[IPSEC]: ah/esp, 0 was used as tunnels protocol.

net/ipv4/ah.c

@@ -189,7 +189,7 @@ int ah_output(struct sk_buff *skb)
 		top_iph->saddr = x->props.saddr.xfrm4_addr;
 		top_iph->daddr = x->id.daddr.xfrm4_addr;
 		ah = (struct ip_auth_hdr*)(top_iph+1);
-		ah->nexthdr = IPPROTO_IP;
+		ah->nexthdr = IPPROTO_IPIP;
 	} else {
 		memcpy(&tmp_iph, skb->data, iph->ihl*4);
 		top_iph = (struct iphdr*)skb_push(skb, x->props.header_len);

net/ipv4/esp.c

@@ -370,7 +370,7 @@ int esp_output(struct sk_buff *skb)
 	if (x->props.mode) {
 		top_iph = (struct iphdr*)skb_push(skb, x->props.header_len);
 		esph = (struct ip_esp_hdr*)(top_iph+1);
-		*(u8*)(trailer->tail - 1) = IPPROTO_IP;
+		*(u8*)(trailer->tail - 1) = IPPROTO_IPIP;
 		top_iph->ihl = 5;
 		top_iph->version = 4;
 		top_iph->tos = iph->tos;	/* DS disclosed */

net/ipv4/xfrm_input.c

@@ -91,7 +91,7 @@ int xfrm4_rcv(struct sk_buff *skb)
 		iph = skb->nh.iph;
 
 		if (x->props.mode) {
-			if (iph->protocol != IPPROTO_IP)
+			if (iph->protocol != IPPROTO_IPIP)
 				goto drop;
 			skb->nh.raw = skb->data;
 			iph = skb->nh.iph;