nf_conntrack_ftp.c 17 KB

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  1. /* FTP extension for connection tracking. */
  2. /* (C) 1999-2001 Paul `Rusty' Russell
  3. * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
  4. * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
  5. *
  6. * This program is free software; you can redistribute it and/or modify
  7. * it under the terms of the GNU General Public License version 2 as
  8. * published by the Free Software Foundation.
  9. *
  10. * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  11. * - enable working with Layer 3 protocol independent connection tracking.
  12. * - track EPRT and EPSV commands with IPv6 address.
  13. *
  14. * Derived from net/ipv4/netfilter/ip_conntrack_ftp.c
  15. */
  16. #include <linux/module.h>
  17. #include <linux/moduleparam.h>
  18. #include <linux/netfilter.h>
  19. #include <linux/ip.h>
  20. #include <linux/ipv6.h>
  21. #include <linux/ctype.h>
  22. #include <linux/inet.h>
  23. #include <net/checksum.h>
  24. #include <net/tcp.h>
  25. #include <net/netfilter/nf_conntrack.h>
  26. #include <net/netfilter/nf_conntrack_expect.h>
  27. #include <net/netfilter/nf_conntrack_ecache.h>
  28. #include <net/netfilter/nf_conntrack_helper.h>
  29. #include <linux/netfilter/nf_conntrack_ftp.h>
  30. MODULE_LICENSE("GPL");
  31. MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
  32. MODULE_DESCRIPTION("ftp connection tracking helper");
  33. MODULE_ALIAS("ip_conntrack_ftp");
  34. /* This is slow, but it's simple. --RR */
  35. static char *ftp_buffer;
  36. static DEFINE_SPINLOCK(nf_ftp_lock);
  37. #define MAX_PORTS 8
  38. static u_int16_t ports[MAX_PORTS];
  39. static unsigned int ports_c;
  40. module_param_array(ports, ushort, &ports_c, 0400);
  41. static int loose;
  42. module_param(loose, bool, 0600);
  43. unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb,
  44. enum ip_conntrack_info ctinfo,
  45. enum nf_ct_ftp_type type,
  46. unsigned int matchoff,
  47. unsigned int matchlen,
  48. struct nf_conntrack_expect *exp,
  49. u32 *seq);
  50. EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
  51. #if 0
  52. #define DEBUGP printk
  53. #else
  54. #define DEBUGP(format, args...)
  55. #endif
  56. static int try_rfc959(const char *, size_t, struct nf_conntrack_man *, char);
  57. static int try_eprt(const char *, size_t, struct nf_conntrack_man *, char);
  58. static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
  59. char);
  60. static struct ftp_search {
  61. const char *pattern;
  62. size_t plen;
  63. char skip;
  64. char term;
  65. enum nf_ct_ftp_type ftptype;
  66. int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char);
  67. } search[IP_CT_DIR_MAX][2] = {
  68. [IP_CT_DIR_ORIGINAL] = {
  69. {
  70. .pattern = "PORT",
  71. .plen = sizeof("PORT") - 1,
  72. .skip = ' ',
  73. .term = '\r',
  74. .ftptype = NF_CT_FTP_PORT,
  75. .getnum = try_rfc959,
  76. },
  77. {
  78. .pattern = "EPRT",
  79. .plen = sizeof("EPRT") - 1,
  80. .skip = ' ',
  81. .term = '\r',
  82. .ftptype = NF_CT_FTP_EPRT,
  83. .getnum = try_eprt,
  84. },
  85. },
  86. [IP_CT_DIR_REPLY] = {
  87. {
  88. .pattern = "227 ",
  89. .plen = sizeof("227 ") - 1,
  90. .skip = '(',
  91. .term = ')',
  92. .ftptype = NF_CT_FTP_PASV,
  93. .getnum = try_rfc959,
  94. },
  95. {
  96. .pattern = "229 ",
  97. .plen = sizeof("229 ") - 1,
  98. .skip = '(',
  99. .term = ')',
  100. .ftptype = NF_CT_FTP_EPSV,
  101. .getnum = try_epsv_response,
  102. },
  103. },
  104. };
  105. static int
  106. get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
  107. {
  108. const char *end;
  109. int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
  110. if (ret > 0)
  111. return (int)(end - src);
  112. return 0;
  113. }
  114. static int try_number(const char *data, size_t dlen, u_int32_t array[],
  115. int array_size, char sep, char term)
  116. {
  117. u_int32_t i, len;
  118. memset(array, 0, sizeof(array[0])*array_size);
  119. /* Keep data pointing at next char. */
  120. for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
  121. if (*data >= '0' && *data <= '9') {
  122. array[i] = array[i]*10 + *data - '0';
  123. }
  124. else if (*data == sep)
  125. i++;
  126. else {
  127. /* Unexpected character; true if it's the
  128. terminator and we're finished. */
  129. if (*data == term && i == array_size - 1)
  130. return len;
  131. DEBUGP("Char %u (got %u nums) `%u' unexpected\n",
  132. len, i, *data);
  133. return 0;
  134. }
  135. }
  136. DEBUGP("Failed to fill %u numbers separated by %c\n", array_size, sep);
  137. return 0;
  138. }
  139. /* Returns 0, or length of numbers: 192,168,1,1,5,6 */
  140. static int try_rfc959(const char *data, size_t dlen,
  141. struct nf_conntrack_man *cmd, char term)
  142. {
  143. int length;
  144. u_int32_t array[6];
  145. length = try_number(data, dlen, array, 6, ',', term);
  146. if (length == 0)
  147. return 0;
  148. cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) |
  149. (array[2] << 8) | array[3]);
  150. cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
  151. return length;
  152. }
  153. /* Grab port: number up to delimiter */
  154. static int get_port(const char *data, int start, size_t dlen, char delim,
  155. __be16 *port)
  156. {
  157. u_int16_t tmp_port = 0;
  158. int i;
  159. for (i = start; i < dlen; i++) {
  160. /* Finished? */
  161. if (data[i] == delim) {
  162. if (tmp_port == 0)
  163. break;
  164. *port = htons(tmp_port);
  165. DEBUGP("get_port: return %d\n", tmp_port);
  166. return i + 1;
  167. }
  168. else if (data[i] >= '0' && data[i] <= '9')
  169. tmp_port = tmp_port*10 + data[i] - '0';
  170. else { /* Some other crap */
  171. DEBUGP("get_port: invalid char.\n");
  172. break;
  173. }
  174. }
  175. return 0;
  176. }
  177. /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
  178. static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
  179. char term)
  180. {
  181. char delim;
  182. int length;
  183. /* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
  184. then delimiter again. */
  185. if (dlen <= 3) {
  186. DEBUGP("EPRT: too short\n");
  187. return 0;
  188. }
  189. delim = data[0];
  190. if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
  191. DEBUGP("try_eprt: invalid delimitter.\n");
  192. return 0;
  193. }
  194. if ((cmd->l3num == PF_INET && data[1] != '1') ||
  195. (cmd->l3num == PF_INET6 && data[1] != '2')) {
  196. DEBUGP("EPRT: invalid protocol number.\n");
  197. return 0;
  198. }
  199. DEBUGP("EPRT: Got %c%c%c\n", delim, data[1], delim);
  200. if (data[1] == '1') {
  201. u_int32_t array[4];
  202. /* Now we have IP address. */
  203. length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
  204. if (length != 0)
  205. cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
  206. | (array[2] << 8) | array[3]);
  207. } else {
  208. /* Now we have IPv6 address. */
  209. length = get_ipv6_addr(data + 3, dlen - 3,
  210. (struct in6_addr *)cmd->u3.ip6, delim);
  211. }
  212. if (length == 0)
  213. return 0;
  214. DEBUGP("EPRT: Got IP address!\n");
  215. /* Start offset includes initial "|1|", and trailing delimiter */
  216. return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
  217. }
  218. /* Returns 0, or length of numbers: |||6446| */
  219. static int try_epsv_response(const char *data, size_t dlen,
  220. struct nf_conntrack_man *cmd, char term)
  221. {
  222. char delim;
  223. /* Three delimiters. */
  224. if (dlen <= 3) return 0;
  225. delim = data[0];
  226. if (isdigit(delim) || delim < 33 || delim > 126
  227. || data[1] != delim || data[2] != delim)
  228. return 0;
  229. return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
  230. }
  231. /* Return 1 for match, 0 for accept, -1 for partial. */
  232. static int find_pattern(const char *data, size_t dlen,
  233. const char *pattern, size_t plen,
  234. char skip, char term,
  235. unsigned int *numoff,
  236. unsigned int *numlen,
  237. struct nf_conntrack_man *cmd,
  238. int (*getnum)(const char *, size_t,
  239. struct nf_conntrack_man *, char))
  240. {
  241. size_t i;
  242. DEBUGP("find_pattern `%s': dlen = %u\n", pattern, dlen);
  243. if (dlen == 0)
  244. return 0;
  245. if (dlen <= plen) {
  246. /* Short packet: try for partial? */
  247. if (strnicmp(data, pattern, dlen) == 0)
  248. return -1;
  249. else return 0;
  250. }
  251. if (strnicmp(data, pattern, plen) != 0) {
  252. #if 0
  253. size_t i;
  254. DEBUGP("ftp: string mismatch\n");
  255. for (i = 0; i < plen; i++) {
  256. DEBUGP("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
  257. i, data[i], data[i],
  258. pattern[i], pattern[i]);
  259. }
  260. #endif
  261. return 0;
  262. }
  263. DEBUGP("Pattern matches!\n");
  264. /* Now we've found the constant string, try to skip
  265. to the 'skip' character */
  266. for (i = plen; data[i] != skip; i++)
  267. if (i == dlen - 1) return -1;
  268. /* Skip over the last character */
  269. i++;
  270. DEBUGP("Skipped up to `%c'!\n", skip);
  271. *numoff = i;
  272. *numlen = getnum(data + i, dlen - i, cmd, term);
  273. if (!*numlen)
  274. return -1;
  275. DEBUGP("Match succeeded!\n");
  276. return 1;
  277. }
  278. /* Look up to see if we're just after a \n. */
  279. static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
  280. {
  281. unsigned int i;
  282. for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
  283. if (info->seq_aft_nl[dir][i] == seq)
  284. return 1;
  285. return 0;
  286. }
  287. /* We don't update if it's older than what we have. */
  288. static void update_nl_seq(u32 nl_seq, struct nf_ct_ftp_master *info, int dir,
  289. struct sk_buff *skb)
  290. {
  291. unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
  292. /* Look for oldest: if we find exact match, we're done. */
  293. for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
  294. if (info->seq_aft_nl[dir][i] == nl_seq)
  295. return;
  296. if (oldest == info->seq_aft_nl_num[dir]
  297. || before(info->seq_aft_nl[dir][i], oldest))
  298. oldest = i;
  299. }
  300. if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
  301. info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
  302. nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
  303. } else if (oldest != NUM_SEQ_TO_REMEMBER) {
  304. info->seq_aft_nl[dir][oldest] = nl_seq;
  305. nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
  306. }
  307. }
  308. static int help(struct sk_buff **pskb,
  309. unsigned int protoff,
  310. struct nf_conn *ct,
  311. enum ip_conntrack_info ctinfo)
  312. {
  313. unsigned int dataoff, datalen;
  314. struct tcphdr _tcph, *th;
  315. char *fb_ptr;
  316. int ret;
  317. u32 seq;
  318. int dir = CTINFO2DIR(ctinfo);
  319. unsigned int matchlen, matchoff;
  320. struct nf_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
  321. struct nf_conntrack_expect *exp;
  322. struct nf_conntrack_man cmd = {};
  323. unsigned int i;
  324. int found = 0, ends_in_nl;
  325. typeof(nf_nat_ftp_hook) nf_nat_ftp;
  326. /* Until there's been traffic both ways, don't look in packets. */
  327. if (ctinfo != IP_CT_ESTABLISHED
  328. && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
  329. DEBUGP("ftp: Conntrackinfo = %u\n", ctinfo);
  330. return NF_ACCEPT;
  331. }
  332. th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
  333. if (th == NULL)
  334. return NF_ACCEPT;
  335. dataoff = protoff + th->doff * 4;
  336. /* No data? */
  337. if (dataoff >= (*pskb)->len) {
  338. DEBUGP("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
  339. (*pskb)->len);
  340. return NF_ACCEPT;
  341. }
  342. datalen = (*pskb)->len - dataoff;
  343. spin_lock_bh(&nf_ftp_lock);
  344. fb_ptr = skb_header_pointer(*pskb, dataoff, datalen, ftp_buffer);
  345. BUG_ON(fb_ptr == NULL);
  346. ends_in_nl = (fb_ptr[datalen - 1] == '\n');
  347. seq = ntohl(th->seq) + datalen;
  348. /* Look up to see if we're just after a \n. */
  349. if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
  350. /* Now if this ends in \n, update ftp info. */
  351. DEBUGP("nf_conntrack_ftp_help: wrong seq pos %s(%u) or %s(%u)\n",
  352. ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
  353. ct_ftp_info->seq_aft_nl[dir][0],
  354. ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
  355. ct_ftp_info->seq_aft_nl[dir][1]);
  356. ret = NF_ACCEPT;
  357. goto out_update_nl;
  358. }
  359. /* Initialize IP/IPv6 addr to expected address (it's not mentioned
  360. in EPSV responses) */
  361. cmd.l3num = ct->tuplehash[dir].tuple.src.l3num;
  362. memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
  363. sizeof(cmd.u3.all));
  364. for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
  365. found = find_pattern(fb_ptr, datalen,
  366. search[dir][i].pattern,
  367. search[dir][i].plen,
  368. search[dir][i].skip,
  369. search[dir][i].term,
  370. &matchoff, &matchlen,
  371. &cmd,
  372. search[dir][i].getnum);
  373. if (found) break;
  374. }
  375. if (found == -1) {
  376. /* We don't usually drop packets. After all, this is
  377. connection tracking, not packet filtering.
  378. However, it is necessary for accurate tracking in
  379. this case. */
  380. if (net_ratelimit())
  381. printk("conntrack_ftp: partial %s %u+%u\n",
  382. search[dir][i].pattern,
  383. ntohl(th->seq), datalen);
  384. ret = NF_DROP;
  385. goto out;
  386. } else if (found == 0) { /* No match */
  387. ret = NF_ACCEPT;
  388. goto out_update_nl;
  389. }
  390. DEBUGP("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
  391. (int)matchlen, fb_ptr + matchoff,
  392. matchlen, ntohl(th->seq) + matchoff);
  393. exp = nf_conntrack_expect_alloc(ct);
  394. if (exp == NULL) {
  395. ret = NF_DROP;
  396. goto out;
  397. }
  398. /* We refer to the reverse direction ("!dir") tuples here,
  399. * because we're expecting something in the other direction.
  400. * Doesn't matter unless NAT is happening. */
  401. exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3;
  402. /* Update the ftp info */
  403. if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) &&
  404. memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
  405. sizeof(cmd.u3.all))) {
  406. /* Enrico Scholz's passive FTP to partially RNAT'd ftp
  407. server: it really wants us to connect to a
  408. different IP address. Simply don't record it for
  409. NAT. */
  410. if (cmd.l3num == PF_INET) {
  411. DEBUGP("conntrack_ftp: NOT RECORDING: " NIPQUAD_FMT " != " NIPQUAD_FMT "\n",
  412. NIPQUAD(cmd.u3.ip),
  413. NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip));
  414. } else {
  415. DEBUGP("conntrack_ftp: NOT RECORDING: " NIP6_FMT " != " NIP6_FMT "\n",
  416. NIP6(*((struct in6_addr *)cmd.u3.ip6)),
  417. NIP6(*((struct in6_addr *)ct->tuplehash[dir]
  418. .tuple.src.u3.ip6)));
  419. }
  420. /* Thanks to Cristiano Lincoln Mattos
  421. <lincoln@cesar.org.br> for reporting this potential
  422. problem (DMZ machines opening holes to internal
  423. networks, or the packet filter itself). */
  424. if (!loose) {
  425. ret = NF_ACCEPT;
  426. goto out_put_expect;
  427. }
  428. memcpy(&exp->tuple.dst.u3, &cmd.u3.all,
  429. sizeof(exp->tuple.dst.u3));
  430. }
  431. exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3;
  432. exp->tuple.src.l3num = cmd.l3num;
  433. exp->tuple.src.u.tcp.port = 0;
  434. exp->tuple.dst.u.tcp.port = cmd.u.tcp.port;
  435. exp->tuple.dst.protonum = IPPROTO_TCP;
  436. exp->mask = (struct nf_conntrack_tuple)
  437. { .src = { .l3num = 0xFFFF,
  438. .u = { .tcp = { 0 }},
  439. },
  440. .dst = { .protonum = 0xFF,
  441. .u = { .tcp = { __constant_htons(0xFFFF) }},
  442. },
  443. };
  444. if (cmd.l3num == PF_INET) {
  445. exp->mask.src.u3.ip = htonl(0xFFFFFFFF);
  446. exp->mask.dst.u3.ip = htonl(0xFFFFFFFF);
  447. } else {
  448. memset(exp->mask.src.u3.ip6, 0xFF,
  449. sizeof(exp->mask.src.u3.ip6));
  450. memset(exp->mask.dst.u3.ip6, 0xFF,
  451. sizeof(exp->mask.src.u3.ip6));
  452. }
  453. exp->expectfn = NULL;
  454. exp->helper = NULL;
  455. exp->flags = 0;
  456. /* Now, NAT might want to mangle the packet, and register the
  457. * (possibly changed) expectation itself. */
  458. nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
  459. if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
  460. ret = nf_nat_ftp(pskb, ctinfo, search[dir][i].ftptype,
  461. matchoff, matchlen, exp, &seq);
  462. else {
  463. /* Can't expect this? Best to drop packet now. */
  464. if (nf_conntrack_expect_related(exp) != 0)
  465. ret = NF_DROP;
  466. else
  467. ret = NF_ACCEPT;
  468. }
  469. out_put_expect:
  470. nf_conntrack_expect_put(exp);
  471. out_update_nl:
  472. /* Now if this ends in \n, update ftp info. Seq may have been
  473. * adjusted by NAT code. */
  474. if (ends_in_nl)
  475. update_nl_seq(seq, ct_ftp_info, dir, *pskb);
  476. out:
  477. spin_unlock_bh(&nf_ftp_lock);
  478. return ret;
  479. }
  480. static struct nf_conntrack_helper ftp[MAX_PORTS][2];
  481. static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")];
  482. /* don't make this __exit, since it's called from __init ! */
  483. static void nf_conntrack_ftp_fini(void)
  484. {
  485. int i, j;
  486. for (i = 0; i < ports_c; i++) {
  487. for (j = 0; j < 2; j++) {
  488. if (ftp[i][j].me == NULL)
  489. continue;
  490. DEBUGP("nf_ct_ftp: unregistering helper for pf: %d "
  491. "port: %d\n",
  492. ftp[i][j].tuple.src.l3num, ports[i]);
  493. nf_conntrack_helper_unregister(&ftp[i][j]);
  494. }
  495. }
  496. kfree(ftp_buffer);
  497. }
  498. static int __init nf_conntrack_ftp_init(void)
  499. {
  500. int i, j = -1, ret = 0;
  501. char *tmpname;
  502. ftp_buffer = kmalloc(65536, GFP_KERNEL);
  503. if (!ftp_buffer)
  504. return -ENOMEM;
  505. if (ports_c == 0)
  506. ports[ports_c++] = FTP_PORT;
  507. /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
  508. are tracked or not - YK */
  509. for (i = 0; i < ports_c; i++) {
  510. ftp[i][0].tuple.src.l3num = PF_INET;
  511. ftp[i][1].tuple.src.l3num = PF_INET6;
  512. for (j = 0; j < 2; j++) {
  513. ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
  514. ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
  515. ftp[i][j].mask.src.l3num = 0xFFFF;
  516. ftp[i][j].mask.src.u.tcp.port = htons(0xFFFF);
  517. ftp[i][j].mask.dst.protonum = 0xFF;
  518. ftp[i][j].max_expected = 1;
  519. ftp[i][j].timeout = 5 * 60; /* 5 Minutes */
  520. ftp[i][j].me = THIS_MODULE;
  521. ftp[i][j].help = help;
  522. tmpname = &ftp_names[i][j][0];
  523. if (ports[i] == FTP_PORT)
  524. sprintf(tmpname, "ftp");
  525. else
  526. sprintf(tmpname, "ftp-%d", ports[i]);
  527. ftp[i][j].name = tmpname;
  528. DEBUGP("nf_ct_ftp: registering helper for pf: %d "
  529. "port: %d\n",
  530. ftp[i][j].tuple.src.l3num, ports[i]);
  531. ret = nf_conntrack_helper_register(&ftp[i][j]);
  532. if (ret) {
  533. printk("nf_ct_ftp: failed to register helper "
  534. " for pf: %d port: %d\n",
  535. ftp[i][j].tuple.src.l3num, ports[i]);
  536. nf_conntrack_ftp_fini();
  537. return ret;
  538. }
  539. }
  540. }
  541. return 0;
  542. }
  543. module_init(nf_conntrack_ftp_init);
  544. module_exit(nf_conntrack_ftp_fini);