diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
new file mode 100644
index 0000000..e3ecf62
--- /dev/null
+++ b/net/ipv6/ah6.c
@@ -0,0 +1,478 @@
+/*
+ * Copyright (C)2002 USAGI/WIDE Project
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Authors
+ *
+ *	Mitsuru KANDA @USAGI       : IPv6 Support 
+ * 	Kazunori MIYAZAWA @USAGI   :
+ * 	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
+ * 	
+ * 	This file is derived from net/ipv4/ah.c.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <net/ip.h>
+#include <net/ah.h>
+#include <linux/crypto.h>
+#include <linux/pfkeyv2.h>
+#include <linux/string.h>
+#include <net/icmp.h>
+#include <net/ipv6.h>
+#include <net/xfrm.h>
+#include <asm/scatterlist.h>
+
+static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
+{
+	u8 *opt = (u8 *)opthdr;
+	int len = ipv6_optlen(opthdr);
+	int off = 0;
+	int optlen = 0;
+
+	off += 2;
+	len -= 2;
+
+	while (len > 0) {
+
+		switch (opt[off]) {
+
+		case IPV6_TLV_PAD0:
+			optlen = 1;
+			break;
+		default:
+			if (len < 2) 
+				goto bad;
+			optlen = opt[off+1]+2;
+			if (len < optlen)
+				goto bad;
+			if (opt[off] & 0x20)
+				memset(&opt[off+2], 0, opt[off+1]);
+			break;
+		}
+
+		off += optlen;
+		len -= optlen;
+	}
+	if (len == 0)
+		return 1;
+
+bad:
+	return 0;
+}
+
+/**
+ *	ipv6_rearrange_rthdr - rearrange IPv6 routing header
+ *	@iph: IPv6 header
+ *	@rthdr: routing header
+ *
+ *	Rearrange the destination address in @iph and the addresses in @rthdr
+ *	so that they appear in the order they will at the final destination.
+ *	See Appendix A2 of RFC 2402 for details.
+ */
+static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
+{
+	int segments, segments_left;
+	struct in6_addr *addrs;
+	struct in6_addr final_addr;
+
+	segments_left = rthdr->segments_left;
+	if (segments_left == 0)
+		return;
+	rthdr->segments_left = 0; 
+
+	/* The value of rthdr->hdrlen has been verified either by the system
+	 * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
+	 * packets.  So we can assume that it is even and that segments is
+	 * greater than or equal to segments_left.
+	 *
+	 * For the same reason we can assume that this option is of type 0.
+	 */
+	segments = rthdr->hdrlen >> 1;
+
+	addrs = ((struct rt0_hdr *)rthdr)->addr;
+	ipv6_addr_copy(&final_addr, addrs + segments - 1);
+
+	addrs += segments - segments_left;
+	memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
+
+	ipv6_addr_copy(addrs, &iph->daddr);
+	ipv6_addr_copy(&iph->daddr, &final_addr);
+}
+
+static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
+{
+	union {
+		struct ipv6hdr *iph;
+		struct ipv6_opt_hdr *opth;
+		struct ipv6_rt_hdr *rth;
+		char *raw;
+	} exthdr = { .iph = iph };
+	char *end = exthdr.raw + len;
+	int nexthdr = iph->nexthdr;
+
+	exthdr.iph++;
+
+	while (exthdr.raw < end) {
+		switch (nexthdr) {
+		case NEXTHDR_HOP:
+		case NEXTHDR_DEST:
+			if (!zero_out_mutable_opts(exthdr.opth)) {
+				LIMIT_NETDEBUG(printk(
+					KERN_WARNING "overrun %sopts\n",
+					nexthdr == NEXTHDR_HOP ?
+						"hop" : "dest"));
+				return -EINVAL;
+			}
+			break;
+
+		case NEXTHDR_ROUTING:
+			ipv6_rearrange_rthdr(iph, exthdr.rth);
+			break;
+
+		default :
+			return 0;
+		}
+
+		nexthdr = exthdr.opth->nexthdr;
+		exthdr.raw += ipv6_optlen(exthdr.opth);
+	}
+
+	return 0;
+}
+
+static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+	int extlen;
+	struct ipv6hdr *top_iph;
+	struct ip_auth_hdr *ah;
+	struct ah_data *ahp;
+	u8 nexthdr;
+	char tmp_base[8];
+	struct {
+		struct in6_addr daddr;
+		char hdrs[0];
+	} *tmp_ext;
+
+	top_iph = (struct ipv6hdr *)skb->data;
+	top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
+
+	nexthdr = *skb->nh.raw;
+	*skb->nh.raw = IPPROTO_AH;
+
+	/* When there are no extension headers, we only need to save the first
+	 * 8 bytes of the base IP header.
+	 */
+	memcpy(tmp_base, top_iph, sizeof(tmp_base));
+
+	tmp_ext = NULL;
+	extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
+	if (extlen) {
+		extlen += sizeof(*tmp_ext);
+		tmp_ext = kmalloc(extlen, GFP_ATOMIC);
+		if (!tmp_ext) {
+			err = -ENOMEM;
+			goto error;
+		}
+		memcpy(tmp_ext, &top_iph->daddr, extlen);
+		err = ipv6_clear_mutable_options(top_iph,
+						 extlen - sizeof(*tmp_ext) +
+						 sizeof(*top_iph));
+		if (err)
+			goto error_free_iph;
+	}
+
+	ah = (struct ip_auth_hdr *)skb->h.raw;
+	ah->nexthdr = nexthdr;
+
+	top_iph->priority    = 0;
+	top_iph->flow_lbl[0] = 0;
+	top_iph->flow_lbl[1] = 0;
+	top_iph->flow_lbl[2] = 0;
+	top_iph->hop_limit   = 0;
+
+	ahp = x->data;
+	ah->hdrlen  = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + 
+				   ahp->icv_trunc_len) >> 2) - 2;
+
+	ah->reserved = 0;
+	ah->spi = x->id.spi;
+	ah->seq_no = htonl(++x->replay.oseq);
+	ahp->icv(ahp, skb, ah->auth_data);
+
+	err = 0;
+
+	memcpy(top_iph, tmp_base, sizeof(tmp_base));
+	if (tmp_ext) {
+		memcpy(&top_iph->daddr, tmp_ext, extlen);
+error_free_iph:
+		kfree(tmp_ext);
+	}
+
+error:
+	return err;
+}
+
+static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
+{
+	/*
+	 * Before process AH
+	 * [IPv6][Ext1][Ext2][AH][Dest][Payload]
+	 * |<-------------->| hdr_len
+	 *
+	 * To erase AH:
+	 * Keeping copy of cleared headers. After AH processing,
+	 * Moving the pointer of skb->nh.raw by using skb_pull as long as AH
+	 * header length. Then copy back the copy as long as hdr_len
+	 * If destination header following AH exists, copy it into after [Ext2].
+	 * 
+	 * |<>|[IPv6][Ext1][Ext2][Dest][Payload]
+	 * There is offset of AH before IPv6 header after the process.
+	 */
+
+	struct ipv6_auth_hdr *ah;
+	struct ah_data *ahp;
+	unsigned char *tmp_hdr = NULL;
+	u16 hdr_len;
+	u16 ah_hlen;
+	int nexthdr;
+
+	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
+		goto out;
+
+	/* We are going to _remove_ AH header to keep sockets happy,
+	 * so... Later this can change. */
+	if (skb_cloned(skb) &&
+	    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+		goto out;
+
+	hdr_len = skb->data - skb->nh.raw;
+	ah = (struct ipv6_auth_hdr*)skb->data;
+	ahp = x->data;
+	nexthdr = ah->nexthdr;
+	ah_hlen = (ah->hdrlen + 2) << 2;
+
+        if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
+            ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
+                goto out;
+
+	if (!pskb_may_pull(skb, ah_hlen))
+		goto out;
+
+	tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
+	if (!tmp_hdr)
+		goto out;
+	memcpy(tmp_hdr, skb->nh.raw, hdr_len);
+	if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
+		goto out;
+	skb->nh.ipv6h->priority    = 0;
+	skb->nh.ipv6h->flow_lbl[0] = 0;
+	skb->nh.ipv6h->flow_lbl[1] = 0;
+	skb->nh.ipv6h->flow_lbl[2] = 0;
+	skb->nh.ipv6h->hop_limit   = 0;
+
+        {
+		u8 auth_data[MAX_AH_AUTH_LEN];
+
+		memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
+		memset(ah->auth_data, 0, ahp->icv_trunc_len);
+		skb_push(skb, skb->data - skb->nh.raw);
+		ahp->icv(ahp, skb, ah->auth_data);
+		if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
+			LIMIT_NETDEBUG(
+				printk(KERN_WARNING "ipsec ah authentication error\n"));
+			x->stats.integrity_failed++;
+			goto free_out;
+		}
+	}
+
+	skb->nh.raw = skb_pull(skb, ah_hlen);
+	memcpy(skb->nh.raw, tmp_hdr, hdr_len);
+	skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
+	skb_pull(skb, hdr_len);
+	skb->h.raw = skb->data;
+
+
+	kfree(tmp_hdr);
+
+	return nexthdr;
+
+free_out:
+	kfree(tmp_hdr);
+out:
+	return -EINVAL;
+}
+
+static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
+                    int type, int code, int offset, __u32 info)
+{
+	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
+	struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
+	struct xfrm_state *x;
+
+	if (type != ICMPV6_DEST_UNREACH &&
+	    type != ICMPV6_PKT_TOOBIG)
+		return;
+
+	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
+	if (!x)
+		return;
+
+	NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
+			"%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
+	       ntohl(ah->spi), NIP6(iph->daddr)));
+
+	xfrm_state_put(x);
+}
+
+static int ah6_init_state(struct xfrm_state *x, void *args)
+{
+	struct ah_data *ahp = NULL;
+	struct xfrm_algo_desc *aalg_desc;
+
+	if (!x->aalg)
+		goto error;
+
+	/* null auth can use a zero length key */
+	if (x->aalg->alg_key_len > 512)
+		goto error;
+
+	if (x->encap)
+		goto error;
+
+	ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
+	if (ahp == NULL)
+		return -ENOMEM;
+
+	memset(ahp, 0, sizeof(*ahp));
+
+	ahp->key = x->aalg->alg_key;
+	ahp->key_len = (x->aalg->alg_key_len+7)/8;
+	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
+	if (!ahp->tfm)
+		goto error;
+	ahp->icv = ah_hmac_digest;
+	
+	/*
+	 * Lookup the algorithm description maintained by xfrm_algo,
+	 * verify crypto transform properties, and store information
+	 * we need for AH processing.  This lookup cannot fail here
+	 * after a successful crypto_alloc_tfm().
+	 */
+	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
+	BUG_ON(!aalg_desc);
+
+	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
+	    crypto_tfm_alg_digestsize(ahp->tfm)) {
+		printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
+		       x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
+		       aalg_desc->uinfo.auth.icv_fullbits/8);
+		goto error;
+	}
+	
+	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
+	ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
+	
+	BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
+	
+	ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
+	if (!ahp->work_icv)
+		goto error;
+	
+	x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len);
+	if (x->props.mode)
+		x->props.header_len += sizeof(struct ipv6hdr);
+	x->data = ahp;
+
+	return 0;
+
+error:
+	if (ahp) {
+		if (ahp->work_icv)
+			kfree(ahp->work_icv);
+		if (ahp->tfm)
+			crypto_free_tfm(ahp->tfm);
+		kfree(ahp);
+	}
+	return -EINVAL;
+}
+
+static void ah6_destroy(struct xfrm_state *x)
+{
+	struct ah_data *ahp = x->data;
+
+	if (!ahp)
+		return;
+
+	if (ahp->work_icv) {
+		kfree(ahp->work_icv);
+		ahp->work_icv = NULL;
+	}
+	if (ahp->tfm) {
+		crypto_free_tfm(ahp->tfm);
+		ahp->tfm = NULL;
+	}
+	kfree(ahp);
+}
+
+static struct xfrm_type ah6_type =
+{
+	.description	= "AH6",
+	.owner		= THIS_MODULE,
+	.proto	     	= IPPROTO_AH,
+	.init_state	= ah6_init_state,
+	.destructor	= ah6_destroy,
+	.input		= ah6_input,
+	.output		= ah6_output
+};
+
+static struct inet6_protocol ah6_protocol = {
+	.handler	=	xfrm6_rcv,
+	.err_handler	=	ah6_err,
+	.flags		=	INET6_PROTO_NOPOLICY,
+};
+
+static int __init ah6_init(void)
+{
+	if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
+		printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
+		return -EAGAIN;
+	}
+
+	if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
+		printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
+		xfrm_unregister_type(&ah6_type, AF_INET6);
+		return -EAGAIN;
+	}
+
+	return 0;
+}
+
+static void __exit ah6_fini(void)
+{
+	if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
+		printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
+
+	if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
+		printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
+
+}
+
+module_init(ah6_init);
+module_exit(ah6_fini);
+
+MODULE_LICENSE("GPL");