code: private synchronized void writeObject(java.io.ObjectOutputStream s)
          throws IOException
      {
          if (scope_ifname_set) {
              ifname = scope_ifname.getName();
          }
          s.defaultWriteObject();
      }
docs: default behavior is overridden in order to write the
  scope_ifname field as a String, rather than a NetworkInterface
  which is not serializable