diff --git a/include/net/ipip.h b/include/net/ipip.h
new file mode 100644
index 0000000..f490c3c
--- /dev/null
+++ b/include/net/ipip.h
@@ -0,0 +1,51 @@
+#ifndef __NET_IPIP_H
+#define __NET_IPIP_H 1
+
+#include <linux/if_tunnel.h>
+
+/* Keep error state on tunnel for 30 sec */
+#define IPTUNNEL_ERR_TIMEO	(30*HZ)
+
+struct ip_tunnel
+{
+	struct ip_tunnel	*next;
+	struct net_device	*dev;
+	struct net_device_stats	stat;
+
+	int			recursion;	/* Depth of hard_start_xmit recursion */
+	int			err_count;	/* Number of arrived ICMP errors */
+	unsigned long		err_time;	/* Time when the last ICMP error arrived */
+
+	/* These four fields used only by GRE */
+	__u32			i_seqno;	/* The last seen seqno	*/
+	__u32			o_seqno;	/* The last output seqno */
+	int			hlen;		/* Precalculated GRE header length */
+	int			mlink;
+
+	struct ip_tunnel_parm	parms;
+};
+
+#define IPTUNNEL_XMIT() do {						\
+	int err;							\
+	int pkt_len = skb->len;						\
+									\
+	skb->ip_summed = CHECKSUM_NONE;					\
+	iph->tot_len = htons(skb->len);					\
+	ip_select_ident(iph, &rt->u.dst, NULL);				\
+	ip_send_check(iph);						\
+									\
+	err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, dst_output);\
+	if (err == NET_XMIT_SUCCESS || err == NET_XMIT_CN) {		\
+		stats->tx_bytes += pkt_len;				\
+		stats->tx_packets++;					\
+	} else {							\
+		stats->tx_errors++;					\
+		stats->tx_aborted_errors++;				\
+	}								\
+} while (0)
+
+
+extern int	sit_init(void);
+extern void	sit_cleanup(void);
+
+#endif