code: public ServerAuthenticator startSession(Socket s)
                                    throws IOException{
  
       PushbackInputStream in =  new PushbackInputStream(s.getInputStream());
       OutputStream out = s.getOutputStream();
  
       int version = in.read();
       if(version == 5){
         if(!selectSocks5Authentication(in,out,0))
            return null;
       }else if(version == 4){
         //Else it is the request message allready, version 4
         in.unread(version);
       }else
         return null;
       
  
       return new ServerAuthenticatorNone(in,out);
     }
docs: Grants access to everyone.Removes authentication related bytes from
  the stream, when a SOCKS5 connection is being made, selects an
  authentication NONE.