2 * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
3 * PPTP is a a protocol for creating virtual private networks.
4 * It is a specification defined by Microsoft and some vendors
5 * working with Microsoft. PPTP is built on top of a modified
6 * version of the Internet Generic Routing Encapsulation Protocol.
7 * GRE is defined in RFC 1701 and RFC 1702. Documentation of
8 * PPTP can be found in RFC 2637
10 * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
12 * Development of this code funded by Astaro AG (http://www.astaro.com/)
15 * - We blindly assume that control connections are always
16 * established in PNS->PAC direction. This is a violation
18 * - We can only support one single call within each session
20 * - testing of incoming PPTP calls
23 #include <linux/module.h>
24 #include <linux/skbuff.h>
26 #include <linux/tcp.h>
28 #include <net/netfilter/nf_conntrack.h>
29 #include <net/netfilter/nf_conntrack_core.h>
30 #include <net/netfilter/nf_conntrack_helper.h>
31 #include <linux/netfilter/nf_conntrack_proto_gre.h>
32 #include <linux/netfilter/nf_conntrack_pptp.h>
34 #define NF_CT_PPTP_VERSION "3.1"
36 MODULE_LICENSE("GPL");
37 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
38 MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
39 MODULE_ALIAS("ip_conntrack_pptp");
41 static DEFINE_SPINLOCK(nf_pptp_lock
);
44 (*nf_nat_pptp_hook_outbound
)(struct sk_buff
**pskb
,
45 struct nf_conn
*ct
, enum ip_conntrack_info ctinfo
,
46 struct PptpControlHeader
*ctlh
,
47 union pptp_ctrl_union
*pptpReq
) __read_mostly
;
48 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound
);
51 (*nf_nat_pptp_hook_inbound
)(struct sk_buff
**pskb
,
52 struct nf_conn
*ct
, enum ip_conntrack_info ctinfo
,
53 struct PptpControlHeader
*ctlh
,
54 union pptp_ctrl_union
*pptpReq
) __read_mostly
;
55 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound
);
58 (*nf_nat_pptp_hook_exp_gre
)(struct nf_conntrack_expect
*expect_orig
,
59 struct nf_conntrack_expect
*expect_reply
)
61 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre
);
64 (*nf_nat_pptp_hook_expectfn
)(struct nf_conn
*ct
,
65 struct nf_conntrack_expect
*exp
) __read_mostly
;
66 EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn
);
69 /* PptpControlMessageType names */
70 const char *pptp_msg_name
[] = {
72 "START_SESSION_REQUEST",
73 "START_SESSION_REPLY",
74 "STOP_SESSION_REQUEST",
84 "CALL_DISCONNECT_NOTIFY",
88 EXPORT_SYMBOL(pptp_msg_name
);
89 #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
91 #define DEBUGP(format, args...)
95 #define MINS * 60 SECS
96 #define HOURS * 60 MINS
98 #define PPTP_GRE_TIMEOUT (10 MINS)
99 #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
101 static void pptp_expectfn(struct nf_conn
*ct
,
102 struct nf_conntrack_expect
*exp
)
104 typeof(nf_nat_pptp_hook_expectfn
) nf_nat_pptp_expectfn
;
105 DEBUGP("increasing timeouts\n");
107 /* increase timeout of GRE data channel conntrack entry */
108 ct
->proto
.gre
.timeout
= PPTP_GRE_TIMEOUT
;
109 ct
->proto
.gre
.stream_timeout
= PPTP_GRE_STREAM_TIMEOUT
;
111 /* Can you see how rusty this code is, compared with the pre-2.6.11
112 * one? That's what happened to my shiny newnat of 2002 ;( -HW */
115 nf_nat_pptp_expectfn
= rcu_dereference(nf_nat_pptp_hook_expectfn
);
116 if (nf_nat_pptp_expectfn
&& ct
->master
->status
& IPS_NAT_MASK
)
117 nf_nat_pptp_expectfn(ct
, exp
);
119 struct nf_conntrack_tuple inv_t
;
120 struct nf_conntrack_expect
*exp_other
;
122 /* obviously this tuple inversion only works until you do NAT */
123 nf_ct_invert_tuplepr(&inv_t
, &exp
->tuple
);
124 DEBUGP("trying to unexpect other dir: ");
125 NF_CT_DUMP_TUPLE(&inv_t
);
127 exp_other
= nf_conntrack_expect_find_get(&inv_t
);
129 /* delete other expectation. */
131 nf_conntrack_unexpect_related(exp_other
);
132 nf_conntrack_expect_put(exp_other
);
134 DEBUGP("not found\n");
140 static int destroy_sibling_or_exp(const struct nf_conntrack_tuple
*t
)
142 struct nf_conntrack_tuple_hash
*h
;
143 struct nf_conntrack_expect
*exp
;
144 struct nf_conn
*sibling
;
146 DEBUGP("trying to timeout ct or exp for tuple ");
149 h
= nf_conntrack_find_get(t
, NULL
);
151 sibling
= nf_ct_tuplehash_to_ctrack(h
);
152 DEBUGP("setting timeout of conntrack %p to 0\n", sibling
);
153 sibling
->proto
.gre
.timeout
= 0;
154 sibling
->proto
.gre
.stream_timeout
= 0;
155 if (del_timer(&sibling
->timeout
))
156 sibling
->timeout
.function((unsigned long)sibling
);
160 exp
= nf_conntrack_expect_find_get(t
);
162 DEBUGP("unexpect_related of expect %p\n", exp
);
163 nf_conntrack_unexpect_related(exp
);
164 nf_conntrack_expect_put(exp
);
171 /* timeout GRE data connections */
172 static void pptp_destroy_siblings(struct nf_conn
*ct
)
174 struct nf_conn_help
*help
= nfct_help(ct
);
175 struct nf_conntrack_tuple t
;
177 nf_ct_gre_keymap_destroy(ct
);
179 /* try original (pns->pac) tuple */
180 memcpy(&t
, &ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
, sizeof(t
));
181 t
.dst
.protonum
= IPPROTO_GRE
;
182 t
.src
.u
.gre
.key
= help
->help
.ct_pptp_info
.pns_call_id
;
183 t
.dst
.u
.gre
.key
= help
->help
.ct_pptp_info
.pac_call_id
;
184 if (!destroy_sibling_or_exp(&t
))
185 DEBUGP("failed to timeout original pns->pac ct/exp\n");
187 /* try reply (pac->pns) tuple */
188 memcpy(&t
, &ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
, sizeof(t
));
189 t
.dst
.protonum
= IPPROTO_GRE
;
190 t
.src
.u
.gre
.key
= help
->help
.ct_pptp_info
.pac_call_id
;
191 t
.dst
.u
.gre
.key
= help
->help
.ct_pptp_info
.pns_call_id
;
192 if (!destroy_sibling_or_exp(&t
))
193 DEBUGP("failed to timeout reply pac->pns ct/exp\n");
196 /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
197 static int exp_gre(struct nf_conn
*ct
, __be16 callid
, __be16 peer_callid
)
199 struct nf_conntrack_expect
*exp_orig
, *exp_reply
;
200 enum ip_conntrack_dir dir
;
202 typeof(nf_nat_pptp_hook_exp_gre
) nf_nat_pptp_exp_gre
;
204 exp_orig
= nf_conntrack_expect_alloc(ct
);
205 if (exp_orig
== NULL
)
208 exp_reply
= nf_conntrack_expect_alloc(ct
);
209 if (exp_reply
== NULL
)
212 /* original direction, PNS->PAC */
213 dir
= IP_CT_DIR_ORIGINAL
;
214 nf_conntrack_expect_init(exp_orig
, ct
->tuplehash
[dir
].tuple
.src
.l3num
,
215 &ct
->tuplehash
[dir
].tuple
.src
.u3
,
216 &ct
->tuplehash
[dir
].tuple
.dst
.u3
,
217 IPPROTO_GRE
, &peer_callid
, &callid
);
218 exp_orig
->expectfn
= pptp_expectfn
;
220 /* reply direction, PAC->PNS */
221 dir
= IP_CT_DIR_REPLY
;
222 nf_conntrack_expect_init(exp_reply
, ct
->tuplehash
[dir
].tuple
.src
.l3num
,
223 &ct
->tuplehash
[dir
].tuple
.src
.u3
,
224 &ct
->tuplehash
[dir
].tuple
.dst
.u3
,
225 IPPROTO_GRE
, &callid
, &peer_callid
);
226 exp_reply
->expectfn
= pptp_expectfn
;
228 nf_nat_pptp_exp_gre
= rcu_dereference(nf_nat_pptp_hook_exp_gre
);
229 if (nf_nat_pptp_exp_gre
&& ct
->status
& IPS_NAT_MASK
)
230 nf_nat_pptp_exp_gre(exp_orig
, exp_reply
);
231 if (nf_conntrack_expect_related(exp_orig
) != 0)
233 if (nf_conntrack_expect_related(exp_reply
) != 0)
234 goto out_unexpect_orig
;
236 /* Add GRE keymap entries */
237 if (nf_ct_gre_keymap_add(ct
, IP_CT_DIR_ORIGINAL
, &exp_orig
->tuple
) != 0)
238 goto out_unexpect_both
;
239 if (nf_ct_gre_keymap_add(ct
, IP_CT_DIR_REPLY
, &exp_reply
->tuple
) != 0) {
240 nf_ct_gre_keymap_destroy(ct
);
241 goto out_unexpect_both
;
246 nf_conntrack_expect_put(exp_reply
);
248 nf_conntrack_expect_put(exp_orig
);
253 nf_conntrack_unexpect_related(exp_reply
);
255 nf_conntrack_unexpect_related(exp_orig
);
260 pptp_inbound_pkt(struct sk_buff
**pskb
,
261 struct PptpControlHeader
*ctlh
,
262 union pptp_ctrl_union
*pptpReq
,
265 enum ip_conntrack_info ctinfo
)
267 struct nf_ct_pptp_master
*info
= &nfct_help(ct
)->help
.ct_pptp_info
;
269 __be16 cid
= 0, pcid
= 0;
270 typeof(nf_nat_pptp_hook_inbound
) nf_nat_pptp_inbound
;
272 msg
= ntohs(ctlh
->messageType
);
273 DEBUGP("inbound control message %s\n", pptp_msg_name
[msg
]);
276 case PPTP_START_SESSION_REPLY
:
277 /* server confirms new control session */
278 if (info
->sstate
< PPTP_SESSION_REQUESTED
)
280 if (pptpReq
->srep
.resultCode
== PPTP_START_OK
)
281 info
->sstate
= PPTP_SESSION_CONFIRMED
;
283 info
->sstate
= PPTP_SESSION_ERROR
;
286 case PPTP_STOP_SESSION_REPLY
:
287 /* server confirms end of control session */
288 if (info
->sstate
> PPTP_SESSION_STOPREQ
)
290 if (pptpReq
->strep
.resultCode
== PPTP_STOP_OK
)
291 info
->sstate
= PPTP_SESSION_NONE
;
293 info
->sstate
= PPTP_SESSION_ERROR
;
296 case PPTP_OUT_CALL_REPLY
:
297 /* server accepted call, we now expect GRE frames */
298 if (info
->sstate
!= PPTP_SESSION_CONFIRMED
)
300 if (info
->cstate
!= PPTP_CALL_OUT_REQ
&&
301 info
->cstate
!= PPTP_CALL_OUT_CONF
)
304 cid
= pptpReq
->ocack
.callID
;
305 pcid
= pptpReq
->ocack
.peersCallID
;
306 if (info
->pns_call_id
!= pcid
)
308 DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name
[msg
],
309 ntohs(cid
), ntohs(pcid
));
311 if (pptpReq
->ocack
.resultCode
== PPTP_OUTCALL_CONNECT
) {
312 info
->cstate
= PPTP_CALL_OUT_CONF
;
313 info
->pac_call_id
= cid
;
314 exp_gre(ct
, cid
, pcid
);
316 info
->cstate
= PPTP_CALL_NONE
;
319 case PPTP_IN_CALL_REQUEST
:
320 /* server tells us about incoming call request */
321 if (info
->sstate
!= PPTP_SESSION_CONFIRMED
)
324 cid
= pptpReq
->icreq
.callID
;
325 DEBUGP("%s, CID=%X\n", pptp_msg_name
[msg
], ntohs(cid
));
326 info
->cstate
= PPTP_CALL_IN_REQ
;
327 info
->pac_call_id
= cid
;
330 case PPTP_IN_CALL_CONNECT
:
331 /* server tells us about incoming call established */
332 if (info
->sstate
!= PPTP_SESSION_CONFIRMED
)
334 if (info
->cstate
!= PPTP_CALL_IN_REP
&&
335 info
->cstate
!= PPTP_CALL_IN_CONF
)
338 pcid
= pptpReq
->iccon
.peersCallID
;
339 cid
= info
->pac_call_id
;
341 if (info
->pns_call_id
!= pcid
)
344 DEBUGP("%s, PCID=%X\n", pptp_msg_name
[msg
], ntohs(pcid
));
345 info
->cstate
= PPTP_CALL_IN_CONF
;
347 /* we expect a GRE connection from PAC to PNS */
348 exp_gre(ct
, cid
, pcid
);
351 case PPTP_CALL_DISCONNECT_NOTIFY
:
352 /* server confirms disconnect */
353 cid
= pptpReq
->disc
.callID
;
354 DEBUGP("%s, CID=%X\n", pptp_msg_name
[msg
], ntohs(cid
));
355 info
->cstate
= PPTP_CALL_NONE
;
357 /* untrack this call id, unexpect GRE packets */
358 pptp_destroy_siblings(ct
);
361 case PPTP_WAN_ERROR_NOTIFY
:
362 case PPTP_ECHO_REQUEST
:
363 case PPTP_ECHO_REPLY
:
364 /* I don't have to explain these ;) */
371 nf_nat_pptp_inbound
= rcu_dereference(nf_nat_pptp_hook_inbound
);
372 if (nf_nat_pptp_inbound
&& ct
->status
& IPS_NAT_MASK
)
373 return nf_nat_pptp_inbound(pskb
, ct
, ctinfo
, ctlh
, pptpReq
);
377 DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
378 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
379 msg
<= PPTP_MSG_MAX
? pptp_msg_name
[msg
] : pptp_msg_name
[0],
380 msg
, ntohs(cid
), ntohs(pcid
), info
->cstate
, info
->sstate
,
381 ntohs(info
->pns_call_id
), ntohs(info
->pac_call_id
));
386 pptp_outbound_pkt(struct sk_buff
**pskb
,
387 struct PptpControlHeader
*ctlh
,
388 union pptp_ctrl_union
*pptpReq
,
391 enum ip_conntrack_info ctinfo
)
393 struct nf_ct_pptp_master
*info
= &nfct_help(ct
)->help
.ct_pptp_info
;
395 __be16 cid
= 0, pcid
= 0;
396 typeof(nf_nat_pptp_hook_outbound
) nf_nat_pptp_outbound
;
398 msg
= ntohs(ctlh
->messageType
);
399 DEBUGP("outbound control message %s\n", pptp_msg_name
[msg
]);
402 case PPTP_START_SESSION_REQUEST
:
403 /* client requests for new control session */
404 if (info
->sstate
!= PPTP_SESSION_NONE
)
406 info
->sstate
= PPTP_SESSION_REQUESTED
;
409 case PPTP_STOP_SESSION_REQUEST
:
410 /* client requests end of control session */
411 info
->sstate
= PPTP_SESSION_STOPREQ
;
414 case PPTP_OUT_CALL_REQUEST
:
415 /* client initiating connection to server */
416 if (info
->sstate
!= PPTP_SESSION_CONFIRMED
)
418 info
->cstate
= PPTP_CALL_OUT_REQ
;
419 /* track PNS call id */
420 cid
= pptpReq
->ocreq
.callID
;
421 DEBUGP("%s, CID=%X\n", pptp_msg_name
[msg
], ntohs(cid
));
422 info
->pns_call_id
= cid
;
425 case PPTP_IN_CALL_REPLY
:
426 /* client answers incoming call */
427 if (info
->cstate
!= PPTP_CALL_IN_REQ
&&
428 info
->cstate
!= PPTP_CALL_IN_REP
)
431 cid
= pptpReq
->icack
.callID
;
432 pcid
= pptpReq
->icack
.peersCallID
;
433 if (info
->pac_call_id
!= pcid
)
435 DEBUGP("%s, CID=%X PCID=%X\n", pptp_msg_name
[msg
],
436 ntohs(cid
), ntohs(pcid
));
438 if (pptpReq
->icack
.resultCode
== PPTP_INCALL_ACCEPT
) {
439 /* part two of the three-way handshake */
440 info
->cstate
= PPTP_CALL_IN_REP
;
441 info
->pns_call_id
= cid
;
443 info
->cstate
= PPTP_CALL_NONE
;
446 case PPTP_CALL_CLEAR_REQUEST
:
447 /* client requests hangup of call */
448 if (info
->sstate
!= PPTP_SESSION_CONFIRMED
)
450 /* FUTURE: iterate over all calls and check if
451 * call ID is valid. We don't do this without newnat,
452 * because we only know about last call */
453 info
->cstate
= PPTP_CALL_CLEAR_REQ
;
456 case PPTP_SET_LINK_INFO
:
457 case PPTP_ECHO_REQUEST
:
458 case PPTP_ECHO_REPLY
:
459 /* I don't have to explain these ;) */
466 nf_nat_pptp_outbound
= rcu_dereference(nf_nat_pptp_hook_outbound
);
467 if (nf_nat_pptp_outbound
&& ct
->status
& IPS_NAT_MASK
)
468 return nf_nat_pptp_outbound(pskb
, ct
, ctinfo
, ctlh
, pptpReq
);
472 DEBUGP("invalid %s: type=%d cid=%u pcid=%u "
473 "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
474 msg
<= PPTP_MSG_MAX
? pptp_msg_name
[msg
] : pptp_msg_name
[0],
475 msg
, ntohs(cid
), ntohs(pcid
), info
->cstate
, info
->sstate
,
476 ntohs(info
->pns_call_id
), ntohs(info
->pac_call_id
));
480 static const unsigned int pptp_msg_size
[] = {
481 [PPTP_START_SESSION_REQUEST
] = sizeof(struct PptpStartSessionRequest
),
482 [PPTP_START_SESSION_REPLY
] = sizeof(struct PptpStartSessionReply
),
483 [PPTP_STOP_SESSION_REQUEST
] = sizeof(struct PptpStopSessionRequest
),
484 [PPTP_STOP_SESSION_REPLY
] = sizeof(struct PptpStopSessionReply
),
485 [PPTP_OUT_CALL_REQUEST
] = sizeof(struct PptpOutCallRequest
),
486 [PPTP_OUT_CALL_REPLY
] = sizeof(struct PptpOutCallReply
),
487 [PPTP_IN_CALL_REQUEST
] = sizeof(struct PptpInCallRequest
),
488 [PPTP_IN_CALL_REPLY
] = sizeof(struct PptpInCallReply
),
489 [PPTP_IN_CALL_CONNECT
] = sizeof(struct PptpInCallConnected
),
490 [PPTP_CALL_CLEAR_REQUEST
] = sizeof(struct PptpClearCallRequest
),
491 [PPTP_CALL_DISCONNECT_NOTIFY
] = sizeof(struct PptpCallDisconnectNotify
),
492 [PPTP_WAN_ERROR_NOTIFY
] = sizeof(struct PptpWanErrorNotify
),
493 [PPTP_SET_LINK_INFO
] = sizeof(struct PptpSetLinkInfo
),
496 /* track caller id inside control connection, call expect_related */
498 conntrack_pptp_help(struct sk_buff
**pskb
, unsigned int protoff
,
499 struct nf_conn
*ct
, enum ip_conntrack_info ctinfo
)
502 int dir
= CTINFO2DIR(ctinfo
);
503 struct nf_ct_pptp_master
*info
= &nfct_help(ct
)->help
.ct_pptp_info
;
504 struct tcphdr _tcph
, *tcph
;
505 struct pptp_pkt_hdr _pptph
, *pptph
;
506 struct PptpControlHeader _ctlh
, *ctlh
;
507 union pptp_ctrl_union _pptpReq
, *pptpReq
;
508 unsigned int tcplen
= (*pskb
)->len
- protoff
;
509 unsigned int datalen
, reqlen
, nexthdr_off
;
510 int oldsstate
, oldcstate
;
514 /* don't do any tracking before tcp handshake complete */
515 if (ctinfo
!= IP_CT_ESTABLISHED
&&
516 ctinfo
!= IP_CT_ESTABLISHED
+ IP_CT_IS_REPLY
)
519 nexthdr_off
= protoff
;
520 tcph
= skb_header_pointer(*pskb
, nexthdr_off
, sizeof(_tcph
), &_tcph
);
522 nexthdr_off
+= tcph
->doff
* 4;
523 datalen
= tcplen
- tcph
->doff
* 4;
525 pptph
= skb_header_pointer(*pskb
, nexthdr_off
, sizeof(_pptph
), &_pptph
);
527 DEBUGP("no full PPTP header, can't track\n");
530 nexthdr_off
+= sizeof(_pptph
);
531 datalen
-= sizeof(_pptph
);
533 /* if it's not a control message we can't do anything with it */
534 if (ntohs(pptph
->packetType
) != PPTP_PACKET_CONTROL
||
535 ntohl(pptph
->magicCookie
) != PPTP_MAGIC_COOKIE
) {
536 DEBUGP("not a control packet\n");
540 ctlh
= skb_header_pointer(*pskb
, nexthdr_off
, sizeof(_ctlh
), &_ctlh
);
543 nexthdr_off
+= sizeof(_ctlh
);
544 datalen
-= sizeof(_ctlh
);
547 msg
= ntohs(ctlh
->messageType
);
548 if (msg
> 0 && msg
<= PPTP_MSG_MAX
&& reqlen
< pptp_msg_size
[msg
])
550 if (reqlen
> sizeof(*pptpReq
))
551 reqlen
= sizeof(*pptpReq
);
553 pptpReq
= skb_header_pointer(*pskb
, nexthdr_off
, reqlen
, &_pptpReq
);
557 oldsstate
= info
->sstate
;
558 oldcstate
= info
->cstate
;
560 spin_lock_bh(&nf_pptp_lock
);
562 /* FIXME: We just blindly assume that the control connection is always
563 * established from PNS->PAC. However, RFC makes no guarantee */
564 if (dir
== IP_CT_DIR_ORIGINAL
)
565 /* client -> server (PNS -> PAC) */
566 ret
= pptp_outbound_pkt(pskb
, ctlh
, pptpReq
, reqlen
, ct
,
569 /* server -> client (PAC -> PNS) */
570 ret
= pptp_inbound_pkt(pskb
, ctlh
, pptpReq
, reqlen
, ct
,
572 DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
573 oldsstate
, info
->sstate
, oldcstate
, info
->cstate
);
574 spin_unlock_bh(&nf_pptp_lock
);
579 /* control protocol helper */
580 static struct nf_conntrack_helper pptp __read_mostly
= {
585 .tuple
.src
.l3num
= AF_INET
,
586 .tuple
.src
.u
.tcp
.port
= __constant_htons(PPTP_CONTROL_PORT
),
587 .tuple
.dst
.protonum
= IPPROTO_TCP
,
588 .mask
.src
.l3num
= 0xffff,
589 .mask
.src
.u
.tcp
.port
= __constant_htons(0xffff),
590 .mask
.dst
.protonum
= 0xff,
591 .help
= conntrack_pptp_help
,
592 .destroy
= pptp_destroy_siblings
,
595 static int __init
nf_conntrack_pptp_init(void)
597 return nf_conntrack_helper_register(&pptp
);
600 static void __exit
nf_conntrack_pptp_fini(void)
602 nf_conntrack_helper_unregister(&pptp
);
603 nf_ct_gre_keymap_flush();
606 module_init(nf_conntrack_pptp_init
);
607 module_exit(nf_conntrack_pptp_fini
);