1/*
2 * H.323 extension for NAT alteration.
3 *
4 * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
5 * Copyright (c) 2006-2012 Patrick McHardy <kaber@trash.net>
6 *
7 * This source code is licensed under General Public License version 2.
8 *
9 * Based on the 'brute force' H.323 NAT module by
10 * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
11 */
12
13#include <linux/module.h>
14#include <linux/tcp.h>
15#include <net/tcp.h>
16
17#include <net/netfilter/nf_nat.h>
18#include <net/netfilter/nf_nat_helper.h>
19#include <net/netfilter/nf_conntrack_helper.h>
20#include <net/netfilter/nf_conntrack_expect.h>
21#include <linux/netfilter/nf_conntrack_h323.h>
22
23/****************************************************************************/
24static int set_addr(struct sk_buff *skb, unsigned int protoff,
25 unsigned char **data, int dataoff,
26 unsigned int addroff, __be32 ip, __be16 port)
27{
28 enum ip_conntrack_info ctinfo;
29 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
30 struct {
31 __be32 ip;
32 __be16 port;
33 } __attribute__ ((__packed__)) buf;
34 const struct tcphdr *th;
35 struct tcphdr _tcph;
36
37 buf.ip = ip;
38 buf.port = port;
39 addroff += dataoff;
40
41 if (ip_hdr(skb)->protocol == IPPROTO_TCP) {
42 if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
43 protoff, addroff, sizeof(buf),
44 (char *) &buf, sizeof(buf))) {
45 net_notice_ratelimited("nf_nat_h323: nf_nat_mangle_tcp_packet error\n");
46 return -1;
47 }
48
49 /* Relocate data pointer */
50 th = skb_header_pointer(skb, ip_hdrlen(skb),
51 sizeof(_tcph), &_tcph);
52 if (th == NULL)
53 return -1;
54 *data = skb->data + ip_hdrlen(skb) + th->doff * 4 + dataoff;
55 } else {
56 if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
57 protoff, addroff, sizeof(buf),
58 (char *) &buf, sizeof(buf))) {
59 net_notice_ratelimited("nf_nat_h323: nf_nat_mangle_udp_packet error\n");
60 return -1;
61 }
62 /* nf_nat_mangle_udp_packet uses skb_make_writable() to copy
63 * or pull everything in a linear buffer, so we can safely
64 * use the skb pointers now */
65 *data = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
66 }
67
68 return 0;
69}
70
71/****************************************************************************/
72static int set_h225_addr(struct sk_buff *skb, unsigned int protoff,
73 unsigned char **data, int dataoff,
74 TransportAddress *taddr,
75 union nf_inet_addr *addr, __be16 port)
76{
77 return set_addr(skb, protoff, data, dataoff, taddr->ipAddress.ip,
78 addr->ip, port);
79}
80
81/****************************************************************************/
82static int set_h245_addr(struct sk_buff *skb, unsigned protoff,
83 unsigned char **data, int dataoff,
84 H245_TransportAddress *taddr,
85 union nf_inet_addr *addr, __be16 port)
86{
87 return set_addr(skb, protoff, data, dataoff,
88 taddr->unicastAddress.iPAddress.network,
89 addr->ip, port);
90}
91
92/****************************************************************************/
93static int set_sig_addr(struct sk_buff *skb, struct nf_conn *ct,
94 enum ip_conntrack_info ctinfo,
95 unsigned int protoff, unsigned char **data,
96 TransportAddress *taddr, int count)
97{
98 const struct nf_ct_h323_master *info = nfct_help_data(ct);
99 int dir = CTINFO2DIR(ctinfo);
100 int i;
101 __be16 port;
102 union nf_inet_addr addr;
103
104 for (i = 0; i < count; i++) {
105 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port)) {
106 if (addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
107 port == info->sig_port[dir]) {
108 /* GW->GK */
109
110 /* Fix for Gnomemeeting */
111 if (i > 0 &&
112 get_h225_addr(ct, *data, &taddr[0],
113 &addr, &port) &&
114 (ntohl(addr.ip) & 0xff000000) == 0x7f000000)
115 i = 0;
116
117 pr_debug("nf_nat_ras: set signal address %pI4:%hu->%pI4:%hu\n",
118 &addr.ip, port,
119 &ct->tuplehash[!dir].tuple.dst.u3.ip,
120 info->sig_port[!dir]);
121 return set_h225_addr(skb, protoff, data, 0,
122 &taddr[i],
123 &ct->tuplehash[!dir].
124 tuple.dst.u3,
125 info->sig_port[!dir]);
126 } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
127 port == info->sig_port[dir]) {
128 /* GK->GW */
129 pr_debug("nf_nat_ras: set signal address %pI4:%hu->%pI4:%hu\n",
130 &addr.ip, port,
131 &ct->tuplehash[!dir].tuple.src.u3.ip,
132 info->sig_port[!dir]);
133 return set_h225_addr(skb, protoff, data, 0,
134 &taddr[i],
135 &ct->tuplehash[!dir].
136 tuple.src.u3,
137 info->sig_port[!dir]);
138 }
139 }
140 }
141
142 return 0;
143}
144
145/****************************************************************************/
146static int set_ras_addr(struct sk_buff *skb, struct nf_conn *ct,
147 enum ip_conntrack_info ctinfo,
148 unsigned int protoff, unsigned char **data,
149 TransportAddress *taddr, int count)
150{
151 int dir = CTINFO2DIR(ctinfo);
152 int i;
153 __be16 port;
154 union nf_inet_addr addr;
155
156 for (i = 0; i < count; i++) {
157 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
158 addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
159 port == ct->tuplehash[dir].tuple.src.u.udp.port) {
160 pr_debug("nf_nat_ras: set rasAddress %pI4:%hu->%pI4:%hu\n",
161 &addr.ip, ntohs(port),
162 &ct->tuplehash[!dir].tuple.dst.u3.ip,
163 ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port));
164 return set_h225_addr(skb, protoff, data, 0, &taddr[i],
165 &ct->tuplehash[!dir].tuple.dst.u3,
166 ct->tuplehash[!dir].tuple.
167 dst.u.udp.port);
168 }
169 }
170
171 return 0;
172}
173
174/****************************************************************************/
175static int nat_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
176 enum ip_conntrack_info ctinfo,
177 unsigned int protoff, unsigned char **data, int dataoff,
178 H245_TransportAddress *taddr,
179 __be16 port, __be16 rtp_port,
180 struct nf_conntrack_expect *rtp_exp,
181 struct nf_conntrack_expect *rtcp_exp)
182{
183 struct nf_ct_h323_master *info = nfct_help_data(ct);
184 int dir = CTINFO2DIR(ctinfo);
185 int i;
186 u_int16_t nated_port;
187
188 /* Set expectations for NAT */
189 rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
190 rtp_exp->expectfn = nf_nat_follow_master;
191 rtp_exp->dir = !dir;
192 rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
193 rtcp_exp->expectfn = nf_nat_follow_master;
194 rtcp_exp->dir = !dir;
195
196 /* Lookup existing expects */
197 for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
198 if (info->rtp_port[i][dir] == rtp_port) {
199 /* Expected */
200
201 /* Use allocated ports first. This will refresh
202 * the expects */
203 rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
204 rtcp_exp->tuple.dst.u.udp.port =
205 htons(ntohs(info->rtp_port[i][dir]) + 1);
206 break;
207 } else if (info->rtp_port[i][dir] == 0) {
208 /* Not expected */
209 break;
210 }
211 }
212
213 /* Run out of expectations */
214 if (i >= H323_RTP_CHANNEL_MAX) {
215 net_notice_ratelimited("nf_nat_h323: out of expectations\n");
216 return 0;
217 }
218
219 /* Try to get a pair of ports. */
220 for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
221 nated_port != 0; nated_port += 2) {
222 int ret;
223
224 rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
225 ret = nf_ct_expect_related(rtp_exp);
226 if (ret == 0) {
227 rtcp_exp->tuple.dst.u.udp.port =
228 htons(nated_port + 1);
229 ret = nf_ct_expect_related(rtcp_exp);
230 if (ret == 0)
231 break;
232 else if (ret == -EBUSY) {
233 nf_ct_unexpect_related(rtp_exp);
234 continue;
235 } else if (ret < 0) {
236 nf_ct_unexpect_related(rtp_exp);
237 nated_port = 0;
238 break;
239 }
240 } else if (ret != -EBUSY) {
241 nated_port = 0;
242 break;
243 }
244 }
245
246 if (nated_port == 0) { /* No port available */
247 net_notice_ratelimited("nf_nat_h323: out of RTP ports\n");
248 return 0;
249 }
250
251 /* Modify signal */
252 if (set_h245_addr(skb, protoff, data, dataoff, taddr,
253 &ct->tuplehash[!dir].tuple.dst.u3,
254 htons((port & htons(1)) ? nated_port + 1 :
255 nated_port))) {
256 nf_ct_unexpect_related(rtp_exp);
257 nf_ct_unexpect_related(rtcp_exp);
258 return -1;
259 }
260
261 /* Save ports */
262 info->rtp_port[i][dir] = rtp_port;
263 info->rtp_port[i][!dir] = htons(nated_port);
264
265 /* Success */
266 pr_debug("nf_nat_h323: expect RTP %pI4:%hu->%pI4:%hu\n",
267 &rtp_exp->tuple.src.u3.ip,
268 ntohs(rtp_exp->tuple.src.u.udp.port),
269 &rtp_exp->tuple.dst.u3.ip,
270 ntohs(rtp_exp->tuple.dst.u.udp.port));
271 pr_debug("nf_nat_h323: expect RTCP %pI4:%hu->%pI4:%hu\n",
272 &rtcp_exp->tuple.src.u3.ip,
273 ntohs(rtcp_exp->tuple.src.u.udp.port),
274 &rtcp_exp->tuple.dst.u3.ip,
275 ntohs(rtcp_exp->tuple.dst.u.udp.port));
276
277 return 0;
278}
279
280/****************************************************************************/
281static int nat_t120(struct sk_buff *skb, struct nf_conn *ct,
282 enum ip_conntrack_info ctinfo,
283 unsigned int protoff, unsigned char **data, int dataoff,
284 H245_TransportAddress *taddr, __be16 port,
285 struct nf_conntrack_expect *exp)
286{
287 int dir = CTINFO2DIR(ctinfo);
288 u_int16_t nated_port = ntohs(port);
289
290 /* Set expectations for NAT */
291 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
292 exp->expectfn = nf_nat_follow_master;
293 exp->dir = !dir;
294
295 /* Try to get same port: if not, try to change it. */
296 for (; nated_port != 0; nated_port++) {
297 int ret;
298
299 exp->tuple.dst.u.tcp.port = htons(nated_port);
300 ret = nf_ct_expect_related(exp);
301 if (ret == 0)
302 break;
303 else if (ret != -EBUSY) {
304 nated_port = 0;
305 break;
306 }
307 }
308
309 if (nated_port == 0) { /* No port available */
310 net_notice_ratelimited("nf_nat_h323: out of TCP ports\n");
311 return 0;
312 }
313
314 /* Modify signal */
315 if (set_h245_addr(skb, protoff, data, dataoff, taddr,
316 &ct->tuplehash[!dir].tuple.dst.u3,
317 htons(nated_port)) < 0) {
318 nf_ct_unexpect_related(exp);
319 return -1;
320 }
321
322 pr_debug("nf_nat_h323: expect T.120 %pI4:%hu->%pI4:%hu\n",
323 &exp->tuple.src.u3.ip,
324 ntohs(exp->tuple.src.u.tcp.port),
325 &exp->tuple.dst.u3.ip,
326 ntohs(exp->tuple.dst.u.tcp.port));
327
328 return 0;
329}
330
331/****************************************************************************/
332static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
333 enum ip_conntrack_info ctinfo,
334 unsigned int protoff, unsigned char **data, int dataoff,
335 TransportAddress *taddr, __be16 port,
336 struct nf_conntrack_expect *exp)
337{
338 struct nf_ct_h323_master *info = nfct_help_data(ct);
339 int dir = CTINFO2DIR(ctinfo);
340 u_int16_t nated_port = ntohs(port);
341
342 /* Set expectations for NAT */
343 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
344 exp->expectfn = nf_nat_follow_master;
345 exp->dir = !dir;
346
347 /* Check existing expects */
348 if (info->sig_port[dir] == port)
349 nated_port = ntohs(info->sig_port[!dir]);
350
351 /* Try to get same port: if not, try to change it. */
352 for (; nated_port != 0; nated_port++) {
353 int ret;
354
355 exp->tuple.dst.u.tcp.port = htons(nated_port);
356 ret = nf_ct_expect_related(exp);
357 if (ret == 0)
358 break;
359 else if (ret != -EBUSY) {
360 nated_port = 0;
361 break;
362 }
363 }
364
365 if (nated_port == 0) { /* No port available */
366 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
367 return 0;
368 }
369
370 /* Modify signal */
371 if (set_h225_addr(skb, protoff, data, dataoff, taddr,
372 &ct->tuplehash[!dir].tuple.dst.u3,
373 htons(nated_port))) {
374 nf_ct_unexpect_related(exp);
375 return -1;
376 }
377
378 /* Save ports */
379 info->sig_port[dir] = port;
380 info->sig_port[!dir] = htons(nated_port);
381
382 pr_debug("nf_nat_q931: expect H.245 %pI4:%hu->%pI4:%hu\n",
383 &exp->tuple.src.u3.ip,
384 ntohs(exp->tuple.src.u.tcp.port),
385 &exp->tuple.dst.u3.ip,
386 ntohs(exp->tuple.dst.u.tcp.port));
387
388 return 0;
389}
390
391/****************************************************************************
392 * This conntrack expect function replaces nf_conntrack_q931_expect()
393 * which was set by nf_conntrack_h323.c.
394 ****************************************************************************/
395static void ip_nat_q931_expect(struct nf_conn *new,
396 struct nf_conntrack_expect *this)
397{
398 struct nf_nat_range2 range;
399
400 if (this->tuple.src.u3.ip != 0) { /* Only accept calls from GK */
401 nf_nat_follow_master(new, this);
402 return;
403 }
404
405 /* This must be a fresh one. */
406 BUG_ON(new->status & IPS_NAT_DONE_MASK);
407
408 /* Change src to where master sends to */
409 range.flags = NF_NAT_RANGE_MAP_IPS;
410 range.min_addr = range.max_addr =
411 new->tuplehash[!this->dir].tuple.src.u3;
412 nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
413
414 /* For DST manip, map port here to where it's expected. */
415 range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
416 range.min_proto = range.max_proto = this->saved_proto;
417 range.min_addr = range.max_addr =
418 new->master->tuplehash[!this->dir].tuple.src.u3;
419 nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
420}
421
422/****************************************************************************/
423static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
424 enum ip_conntrack_info ctinfo,
425 unsigned int protoff, unsigned char **data,
426 TransportAddress *taddr, int idx,
427 __be16 port, struct nf_conntrack_expect *exp)
428{
429 struct nf_ct_h323_master *info = nfct_help_data(ct);
430 int dir = CTINFO2DIR(ctinfo);
431 u_int16_t nated_port = ntohs(port);
432 union nf_inet_addr addr;
433
434 /* Set expectations for NAT */
435 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
436 exp->expectfn = ip_nat_q931_expect;
437 exp->dir = !dir;
438
439 /* Check existing expects */
440 if (info->sig_port[dir] == port)
441 nated_port = ntohs(info->sig_port[!dir]);
442
443 /* Try to get same port: if not, try to change it. */
444 for (; nated_port != 0; nated_port++) {
445 int ret;
446
447 exp->tuple.dst.u.tcp.port = htons(nated_port);
448 ret = nf_ct_expect_related(exp);
449 if (ret == 0)
450 break;
451 else if (ret != -EBUSY) {
452 nated_port = 0;
453 break;
454 }
455 }
456
457 if (nated_port == 0) { /* No port available */
458 net_notice_ratelimited("nf_nat_ras: out of TCP ports\n");
459 return 0;
460 }
461
462 /* Modify signal */
463 if (set_h225_addr(skb, protoff, data, 0, &taddr[idx],
464 &ct->tuplehash[!dir].tuple.dst.u3,
465 htons(nated_port))) {
466 nf_ct_unexpect_related(exp);
467 return -1;
468 }
469
470 /* Save ports */
471 info->sig_port[dir] = port;
472 info->sig_port[!dir] = htons(nated_port);
473
474 /* Fix for Gnomemeeting */
475 if (idx > 0 &&
476 get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
477 (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
478 if (set_h225_addr(skb, protoff, data, 0, &taddr[0],
479 &ct->tuplehash[!dir].tuple.dst.u3,
480 info->sig_port[!dir])) {
481 nf_ct_unexpect_related(exp);
482 return -1;
483 }
484 }
485
486 /* Success */
487 pr_debug("nf_nat_ras: expect Q.931 %pI4:%hu->%pI4:%hu\n",
488 &exp->tuple.src.u3.ip,
489 ntohs(exp->tuple.src.u.tcp.port),
490 &exp->tuple.dst.u3.ip,
491 ntohs(exp->tuple.dst.u.tcp.port));
492
493 return 0;
494}
495
496/****************************************************************************/
497static void ip_nat_callforwarding_expect(struct nf_conn *new,
498 struct nf_conntrack_expect *this)
499{
500 struct nf_nat_range2 range;
501
502 /* This must be a fresh one. */
503 BUG_ON(new->status & IPS_NAT_DONE_MASK);
504
505 /* Change src to where master sends to */
506 range.flags = NF_NAT_RANGE_MAP_IPS;
507 range.min_addr = range.max_addr =
508 new->tuplehash[!this->dir].tuple.src.u3;
509 nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
510
511 /* For DST manip, map port here to where it's expected. */
512 range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
513 range.min_proto = range.max_proto = this->saved_proto;
514 range.min_addr = range.max_addr = this->saved_addr;
515 nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
516}
517
518/****************************************************************************/
519static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
520 enum ip_conntrack_info ctinfo,
521 unsigned int protoff,
522 unsigned char **data, int dataoff,
523 TransportAddress *taddr, __be16 port,
524 struct nf_conntrack_expect *exp)
525{
526 int dir = CTINFO2DIR(ctinfo);
527 u_int16_t nated_port;
528
529 /* Set expectations for NAT */
530 exp->saved_addr = exp->tuple.dst.u3;
531 exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
532 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
533 exp->expectfn = ip_nat_callforwarding_expect;
534 exp->dir = !dir;
535
536 /* Try to get same port: if not, try to change it. */
537 for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
538 int ret;
539
540 exp->tuple.dst.u.tcp.port = htons(nated_port);
541 ret = nf_ct_expect_related(exp);
542 if (ret == 0)
543 break;
544 else if (ret != -EBUSY) {
545 nated_port = 0;
546 break;
547 }
548 }
549
550 if (nated_port == 0) { /* No port available */
551 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
552 return 0;
553 }
554
555 /* Modify signal */
556 if (set_h225_addr(skb, protoff, data, dataoff, taddr,
557 &ct->tuplehash[!dir].tuple.dst.u3,
558 htons(nated_port))) {
559 nf_ct_unexpect_related(exp);
560 return -1;
561 }
562
563 /* Success */
564 pr_debug("nf_nat_q931: expect Call Forwarding %pI4:%hu->%pI4:%hu\n",
565 &exp->tuple.src.u3.ip,
566 ntohs(exp->tuple.src.u.tcp.port),
567 &exp->tuple.dst.u3.ip,
568 ntohs(exp->tuple.dst.u.tcp.port));
569
570 return 0;
571}
572
573static struct nf_ct_helper_expectfn q931_nat = {
574 .name = "Q.931",
575 .expectfn = ip_nat_q931_expect,
576};
577
578static struct nf_ct_helper_expectfn callforwarding_nat = {
579 .name = "callforwarding",
580 .expectfn = ip_nat_callforwarding_expect,
581};
582
583/****************************************************************************/
584static int __init init(void)
585{
586 BUG_ON(set_h245_addr_hook != NULL);
587 BUG_ON(set_h225_addr_hook != NULL);
588 BUG_ON(set_sig_addr_hook != NULL);
589 BUG_ON(set_ras_addr_hook != NULL);
590 BUG_ON(nat_rtp_rtcp_hook != NULL);
591 BUG_ON(nat_t120_hook != NULL);
592 BUG_ON(nat_h245_hook != NULL);
593 BUG_ON(nat_callforwarding_hook != NULL);
594 BUG_ON(nat_q931_hook != NULL);
595
596 RCU_INIT_POINTER(set_h245_addr_hook, set_h245_addr);
597 RCU_INIT_POINTER(set_h225_addr_hook, set_h225_addr);
598 RCU_INIT_POINTER(set_sig_addr_hook, set_sig_addr);
599 RCU_INIT_POINTER(set_ras_addr_hook, set_ras_addr);
600 RCU_INIT_POINTER(nat_rtp_rtcp_hook, nat_rtp_rtcp);
601 RCU_INIT_POINTER(nat_t120_hook, nat_t120);
602 RCU_INIT_POINTER(nat_h245_hook, nat_h245);
603 RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
604 RCU_INIT_POINTER(nat_q931_hook, nat_q931);
605 nf_ct_helper_expectfn_register(&q931_nat);
606 nf_ct_helper_expectfn_register(&callforwarding_nat);
607 return 0;
608}
609
610/****************************************************************************/
611static void __exit fini(void)
612{
613 RCU_INIT_POINTER(set_h245_addr_hook, NULL);
614 RCU_INIT_POINTER(set_h225_addr_hook, NULL);
615 RCU_INIT_POINTER(set_sig_addr_hook, NULL);
616 RCU_INIT_POINTER(set_ras_addr_hook, NULL);
617 RCU_INIT_POINTER(nat_rtp_rtcp_hook, NULL);
618 RCU_INIT_POINTER(nat_t120_hook, NULL);
619 RCU_INIT_POINTER(nat_h245_hook, NULL);
620 RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
621 RCU_INIT_POINTER(nat_q931_hook, NULL);
622 nf_ct_helper_expectfn_unregister(&q931_nat);
623 nf_ct_helper_expectfn_unregister(&callforwarding_nat);
624 synchronize_rcu();
625}
626
627/****************************************************************************/
628module_init(init);
629module_exit(fini);
630
631MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
632MODULE_DESCRIPTION("H.323 NAT helper");
633MODULE_LICENSE("GPL");
634MODULE_ALIAS("ip_nat_h323");
635