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-rw-r--r--net/ipv4/netfilter/nf_nat_h323.c596
1 files changed, 596 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
new file mode 100644
index 00000000000..fb9ab0114c2
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -0,0 +1,596 @@
+/*
+ * H.323 extension for NAT alteration.
+ *
+ * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
+ *
+ * This source code is licensed under General Public License version 2.
+ *
+ * Based on the 'brute force' H.323 NAT module by
+ * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/tcp.h>
+#include <net/tcp.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_h323.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/****************************************************************************/
+static int set_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ unsigned int addroff, __be32 ip, __be16 port)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = ip_conntrack_get(*pskb, &ctinfo);
+ struct {
+ __be32 ip;
+ __be16 port;
+ } __attribute__ ((__packed__)) buf;
+ struct tcphdr _tcph, *th;
+
+ buf.ip = ip;
+ buf.port = port;
+ addroff += dataoff;
+
+ if ((*pskb)->nh.iph->protocol == IPPROTO_TCP) {
+ if (!nf_nat_mangle_tcp_packet(pskb, ct, ctinfo,
+ addroff, sizeof(buf),
+ (char *) &buf, sizeof(buf))) {
+ if (net_ratelimit())
+ printk("nf_nat_h323: nf_nat_mangle_tcp_packet"
+ " error\n");
+ return -1;
+ }
+
+ /* Relocate data pointer */
+ th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl * 4,
+ sizeof(_tcph), &_tcph);
+ if (th == NULL)
+ return -1;
+ *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+ th->doff * 4 + dataoff;
+ } else {
+ if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
+ addroff, sizeof(buf),
+ (char *) &buf, sizeof(buf))) {
+ if (net_ratelimit())
+ printk("nf_nat_h323: nf_nat_mangle_udp_packet"
+ " error\n");
+ return -1;
+ }
+ /* nf_nat_mangle_udp_packet uses skb_make_writable() to copy
+ * or pull everything in a linear buffer, so we can safely
+ * use the skb pointers now */
+ *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+ sizeof(struct udphdr);
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int set_h225_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ TransportAddress *taddr,
+ union nf_conntrack_address *addr, __be16 port)
+{
+ return set_addr(pskb, data, dataoff, taddr->ipAddress.ip,
+ addr->ip, port);
+}
+
+/****************************************************************************/
+static int set_h245_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress *taddr,
+ union nf_conntrack_address *addr, __be16 port)
+{
+ return set_addr(pskb, data, dataoff,
+ taddr->unicastAddress.iPAddress.network,
+ addr->ip, port);
+}
+
+/****************************************************************************/
+static int set_sig_addr(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data,
+ TransportAddress *taddr, int count)
+{
+ struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ __be16 port;
+ union nf_conntrack_address addr;
+
+ for (i = 0; i < count; i++) {
+ if (get_h225_addr(ct, *data, &taddr[i], &addr, &port)) {
+ if (addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
+ port == info->sig_port[dir]) {
+ /* GW->GK */
+
+ /* Fix for Gnomemeeting */
+ if (i > 0 &&
+ get_h225_addr(ct, *data, &taddr[0],
+ &addr, &port) &&
+ (ntohl(addr.ip) & 0xff000000) == 0x7f000000)
+ i = 0;
+
+ DEBUGP
+ ("nf_nat_ras: set signal address "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), port,
+ NIPQUAD(ct->tuplehash[!dir].tuple.dst.
+ ip), info->sig_port[!dir]);
+ return set_h225_addr(pskb, data, 0, &taddr[i],
+ &ct->tuplehash[!dir].
+ tuple.dst.u3,
+ info->sig_port[!dir]);
+ } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
+ port == info->sig_port[dir]) {
+ /* GK->GW */
+ DEBUGP
+ ("nf_nat_ras: set signal address "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), port,
+ NIPQUAD(ct->tuplehash[!dir].tuple.src.
+ ip), info->sig_port[!dir]);
+ return set_h225_addr(pskb, data, 0, &taddr[i],
+ &ct->tuplehash[!dir].
+ tuple.src.u3,
+ info->sig_port[!dir]);
+ }
+ }
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int set_ras_addr(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data,
+ TransportAddress *taddr, int count)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ __be16 port;
+ union nf_conntrack_address addr;
+
+ for (i = 0; i < count; i++) {
+ if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
+ addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
+ port == ct->tuplehash[dir].tuple.src.u.udp.port) {
+ DEBUGP("nf_nat_ras: set rasAddress "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), ntohs(port),
+ NIPQUAD(ct->tuplehash[!dir].tuple.dst.u3.ip),
+ ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.
+ port));
+ return set_h225_addr(pskb, data, 0, &taddr[i],
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ ct->tuplehash[!dir].tuple.
+ dst.u.udp.port);
+ }
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int nat_rtp_rtcp(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress *taddr,
+ __be16 port, __be16 rtp_port,
+ struct nf_conntrack_expect *rtp_exp,
+ struct nf_conntrack_expect *rtcp_exp)
+{
+ struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ u_int16_t nated_port;
+
+ /* Set expectations for NAT */
+ rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
+ rtp_exp->expectfn = nf_nat_follow_master;
+ rtp_exp->dir = !dir;
+ rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
+ rtcp_exp->expectfn = nf_nat_follow_master;
+ rtcp_exp->dir = !dir;
+
+ /* Lookup existing expects */
+ for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
+ if (info->rtp_port[i][dir] == rtp_port) {
+ /* Expected */
+
+ /* Use allocated ports first. This will refresh
+ * the expects */
+ rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
+ rtcp_exp->tuple.dst.u.udp.port =
+ htons(ntohs(info->rtp_port[i][dir]) + 1);
+ break;
+ } else if (info->rtp_port[i][dir] == 0) {
+ /* Not expected */
+ break;
+ }
+ }
+
+ /* Run out of expectations */
+ if (i >= H323_RTP_CHANNEL_MAX) {
+ if (net_ratelimit())
+ printk("nf_nat_h323: out of expectations\n");
+ return 0;
+ }
+
+ /* Try to get a pair of ports. */
+ for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
+ nated_port != 0; nated_port += 2) {
+ rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
+ if (nf_conntrack_expect_related(rtp_exp) == 0) {
+ rtcp_exp->tuple.dst.u.udp.port =
+ htons(nated_port + 1);
+ if (nf_conntrack_expect_related(rtcp_exp) == 0)
+ break;
+ nf_conntrack_unexpect_related(rtp_exp);
+ }
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("nf_nat_h323: out of RTP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h245_addr(pskb, data, dataoff, taddr,
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ htons((port & htons(1)) ? nated_port + 1 :
+ nated_port)) == 0) {
+ /* Save ports */
+ info->rtp_port[i][dir] = rtp_port;
+ info->rtp_port[i][!dir] = htons(nated_port);
+ } else {
+ nf_conntrack_unexpect_related(rtp_exp);
+ nf_conntrack_unexpect_related(rtcp_exp);
+ return -1;
+ }
+
+ /* Success */
+ DEBUGP("nf_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(rtp_exp->tuple.src.ip),
+ ntohs(rtp_exp->tuple.src.u.udp.port),
+ NIPQUAD(rtp_exp->tuple.dst.ip),
+ ntohs(rtp_exp->tuple.dst.u.udp.port));
+ DEBUGP("nf_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(rtcp_exp->tuple.src.ip),
+ ntohs(rtcp_exp->tuple.src.u.udp.port),
+ NIPQUAD(rtcp_exp->tuple.dst.ip),
+ ntohs(rtcp_exp->tuple.dst.u.udp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static int nat_t120(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress *taddr, __be16 port,
+ struct nf_conntrack_expect *exp)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = ntohs(port);
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = nf_nat_follow_master;
+ exp->dir = !dir;
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("nf_nat_h323: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h245_addr(pskb, data, dataoff, taddr,
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ htons(nated_port)) < 0) {
+ nf_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ DEBUGP("nf_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static int nat_h245(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ TransportAddress *taddr, __be16 port,
+ struct nf_conntrack_expect *exp)
+{
+ struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = ntohs(port);
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = nf_nat_follow_master;
+ exp->dir = !dir;
+
+ /* Check existing expects */
+ if (info->sig_port[dir] == port)
+ nated_port = ntohs(info->sig_port[!dir]);
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("nf_nat_q931: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h225_addr(pskb, data, dataoff, taddr,
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ htons(nated_port)) == 0) {
+ /* Save ports */
+ info->sig_port[dir] = port;
+ info->sig_port[!dir] = htons(nated_port);
+ } else {
+ nf_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ DEBUGP("nf_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************
+ * This conntrack expect function replaces nf_conntrack_q931_expect()
+ * which was set by nf_conntrack_h323.c.
+ ****************************************************************************/
+static void ip_nat_q931_expect(struct nf_conn *new,
+ struct nf_conntrack_expect *this)
+{
+ struct ip_nat_range range;
+
+ if (this->tuple.src.u3.ip != 0) { /* Only accept calls from GK */
+ nf_nat_follow_master(new, this);
+ return;
+ }
+
+ /* This must be a fresh one. */
+ BUG_ON(new->status & IPS_NAT_DONE_MASK);
+
+ /* Change src to where master sends to */
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
+
+ /* hook doesn't matter, but it has to do source manip */
+ nf_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
+
+ /* For DST manip, map port here to where it's expected. */
+ range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+ range.min = range.max = this->saved_proto;
+ range.min_ip = range.max_ip =
+ new->master->tuplehash[!this->dir].tuple.src.u3.ip;
+
+ /* hook doesn't matter, but it has to do destination manip */
+ nf_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
+}
+
+/****************************************************************************/
+static int nat_q931(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, TransportAddress *taddr, int idx,
+ __be16 port, struct nf_conntrack_expect *exp)
+{
+ struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = ntohs(port);
+ union nf_conntrack_address addr;
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = ip_nat_q931_expect;
+ exp->dir = !dir;
+
+ /* Check existing expects */
+ if (info->sig_port[dir] == port)
+ nated_port = ntohs(info->sig_port[!dir]);
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("nf_nat_ras: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h225_addr(pskb, data, 0, &taddr[idx],
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ htons(nated_port)) == 0) {
+ /* Save ports */
+ info->sig_port[dir] = port;
+ info->sig_port[!dir] = htons(nated_port);
+
+ /* Fix for Gnomemeeting */
+ if (idx > 0 &&
+ get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
+ (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
+ set_h225_addr_hook(pskb, data, 0, &taddr[0],
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ info->sig_port[!dir]);
+ }
+ } else {
+ nf_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ /* Success */
+ DEBUGP("nf_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static void ip_nat_callforwarding_expect(struct nf_conn *new,
+ struct nf_conntrack_expect *this)
+{
+ struct nf_nat_range range;
+
+ /* This must be a fresh one. */
+ BUG_ON(new->status & IPS_NAT_DONE_MASK);
+
+ /* Change src to where master sends to */
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
+
+ /* hook doesn't matter, but it has to do source manip */
+ nf_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
+
+ /* For DST manip, map port here to where it's expected. */
+ range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+ range.min = range.max = this->saved_proto;
+ range.min_ip = range.max_ip = this->saved_ip;
+
+ /* hook doesn't matter, but it has to do destination manip */
+ nf_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
+}
+
+/****************************************************************************/
+static int nat_callforwarding(struct sk_buff **pskb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ TransportAddress *taddr, __be16 port,
+ struct nf_conntrack_expect *exp)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port;
+
+ /* Set expectations for NAT */
+ exp->saved_ip = exp->tuple.dst.u3.ip;
+ exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = ip_nat_callforwarding_expect;
+ exp->dir = !dir;
+
+ /* Try to get same port: if not, try to change it. */
+ for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("nf_nat_q931: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (!set_h225_addr(pskb, data, dataoff, taddr,
+ &ct->tuplehash[!dir].tuple.dst.u3,
+ htons(nated_port)) == 0) {
+ nf_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ /* Success */
+ DEBUGP("nf_nat_q931: expect Call Forwarding "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static int __init init(void)
+{
+ BUG_ON(rcu_dereference(set_h245_addr_hook) != NULL);
+ BUG_ON(rcu_dereference(set_h225_addr_hook) != NULL);
+ BUG_ON(rcu_dereference(set_sig_addr_hook) != NULL);
+ BUG_ON(rcu_dereference(set_ras_addr_hook) != NULL);
+ BUG_ON(rcu_dereference(nat_rtp_rtcp_hook) != NULL);
+ BUG_ON(rcu_dereference(nat_t120_hook) != NULL);
+ BUG_ON(rcu_dereference(nat_h245_hook) != NULL);
+ BUG_ON(rcu_dereference(nat_callforwarding_hook) != NULL);
+ BUG_ON(rcu_dereference(nat_q931_hook) != NULL);
+
+ rcu_assign_pointer(set_h245_addr_hook, set_h245_addr);
+ rcu_assign_pointer(set_h225_addr_hook, set_h225_addr);
+ rcu_assign_pointer(set_sig_addr_hook, set_sig_addr);
+ rcu_assign_pointer(set_ras_addr_hook, set_ras_addr);
+ rcu_assign_pointer(nat_rtp_rtcp_hook, nat_rtp_rtcp);
+ rcu_assign_pointer(nat_t120_hook, nat_t120);
+ rcu_assign_pointer(nat_h245_hook, nat_h245);
+ rcu_assign_pointer(nat_callforwarding_hook, nat_callforwarding);
+ rcu_assign_pointer(nat_q931_hook, nat_q931);
+
+ DEBUGP("nf_nat_h323: init success\n");
+ return 0;
+}
+
+/****************************************************************************/
+static void __exit fini(void)
+{
+ rcu_assign_pointer(set_h245_addr_hook, NULL);
+ rcu_assign_pointer(set_h225_addr_hook, NULL);
+ rcu_assign_pointer(set_sig_addr_hook, NULL);
+ rcu_assign_pointer(set_ras_addr_hook, NULL);
+ rcu_assign_pointer(nat_rtp_rtcp_hook, NULL);
+ rcu_assign_pointer(nat_t120_hook, NULL);
+ rcu_assign_pointer(nat_h245_hook, NULL);
+ rcu_assign_pointer(nat_callforwarding_hook, NULL);
+ rcu_assign_pointer(nat_q931_hook, NULL);
+ synchronize_rcu();
+}
+
+/****************************************************************************/
+module_init(init);
+module_exit(fini);
+
+MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
+MODULE_DESCRIPTION("H.323 NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat_h323");