Java GSS is a framework that can support multiple security mechanisms; a way to negotiate a security mechanism underneath GSS-API is needed. This is available via SPNEGO.
SPNEGO is standardized at IETF in RFC 4178. It is a pseudo-security mechanism used to negotiate an underlying security mechanism. It provides the flexibility for client and server to securely negotiate a common GSS security mechanism.
Microsoft makes heavy use of SPNEGO. SPNEGO can be used to inter-operate with Microsoft Server over HTTP, to support HTTP-based cross-platform authentication via the Negotiate Protocol.
Currently, when using Java GSS with Kerberos, we specify the Kerberos OID as follows:
Oid krb5Oid = new Oid("1.2.840.113554.1.2.2");
In order to use SPNEGO, you only need to specify the SPNEGO OID as follows:
Oid spnegoOid = new Oid("1.3.6.1.5.5.2");
Then you can use the SPNEGO OID when creating a
GSSCredential, GSSContext, etc.
Currently the only security mechansim available with Java GSS is Kerberos. The goal of this exercise is to learn how to use other Java GSS mechanisms, such as the Simple and Protected GSS-API Negotiation Mechanism (SPNEGO), to secure the association.
Read the GssSpNegoClient.java code.
Compile the sample code:
% javac GssSpNegoClient.java
Read the src/GssSpNegoServer.java code.
Compile the sample code:
% javac GssSpNegoServer.java
Launch a new window and start the server:
% xterm & % java -Djava.security.auth.login.config=jaas-krb5.conf GssSpNegoServer
Run the client application. GssSpNegoClient takes two
parameters: the service name and the name of the server that the
service is running on. For example, if the service is
host running on the machine j1hol-001, use the following (provide a secure password when prompted):
% java -Djava.security.auth.login.config=jaas-krb5.conf \ GssSpNegoClient host j1hol-001
Sample output for running GssSpNegoServer:
Authenticated principal: [host/[email protected]] Waiting for incoming connections... Got connection from client /129.145.128.102 SPNEGO Negotiated Mechanism = 1.2.840.113554.1.2.2 Kerberos V5 Context Established! Client principal is [email protected] Server principal is host/[email protected] Mutual authentication took place! Received data "Hello There!" of length 12 Confidentiality applied: true Sending: Hello There! Thu May 06 12:11:15 PDT 2005
Sample output for running GssSpNegoClient (password is replaced with the password you provided before):
Kerberos password for test: password Authenticated principal: [[email protected]] Connected to address j1hol-001/129.145.128.102 SPNEGO Negotiated Mechanism = 1.2.840.113554.1.2.2 Kerberos V5 Context Established! Client principal is [email protected] Server principal is host@j1hol-001 Mutual authentication took place! Sending message: Hello There! Will read token of size 93 Received message: Hello There! Thu May 06 12:11:15 PDT 2005
In this exercise, you learned how to write a client-server application that uses the Java GSS API with SPNEGO to negotiate an underlying security mechanism, such as Kerberos, and communicate securely using Kerberos as the underlying authentication system.
NOTE: Microsoft has implemented certain variations of the
SPNEGO protocol, hence to inter-operate with Microsoft, we have
added a separate mode via a new system property
sun.security.spnego.msinterop. This property is enabled to true
by default. To disable it, you need to explicitly set this property
to false. To enable SPNEGO debugging, you can set the system
property sun.security.spnego.debug=true.
