code: public static void setProperties( Properties prp ) {
          Config.prp = new Properties( prp );
          try {
              Config.prp.putAll( System.getProperties() );
          } catch( SecurityException se ) {
              if( log.level > 1 )
                  log.println( "SecurityException: jcifs.smb1 will ignore System properties" );
          }
      }
docs: Set the default properties of the static Properties used by <tt>Config</tt>. This permits
  a different Properties object/file to be used as the source of properties for
  use by the jCIFS library. The Properties must be set <i>before jCIFS
  classes are accessed</i> as most jCIFS classes load properties statically once.
  Using this method will also override properties loaded
  using the <tt>-Djcifs.properties=</tt> commandline parameter.