code: public SockAddr getNetmask() {
  		SockAddr sockAddr = null;
  		if (this.netmask != null) {
  			sockAddr = new SockAddr(this.netmask.getSaFamily().getValue(), this.netmask.getData());
  		}
  		return sockAddr;
  	}
docs: Getting interface netmask.
  @return returns interface netmask.