAIL PROTECTED] 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 [email protected]
https://mailman.mit.edu/mailman/listinfo/kerberos
--
Douglas E. Engert <[EMAIL PROTECTED]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
--
Douglas E. Engert <[EMAIL PROTECTED]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
--
Douglas E. Engert <[EMAIL PROTECTED]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
--
Douglas E. Engert <[EMAIL PROTECTED]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
________________________________________________
Kerberos mailing list [email protected]
https://mailman.mit.edu/mailman/listinfo/kerberos
