--- a/include/linux/netfilter/nf_conntrack_proto_gre.h
+++ b/include/linux/netfilter/nf_conntrack_proto_gre.h
@@ -30,4 +30,36 @@ void nf_ct_gre_keymap_destroy(struct nf_
 
 bool gre_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
 		      struct net *net, struct nf_conntrack_tuple *tuple);
+
+
+/* GRE is a mess: Four different standards */
+struct gre_hdr {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+        __u16   rec:3,
+                srr:1,
+                seq:1,
+                key:1,
+                routing:1,
+                csum:1,
+                version:3,
+                reserved:4,
+                ack:1;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+        __u16   csum:1,
+                routing:1,
+                key:1,
+                seq:1,
+                srr:1,
+                rec:3,
+                ack:1,
+                reserved:4,
+                version:3;
+#else
+#error "Adjust your <asm/byteorder.h> defines"
+#endif
+        __be16  protocol;
+};
+
+
+
 #endif /* _CONNTRACK_PROTO_GRE_H */