Authenticating against Active Directory

Code to check that user credentials are valid

The method "checkPass" is called with three parameters.
The method returns the string "fail" or "success".
The basic code came from a google search.

package myservlets;
 
import java.util.*;
import javax.naming.*;
import javax.naming.directory.*;
 
public class QueryNewAd {
 
 public String checkPass(String SERVER, String USERNAME, String PASS){
String server = "";
String userName = "";
String pass = "";
 
server = SERVER;
userName = USERNAME;
pass = PASS;
 
 
 
 try {
    Hashtable env = new Hashtable();
    env.put(Context.INITIAL_CONTEXT_FACTORY,
             "com.sun.jndi.ldap.LdapCtxFactory");
    env.put(Context.PROVIDER_URL,
             "LDAP://"+server+".camping.goldfinger.ac.uk:389"); //replace with your server URL/IP
             //only DIGEST-MD5 works with our Windows Active Directory
    env.put(Context.SECURITY_AUTHENTICATION,
             "DIGEST-MD5"); //No other SALS worked with me
    env.put(Context.SECURITY_PRINCIPAL,
            userName); // specify the username ONLY to let Microsoft Happy
    env.put(Context.SECURITY_CREDENTIALS, pass);   //the password
 
    DirContext ctx = new InitialDirContext(env);
 
    ctx.close();
 
  } catch(NamingException ne) {
    return "fail";
}
 
  //if no exception, the user is already authenticated.
    return "success";
}}