MFC r303012:

  Add ipfw_nptv6 module that implements Network Prefix Translation for IPv6
  as defined in RFC 6296. The module works together with ipfw(4) and
  implemented as its external action module. When it is loaded, it registers
  as eaction and can be used in rules. The usage pattern is similar to
  ipfw_nat(4). All matched by rule traffic goes to the NPT module.

  Reviewed by:	hrs
  Obtained from:	Yandex LLC
  Relnotes:	yes
  Sponsored by:	Yandex LLC
  Differential Revision:	https://reviews.freebsd.org/D6420

MFC r304049:
  Add `stats reset` command implementation to NPTv6 module
  to be able reset statistics counters.

  Obtained from:	Yandex LLC
  Sponsored by:	Yandex LLC

MFC r304076:
  Make statistics nat64lsn, nat64stl an nptv6 output netstat-like:
  "@value @description" and fix build due to -Wformat errors.

MFC r314507:
  Fix NPTv6 rule counters when one_pass is not enabled.

  Consider the rule matching when both @done and @retval values
  returned from ipfw_run_eaction() are zero. And modify ipfw_nptv6()
  to return IP_FW_DENY and @done=0 when addresses do not match.

  Obtained from:	Yandex LLC
  Sponsored by:	Yandex LLC

(cherry picked from commit f2b9d4d15428a360ba4692447f87aa3b7c7b4d83)

17 files changed, 1646 insertions, 0 deletions

diff --git a/sbin/ipfw/Makefile b/sbin/ipfw/Makefile
index 668f22a..54809b2 100644
--- a/sbin/ipfw/Makefile
+++ b/sbin/ipfw/Makefile
@@ -5,6 +5,7 @@
 PACKAGE=ipfw
 PROG=	ipfw
 SRCS=	ipfw2.c dummynet.c ipv6.c main.c nat.c tables.c
+SRCS+=	nptv6.c
 WARNS?=	2
 
 .if ${MK_PF} != "no"
diff --git a/sbin/ipfw/ipfw.8 b/sbin/ipfw/ipfw.8
index b3eba15..2035637 100644
--- a/sbin/ipfw/ipfw.8
+++ b/sbin/ipfw/ipfw.8
@@ -113,6 +113,19 @@ in-kernel NAT.
 .Oc
 .Oc
 .Ar pathname
+.Ss IPv6-to-IPv6 NETWORK PREFIX TRANSLATION
+.Nm
+.Oo Cm set Ar N Oc Cm nptv6 Ar name Cm create Ar create-options
+.Nm
+.Oo Cm set Ar N Oc Cm nptv6
+.Brq Ar name | all
+.Brq Cm list | show
+.Nm
+.Oo Cm set Ar N Oc Cm nptv6
+.Brq Ar name | all
+.Cm destroy
+.Nm
+.Oo Cm set Ar N Oc Cm nptv6 Ar name Cm stats Op Cm reset
 .Ss INTERNAL DIAGNOSTICS
 .Nm
 .Cm internal iflist
@@ -824,6 +837,11 @@ nat instance
 see the
 .Sx NETWORK ADDRESS TRANSLATION (NAT)
 Section for further information.
+.It Cm nptv6 Ar name
+Pass packet to a NPTv6 instance (for IPv6-to-IPv6 network prefix translation):
+see the
+.Sx IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
+Section for further information.
 .It Cm pipe Ar pipe_nr
 Pass packet to a
 .Nm dummynet
@@ -2909,6 +2927,47 @@ instances.
 See
 .Sx SYSCTL VARIABLES
 for more info.
+.Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
+.Nm
+support in-kernel IPv6-to-IPv6 network prefix translation as described
+in RFC6296.
+The kernel module
+.Cm ipfw_nptv6
+should be loaded or kernel should has
+.Cm options IPFIREWALL_NPTV6
+to be able use NPTv6 translator.
+.Pp
+The NPTv6 configuration command is the following:
+.Bd -ragged -offset indent
+.Bk -words
+.Cm nptv6
+.Ar name
+.Cm create
+.Ar create-options
+.Ek
+.Ed
+.Pp
+The following parameters can be configured:
+.Bl -tag -width indent
+.It Cm int_prefix Ar ipv6_prefix
+IPv6 prefix used in internal network.
+NPTv6 module translates source address when it matches this prefix.
+.It Cm ext_prefix Ar ipv6_prefix
+IPv6 prefix used in external network.
+NPTv6 module translates destination address when it matches this prefix.
+.It Cm prefixlen Ar length
+The length of specified IPv6 prefixes. It must be in range from 8 to 64.
+.El
+.Pp
+Note that the prefix translation rules are silently ignored when IPv6 packet
+forwarding is disabled.
+To enable the packet forwarding, set the sysctl variable
+.Va net.inet6.ip6.forwarding
+to 1.
+.Pp
+To let the packet continue after being translated, set the sysctl variable
+.Va net.inet.ip.fw.one_pass
+to 0.
 .Sh LOADER TUNABLES
 Tunables can be set in
 .Xr loader 8
diff --git a/sbin/ipfw/ipfw2.c b/sbin/ipfw/ipfw2.c
index faf7b97..0faff36 100644
--- a/sbin/ipfw/ipfw2.c
+++ b/sbin/ipfw/ipfw2.c
@@ -235,6 +235,7 @@ static struct _s_x ether_types[] = {
 };
 
 static struct _s_x rule_eactions[] = {
+	{ "nptv6",		TOK_NPTV6 },
 	{ NULL, 0 }	/* terminator */
 };
 
diff --git a/sbin/ipfw/ipfw2.h b/sbin/ipfw/ipfw2.h
index 3e90446..39b7dd9 100644
--- a/sbin/ipfw/ipfw2.h
+++ b/sbin/ipfw/ipfw2.h
@@ -254,6 +254,13 @@ enum tokens {
 	TOK_UNLOCK,
 	TOK_VLIST,
 	TOK_OLIST,
+	TOK_STATS,
+
+	/* NPTv6 tokens */
+	TOK_NPTV6,
+	TOK_INTPREFIX,
+	TOK_EXTPREFIX,
+	TOK_PREFIXLEN,
 };
 
 /*
@@ -342,6 +349,7 @@ void ipfw_flush(int force);
 void ipfw_zero(int ac, char *av[], int optname);
 void ipfw_list(int ac, char *av[], int show_counters);
 void ipfw_internal_handler(int ac, char *av[]);
+void ipfw_nptv6_handler(int ac, char *av[]);
 int ipfw_check_object_name(const char *name);
 
 #ifdef PF
diff --git a/sbin/ipfw/main.c b/sbin/ipfw/main.c
index f25578f..cb4168f 100644
--- a/sbin/ipfw/main.c
+++ b/sbin/ipfw/main.c
@@ -425,6 +425,8 @@ ipfw_main(int oldac, char **oldav)
 	if (co.use_set || try_next) {
 		if (_substrcmp(*av, "delete") == 0)
 			ipfw_delete(av);
+		else if (!strncmp(*av, "nptv6", strlen(*av)))
+			ipfw_nptv6_handler(ac, av);
 		else if (_substrcmp(*av, "flush") == 0)
 			ipfw_flush(co.do_force);
 		else if (_substrcmp(*av, "zero") == 0)
diff --git a/sbin/ipfw/nptv6.c b/sbin/ipfw/nptv6.c
new file mode 100644
index 0000000..6164d8b
--- /dev/null
+++ b/sbin/ipfw/nptv6.c
@@ -0,0 +1,430 @@
+/*-
+ * Copyright (c) 2016 Yandex LLC
+ * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/socket.h>
+
+#include "ipfw2.h"
+
+#include <ctype.h>
+#include <err.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netinet/ip_fw.h>
+#include <netinet6/ip_fw_nptv6.h>
+#include <arpa/inet.h>
+
+
+typedef int (nptv6_cb_t)(ipfw_nptv6_cfg *i, const char *name, uint8_t set);
+static int nptv6_foreach(nptv6_cb_t *f, const char *name, uint8_t set,
+    int sort);
+
+static void nptv6_create(const char *name, uint8_t set, int ac, char **av);
+static void nptv6_destroy(const char *name, uint8_t set);
+static void nptv6_stats(const char *name, uint8_t set);
+static void nptv6_reset_stats(const char *name, uint8_t set);
+static int nptv6_show_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set);
+static int nptv6_destroy_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set);
+
+static struct _s_x nptv6cmds[] = {
+      { "create",	TOK_CREATE },
+      { "destroy",	TOK_DESTROY },
+      { "list",		TOK_LIST },
+      { "show",		TOK_LIST },
+      { "stats",	TOK_STATS },
+      { NULL, 0 }
+};
+
+static struct _s_x nptv6statscmds[] = {
+      { "reset",	TOK_RESET },
+      { NULL, 0 }
+};
+
+/*
+ * This one handles all NPTv6-related commands
+ *	ipfw [set N] nptv6 NAME {create | config} ...
+ *	ipfw [set N] nptv6 NAME stats [reset]
+ *	ipfw [set N] nptv6 {NAME | all} destroy
+ *	ipfw [set N] nptv6 {NAME | all} {list | show}
+ */
+#define	nptv6_check_name	table_check_name
+void
+ipfw_nptv6_handler(int ac, char *av[])
+{
+	const char *name;
+	int tcmd;
+	uint8_t set;
+
+	if (co.use_set != 0)
+		set = co.use_set - 1;
+	else
+		set = 0;
+	ac--; av++;
+
+	NEED1("nptv6 needs instance name");
+	name = *av;
+	if (nptv6_check_name(name) != 0) {
+		if (strcmp(name, "all") == 0) {
+			name = NULL;
+		} else
+			errx(EX_USAGE, "nptv6 instance name %s is invalid",
+			    name);
+	}
+	ac--; av++;
+	NEED1("nptv6 needs command");
+
+	tcmd = get_token(nptv6cmds, *av, "nptv6 command");
+	if (name == NULL && tcmd != TOK_DESTROY && tcmd != TOK_LIST)
+		errx(EX_USAGE, "nptv6 instance name required");
+	switch (tcmd) {
+	case TOK_CREATE:
+		ac--; av++;
+		nptv6_create(name, set, ac, av);
+		break;
+	case TOK_LIST:
+		nptv6_foreach(nptv6_show_cb, name, set, 1);
+		break;
+	case TOK_DESTROY:
+		if (name == NULL)
+			nptv6_foreach(nptv6_destroy_cb, NULL, set, 0);
+		else
+			nptv6_destroy(name, set);
+		break;
+	case TOK_STATS:
+		ac--; av++;
+		if (ac == 0) {
+			nptv6_stats(name, set);
+			break;
+		}
+		tcmd = get_token(nptv6statscmds, *av, "stats command");
+		if (tcmd == TOK_RESET)
+			nptv6_reset_stats(name, set);
+	}
+}
+
+
+static void
+nptv6_fill_ntlv(ipfw_obj_ntlv *ntlv, const char *name, uint8_t set)
+{
+
+	ntlv->head.type = IPFW_TLV_EACTION_NAME(1); /* it doesn't matter */
+	ntlv->head.length = sizeof(ipfw_obj_ntlv);
+	ntlv->idx = 1;
+	ntlv->set = set;
+	strlcpy(ntlv->name, name, sizeof(ntlv->name));
+}
+
+static struct _s_x nptv6newcmds[] = {
+      { "int_prefix",	TOK_INTPREFIX },
+      { "ext_prefix",	TOK_EXTPREFIX },
+      { "prefixlen",	TOK_PREFIXLEN },
+      { NULL, 0 }
+};
+
+
+static void
+nptv6_parse_prefix(const char *arg, struct in6_addr *prefix, int *len)
+{
+	char *p, *l;
+
+	p = strdup(arg);
+	if (p == NULL)
+		err(EX_OSERR, NULL);
+	if ((l = strchr(p, '/')) != NULL)
+		*l++ = '\0';
+	if (inet_pton(AF_INET6, p, prefix) != 1)
+		errx(EX_USAGE, "Bad prefix: %s", p);
+	if (l != NULL) {
+		*len = (int)strtol(l, &l, 10);
+		if (*l != '\0' || *len <= 0 || *len > 64)
+			errx(EX_USAGE, "Bad prefix length: %s", arg);
+	} else
+		*len = 0;
+	free(p);
+}
+/*
+ * Creates new nptv6 instance
+ * ipfw nptv6 <NAME> create int_prefix <prefix> ext_prefix <prefix>
+ * Request: [ ipfw_obj_lheader ipfw_nptv6_cfg ]
+ */
+#define	NPTV6_HAS_INTPREFIX	0x01
+#define	NPTV6_HAS_EXTPREFIX	0x02
+#define	NPTV6_HAS_PREFIXLEN	0x04
+static void
+nptv6_create(const char *name, uint8_t set, int ac, char *av[])
+{
+	char buf[sizeof(ipfw_obj_lheader) + sizeof(ipfw_nptv6_cfg)];
+	struct in6_addr mask;
+	ipfw_nptv6_cfg *cfg;
+	ipfw_obj_lheader *olh;
+	int tcmd, flags, plen;
+	char *p = "\0";
+
+	plen = 0;
+	memset(buf, 0, sizeof(buf));
+	olh = (ipfw_obj_lheader *)buf;
+	cfg = (ipfw_nptv6_cfg *)(olh + 1);
+	cfg->set = set;
+	flags = 0;
+	while (ac > 0) {
+		tcmd = get_token(nptv6newcmds, *av, "option");
+		ac--; av++;
+
+		switch (tcmd) {
+		case TOK_INTPREFIX:
+			NEED1("IPv6 prefix required");
+			nptv6_parse_prefix(*av, &cfg->internal, &plen);
+			flags |= NPTV6_HAS_INTPREFIX;
+			if (plen > 0)
+				goto check_prefix;
+			ac--; av++;
+			break;
+		case TOK_EXTPREFIX:
+			NEED1("IPv6 prefix required");
+			nptv6_parse_prefix(*av, &cfg->external, &plen);
+			flags |= NPTV6_HAS_EXTPREFIX;
+			if (plen > 0)
+				goto check_prefix;
+			ac--; av++;
+			break;
+		case TOK_PREFIXLEN:
+			NEED1("IPv6 prefix length required");
+			plen = strtol(*av, &p, 10);
+check_prefix:
+			if (*p != '\0' || plen < 8 || plen > 64)
+				errx(EX_USAGE, "wrong prefix length: %s", *av);
+			/* RFC 6296 Sec. 3.1 */
+			if (cfg->plen > 0 && cfg->plen != plen) {
+				warnx("Prefix length mismatch (%d vs %d).  "
+				    "It was extended up to %d",
+				    cfg->plen, plen, MAX(plen, cfg->plen));
+				plen = MAX(plen, cfg->plen);
+			}
+			cfg->plen = plen;
+			flags |= NPTV6_HAS_PREFIXLEN;
+			ac--; av++;
+			break;
+		}
+	}
+
+	/* Check validness */
+	if ((flags & NPTV6_HAS_INTPREFIX) != NPTV6_HAS_INTPREFIX)
+		errx(EX_USAGE, "int_prefix required");
+	if ((flags & NPTV6_HAS_EXTPREFIX) != NPTV6_HAS_EXTPREFIX)
+		errx(EX_USAGE, "ext_prefix required");
+	if ((flags & NPTV6_HAS_PREFIXLEN) != NPTV6_HAS_PREFIXLEN)
+		errx(EX_USAGE, "prefixlen required");
+
+	n2mask(&mask, cfg->plen);
+	APPLY_MASK(&cfg->internal, &mask);
+	APPLY_MASK(&cfg->external, &mask);
+
+	olh->count = 1;
+	olh->objsize = sizeof(*cfg);
+	olh->size = sizeof(buf);
+	strlcpy(cfg->name, name, sizeof(cfg->name));
+	if (do_set3(IP_FW_NPTV6_CREATE, &olh->opheader, sizeof(buf)) != 0)
+		err(EX_OSERR, "nptv6 instance creation failed");
+}
+
+/*
+ * Destroys NPTv6 instance.
+ * Request: [ ipfw_obj_header ]
+ */
+static void
+nptv6_destroy(const char *name, uint8_t set)
+{
+	ipfw_obj_header oh;
+
+	memset(&oh, 0, sizeof(oh));
+	nptv6_fill_ntlv(&oh.ntlv, name, set);
+	if (do_set3(IP_FW_NPTV6_DESTROY, &oh.opheader, sizeof(oh)) != 0)
+		err(EX_OSERR, "failed to destroy nat instance %s", name);
+}
+
+/*
+ * Get NPTv6 instance statistics.
+ * Request: [ ipfw_obj_header ]
+ * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ] ]
+ */
+static int
+nptv6_get_stats(const char *name, uint8_t set, struct ipfw_nptv6_stats *stats)
+{
+	ipfw_obj_header *oh;
+	ipfw_obj_ctlv *oc;
+	size_t sz;
+
+	sz = sizeof(*oh) + sizeof(*oc) + sizeof(*stats);
+	oh = calloc(1, sz);
+	nptv6_fill_ntlv(&oh->ntlv, name, set);
+	if (do_get3(IP_FW_NPTV6_STATS, &oh->opheader, &sz) == 0) {
+		oc = (ipfw_obj_ctlv *)(oh + 1);
+		memcpy(stats, oc + 1, sizeof(*stats));
+		free(oh);
+		return (0);
+	}
+	free(oh);
+	return (-1);
+}
+
+static void
+nptv6_stats(const char *name, uint8_t set)
+{
+	struct ipfw_nptv6_stats stats;
+
+	if (nptv6_get_stats(name, set, &stats) != 0)
+		err(EX_OSERR, "Error retrieving stats");
+
+	if (co.use_set != 0 || set != 0)
+		printf("set %u ", set);
+	printf("nptv6 %s\n", name);
+	printf("\t%ju packets translated (internal to external)\n",
+	    (uintmax_t)stats.in2ex);
+	printf("\t%ju packets translated (external to internal)\n",
+	    (uintmax_t)stats.ex2in);
+	printf("\t%ju packets dropped due to some error\n",
+	    (uintmax_t)stats.dropped);
+}
+
+/*
+ * Reset NPTv6 instance statistics specified by @oh->ntlv.
+ * Request: [ ipfw_obj_header ]
+ */
+static void
+nptv6_reset_stats(const char *name, uint8_t set)
+{
+	ipfw_obj_header oh;
+
+	memset(&oh, 0, sizeof(oh));
+	nptv6_fill_ntlv(&oh.ntlv, name, set);
+	if (do_set3(IP_FW_NPTV6_RESET_STATS, &oh.opheader, sizeof(oh)) != 0)
+		err(EX_OSERR, "failed to reset stats for instance %s", name);
+}
+
+static int
+nptv6_show_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set)
+{
+	char abuf[INET6_ADDRSTRLEN];
+
+	if (name != NULL && strcmp(cfg->name, name) != 0)
+		return (ESRCH);
+
+	if (co.use_set != 0 && cfg->set != set)
+		return (ESRCH);
+
+	if (co.use_set != 0 || cfg->set != 0)
+		printf("set %u ", cfg->set);
+	inet_ntop(AF_INET6, &cfg->internal, abuf, sizeof(abuf));
+	printf("nptv6 %s int_prefix %s ", cfg->name, abuf);
+	inet_ntop(AF_INET6, &cfg->external, abuf, sizeof(abuf));
+	printf("ext_prefix %s prefixlen %u\n", abuf, cfg->plen);
+	return (0);
+}
+
+static int
+nptv6_destroy_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set)
+{
+
+	if (co.use_set != 0 && cfg->set != set)
+		return (ESRCH);
+
+	nptv6_destroy(cfg->name, cfg->set);
+	return (0);
+}
+
+
+/*
+ * Compare NPTv6 instances names.
+ * Honor number comparison.
+ */
+static int
+nptv6name_cmp(const void *a, const void *b)
+{
+	ipfw_nptv6_cfg *ca, *cb;
+
+	ca = (ipfw_nptv6_cfg *)a;
+	cb = (ipfw_nptv6_cfg *)b;
+
+	if (ca->set > cb->set)
+		return (1);
+	else if (ca->set < cb->set)
+		return (-1);
+	return (stringnum_cmp(ca->name, cb->name));
+}
+
+/*
+ * Retrieves NPTv6 instance list from kernel,
+ * Request: [ ipfw_obj_lheader ]
+ * Reply: [ ipfw_obj_lheader ipfw_nptv6_cfg x N ]
+ */
+static int
+nptv6_foreach(nptv6_cb_t *f, const char *name, uint8_t set, int sort)
+{
+	ipfw_obj_lheader *olh;
+	ipfw_nptv6_cfg *cfg;
+	size_t sz;
+	int i, error;
+
+	/* Start with reasonable default */
+	sz = sizeof(*olh) + 16 * sizeof(*cfg);
+	for (;;) {
+		if ((olh = calloc(1, sz)) == NULL)
+			return (ENOMEM);
+
+		olh->size = sz;
+		if (do_get3(IP_FW_NPTV6_LIST, &olh->opheader, &sz) != 0) {
+			sz = olh->size;
+			free(olh);
+			if (errno != ENOMEM)
+				return (errno);
+			continue;
+		}
+
+		if (sort != 0)
+			qsort(olh + 1, olh->count, olh->objsize, nptv6name_cmp);
+
+		cfg = (ipfw_nptv6_cfg *)(olh + 1);
+		for (i = 0; i < olh->count; i++) {
+			error = f(cfg, name, set);
+			cfg = (ipfw_nptv6_cfg *)((caddr_t)cfg + olh->objsize);
+		}
+		free(olh);
+		break;
+	}
+	return (0);
+}
+
diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index 837cf71..00cdd65 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -965,6 +965,8 @@ device		lagg
 # IPFIREWALL_NAT adds support for in kernel nat in ipfw, and it requires
 # LIBALIAS.
 #
+# IPFIREWALL_NPTV6 adds support for in kernel NPTv6 in ipfw.
+#
 # IPSTEALTH enables code to support stealth forwarding (i.e., forwarding
 # packets without touching the TTL).  This can be useful to hide firewalls
 # from traceroute and similar tools.
@@ -986,6 +988,7 @@ options 	IPFIREWALL_VERBOSE	#enable logging to syslogd(8)
 options 	IPFIREWALL_VERBOSE_LIMIT=100	#limit verbosity
 options 	IPFIREWALL_DEFAULT_TO_ACCEPT	#allow everything by default
 options 	IPFIREWALL_NAT		#ipfw kernel nat support
+options 	IPFIREWALL_NPTV6	#ipfw kernel IPv6 NPT support
 options 	IPDIVERT		#divert sockets
 options 	IPFILTER		#ipfilter support
 options 	IPFILTER_LOG		#ipfilter logging
diff --git a/sys/conf/files b/sys/conf/files
index 41a23af..e13e374 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -3879,6 +3879,10 @@ netpfil/ipfw/ip_fw_table_algo.c	optional inet ipfirewall
 netpfil/ipfw/ip_fw_table_value.c	optional inet ipfirewall
 netpfil/ipfw/ip_fw_iface.c	optional inet ipfirewall
 netpfil/ipfw/ip_fw_nat.c	optional inet ipfirewall_nat
+netpfil/ipfw/nptv6/ip_fw_nptv6.c	optional inet inet6 ipfirewall \
+	ipfirewall_nptv6
+netpfil/ipfw/nptv6/nptv6.c	optional inet inet6 ipfirewall \
+	ipfirewall_nptv6
 netpfil/pf/if_pflog.c		optional pflog pf inet
 netpfil/pf/if_pfsync.c		optional pfsync pf inet
 netpfil/pf/pf.c			optional pf inet
diff --git a/sys/conf/options b/sys/conf/options
index ba410ee..d54bff2 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -417,6 +417,7 @@ IPFILTER_LOOKUP		opt_ipfilter.h
 IPFIREWALL		opt_ipfw.h
 IPFIREWALL_DEFAULT_TO_ACCEPT	opt_ipfw.h
 IPFIREWALL_NAT		opt_ipfw.h
+IPFIREWALL_NPTV6	opt_ipfw.h
 IPFIREWALL_VERBOSE	opt_ipfw.h
 IPFIREWALL_VERBOSE_LIMIT	opt_ipfw.h
 IPSEC			opt_ipsec.h
diff --git a/sys/modules/Makefile b/sys/modules/Makefile
index 87cd84d..71bc99c 100644
--- a/sys/modules/Makefile
+++ b/sys/modules/Makefile
@@ -167,6 +167,7 @@ SUBDIR=	\
 	${_ipfilter} \
 	${_ipfw} \
 	ipfw_nat \
+	${_ipfw_nptv6} \
 	${_ipmi} \
 	ip6_mroute_mod \
 	ip_mroute_mod \
@@ -460,6 +461,10 @@ _ipdivert=	ipdivert
 _ipfw=		ipfw
 .endif
 
+.if ${MK_INET6_SUPPORT} != "no" || defined(ALL_MODULES)
+_ipfw_nptv6=	ipfw_nptv6
+.endif
+
 .if ${MK_IPFILTER} != "no" || defined(ALL_MODULES)
 _ipfilter=	ipfilter
 .endif
diff --git a/sys/modules/ipfw_nptv6/Makefile b/sys/modules/ipfw_nptv6/Makefile
new file mode 100644
index 0000000..a3cf004
--- /dev/null
+++ b/sys/modules/ipfw_nptv6/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../../netpfil/ipfw/nptv6
+
+KMOD=	ipfw_nptv6
+SRCS=	ip_fw_nptv6.c nptv6.c opt_ipfw.h
+
+.include <bsd.kmod.mk>
diff --git a/sys/netinet/ip_fw.h b/sys/netinet/ip_fw.h
index 843c0cb..6e65c70 100644
--- a/sys/netinet/ip_fw.h
+++ b/sys/netinet/ip_fw.h
@@ -110,6 +110,13 @@ typedef struct _ip_fw3_opheader {
 #define	IP_FW_DUMP_SOPTCODES	116	/* Dump available sopts/versions */
 #define	IP_FW_DUMP_SRVOBJECTS	117	/* Dump existing named objects */
 
+#define	IP_FW_NPTV6_CREATE	150	/* Create NPTv6 instance */
+#define	IP_FW_NPTV6_DESTROY	151	/* Destroy NPTv6 instance */
+#define	IP_FW_NPTV6_CONFIG	152	/* Modify NPTv6 instance */
+#define	IP_FW_NPTV6_LIST	153	/* List NPTv6 instances */
+#define	IP_FW_NPTV6_STATS	154	/* Get NPTv6 instance statistics */
+#define	IP_FW_NPTV6_RESET_STATS	155	/* Reset NPTv6 instance statistics */
+
 /*
  * The kernel representation of ipfw rules is made of a list of
  * 'instructions' (for all practical purposes equivalent to BPF
@@ -788,6 +795,7 @@ typedef struct  _ipfw_obj_tlv {
 #define	IPFW_TLV_TBLENT_LIST	8
 #define	IPFW_TLV_RANGE		9
 #define	IPFW_TLV_EACTION	10
+#define	IPFW_TLV_COUNTERS	11
 #define	IPFW_TLV_STATE_NAME	14
 
 #define	IPFW_TLV_EACTION_BASE	1000
diff --git a/sys/netinet6/ip_fw_nptv6.h b/sys/netinet6/ip_fw_nptv6.h
new file mode 100644
index 0000000..e2357ef
--- /dev/null
+++ b/sys/netinet6/ip_fw_nptv6.h
@@ -0,0 +1,51 @@
+/*-
+ * Copyright (c) 2016 Yandex LLC
+ * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_NETINET6_IP_FW_NPTV6_H_
+#define	_NETINET6_IP_FW_NPTV6_H_
+
+struct ipfw_nptv6_stats {
+	uint64_t	in2ex;		/* Int->Ext packets translated */
+	uint64_t	ex2in;		/* Ext->Int packets translated */
+	uint64_t	dropped;	/* dropped due to some errors */
+	uint64_t	reserved[5];
+};
+
+typedef struct _ipfw_nptv6_cfg {
+	char		name[64];	/* NPTv6 instance name */
+	struct in6_addr	internal;	/* NPTv6 internal prefix */
+	struct in6_addr	external;	/* NPTv6 external prefix */
+	uint8_t		plen;		/* Prefix length */
+	uint8_t		set;		/* Named instance set [0..31] */
+	uint8_t		spare[2];
+	uint32_t	flags;
+} ipfw_nptv6_cfg;
+
+#endif /* _NETINET6_IP_FW_NPTV6_H_ */
+
diff --git a/sys/netpfil/ipfw/ip_fw2.c b/sys/netpfil/ipfw/ip_fw2.c
index 1c45b84..5054d7b 100644
--- a/sys/netpfil/ipfw/ip_fw2.c
+++ b/sys/netpfil/ipfw/ip_fw2.c
@@ -2619,6 +2619,13 @@ do {								\
 				l = 0; /* in any case exit inner loop */
 				retval = ipfw_run_eaction(chain, args,
 				    cmd, &done);
+				/*
+				 * If both @retval and @done are zero,
+				 * consider this as rule matching and
+				 * update counters.
+				 */
+				if (retval == 0 && done == 0)
+					IPFW_INC_RULE_COUNTER(f, pktlen);
 				break;
 
 			default:
diff --git a/sys/netpfil/ipfw/nptv6/ip_fw_nptv6.c b/sys/netpfil/ipfw/nptv6/ip_fw_nptv6.c
new file mode 100644
index 0000000..ec63ad0
--- /dev/null
+++ b/sys/netpfil/ipfw/nptv6/ip_fw_nptv6.c
@@ -0,0 +1,99 @@
+/*-
+ * Copyright (c) 2016 Yandex LLC
+ * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/rwlock.h>
+#include <sys/socket.h>
+
+#include <net/if.h>
+#include <net/vnet.h>
+
+#include <netinet/in.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_fw.h>
+
+#include <netpfil/ipfw/ip_fw_private.h>
+#include <netpfil/ipfw/nptv6/nptv6.h>
+
+static int
+vnet_ipfw_nptv6_init(const void *arg __unused)
+{
+
+	return (nptv6_init(&V_layer3_chain, IS_DEFAULT_VNET(curvnet)));
+}
+
+static int
+vnet_ipfw_nptv6_uninit(const void *arg __unused)
+{
+
+	nptv6_uninit(&V_layer3_chain, IS_DEFAULT_VNET(curvnet));
+	return (0);
+}
+
+static int
+ipfw_nptv6_modevent(module_t mod, int type, void *unused)
+{
+
+	switch (type) {
+	case MOD_LOAD:
+	case MOD_UNLOAD:
+		break;
+	default:
+		return (EOPNOTSUPP);
+	}
+	return (0);
+}
+
+static moduledata_t ipfw_nptv6_mod = {
+	"ipfw_nptv6",
+	ipfw_nptv6_modevent,
+	0
+};
+
+/* Define startup order. */
+#define	IPFW_NPTV6_SI_SUB_FIREWALL	SI_SUB_PROTO_IFATTACHDOMAIN
+#define	IPFW_NPTV6_MODEVENT_ORDER	(SI_ORDER_ANY - 128) /* after ipfw */
+#define	IPFW_NPTV6_MODULE_ORDER		(IPFW_NPTV6_MODEVENT_ORDER + 1)
+#define	IPFW_NPTV6_VNET_ORDER		(IPFW_NPTV6_MODEVENT_ORDER + 2)
+
+DECLARE_MODULE(ipfw_nptv6, ipfw_nptv6_mod, IPFW_NPTV6_SI_SUB_FIREWALL,
+    IPFW_NPTV6_MODULE_ORDER);
+MODULE_DEPEND(ipfw_nptv6, ipfw, 3, 3, 3);
+MODULE_VERSION(ipfw_nptv6, 1);
+
+VNET_SYSINIT(vnet_ipfw_nptv6_init, IPFW_NPTV6_SI_SUB_FIREWALL,
+    IPFW_NPTV6_VNET_ORDER, vnet_ipfw_nptv6_init, NULL);
+VNET_SYSUNINIT(vnet_ipfw_nptv6_uninit, IPFW_NPTV6_SI_SUB_FIREWALL,
+    IPFW_NPTV6_VNET_ORDER, vnet_ipfw_nptv6_uninit, NULL);
diff --git a/sys/netpfil/ipfw/nptv6/nptv6.c b/sys/netpfil/ipfw/nptv6/nptv6.c
new file mode 100644
index 0000000..da86975
--- /dev/null
+++ b/sys/netpfil/ipfw/nptv6/nptv6.c
@@ -0,0 +1,894 @@
+/*-
+ * Copyright (c) 2016 Yandex LLC
+ * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/counter.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/rmlock.h>
+#include <sys/rwlock.h>
+#include <sys/socket.h>
+#include <sys/queue.h>
+#include <sys/syslog.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/netisr.h>
+#include <net/pfil.h>
+#include <net/vnet.h>
+
+#include <netinet/in.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_fw.h>
+#include <netinet/ip6.h>
+#include <netinet/icmp6.h>
+#include <netinet6/in6_var.h>
+#include <netinet6/ip6_var.h>
+
+#include <netpfil/ipfw/ip_fw_private.h>
+#include <netpfil/ipfw/nptv6/nptv6.h>
+
+static VNET_DEFINE(uint16_t, nptv6_eid) = 0;
+#define	V_nptv6_eid	VNET(nptv6_eid)
+#define	IPFW_TLV_NPTV6_NAME	IPFW_TLV_EACTION_NAME(V_nptv6_eid)
+
+static struct nptv6_cfg *nptv6_alloc_config(const char *name, uint8_t set);
+static void nptv6_free_config(struct nptv6_cfg *cfg);
+static struct nptv6_cfg *nptv6_find(struct namedobj_instance *ni,
+    const char *name, uint8_t set);
+static int nptv6_rewrite_internal(struct nptv6_cfg *cfg, struct mbuf **mp,
+    int offset);
+static int nptv6_rewrite_external(struct nptv6_cfg *cfg, struct mbuf **mp,
+    int offset);
+
+#define	NPTV6_LOOKUP(chain, cmd)	\
+    (struct nptv6_cfg *)SRV_OBJECT((chain), (cmd)->arg1)
+
+#ifndef IN6_MASK_ADDR
+#define IN6_MASK_ADDR(a, m)	do { \
+	(a)->s6_addr32[0] &= (m)->s6_addr32[0]; \
+	(a)->s6_addr32[1] &= (m)->s6_addr32[1]; \
+	(a)->s6_addr32[2] &= (m)->s6_addr32[2]; \
+	(a)->s6_addr32[3] &= (m)->s6_addr32[3]; \
+} while (0)
+#endif
+#ifndef IN6_ARE_MASKED_ADDR_EQUAL
+#define IN6_ARE_MASKED_ADDR_EQUAL(d, a, m)	(	\
+	(((d)->s6_addr32[0] ^ (a)->s6_addr32[0]) & (m)->s6_addr32[0]) == 0 && \
+	(((d)->s6_addr32[1] ^ (a)->s6_addr32[1]) & (m)->s6_addr32[1]) == 0 && \
+	(((d)->s6_addr32[2] ^ (a)->s6_addr32[2]) & (m)->s6_addr32[2]) == 0 && \
+	(((d)->s6_addr32[3] ^ (a)->s6_addr32[3]) & (m)->s6_addr32[3]) == 0 )
+#endif
+
+#if 0
+#define	NPTV6_DEBUG(fmt, ...)	do {			\
+	printf("%s: " fmt "\n", __func__, ## __VA_ARGS__);	\
+} while (0)
+#define	NPTV6_IPDEBUG(fmt, ...)	do {			\
+	char _s[INET6_ADDRSTRLEN], _d[INET6_ADDRSTRLEN];	\
+	printf("%s: " fmt "\n", __func__, ## __VA_ARGS__);	\
+} while (0)
+#else
+#define	NPTV6_DEBUG(fmt, ...)
+#define	NPTV6_IPDEBUG(fmt, ...)
+#endif
+
+static int
+nptv6_getlasthdr(struct nptv6_cfg *cfg, struct mbuf *m, int *offset)
+{
+	struct ip6_hdr *ip6;
+	struct ip6_hbh *hbh;
+	int proto, hlen;
+
+	hlen = (offset == NULL) ? 0: *offset;
+	if (m->m_len < hlen)
+		return (-1);
+	ip6 = mtodo(m, hlen);
+	hlen += sizeof(*ip6);
+	proto = ip6->ip6_nxt;
+	while (proto == IPPROTO_HOPOPTS || proto == IPPROTO_ROUTING ||
+	    proto == IPPROTO_DSTOPTS) {
+		hbh = mtodo(m, hlen);
+		if (m->m_len < hlen)
+			return (-1);
+		proto = hbh->ip6h_nxt;
+		hlen += hbh->ip6h_len << 3;
+	}
+	if (offset != NULL)
+		*offset = hlen;
+	return (proto);
+}
+
+static int
+nptv6_translate_icmpv6(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
+{
+	struct icmp6_hdr *icmp6;
+	struct ip6_hdr *ip6;
+	struct mbuf *m;
+
+	m = *mp;
+	if (offset > m->m_len)
+		return (-1);
+	icmp6 = mtodo(m, offset);
+	NPTV6_DEBUG("ICMPv6 type %d", icmp6->icmp6_type);
+	switch (icmp6->icmp6_type) {
+	case ICMP6_DST_UNREACH:
+	case ICMP6_PACKET_TOO_BIG:
+	case ICMP6_TIME_EXCEEDED:
+	case ICMP6_PARAM_PROB:
+		break;
+	case ICMP6_ECHO_REQUEST:
+	case ICMP6_ECHO_REPLY:
+		/* nothing to translate */
+		return (0);
+	default:
+		/*
+		 * XXX: We can add some checks to not translate NDP and MLD
+		 * messages. Currently user must explicitly allow these message
+		 * types, otherwise packets will be dropped.
+		 */
+		return (-1);
+	}
+	offset += sizeof(*icmp6);
+	if (offset + sizeof(*ip6) > m->m_pkthdr.len)
+		return (-1);
+	if (offset + sizeof(*ip6) > m->m_len)
+		*mp = m = m_pullup(m, offset + sizeof(*ip6));
+	if (m == NULL)
+		return (-1);
+	ip6 = mtodo(m, offset);
+	NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
+	    inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
+	    inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
+	    ip6->ip6_nxt);
+	if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_src,
+	    &cfg->external, &cfg->mask))
+		return (nptv6_rewrite_external(cfg, mp, offset));
+	else if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
+	    &cfg->internal, &cfg->mask))
+		return (nptv6_rewrite_internal(cfg, mp, offset));
+	/*
+	 * Addresses in the inner IPv6 header doesn't matched to
+	 * our prefixes.
+	 */
+	return (-1);
+}
+
+static int
+nptv6_search_index(struct nptv6_cfg *cfg, struct in6_addr *a)
+{
+	int idx;
+
+	if (cfg->flags & NPTV6_48PLEN)
+		return (3);
+
+	/* Search suitable word index for adjustment */
+	for (idx = 4; idx < 8; idx++)
+		if (a->s6_addr16[idx] != 0xffff)
+			break;
+	/*
+	 * RFC 6296 p3.7: If an NPTv6 Translator discovers a datagram with
+	 * an IID of all-zeros while performing address mapping, that
+	 * datagram MUST be dropped, and an ICMPv6 Parameter Problem error
+	 * SHOULD be generated.
+	 */
+	if (idx == 8 ||
+	    (a->s6_addr32[2] == 0 && a->s6_addr32[3] == 0))
+		return (-1);
+	return (idx);
+}
+
+static void
+nptv6_copy_addr(struct in6_addr *src, struct in6_addr *dst,
+    struct in6_addr *mask)
+{
+	int i;
+
+	for (i = 0; i < 8 && mask->s6_addr8[i] != 0; i++) {
+		dst->s6_addr8[i] &=  ~mask->s6_addr8[i];
+		dst->s6_addr8[i] |= src->s6_addr8[i] & mask->s6_addr8[i];
+	}
+}
+
+static int
+nptv6_rewrite_internal(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
+{
+	struct in6_addr *addr;
+	struct ip6_hdr *ip6;
+	int idx, proto;
+	uint16_t adj;
+
+	ip6 = mtodo(*mp, offset);
+	NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
+	    inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
+	    inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
+	    ip6->ip6_nxt);
+	if (offset == 0)
+		addr = &ip6->ip6_src;
+	else {
+		/*
+		 * When we rewriting inner IPv6 header, we need to rewrite
+		 * destination address back to external prefix. The datagram in
+		 * the ICMPv6 payload should looks like it was send from
+		 * external prefix.
+		 */
+		addr = &ip6->ip6_dst;
+	}
+	idx = nptv6_search_index(cfg, addr);
+	if (idx < 0) {
+		/*
+		 * Do not send ICMPv6 error when offset isn't zero.
+		 * This means we are rewriting inner IPv6 header in the
+		 * ICMPv6 error message.
+		 */
+		if (offset == 0) {
+			icmp6_error2(*mp, ICMP6_DST_UNREACH,
+			    ICMP6_DST_UNREACH_ADDR, 0, (*mp)->m_pkthdr.rcvif);
+			*mp = NULL;
+		}
+		return (IP_FW_DENY);
+	}
+	adj = addr->s6_addr16[idx];
+	nptv6_copy_addr(&cfg->external, addr, &cfg->mask);
+	adj = cksum_add(adj, cfg->adjustment);
+	if (adj == 0xffff)
+		adj = 0;
+	addr->s6_addr16[idx] = adj;
+	if (offset == 0) {
+		/*
+		 * We may need to translate addresses in the inner IPv6
+		 * header for ICMPv6 error messages.
+		 */
+		proto = nptv6_getlasthdr(cfg, *mp, &offset);
+		if (proto < 0 || (proto == IPPROTO_ICMPV6 &&
+		    nptv6_translate_icmpv6(cfg, mp, offset) != 0))
+			return (IP_FW_DENY);
+		NPTV6STAT_INC(cfg, in2ex);
+	}
+	return (0);
+}
+
+static int
+nptv6_rewrite_external(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
+{
+	struct in6_addr *addr;
+	struct ip6_hdr *ip6;
+	int idx, proto;
+	uint16_t adj;
+
+	ip6 = mtodo(*mp, offset);
+	NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
+	    inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
+	    inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
+	    ip6->ip6_nxt);
+	if (offset == 0)
+		addr = &ip6->ip6_dst;
+	else {
+		/*
+		 * When we rewriting inner IPv6 header, we need to rewrite
+		 * source address back to internal prefix. The datagram in
+		 * the ICMPv6 payload should looks like it was send from
+		 * internal prefix.
+		 */
+		addr = &ip6->ip6_src;
+	}
+	idx = nptv6_search_index(cfg, addr);
+	if (idx < 0) {
+		/*
+		 * Do not send ICMPv6 error when offset isn't zero.
+		 * This means we are rewriting inner IPv6 header in the
+		 * ICMPv6 error message.
+		 */
+		if (offset == 0) {
+			icmp6_error2(*mp, ICMP6_DST_UNREACH,
+			    ICMP6_DST_UNREACH_ADDR, 0, (*mp)->m_pkthdr.rcvif);
+			*mp = NULL;
+		}
+		return (IP_FW_DENY);
+	}
+	adj = addr->s6_addr16[idx];
+	nptv6_copy_addr(&cfg->internal, addr, &cfg->mask);
+	adj = cksum_add(adj, ~cfg->adjustment);
+	if (adj == 0xffff)
+		adj = 0;
+	addr->s6_addr16[idx] = adj;
+	if (offset == 0) {
+		/*
+		 * We may need to translate addresses in the inner IPv6
+		 * header for ICMPv6 error messages.
+		 */
+		proto = nptv6_getlasthdr(cfg, *mp, &offset);
+		if (proto < 0 || (proto == IPPROTO_ICMPV6 &&
+		    nptv6_translate_icmpv6(cfg, mp, offset) != 0))
+			return (IP_FW_DENY);
+		NPTV6STAT_INC(cfg, ex2in);
+	}
+	return (0);
+}
+
+/*
+ * ipfw external action handler.
+ */
+static int
+ipfw_nptv6(struct ip_fw_chain *chain, struct ip_fw_args *args,
+    ipfw_insn *cmd, int *done)
+{
+	struct ip6_hdr *ip6;
+	struct nptv6_cfg *cfg;
+	ipfw_insn *icmd;
+	int ret;
+
+	*done = 0; /* try next rule if not matched */
+	ret = IP_FW_DENY;
+	icmd = cmd + 1;
+	if (cmd->opcode != O_EXTERNAL_ACTION ||
+	    cmd->arg1 != V_nptv6_eid ||
+	    icmd->opcode != O_EXTERNAL_INSTANCE ||
+	    (cfg = NPTV6_LOOKUP(chain, icmd)) == NULL)
+		return (ret);
+	/*
+	 * We need act as router, so when forwarding is disabled -
+	 * do nothing.
+	 */
+	if (V_ip6_forwarding == 0 || args->f_id.addr_type != 6)
+		return (ret);
+	/*
+	 * NOTE: we expect ipfw_chk() did m_pullup() up to upper level
+	 * protocol's headers. Also we skip some checks, that ip6_input(),
+	 * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did.
+	 */
+	ip6 = mtod(args->m, struct ip6_hdr *);
+	NPTV6_IPDEBUG("eid %u, oid %u, %s -> %s %d",
+	    cmd->arg1, icmd->arg1,
+	    inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
+	    inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
+	    ip6->ip6_nxt);
+	if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_src,
+	    &cfg->internal, &cfg->mask)) {
+		/*
+		 * XXX: Do not translate packets when both src and dst
+		 * are from internal prefix.
+		 */
+		if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
+		    &cfg->internal, &cfg->mask))
+			return (ret);
+		ret = nptv6_rewrite_internal(cfg, &args->m, 0);
+	} else if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
+	    &cfg->external, &cfg->mask))
+		ret = nptv6_rewrite_external(cfg, &args->m, 0);
+	else
+		return (ret);
+	/*
+	 * If address wasn't rewrited - free mbuf and terminate the search.
+	 */
+	if (ret != 0) {
+		if (args->m != NULL) {
+			m_freem(args->m);
+			args->m = NULL; /* mark mbuf as consumed */
+		}
+		NPTV6STAT_INC(cfg, dropped);
+		*done = 1;
+	} else {
+		/* Terminate the search if one_pass is set */
+		*done = V_fw_one_pass;
+		/* Update args->f_id when one_pass is off */
+		if (*done == 0) {
+			ip6 = mtod(args->m, struct ip6_hdr *);
+			args->f_id.src_ip6 = ip6->ip6_src;
+			args->f_id.dst_ip6 = ip6->ip6_dst;
+		}
+	}
+	return (ret);
+}
+
+static struct nptv6_cfg *
+nptv6_alloc_config(const char *name, uint8_t set)
+{
+	struct nptv6_cfg *cfg;
+
+	cfg = malloc(sizeof(struct nptv6_cfg), M_IPFW, M_WAITOK | M_ZERO);
+	COUNTER_ARRAY_ALLOC(cfg->stats, NPTV6STATS, M_WAITOK);
+	cfg->no.name = cfg->name;
+	cfg->no.etlv = IPFW_TLV_NPTV6_NAME;
+	cfg->no.set = set;
+	strlcpy(cfg->name, name, sizeof(cfg->name));
+	return (cfg);
+}
+
+static void
+nptv6_free_config(struct nptv6_cfg *cfg)
+{
+
+	COUNTER_ARRAY_FREE(cfg->stats, NPTV6STATS);
+	free(cfg, M_IPFW);
+}
+
+static void
+nptv6_export_config(struct ip_fw_chain *ch, struct nptv6_cfg *cfg,
+    ipfw_nptv6_cfg *uc)
+{
+
+	uc->internal = cfg->internal;
+	uc->external = cfg->external;
+	uc->plen = cfg->plen;
+	uc->flags = cfg->flags & NPTV6_FLAGSMASK;
+	uc->set = cfg->no.set;
+	strlcpy(uc->name, cfg->no.name, sizeof(uc->name));
+}
+
+struct nptv6_dump_arg {
+	struct ip_fw_chain *ch;
+	struct sockopt_data *sd;
+};
+
+static int
+export_config_cb(struct namedobj_instance *ni, struct named_object *no,
+    void *arg)
+{
+	struct nptv6_dump_arg *da = (struct nptv6_dump_arg *)arg;
+	ipfw_nptv6_cfg *uc;
+
+	uc = (ipfw_nptv6_cfg *)ipfw_get_sopt_space(da->sd, sizeof(*uc));
+	nptv6_export_config(da->ch, (struct nptv6_cfg *)no, uc);
+	return (0);
+}
+
+static struct nptv6_cfg *
+nptv6_find(struct namedobj_instance *ni, const char *name, uint8_t set)
+{
+	struct nptv6_cfg *cfg;
+
+	cfg = (struct nptv6_cfg *)ipfw_objhash_lookup_name_type(ni, set,
+	    IPFW_TLV_NPTV6_NAME, name);
+
+	return (cfg);
+}
+
+static void
+nptv6_calculate_adjustment(struct nptv6_cfg *cfg)
+{
+	uint16_t i, e;
+	uint16_t *p;
+
+	/* Calculate checksum of internal prefix */
+	for (i = 0, p = (uint16_t *)&cfg->internal;
+	    p < (uint16_t *)(&cfg->internal + 1); p++)
+		i = cksum_add(i, *p);
+
+	/* Calculate checksum of external prefix */
+	for (e = 0, p = (uint16_t *)&cfg->external;
+	    p < (uint16_t *)(&cfg->external + 1); p++)
+		e = cksum_add(e, *p);
+
+	/* Adjustment value for Int->Ext direction */
+	cfg->adjustment = cksum_add(~e, i);
+}
+
+/*
+ * Creates new NPTv6 instance.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_lheader ipfw_nptv6_cfg ]
+ *
+ * Returns 0 on success
+ */
+static int
+nptv6_create(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	struct in6_addr mask;
+	ipfw_obj_lheader *olh;
+	ipfw_nptv6_cfg *uc;
+	struct namedobj_instance *ni;
+	struct nptv6_cfg *cfg;
+
+	if (sd->valsize != sizeof(*olh) + sizeof(*uc))
+		return (EINVAL);
+
+	olh = (ipfw_obj_lheader *)sd->kbuf;
+	uc = (ipfw_nptv6_cfg *)(olh + 1);
+	if (ipfw_check_object_name_generic(uc->name) != 0)
+		return (EINVAL);
+	if (uc->plen < 8 || uc->plen > 64 || uc->set >= IPFW_MAX_SETS)
+		return (EINVAL);
+	if (IN6_IS_ADDR_MULTICAST(&uc->internal) ||
+	    IN6_IS_ADDR_MULTICAST(&uc->external) ||
+	    IN6_IS_ADDR_UNSPECIFIED(&uc->internal) ||
+	    IN6_IS_ADDR_UNSPECIFIED(&uc->external) ||
+	    IN6_IS_ADDR_LINKLOCAL(&uc->internal) ||
+	    IN6_IS_ADDR_LINKLOCAL(&uc->external))
+		return (EINVAL);
+	in6_prefixlen2mask(&mask, uc->plen);
+	if (IN6_ARE_MASKED_ADDR_EQUAL(&uc->internal, &uc->external, &mask))
+		return (EINVAL);
+
+	ni = CHAIN_TO_SRV(ch);
+	IPFW_UH_RLOCK(ch);
+	if (nptv6_find(ni, uc->name, uc->set) != NULL) {
+		IPFW_UH_RUNLOCK(ch);
+		return (EEXIST);
+	}
+	IPFW_UH_RUNLOCK(ch);
+
+	cfg = nptv6_alloc_config(uc->name, uc->set);
+	cfg->plen = uc->plen;
+	if (cfg->plen <= 48)
+		cfg->flags |= NPTV6_48PLEN;
+	cfg->internal = uc->internal;
+	cfg->external = uc->external;
+	cfg->mask = mask;
+	IN6_MASK_ADDR(&cfg->internal, &mask);
+	IN6_MASK_ADDR(&cfg->external, &mask);
+	nptv6_calculate_adjustment(cfg);
+
+	IPFW_UH_WLOCK(ch);
+	if (ipfw_objhash_alloc_idx(ni, &cfg->no.kidx) != 0) {
+		IPFW_UH_WUNLOCK(ch);
+		nptv6_free_config(cfg);
+		return (ENOSPC);
+	}
+	ipfw_objhash_add(ni, &cfg->no);
+	IPFW_WLOCK(ch);
+	SRV_OBJECT(ch, cfg->no.kidx) = cfg;
+	IPFW_WUNLOCK(ch);
+	IPFW_UH_WUNLOCK(ch);
+	return (0);
+}
+
+/*
+ * Destroys NPTv6 instance.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ *
+ * Returns 0 on success
+ */
+static int
+nptv6_destroy(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_header *oh;
+	struct nptv6_cfg *cfg;
+
+	if (sd->valsize != sizeof(*oh))
+		return (EINVAL);
+
+	oh = (ipfw_obj_header *)sd->kbuf;
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0)
+		return (EINVAL);
+
+	IPFW_UH_WLOCK(ch);
+	cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		return (ESRCH);
+	}
+	if (cfg->no.refcnt > 0) {
+		IPFW_UH_WUNLOCK(ch);
+		return (EBUSY);
+	}
+
+	IPFW_WLOCK(ch);
+	SRV_OBJECT(ch, cfg->no.kidx) = NULL;
+	IPFW_WUNLOCK(ch);
+
+	ipfw_objhash_del(CHAIN_TO_SRV(ch), &cfg->no);
+	ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), cfg->no.kidx);
+	IPFW_UH_WUNLOCK(ch);
+
+	nptv6_free_config(cfg);
+	return (0);
+}
+
+/*
+ * Get or change nptv6 instance config.
+ * Request: [ ipfw_obj_header [ ipfw_nptv6_cfg ] ]
+ */
+static int
+nptv6_config(struct ip_fw_chain *chain, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+
+	return (EOPNOTSUPP);
+}
+
+/*
+ * Lists all NPTv6 instances currently available in kernel.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_lheader ]
+ * Reply: [ ipfw_obj_lheader ipfw_nptv6_cfg x N ]
+ *
+ * Returns 0 on success
+ */
+static int
+nptv6_list(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_lheader *olh;
+	struct nptv6_dump_arg da;
+
+	/* Check minimum header size */
+	if (sd->valsize < sizeof(ipfw_obj_lheader))
+		return (EINVAL);
+
+	olh = (ipfw_obj_lheader *)ipfw_get_sopt_header(sd, sizeof(*olh));
+
+	IPFW_UH_RLOCK(ch);
+	olh->count = ipfw_objhash_count_type(CHAIN_TO_SRV(ch),
+	    IPFW_TLV_NPTV6_NAME);
+	olh->objsize = sizeof(ipfw_nptv6_cfg);
+	olh->size = sizeof(*olh) + olh->count * olh->objsize;
+
+	if (sd->valsize < olh->size) {
+		IPFW_UH_RUNLOCK(ch);
+		return (ENOMEM);
+	}
+	memset(&da, 0, sizeof(da));
+	da.ch = ch;
+	da.sd = sd;
+	ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), export_config_cb,
+	    &da, IPFW_TLV_NPTV6_NAME);
+	IPFW_UH_RUNLOCK(ch);
+
+	return (0);
+}
+
+#define	__COPY_STAT_FIELD(_cfg, _stats, _field)	\
+	(_stats)->_field = NPTV6STAT_FETCH(_cfg, _field)
+static void
+export_stats(struct ip_fw_chain *ch, struct nptv6_cfg *cfg,
+    struct ipfw_nptv6_stats *stats)
+{
+
+	__COPY_STAT_FIELD(cfg, stats, in2ex);
+	__COPY_STAT_FIELD(cfg, stats, ex2in);
+	__COPY_STAT_FIELD(cfg, stats, dropped);
+}
+
+/*
+ * Get NPTv6 statistics.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ]]
+ *
+ * Returns 0 on success
+ */
+static int
+nptv6_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+	struct ipfw_nptv6_stats stats;
+	struct nptv6_cfg *cfg;
+	ipfw_obj_header *oh;
+	ipfw_obj_ctlv *ctlv;
+	size_t sz;
+
+	sz = sizeof(ipfw_obj_header) + sizeof(ipfw_obj_ctlv) + sizeof(stats);
+	if (sd->valsize % sizeof(uint64_t))
+		return (EINVAL);
+	if (sd->valsize < sz)
+		return (ENOMEM);
+	oh = (ipfw_obj_header *)ipfw_get_sopt_header(sd, sz);
+	if (oh == NULL)
+		return (EINVAL);
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
+	    oh->ntlv.set >= IPFW_MAX_SETS)
+		return (EINVAL);
+	memset(&stats, 0, sizeof(stats));
+
+	IPFW_UH_RLOCK(ch);
+	cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_RUNLOCK(ch);
+		return (ESRCH);
+	}
+	export_stats(ch, cfg, &stats);
+	IPFW_UH_RUNLOCK(ch);
+
+	ctlv = (ipfw_obj_ctlv *)(oh + 1);
+	memset(ctlv, 0, sizeof(*ctlv));
+	ctlv->head.type = IPFW_TLV_COUNTERS;
+	ctlv->head.length = sz - sizeof(ipfw_obj_header);
+	ctlv->count = sizeof(stats) / sizeof(uint64_t);
+	ctlv->objsize = sizeof(uint64_t);
+	ctlv->version = 1;
+	memcpy(ctlv + 1, &stats, sizeof(stats));
+	return (0);
+}
+
+/*
+ * Reset NPTv6 statistics.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ *
+ * Returns 0 on success
+ */
+static int
+nptv6_reset_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+	struct nptv6_cfg *cfg;
+	ipfw_obj_header *oh;
+
+	if (sd->valsize != sizeof(*oh))
+		return (EINVAL);
+	oh = (ipfw_obj_header *)sd->kbuf;
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
+	    oh->ntlv.set >= IPFW_MAX_SETS)
+		return (EINVAL);
+
+	IPFW_UH_WLOCK(ch);
+	cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		return (ESRCH);
+	}
+	COUNTER_ARRAY_ZERO(cfg->stats, NPTV6STATS);
+	IPFW_UH_WUNLOCK(ch);
+	return (0);
+}
+
+static struct ipfw_sopt_handler	scodes[] = {
+	{ IP_FW_NPTV6_CREATE, 0,	HDIR_SET,	nptv6_create },
+	{ IP_FW_NPTV6_DESTROY,0,	HDIR_SET,	nptv6_destroy },
+	{ IP_FW_NPTV6_CONFIG, 0,	HDIR_BOTH,	nptv6_config },
+	{ IP_FW_NPTV6_LIST,   0,	HDIR_GET,	nptv6_list },
+	{ IP_FW_NPTV6_STATS,  0,	HDIR_GET,	nptv6_stats },
+	{ IP_FW_NPTV6_RESET_STATS,0,	HDIR_SET,	nptv6_reset_stats },
+};
+
+static int
+nptv6_classify(ipfw_insn *cmd, uint16_t *puidx, uint8_t *ptype)
+{
+	ipfw_insn *icmd;
+
+	icmd = cmd - 1;
+	NPTV6_DEBUG("opcode %d, arg1 %d, opcode0 %d, arg1 %d",
+	    cmd->opcode, cmd->arg1, icmd->opcode, icmd->arg1);
+	if (icmd->opcode != O_EXTERNAL_ACTION ||
+	    icmd->arg1 != V_nptv6_eid)
+		return (1);
+
+	*puidx = cmd->arg1;
+	*ptype = 0;
+	return (0);
+}
+
+static void
+nptv6_update_arg1(ipfw_insn *cmd, uint16_t idx)
+{
+
+	cmd->arg1 = idx;
+	NPTV6_DEBUG("opcode %d, arg1 -> %d", cmd->opcode, cmd->arg1);
+}
+
+static int
+nptv6_findbyname(struct ip_fw_chain *ch, struct tid_info *ti,
+    struct named_object **pno)
+{
+	int err;
+
+	err = ipfw_objhash_find_type(CHAIN_TO_SRV(ch), ti,
+	    IPFW_TLV_NPTV6_NAME, pno);
+	NPTV6_DEBUG("uidx %u, type %u, err %d", ti->uidx, ti->type, err);
+	return (err);
+}
+
+static struct named_object *
+nptv6_findbykidx(struct ip_fw_chain *ch, uint16_t idx)
+{
+	struct namedobj_instance *ni;
+	struct named_object *no;
+
+	IPFW_UH_WLOCK_ASSERT(ch);
+	ni = CHAIN_TO_SRV(ch);
+	no = ipfw_objhash_lookup_kidx(ni, idx);
+	KASSERT(no != NULL, ("NPT with index %d not found", idx));
+
+	NPTV6_DEBUG("kidx %u -> %s", idx, no->name);
+	return (no);
+}
+
+static int
+nptv6_manage_sets(struct ip_fw_chain *ch, uint16_t set, uint8_t new_set,
+    enum ipfw_sets_cmd cmd)
+{
+
+	return (ipfw_obj_manage_sets(CHAIN_TO_SRV(ch), IPFW_TLV_NPTV6_NAME,
+	    set, new_set, cmd));
+}
+
+static struct opcode_obj_rewrite opcodes[] = {
+	{
+		.opcode	= O_EXTERNAL_INSTANCE,
+		.etlv = IPFW_TLV_EACTION /* just show it isn't table */,
+		.classifier = nptv6_classify,
+		.update = nptv6_update_arg1,
+		.find_byname = nptv6_findbyname,
+		.find_bykidx = nptv6_findbykidx,
+		.manage_sets = nptv6_manage_sets,
+	},
+};
+
+static int
+destroy_config_cb(struct namedobj_instance *ni, struct named_object *no,
+    void *arg)
+{
+	struct nptv6_cfg *cfg;
+	struct ip_fw_chain *ch;
+
+	ch = (struct ip_fw_chain *)arg;
+	IPFW_UH_WLOCK_ASSERT(ch);
+
+	cfg = (struct nptv6_cfg *)SRV_OBJECT(ch, no->kidx);
+	SRV_OBJECT(ch, no->kidx) = NULL;
+	ipfw_objhash_del(ni, &cfg->no);
+	ipfw_objhash_free_idx(ni, cfg->no.kidx);
+	nptv6_free_config(cfg);
+	return (0);
+}
+
+int
+nptv6_init(struct ip_fw_chain *ch, int first)
+{
+
+	V_nptv6_eid = ipfw_add_eaction(ch, ipfw_nptv6, "nptv6");
+	if (V_nptv6_eid == 0)
+		return (ENXIO);
+	IPFW_ADD_SOPT_HANDLER(first, scodes);
+	IPFW_ADD_OBJ_REWRITER(first, opcodes);
+	return (0);
+}
+
+void
+nptv6_uninit(struct ip_fw_chain *ch, int last)
+{
+
+	IPFW_DEL_OBJ_REWRITER(last, opcodes);
+	IPFW_DEL_SOPT_HANDLER(last, scodes);
+	ipfw_del_eaction(ch, V_nptv6_eid);
+	/*
+	 * Since we already have deregistered external action,
+	 * our named objects become unaccessible via rules, because
+	 * all rules were truncated by ipfw_del_eaction().
+	 * So, we can unlink and destroy our named objects without holding
+	 * IPFW_WLOCK().
+	 */
+	IPFW_UH_WLOCK(ch);
+	ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), destroy_config_cb, ch,
+	    IPFW_TLV_NPTV6_NAME);
+	V_nptv6_eid = 0;
+	IPFW_UH_WUNLOCK(ch);
+}
+
diff --git a/sys/netpfil/ipfw/nptv6/nptv6.h b/sys/netpfil/ipfw/nptv6/nptv6.h
new file mode 100644
index 0000000..95b04bf
--- /dev/null
+++ b/sys/netpfil/ipfw/nptv6/nptv6.h
@@ -0,0 +1,65 @@
+/*-
+ * Copyright (c) 2016 Yandex LLC
+ * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_IP_FW_NPTV6_H_
+#define	_IP_FW_NPTV6_H_
+
+#include <netinet6/ip_fw_nptv6.h>
+
+#ifdef _KERNEL
+#define	NPTV6STATS	(sizeof(struct ipfw_nptv6_stats) / sizeof(uint64_t))
+#define	NPTV6STAT_ADD(c, f, v)		\
+    counter_u64_add((c)->stats[		\
+	offsetof(struct ipfw_nptv6_stats, f) / sizeof(uint64_t)], (v))
+#define	NPTV6STAT_INC(c, f)	NPTV6STAT_ADD(c, f, 1)
+#define	NPTV6STAT_FETCH(c, f)		\
+    counter_u64_fetch((c)->stats[	\
+	offsetof(struct ipfw_nptv6_stats, f) / sizeof(uint64_t)])
+
+struct nptv6_cfg {
+	struct named_object	no;
+
+	struct in6_addr		internal;   /* Internal IPv6 prefix */
+	struct in6_addr		external;   /* External IPv6 prefix */
+	struct in6_addr		mask;	    /* IPv6 prefix mask */
+	uint16_t		adjustment; /* Checksum adjustment value */
+	uint8_t			plen;	    /* Prefix length */
+	uint8_t			flags;	    /* Flags for internal use */
+#define	NPTV6_48PLEN		0x0001
+	char			name[64];   /* Instance name */
+	counter_u64_t		stats[NPTV6STATS]; /* Statistics counters */
+};
+#define	NPTV6_FLAGSMASK		0
+
+int nptv6_init(struct ip_fw_chain *ch, int first);
+void nptv6_uninit(struct ip_fw_chain *ch, int last);
+#endif /* _KERNEL */
+
+#endif /* _IP_FW_NPTV6_H_ */
+