o Create directory sys/netpfil, where all packet filters should

  reside, and move there ipfw(4) and pf(4).

o Move most modified parts of pf out of contrib.

Actual movements:

sys/contrib/pf/net/*.c		-> sys/netpfil/pf/
sys/contrib/pf/net/*.h		-> sys/net/
contrib/pf/pfctl/*.c		-> sbin/pfctl
contrib/pf/pfctl/*.h		-> sbin/pfctl
contrib/pf/pfctl/pfctl.8	-> sbin/pfctl
contrib/pf/pfctl/*.4		-> share/man/man4
contrib/pf/pfctl/*.5		-> share/man/man5

sys/netinet/ipfw		-> sys/netpfil/ipfw

The arguable movement is pf/net/*.h -> sys/net. There are
future plans to refactor pf includes, so I decided not to
break things twice.

Not modified bits of pf left in contrib: authpf, ftp-proxy,
tftp-proxy, pflogd.

The ipfw(4) movement is planned to be merged to stable/9,
to make head and stable match.

Discussed with:		bz, luigi

1 files changed, 662 insertions, 0 deletions

diff --git a/sys/netpfil/ipfw/ip_fw_nat.c b/sys/netpfil/ipfw/ip_fw_nat.c
new file mode 100644
index 0000000..6318633
--- /dev/null
+++ b/sys/netpfil/ipfw/ip_fw_nat.c
@@ -0,0 +1,662 @@
+/*-
+ * Copyright (c) 2008 Paolo Pisati
+ * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/eventhandler.h>
+#include <sys/malloc.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/module.h>
+#include <sys/rwlock.h>
+
+#define        IPFW_INTERNAL   /* Access to protected data structures in ip_fw.h. */
+
+#include <netinet/libalias/alias.h>
+#include <netinet/libalias/alias_local.h>
+
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_fw.h>
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
+
+#include <netpfil/ipfw/ip_fw_private.h>
+
+#include <machine/in_cksum.h>	/* XXX for in_cksum */
+
+static VNET_DEFINE(eventhandler_tag, ifaddr_event_tag);
+#define	V_ifaddr_event_tag	VNET(ifaddr_event_tag)
+
+static void
+ifaddr_change(void *arg __unused, struct ifnet *ifp)
+{
+	struct cfg_nat *ptr;
+	struct ifaddr *ifa;
+	struct ip_fw_chain *chain;
+
+	chain = &V_layer3_chain;
+	IPFW_WLOCK(chain);
+	/* Check every nat entry... */
+	LIST_FOREACH(ptr, &chain->nat, _next) {
+		/* ...using nic 'ifp->if_xname' as dynamic alias address. */
+		if (strncmp(ptr->if_name, ifp->if_xname, IF_NAMESIZE) != 0)
+			continue;
+		if_addr_rlock(ifp);
+		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
+			if (ifa->ifa_addr == NULL)
+				continue;
+			if (ifa->ifa_addr->sa_family != AF_INET)
+				continue;
+			ptr->ip = ((struct sockaddr_in *)
+			    (ifa->ifa_addr))->sin_addr;
+			LibAliasSetAddress(ptr->lib, ptr->ip);
+		}
+		if_addr_runlock(ifp);
+	}
+	IPFW_WUNLOCK(chain);
+}
+
+/*
+ * delete the pointers for nat entry ix, or all of them if ix < 0
+ */
+static void
+flush_nat_ptrs(struct ip_fw_chain *chain, const int ix)
+{
+	int i;
+	ipfw_insn_nat *cmd;
+
+	IPFW_WLOCK_ASSERT(chain);
+	for (i = 0; i < chain->n_rules; i++) {
+		cmd = (ipfw_insn_nat *)ACTION_PTR(chain->map[i]);
+		/* XXX skip log and the like ? */
+		if (cmd->o.opcode == O_NAT && cmd->nat != NULL &&
+			    (ix < 0 || cmd->nat->id == ix))
+			cmd->nat = NULL;
+	}
+}
+
+static void
+del_redir_spool_cfg(struct cfg_nat *n, struct redir_chain *head)
+{
+	struct cfg_redir *r, *tmp_r;
+	struct cfg_spool *s, *tmp_s;
+	int i, num;
+
+	LIST_FOREACH_SAFE(r, head, _next, tmp_r) {
+		num = 1; /* Number of alias_link to delete. */
+		switch (r->mode) {
+		case REDIR_PORT:
+			num = r->pport_cnt;
+			/* FALLTHROUGH */
+		case REDIR_ADDR:
+		case REDIR_PROTO:
+			/* Delete all libalias redirect entry. */
+			for (i = 0; i < num; i++)
+				LibAliasRedirectDelete(n->lib, r->alink[i]);
+			/* Del spool cfg if any. */
+			LIST_FOREACH_SAFE(s, &r->spool_chain, _next, tmp_s) {
+				LIST_REMOVE(s, _next);
+				free(s, M_IPFW);
+			}
+			free(r->alink, M_IPFW);
+			LIST_REMOVE(r, _next);
+			free(r, M_IPFW);
+			break;
+		default:
+			printf("unknown redirect mode: %u\n", r->mode);
+			/* XXX - panic?!?!? */
+			break;
+		}
+	}
+}
+
+static void
+add_redir_spool_cfg(char *buf, struct cfg_nat *ptr)
+{
+	struct cfg_redir *r, *ser_r;
+	struct cfg_spool *s, *ser_s;
+	int cnt, off, i;
+
+	for (cnt = 0, off = 0; cnt < ptr->redir_cnt; cnt++) {
+		ser_r = (struct cfg_redir *)&buf[off];
+		r = malloc(SOF_REDIR, M_IPFW, M_WAITOK | M_ZERO);
+		memcpy(r, ser_r, SOF_REDIR);
+		LIST_INIT(&r->spool_chain);
+		off += SOF_REDIR;
+		r->alink = malloc(sizeof(struct alias_link *) * r->pport_cnt,
+		    M_IPFW, M_WAITOK | M_ZERO);
+		switch (r->mode) {
+		case REDIR_ADDR:
+			r->alink[0] = LibAliasRedirectAddr(ptr->lib, r->laddr,
+			    r->paddr);
+			break;
+		case REDIR_PORT:
+			for (i = 0 ; i < r->pport_cnt; i++) {
+				/* If remotePort is all ports, set it to 0. */
+				u_short remotePortCopy = r->rport + i;
+				if (r->rport_cnt == 1 && r->rport == 0)
+					remotePortCopy = 0;
+				r->alink[i] = LibAliasRedirectPort(ptr->lib,
+				    r->laddr, htons(r->lport + i), r->raddr,
+				    htons(remotePortCopy), r->paddr,
+				    htons(r->pport + i), r->proto);
+				if (r->alink[i] == NULL) {
+					r->alink[0] = NULL;
+					break;
+				}
+			}
+			break;
+		case REDIR_PROTO:
+			r->alink[0] = LibAliasRedirectProto(ptr->lib ,r->laddr,
+			    r->raddr, r->paddr, r->proto);
+			break;
+		default:
+			printf("unknown redirect mode: %u\n", r->mode);
+			break;
+		}
+		/* XXX perhaps return an error instead of panic ? */
+		if (r->alink[0] == NULL)
+			panic("LibAliasRedirect* returned NULL");
+		/* LSNAT handling. */
+		for (i = 0; i < r->spool_cnt; i++) {
+			ser_s = (struct cfg_spool *)&buf[off];
+			s = malloc(SOF_REDIR, M_IPFW, M_WAITOK | M_ZERO);
+			memcpy(s, ser_s, SOF_SPOOL);
+			LibAliasAddServer(ptr->lib, r->alink[0],
+			    s->addr, htons(s->port));
+			off += SOF_SPOOL;
+			/* Hook spool entry. */
+			LIST_INSERT_HEAD(&r->spool_chain, s, _next);
+		}
+		/* And finally hook this redir entry. */
+		LIST_INSERT_HEAD(&ptr->redir_chain, r, _next);
+	}
+}
+
+static int
+ipfw_nat(struct ip_fw_args *args, struct cfg_nat *t, struct mbuf *m)
+{
+	struct mbuf *mcl;
+	struct ip *ip;
+	/* XXX - libalias duct tape */
+	int ldt, retval, found;
+	struct ip_fw_chain *chain;
+	char *c;
+
+	ldt = 0;
+	retval = 0;
+	mcl = m_megapullup(m, m->m_pkthdr.len);
+	if (mcl == NULL) {
+		args->m = NULL;
+		return (IP_FW_DENY);
+	}
+	ip = mtod(mcl, struct ip *);
+
+	/*
+	 * XXX - Libalias checksum offload 'duct tape':
+	 *
+	 * locally generated packets have only pseudo-header checksum
+	 * calculated and libalias will break it[1], so mark them for
+	 * later fix.  Moreover there are cases when libalias modifies
+	 * tcp packet data[2], mark them for later fix too.
+	 *
+	 * [1] libalias was never meant to run in kernel, so it does
+	 * not have any knowledge about checksum offloading, and
+	 * expects a packet with a full internet checksum.
+	 * Unfortunately, packets generated locally will have just the
+	 * pseudo header calculated, and when libalias tries to adjust
+	 * the checksum it will actually compute a wrong value.
+	 *
+	 * [2] when libalias modifies tcp's data content, full TCP
+	 * checksum has to be recomputed: the problem is that
+	 * libalias does not have any idea about checksum offloading.
+	 * To work around this, we do not do checksumming in LibAlias,
+	 * but only mark the packets in th_x2 field. If we receive a
+	 * marked packet, we calculate correct checksum for it
+	 * aware of offloading.  Why such a terrible hack instead of
+	 * recalculating checksum for each packet?
+	 * Because the previous checksum was not checked!
+	 * Recalculating checksums for EVERY packet will hide ALL
+	 * transmission errors. Yes, marked packets still suffer from
+	 * this problem. But, sigh, natd(8) has this problem, too.
+	 *
+	 * TODO: -make libalias mbuf aware (so
+	 * it can handle delayed checksum and tso)
+	 */
+
+	if (mcl->m_pkthdr.rcvif == NULL &&
+	    mcl->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
+		ldt = 1;
+
+	c = mtod(mcl, char *);
+
+	/* Check if this is 'global' instance */
+	if (t == NULL) {
+		if (args->oif == NULL) {
+			/* Wrong direction, skip processing */
+			args->m = mcl;
+			return (IP_FW_NAT);
+		}
+
+		found = 0;
+		chain = &V_layer3_chain;
+		IPFW_RLOCK(chain);
+		/* Check every nat entry... */
+		LIST_FOREACH(t, &chain->nat, _next) {
+			if ((t->mode & PKT_ALIAS_SKIP_GLOBAL) != 0)
+				continue;
+			retval = LibAliasOutTry(t->lib, c,
+			    mcl->m_len + M_TRAILINGSPACE(mcl), 0);
+			if (retval == PKT_ALIAS_OK) {
+				/* Nat instance recognises state */
+				found = 1;
+				break;
+			}
+		}
+		IPFW_RUNLOCK(chain);
+		if (found != 1) {
+			/* No instance found, return ignore */
+			args->m = mcl;
+			return (IP_FW_NAT);
+		}
+	} else {
+		if (args->oif == NULL)
+			retval = LibAliasIn(t->lib, c,
+				mcl->m_len + M_TRAILINGSPACE(mcl));
+		else
+			retval = LibAliasOut(t->lib, c,
+				mcl->m_len + M_TRAILINGSPACE(mcl));
+	}
+
+	/*
+	 * We drop packet when:
+	 * 1. libalias returns PKT_ALIAS_ERROR;
+	 * 2. For incoming packets:
+	 *	a) for unresolved fragments;
+	 *	b) libalias returns PKT_ALIAS_IGNORED and
+	 *		PKT_ALIAS_DENY_INCOMING flag is set.
+	 */
+	if (retval == PKT_ALIAS_ERROR ||
+	    (args->oif == NULL && (retval == PKT_ALIAS_UNRESOLVED_FRAGMENT ||
+	    (retval == PKT_ALIAS_IGNORED &&
+	    (t->mode & PKT_ALIAS_DENY_INCOMING) != 0)))) {
+		/* XXX - should i add some logging? */
+		m_free(mcl);
+		args->m = NULL;
+		return (IP_FW_DENY);
+	}
+
+	if (retval == PKT_ALIAS_RESPOND)
+		mcl->m_flags |= M_SKIP_FIREWALL;
+	mcl->m_pkthdr.len = mcl->m_len = ntohs(ip->ip_len);
+
+	/*
+	 * XXX - libalias checksum offload
+	 * 'duct tape' (see above)
+	 */
+
+	if ((ip->ip_off & htons(IP_OFFMASK)) == 0 &&
+	    ip->ip_p == IPPROTO_TCP) {
+		struct tcphdr 	*th;
+
+		th = (struct tcphdr *)(ip + 1);
+		if (th->th_x2)
+			ldt = 1;
+	}
+
+	if (ldt) {
+		struct tcphdr 	*th;
+		struct udphdr 	*uh;
+		u_short cksum;
+
+		ip->ip_len = ntohs(ip->ip_len);
+		cksum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
+		    htons(ip->ip_p + ip->ip_len - (ip->ip_hl << 2)));
+
+		switch (ip->ip_p) {
+		case IPPROTO_TCP:
+			th = (struct tcphdr *)(ip + 1);
+			/*
+			 * Maybe it was set in
+			 * libalias...
+			 */
+			th->th_x2 = 0;
+			th->th_sum = cksum;
+			mcl->m_pkthdr.csum_data =
+			    offsetof(struct tcphdr, th_sum);
+			break;
+		case IPPROTO_UDP:
+			uh = (struct udphdr *)(ip + 1);
+			uh->uh_sum = cksum;
+			mcl->m_pkthdr.csum_data =
+			    offsetof(struct udphdr, uh_sum);
+			break;
+		}
+		/* No hw checksum offloading: do it ourselves */
+		if ((mcl->m_pkthdr.csum_flags & CSUM_DELAY_DATA) == 0) {
+			in_delayed_cksum(mcl);
+			mcl->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
+		}
+		ip->ip_len = htons(ip->ip_len);
+	}
+	args->m = mcl;
+	return (IP_FW_NAT);
+}
+
+static struct cfg_nat *
+lookup_nat(struct nat_list *l, int nat_id)
+{
+	struct cfg_nat *res;
+
+	LIST_FOREACH(res, l, _next) {
+		if (res->id == nat_id)
+			break;
+	}
+	return res;
+}
+
+static int
+ipfw_nat_cfg(struct sockopt *sopt)
+{
+	struct cfg_nat *cfg, *ptr;
+	char *buf;
+	struct ip_fw_chain *chain = &V_layer3_chain;
+	size_t len;
+	int gencnt, error = 0;
+
+	len = sopt->sopt_valsize;
+	buf = malloc(len, M_TEMP, M_WAITOK | M_ZERO);
+	if ((error = sooptcopyin(sopt, buf, len, sizeof(struct cfg_nat))) != 0)
+		goto out;
+
+	cfg = (struct cfg_nat *)buf;
+	if (cfg->id < 0) {
+		error = EINVAL;
+		goto out;
+	}
+
+	/*
+	 * Find/create nat rule.
+	 */
+	IPFW_WLOCK(chain);
+	gencnt = chain->gencnt;
+	ptr = lookup_nat(&chain->nat, cfg->id);
+	if (ptr == NULL) {
+		IPFW_WUNLOCK(chain);
+		/* New rule: allocate and init new instance. */
+		ptr = malloc(sizeof(struct cfg_nat), M_IPFW, M_WAITOK | M_ZERO);
+		ptr->lib = LibAliasInit(NULL);
+		LIST_INIT(&ptr->redir_chain);
+	} else {
+		/* Entry already present: temporarily unhook it. */
+		LIST_REMOVE(ptr, _next);
+		flush_nat_ptrs(chain, cfg->id);
+		IPFW_WUNLOCK(chain);
+	}
+
+	/*
+	 * Basic nat configuration.
+	 */
+	ptr->id = cfg->id;
+	/*
+	 * XXX - what if this rule doesn't nat any ip and just
+	 * redirect?
+	 * do we set aliasaddress to 0.0.0.0?
+	 */
+	ptr->ip = cfg->ip;
+	ptr->redir_cnt = cfg->redir_cnt;
+	ptr->mode = cfg->mode;
+	LibAliasSetMode(ptr->lib, cfg->mode, cfg->mode);
+	LibAliasSetAddress(ptr->lib, ptr->ip);
+	memcpy(ptr->if_name, cfg->if_name, IF_NAMESIZE);
+
+	/*
+	 * Redir and LSNAT configuration.
+	 */
+	/* Delete old cfgs. */
+	del_redir_spool_cfg(ptr, &ptr->redir_chain);
+	/* Add new entries. */
+	add_redir_spool_cfg(&buf[(sizeof(struct cfg_nat))], ptr);
+
+	IPFW_WLOCK(chain);
+	/* Extra check to avoid race with another ipfw_nat_cfg() */
+	if (gencnt != chain->gencnt &&
+	    ((cfg = lookup_nat(&chain->nat, ptr->id)) != NULL))
+		LIST_REMOVE(cfg, _next);
+	LIST_INSERT_HEAD(&chain->nat, ptr, _next);
+	chain->gencnt++;
+	IPFW_WUNLOCK(chain);
+
+out:
+	free(buf, M_TEMP);
+	return (error);
+}
+
+static int
+ipfw_nat_del(struct sockopt *sopt)
+{
+	struct cfg_nat *ptr;
+	struct ip_fw_chain *chain = &V_layer3_chain;
+	int i;
+
+	sooptcopyin(sopt, &i, sizeof i, sizeof i);
+	/* XXX validate i */
+	IPFW_WLOCK(chain);
+	ptr = lookup_nat(&chain->nat, i);
+	if (ptr == NULL) {
+		IPFW_WUNLOCK(chain);
+		return (EINVAL);
+	}
+	LIST_REMOVE(ptr, _next);
+	flush_nat_ptrs(chain, i);
+	IPFW_WUNLOCK(chain);
+	del_redir_spool_cfg(ptr, &ptr->redir_chain);
+	LibAliasUninit(ptr->lib);
+	free(ptr, M_IPFW);
+	return (0);
+}
+
+static int
+ipfw_nat_get_cfg(struct sockopt *sopt)
+{
+	struct ip_fw_chain *chain = &V_layer3_chain;
+	struct cfg_nat *n;
+	struct cfg_redir *r;
+	struct cfg_spool *s;
+	char *data;
+	int gencnt, nat_cnt, len, error;
+
+	nat_cnt = 0;
+	len = sizeof(nat_cnt);
+
+	IPFW_RLOCK(chain);
+retry:
+	gencnt = chain->gencnt;
+	/* Estimate memory amount */
+	LIST_FOREACH(n, &chain->nat, _next) {
+		nat_cnt++;
+		len += sizeof(struct cfg_nat);
+		LIST_FOREACH(r, &n->redir_chain, _next) {
+			len += sizeof(struct cfg_redir);
+			LIST_FOREACH(s, &r->spool_chain, _next)
+				len += sizeof(struct cfg_spool);
+		}
+	}
+	IPFW_RUNLOCK(chain);
+
+	data = malloc(len, M_TEMP, M_WAITOK | M_ZERO);
+	bcopy(&nat_cnt, data, sizeof(nat_cnt));
+
+	nat_cnt = 0;
+	len = sizeof(nat_cnt);
+
+	IPFW_RLOCK(chain);
+	if (gencnt != chain->gencnt) {
+		free(data, M_TEMP);
+		goto retry;
+	}
+	/* Serialize all the data. */
+	LIST_FOREACH(n, &chain->nat, _next) {
+		bcopy(n, &data[len], sizeof(struct cfg_nat));
+		len += sizeof(struct cfg_nat);
+		LIST_FOREACH(r, &n->redir_chain, _next) {
+			bcopy(r, &data[len], sizeof(struct cfg_redir));
+			len += sizeof(struct cfg_redir);
+			LIST_FOREACH(s, &r->spool_chain, _next) {
+				bcopy(s, &data[len], sizeof(struct cfg_spool));
+				len += sizeof(struct cfg_spool);
+			}
+		}
+	}
+	IPFW_RUNLOCK(chain);
+
+	error = sooptcopyout(sopt, data, len);
+	free(data, M_TEMP);
+
+	return (error);
+}
+
+static int
+ipfw_nat_get_log(struct sockopt *sopt)
+{
+	uint8_t *data;
+	struct cfg_nat *ptr;
+	int i, size;
+	struct ip_fw_chain *chain;
+
+	chain = &V_layer3_chain;
+
+	IPFW_RLOCK(chain);
+	/* one pass to count, one to copy the data */
+	i = 0;
+	LIST_FOREACH(ptr, &chain->nat, _next) {
+		if (ptr->lib->logDesc == NULL)
+			continue;
+		i++;
+	}
+	size = i * (LIBALIAS_BUF_SIZE + sizeof(int));
+	data = malloc(size, M_IPFW, M_NOWAIT | M_ZERO);
+	if (data == NULL) {
+		IPFW_RUNLOCK(chain);
+		return (ENOSPC);
+	}
+	i = 0;
+	LIST_FOREACH(ptr, &chain->nat, _next) {
+		if (ptr->lib->logDesc == NULL)
+			continue;
+		bcopy(&ptr->id, &data[i], sizeof(int));
+		i += sizeof(int);
+		bcopy(ptr->lib->logDesc, &data[i], LIBALIAS_BUF_SIZE);
+		i += LIBALIAS_BUF_SIZE;
+	}
+	IPFW_RUNLOCK(chain);
+	sooptcopyout(sopt, data, size);
+	free(data, M_IPFW);
+	return(0);
+}
+
+static void
+ipfw_nat_init(void)
+{
+
+	IPFW_WLOCK(&V_layer3_chain);
+	/* init ipfw hooks */
+	ipfw_nat_ptr = ipfw_nat;
+	lookup_nat_ptr = lookup_nat;
+	ipfw_nat_cfg_ptr = ipfw_nat_cfg;
+	ipfw_nat_del_ptr = ipfw_nat_del;
+	ipfw_nat_get_cfg_ptr = ipfw_nat_get_cfg;
+	ipfw_nat_get_log_ptr = ipfw_nat_get_log;
+	IPFW_WUNLOCK(&V_layer3_chain);
+	V_ifaddr_event_tag = EVENTHANDLER_REGISTER(
+	    ifaddr_event, ifaddr_change,
+	    NULL, EVENTHANDLER_PRI_ANY);
+}
+
+static void
+ipfw_nat_destroy(void)
+{
+	struct cfg_nat *ptr, *ptr_temp;
+	struct ip_fw_chain *chain;
+
+	chain = &V_layer3_chain;
+	IPFW_WLOCK(chain);
+	LIST_FOREACH_SAFE(ptr, &chain->nat, _next, ptr_temp) {
+		LIST_REMOVE(ptr, _next);
+		del_redir_spool_cfg(ptr, &ptr->redir_chain);
+		LibAliasUninit(ptr->lib);
+		free(ptr, M_IPFW);
+	}
+	EVENTHANDLER_DEREGISTER(ifaddr_event, V_ifaddr_event_tag);
+	flush_nat_ptrs(chain, -1 /* flush all */);
+	/* deregister ipfw_nat */
+	ipfw_nat_ptr = NULL;
+	lookup_nat_ptr = NULL;
+	ipfw_nat_cfg_ptr = NULL;
+	ipfw_nat_del_ptr = NULL;
+	ipfw_nat_get_cfg_ptr = NULL;
+	ipfw_nat_get_log_ptr = NULL;
+	IPFW_WUNLOCK(chain);
+}
+
+static int
+ipfw_nat_modevent(module_t mod, int type, void *unused)
+{
+	int err = 0;
+
+	switch (type) {
+	case MOD_LOAD:
+		ipfw_nat_init();
+		break;
+
+	case MOD_UNLOAD:
+		ipfw_nat_destroy();
+		break;
+
+	default:
+		return EOPNOTSUPP;
+		break;
+	}
+	return err;
+}
+
+static moduledata_t ipfw_nat_mod = {
+	"ipfw_nat",
+	ipfw_nat_modevent,
+	0
+};
+
+DECLARE_MODULE(ipfw_nat, ipfw_nat_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
+MODULE_DEPEND(ipfw_nat, libalias, 1, 1, 1);
+MODULE_DEPEND(ipfw_nat, ipfw, 2, 2, 2);
+MODULE_VERSION(ipfw_nat, 1);
+/* end of file */