HttpClient set credentials for Kerberos authentication

Question

I am trying to authenticate with a kerberos/HTTP host. Using Apache HttpClient as my client - and a slightly modified version of this source. My Kerberos authentication goes perfectly fine, and I wish to know how to set the login credentials programatically. At the moment, the credentials are entered manually through the console, but I want to have it chosen by me at run time. [ As I wish to automate and load test the server with a large number of users, actually. ].

EDIT : Here is a code snippet of the relevant parts :

..
        NegotiateSchemeFactory nsf = new NegotiateSchemeFactory();        
        httpclient.getAuthSchemes().register(AuthPolicy.SPNEGO, nsf);

        Credentials use_jaas_creds = new Credentials() {

            public String getPassword() {
                return null;
            }

            public Principal getUserPrincipal() {
                return null;
            }    
        };

        httpclient.getCredentialsProvider().setCredentials(
                new AuthScope(null, -1, null),
                use_jaas_creds);

        HttpUriRequest request = new HttpGet("http://kerberoshost/");
        HttpResponse response = httpclient.execute(request);
 .. 

The interface Credentials has two methods - getPassword() and getUserPrincipal(), but from some debugging I did, they don't seem to be invoked at all.

What am I missing here ? What is a cleaner way to statically set the credentials ?

A very similar question had been asked before, but keytabs/login.conf hack is too cumbersome and not a practical option for an automated load test with a large number of user credentials. Appreciate any help on this.

Answer 1

Because of SPNEGO the snippet code you post (Credentials class stuff setup) is not used by httpclient to authenticate.

You can use a DoAs + a CallBackhandler to pass user & password at runtime.

Then you need a login.conf or whatever the name with this inside:

KrbLogin{
 com.sun.security.auth.module.Krb5LoginModule required doNotPrompt=false debug=true useTicketCache=false;
};

You can change the name from "KrbLogin" to the name you like (remember to use the same name in your java code)

and set this with java system properties:

System.setProperty("java.security.auth.login.config", "login.conf");

or with a

-Djava.security.auth.login.config=login.config

Then you need a krb5 config file (usually krb5.ini or krb5.conf with correct configuration inside)

If your workstation (or server) is properly configured for Kerberos this class should works as is (with propper file login.conf and krb5.ini) I used httpclient 4.3.3 and java 1.7 to test it:

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthSchemeProvider;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.Credentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.HttpClient;
import org.apache.http.client.config.AuthSchemes;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.impl.auth.SPNegoSchemeFactory;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import javax.security.auth.Subject;
import javax.security.auth.callback.*;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import java.io.IOException;
import java.security.AccessController;
import java.security.Principal;
import java.security.PrivilegedAction;
import java.util.Set;

public class HttpClientKerberosDoAS {

    public static void main(String[] args) throws Exception {

        System.setProperty("java.security.auth.login.config", "login.conf");
        System.setProperty("java.security.krb5.conf", "krb5.conf");
        System.setProperty("javax.security.auth.useSubjectCredsOnly", "false");

        String user = "";
        String password = "";
        String url = "";

        if (args.length == 3) {
            user = args[0];
            password = args[1];
            url = args[2];


            HttpClientKerberosDoAS kcd = new HttpClientKerberosDoAS();

            System.out.println("Loggin in with user [" + user + "] password [" + password + "] ");
            kcd.test(user, password, url);
        } else {
            System.out.println("run with User Password URL");
        }

    }

    public void test(String user, String password, final String url) {
        try {

            LoginContext loginCOntext = new LoginContext("KrbLogin", new KerberosCallBackHandler(user, password));
            loginCOntext.login();

            PrivilegedAction sendAction = new PrivilegedAction() {

                @Override
                public Object run() {
                    try {

                        Subject current = Subject.getSubject(AccessController.getContext());
                        System.out.println("----------------------------------------");
                        Set<Principal> principals = current.getPrincipals();
                        for (Principal next : principals) {
                            System.out.println("DOAS Principal: " + next.getName());
                        }
                        System.out.println("----------------------------------------");

                        call(url);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    return true;
                }
            };

            Subject.doAs(loginCOntext.getSubject(), sendAction);

        } catch (LoginException le) {
            le.printStackTrace();
        }
    }

    private void call(String url) throws IOException {
        HttpClient httpclient = getHttpClient();

        try {

            HttpUriRequest request = new HttpGet(url);
            HttpResponse response = httpclient.execute(request);
            HttpEntity entity = response.getEntity();

            System.out.println("----------------------------------------");

            System.out.println("STATUS >> " + response.getStatusLine());

            if (entity != null) {
                System.out.println("RESULT >> " + EntityUtils.toString(entity));
            }

            System.out.println("----------------------------------------");

            EntityUtils.consume(entity);

        } finally {
            httpclient.getConnectionManager().shutdown();
        }
    }

    private  HttpClient getHttpClient() {

        Credentials use_jaas_creds = new Credentials() {
            public String getPassword() {
                return null;
            }

            public Principal getUserPrincipal() {
                return null;
            }
        };

        CredentialsProvider credsProvider = new BasicCredentialsProvider();
        credsProvider.setCredentials(new AuthScope(null, -1, null), use_jaas_creds);
        Registry<AuthSchemeProvider> authSchemeRegistry = RegistryBuilder.<AuthSchemeProvider>create().register(AuthSchemes.SPNEGO, new SPNegoSchemeFactory(true)).build();
        CloseableHttpClient httpclient = HttpClients.custom().setDefaultAuthSchemeRegistry(authSchemeRegistry).setDefaultCredentialsProvider(credsProvider).build();

        return httpclient;
    }

    class KerberosCallBackHandler implements CallbackHandler {

        private final String user;
        private final String password;

        public KerberosCallBackHandler(String user, String password) {
            this.user = user;
            this.password = password;
        }

        public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {

            for (Callback callback : callbacks) {

                if (callback instanceof NameCallback) {
                    NameCallback nc = (NameCallback) callback;
                    nc.setName(user);
                } else if (callback instanceof PasswordCallback) {
                    PasswordCallback pc = (PasswordCallback) callback;
                    pc.setPassword(password.toCharArray());
                } else {
                    throw new UnsupportedCallbackException(callback, "Unknown Callback");
                }

            }
        }
    }

}

Note:

you can use:

System.setProperty("sun.security.krb5.debug", "true");

or:

-Dsun.security.krb5.debug=true

to investigate problems.