+/* Fragment Offset * Flags. */
+#define IPV4_HDR_DF_SHIFT 14
+#define IPV4_HDR_MF_SHIFT 13
+#define IPV4_HDR_FO_SHIFT 3
+
+#define IPV4_HDR_DF_FLAG (1 << IPV4_HDR_DF_SHIFT)
+#define IPV4_HDR_MF_FLAG (1 << IPV4_HDR_MF_SHIFT)
+
+#define IPV4_HDR_OFFSET_MASK ((1 << IPV4_HDR_MF_SHIFT) - 1)
+
+#define IPV4_HDR_OFFSET_UNITS 8
+