git.itanic.dy.fi Git - linux-stable/blob - net/netfilter/nf_conntrack_ftp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* FTP extension for connection tracking. */
   3
   4 /* (C) 1999-2001 Paul `Rusty' Russell
   5  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   6  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   7  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/ip.h>
  16 #include <linux/slab.h>
  17 #include <linux/ipv6.h>
  18 #include <linux/ctype.h>
  19 #include <linux/inet.h>
  20 #include <net/checksum.h>
  21 #include <net/tcp.h>
  22
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_expect.h>
  25 #include <net/netfilter/nf_conntrack_ecache.h>
  26 #include <net/netfilter/nf_conntrack_helper.h>
  27 #include <linux/netfilter/nf_conntrack_ftp.h>
  28
  29 #define HELPER_NAME "ftp"
  30
  31 MODULE_LICENSE("GPL");
  32 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
  33 MODULE_DESCRIPTION("ftp connection tracking helper");
  34 MODULE_ALIAS("ip_conntrack_ftp");
  35 MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
  36
  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
  42 static bool loose;
  43 module_param(loose, bool, 0600);
  44
  45 unsigned int (*nf_nat_ftp_hook)(struct sk_buff *skb,
  46                                 enum ip_conntrack_info ctinfo,
  47                                 enum nf_ct_ftp_type type,
  48                                 unsigned int protoff,
  49                                 unsigned int matchoff,
  50                                 unsigned int matchlen,
  51                                 struct nf_conntrack_expect *exp);
  52 EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
  53
  54 static int try_rfc959(const char *, size_t, struct nf_conntrack_man *,
  55                       char, unsigned int *);
  56 static int try_rfc1123(const char *, size_t, struct nf_conntrack_man *,
  57                        char, unsigned int *);
  58 static int try_eprt(const char *, size_t, struct nf_conntrack_man *,
  59                     char, unsigned int *);
  60 static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
  61                              char, unsigned int *);
  62
  63 static struct ftp_search {
  64         const char *pattern;
  65         size_t plen;
  66         char skip;
  67         char term;
  68         enum nf_ct_ftp_type ftptype;
  69         int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char, unsigned int *);
  70 } search[IP_CT_DIR_MAX][2] = {
  71         [IP_CT_DIR_ORIGINAL] = {
  72                 {
  73                         .pattern        = "PORT",
  74                         .plen           = sizeof("PORT") - 1,
  75                         .skip           = ' ',
  76                         .term           = '\r',
  77                         .ftptype        = NF_CT_FTP_PORT,
  78                         .getnum         = try_rfc959,
  79                 },
  80                 {
  81                         .pattern        = "EPRT",
  82                         .plen           = sizeof("EPRT") - 1,
  83                         .skip           = ' ',
  84                         .term           = '\r',
  85                         .ftptype        = NF_CT_FTP_EPRT,
  86                         .getnum         = try_eprt,
  87                 },
  88         },
  89         [IP_CT_DIR_REPLY] = {
  90                 {
  91                         .pattern        = "227 ",
  92                         .plen           = sizeof("227 ") - 1,
  93                         .ftptype        = NF_CT_FTP_PASV,
  94                         .getnum         = try_rfc1123,
  95                 },
  96                 {
  97                         .pattern        = "229 ",
  98                         .plen           = sizeof("229 ") - 1,
  99                         .skip           = '(',
 100                         .term           = ')',
 101                         .ftptype        = NF_CT_FTP_EPSV,
 102                         .getnum         = try_epsv_response,
 103                 },
 104         },
 105 };
 106
 107 static int
 108 get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
 109 {
 110         const char *end;
 111         int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
 112         if (ret > 0)
 113                 return (int)(end - src);
 114         return 0;
 115 }
 116
 117 static int try_number(const char *data, size_t dlen, u_int32_t array[],
 118                       int array_size, char sep, char term)
 119 {
 120         u_int32_t i, len;
 121
 122         memset(array, 0, sizeof(array[0])*array_size);
 123
 124         /* Keep data pointing at next char. */
 125         for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
 126                 if (*data >= '0' && *data <= '9') {
 127                         array[i] = array[i]*10 + *data - '0';
 128                 }
 129                 else if (*data == sep)
 130                         i++;
 131                 else {
 132                         /* Unexpected character; true if it's the
 133                            terminator (or we don't care about one)
 134                            and we're finished. */
 135                         if ((*data == term || !term) && i == array_size - 1)
 136                                 return len;
 137
 138                         pr_debug("Char %u (got %u nums) `%u' unexpected\n",
 139                                  len, i, *data);
 140                         return 0;
 141                 }
 142         }
 143         pr_debug("Failed to fill %u numbers separated by %c\n",
 144                  array_size, sep);
 145         return 0;
 146 }
 147
 148 /* Returns 0, or length of numbers: 192,168,1,1,5,6 */
 149 static int try_rfc959(const char *data, size_t dlen,
 150                       struct nf_conntrack_man *cmd, char term,
 151                       unsigned int *offset)
 152 {
 153         int length;
 154         u_int32_t array[6];
 155
 156         length = try_number(data, dlen, array, 6, ',', term);
 157         if (length == 0)
 158                 return 0;
 159
 160         cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) |
 161                                     (array[2] << 8) | array[3]);
 162         cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
 163         return length;
 164 }
 165
 166 /*
 167  * From RFC 1123:
 168  * The format of the 227 reply to a PASV command is not
 169  * well standardized.  In particular, an FTP client cannot
 170  * assume that the parentheses shown on page 40 of RFC-959
 171  * will be present (and in fact, Figure 3 on page 43 omits
 172  * them).  Therefore, a User-FTP program that interprets
 173  * the PASV reply must scan the reply for the first digit
 174  * of the host and port numbers.
 175  */
 176 static int try_rfc1123(const char *data, size_t dlen,
 177                        struct nf_conntrack_man *cmd, char term,
 178                        unsigned int *offset)
 179 {
 180         int i;
 181         for (i = 0; i < dlen; i++)
 182                 if (isdigit(data[i]))
 183                         break;
 184
 185         if (i == dlen)
 186                 return 0;
 187
 188         *offset += i;
 189
 190         return try_rfc959(data + i, dlen - i, cmd, 0, offset);
 191 }
 192
 193 /* Grab port: number up to delimiter */
 194 static int get_port(const char *data, int start, size_t dlen, char delim,
 195                     __be16 *port)
 196 {
 197         u_int16_t tmp_port = 0;
 198         int i;
 199
 200         for (i = start; i < dlen; i++) {
 201                 /* Finished? */
 202                 if (data[i] == delim) {
 203                         if (tmp_port == 0)
 204                                 break;
 205                         *port = htons(tmp_port);
 206                         pr_debug("get_port: return %d\n", tmp_port);
 207                         return i + 1;
 208                 }
 209                 else if (data[i] >= '0' && data[i] <= '9')
 210                         tmp_port = tmp_port*10 + data[i] - '0';
 211                 else { /* Some other crap */
 212                         pr_debug("get_port: invalid char.\n");
 213                         break;
 214                 }
 215         }
 216         return 0;
 217 }
 218
 219 /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
 220 static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
 221                     char term, unsigned int *offset)
 222 {
 223         char delim;
 224         int length;
 225
 226         /* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
 227            then delimiter again. */
 228         if (dlen <= 3) {
 229                 pr_debug("EPRT: too short\n");
 230                 return 0;
 231         }
 232         delim = data[0];
 233         if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
 234                 pr_debug("try_eprt: invalid delimiter.\n");
 235                 return 0;
 236         }
 237
 238         if ((cmd->l3num == PF_INET && data[1] != '1') ||
 239             (cmd->l3num == PF_INET6 && data[1] != '2')) {
 240                 pr_debug("EPRT: invalid protocol number.\n");
 241                 return 0;
 242         }
 243
 244         pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim);
 245
 246         if (data[1] == '1') {
 247                 u_int32_t array[4];
 248
 249                 /* Now we have IP address. */
 250                 length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
 251                 if (length != 0)
 252                         cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
 253                                            | (array[2] << 8) | array[3]);
 254         } else {
 255                 /* Now we have IPv6 address. */
 256                 length = get_ipv6_addr(data + 3, dlen - 3,
 257                                        (struct in6_addr *)cmd->u3.ip6, delim);
 258         }
 259
 260         if (length == 0)
 261                 return 0;
 262         pr_debug("EPRT: Got IP address!\n");
 263         /* Start offset includes initial "|1|", and trailing delimiter */
 264         return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
 265 }
 266
 267 /* Returns 0, or length of numbers: |||6446| */
 268 static int try_epsv_response(const char *data, size_t dlen,
 269                              struct nf_conntrack_man *cmd, char term,
 270                              unsigned int *offset)
 271 {
 272         char delim;
 273
 274         /* Three delimiters. */
 275         if (dlen <= 3) return 0;
 276         delim = data[0];
 277         if (isdigit(delim) || delim < 33 || delim > 126 ||
 278             data[1] != delim || data[2] != delim)
 279                 return 0;
 280
 281         return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
 282 }
 283
 284 /* Return 1 for match, 0 for accept, -1 for partial. */
 285 static int find_pattern(const char *data, size_t dlen,
 286                         const char *pattern, size_t plen,
 287                         char skip, char term,
 288                         unsigned int *numoff,
 289                         unsigned int *numlen,
 290                         struct nf_conntrack_man *cmd,
 291                         int (*getnum)(const char *, size_t,
 292                                       struct nf_conntrack_man *, char,
 293                                       unsigned int *))
 294 {
 295         size_t i = plen;
 296
 297         pr_debug("find_pattern `%s': dlen = %zu\n", pattern, dlen);
 298
 299         if (dlen <= plen) {
 300                 /* Short packet: try for partial? */
 301                 if (strncasecmp(data, pattern, dlen) == 0)
 302                         return -1;
 303                 else return 0;
 304         }
 305
 306         if (strncasecmp(data, pattern, plen) != 0)
 307                 return 0;
 308
 309         pr_debug("Pattern matches!\n");
 310         /* Now we've found the constant string, try to skip
 311            to the 'skip' character */
 312         if (skip) {
 313                 for (i = plen; data[i] != skip; i++)
 314                         if (i == dlen - 1) return -1;
 315
 316                 /* Skip over the last character */
 317                 i++;
 318         }
 319
 320         pr_debug("Skipped up to 0x%hhx delimiter!\n", skip);
 321
 322         *numoff = i;
 323         *numlen = getnum(data + i, dlen - i, cmd, term, numoff);
 324         if (!*numlen)
 325                 return -1;
 326
 327         pr_debug("Match succeeded!\n");
 328         return 1;
 329 }
 330
 331 /* Look up to see if we're just after a \n. */
 332 static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
 333 {
 334         unsigned int i;
 335
 336         for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
 337                 if (info->seq_aft_nl[dir][i] == seq)
 338                         return 1;
 339         return 0;
 340 }
 341
 342 /* We don't update if it's older than what we have. */
 343 static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
 344                           struct nf_ct_ftp_master *info, int dir,
 345                           struct sk_buff *skb)
 346 {
 347         unsigned int i, oldest;
 348
 349         /* Look for oldest: if we find exact match, we're done. */
 350         for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
 351                 if (info->seq_aft_nl[dir][i] == nl_seq)
 352                         return;
 353         }
 354
 355         if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
 356                 info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
 357         } else {
 358                 if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
 359                         oldest = 0;
 360                 else
 361                         oldest = 1;
 362
 363                 if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
 364                         info->seq_aft_nl[dir][oldest] = nl_seq;
 365         }
 366 }
 367
 368 static int help(struct sk_buff *skb,
 369                 unsigned int protoff,
 370                 struct nf_conn *ct,
 371                 enum ip_conntrack_info ctinfo)
 372 {
 373         unsigned int dataoff, datalen;
 374         const struct tcphdr *th;
 375         struct tcphdr _tcph;
 376         const char *fb_ptr;
 377         int ret;
 378         u32 seq;
 379         int dir = CTINFO2DIR(ctinfo);
 380         unsigned int matchlen, matchoff;
 381         struct nf_ct_ftp_master *ct_ftp_info = nfct_help_data(ct);
 382         struct nf_conntrack_expect *exp;
 383         union nf_inet_addr *daddr;
 384         struct nf_conntrack_man cmd = {};
 385         unsigned int i;
 386         int found = 0, ends_in_nl;
 387         typeof(nf_nat_ftp_hook) nf_nat_ftp;
 388
 389         /* Until there's been traffic both ways, don't look in packets. */
 390         if (ctinfo != IP_CT_ESTABLISHED &&
 391             ctinfo != IP_CT_ESTABLISHED_REPLY) {
 392                 pr_debug("ftp: Conntrackinfo = %u\n", ctinfo);
 393                 return NF_ACCEPT;
 394         }
 395
 396         if (unlikely(skb_linearize(skb)))
 397                 return NF_DROP;
 398
 399         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
 400         if (th == NULL)
 401                 return NF_ACCEPT;
 402
 403         dataoff = protoff + th->doff * 4;
 404         /* No data? */
 405         if (dataoff >= skb->len) {
 406                 pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
 407                          skb->len);
 408                 return NF_ACCEPT;
 409         }
 410         datalen = skb->len - dataoff;
 411
 412         spin_lock_bh(&ct->lock);
 413         fb_ptr = skb->data + dataoff;
 414
 415         ends_in_nl = (fb_ptr[datalen - 1] == '\n');
 416         seq = ntohl(th->seq) + datalen;
 417
 418         /* Look up to see if we're just after a \n. */
 419         if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
 420                 /* We're picking up this, clear flags and let it continue */
 421                 if (unlikely(ct_ftp_info->flags[dir] & NF_CT_FTP_SEQ_PICKUP)) {
 422                         ct_ftp_info->flags[dir] ^= NF_CT_FTP_SEQ_PICKUP;
 423                         goto skip_nl_seq;
 424                 }
 425
 426                 /* Now if this ends in \n, update ftp info. */
 427                 pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
 428                          ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
 429                          ct_ftp_info->seq_aft_nl[dir][0],
 430                          ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
 431                          ct_ftp_info->seq_aft_nl[dir][1]);
 432                 ret = NF_ACCEPT;
 433                 goto out_update_nl;
 434         }
 435
 436 skip_nl_seq:
 437         /* Initialize IP/IPv6 addr to expected address (it's not mentioned
 438            in EPSV responses) */
 439         cmd.l3num = nf_ct_l3num(ct);
 440         memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 441                sizeof(cmd.u3.all));
 442
 443         for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
 444                 found = find_pattern(fb_ptr, datalen,
 445                                      search[dir][i].pattern,
 446                                      search[dir][i].plen,
 447                                      search[dir][i].skip,
 448                                      search[dir][i].term,
 449                                      &matchoff, &matchlen,
 450                                      &cmd,
 451                                      search[dir][i].getnum);
 452                 if (found) break;
 453         }
 454         if (found == -1) {
 455                 /* We don't usually drop packets.  After all, this is
 456                    connection tracking, not packet filtering.
 457                    However, it is necessary for accurate tracking in
 458                    this case. */
 459                 nf_ct_helper_log(skb, ct, "partial matching of `%s'",
 460                                  search[dir][i].pattern);
 461                 ret = NF_DROP;
 462                 goto out;
 463         } else if (found == 0) { /* No match */
 464                 ret = NF_ACCEPT;
 465                 goto out_update_nl;
 466         }
 467
 468         pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
 469                  matchlen, fb_ptr + matchoff,
 470                  matchlen, ntohl(th->seq) + matchoff);
 471
 472         exp = nf_ct_expect_alloc(ct);
 473         if (exp == NULL) {
 474                 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 475                 ret = NF_DROP;
 476                 goto out;
 477         }
 478
 479         /* We refer to the reverse direction ("!dir") tuples here,
 480          * because we're expecting something in the other direction.
 481          * Doesn't matter unless NAT is happening.  */
 482         daddr = &ct->tuplehash[!dir].tuple.dst.u3;
 483
 484         /* Update the ftp info */
 485         if ((cmd.l3num == nf_ct_l3num(ct)) &&
 486             memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 487                      sizeof(cmd.u3.all))) {
 488                 /* Enrico Scholz's passive FTP to partially RNAT'd ftp
 489                    server: it really wants us to connect to a
 490                    different IP address.  Simply don't record it for
 491                    NAT. */
 492                 if (cmd.l3num == PF_INET) {
 493                         pr_debug("NOT RECORDING: %pI4 != %pI4\n",
 494                                  &cmd.u3.ip,
 495                                  &ct->tuplehash[dir].tuple.src.u3.ip);
 496                 } else {
 497                         pr_debug("NOT RECORDING: %pI6 != %pI6\n",
 498                                  cmd.u3.ip6,
 499                                  ct->tuplehash[dir].tuple.src.u3.ip6);
 500                 }
 501
 502                 /* Thanks to Cristiano Lincoln Mattos
 503                    <lincoln@cesar.org.br> for reporting this potential
 504                    problem (DMZ machines opening holes to internal
 505                    networks, or the packet filter itself). */
 506                 if (!loose) {
 507                         ret = NF_ACCEPT;
 508                         goto out_put_expect;
 509                 }
 510                 daddr = &cmd.u3;
 511         }
 512
 513         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num,
 514                           &ct->tuplehash[!dir].tuple.src.u3, daddr,
 515                           IPPROTO_TCP, NULL, &cmd.u.tcp.port);
 516
 517         /* Now, NAT might want to mangle the packet, and register the
 518          * (possibly changed) expectation itself. */
 519         nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
 520         if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
 521                 ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype,
 522                                  protoff, matchoff, matchlen, exp);
 523         else {
 524                 /* Can't expect this?  Best to drop packet now. */
 525                 if (nf_ct_expect_related(exp, 0) != 0) {
 526                         nf_ct_helper_log(skb, ct, "cannot add expectation");
 527                         ret = NF_DROP;
 528                 } else
 529                         ret = NF_ACCEPT;
 530         }
 531
 532 out_put_expect:
 533         nf_ct_expect_put(exp);
 534
 535 out_update_nl:
 536         /* Now if this ends in \n, update ftp info.  Seq may have been
 537          * adjusted by NAT code. */
 538         if (ends_in_nl)
 539                 update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
 540  out:
 541         spin_unlock_bh(&ct->lock);
 542         return ret;
 543 }
 544
 545 static int nf_ct_ftp_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
 546 {
 547         struct nf_ct_ftp_master *ftp = nfct_help_data(ct);
 548
 549         /* This conntrack has been injected from user-space, always pick up
 550          * sequence tracking. Otherwise, the first FTP command after the
 551          * failover breaks.
 552          */
 553         ftp->flags[IP_CT_DIR_ORIGINAL] |= NF_CT_FTP_SEQ_PICKUP;
 554         ftp->flags[IP_CT_DIR_REPLY] |= NF_CT_FTP_SEQ_PICKUP;
 555         return 0;
 556 }
 557
 558 static struct nf_conntrack_helper ftp[MAX_PORTS * 2] __read_mostly;
 559
 560 static const struct nf_conntrack_expect_policy ftp_exp_policy = {
 561         .max_expected   = 1,
 562         .timeout        = 5 * 60,
 563 };
 564
 565 static void __exit nf_conntrack_ftp_fini(void)
 566 {
 567         nf_conntrack_helpers_unregister(ftp, ports_c * 2);
 568 }
 569
 570 static int __init nf_conntrack_ftp_init(void)
 571 {
 572         int i, ret = 0;
 573
 574         NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_ftp_master));
 575
 576         if (ports_c == 0)
 577                 ports[ports_c++] = FTP_PORT;
 578
 579         /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
 580                  are tracked or not - YK */
 581         for (i = 0; i < ports_c; i++) {
 582                 nf_ct_helper_init(&ftp[2 * i], AF_INET, IPPROTO_TCP,
 583                                   HELPER_NAME, FTP_PORT, ports[i], ports[i],
 584                                   &ftp_exp_policy, 0, help,
 585                                   nf_ct_ftp_from_nlattr, THIS_MODULE);
 586                 nf_ct_helper_init(&ftp[2 * i + 1], AF_INET6, IPPROTO_TCP,
 587                                   HELPER_NAME, FTP_PORT, ports[i], ports[i],
 588                                   &ftp_exp_policy, 0, help,
 589                                   nf_ct_ftp_from_nlattr, THIS_MODULE);
 590         }
 591
 592         ret = nf_conntrack_helpers_register(ftp, ports_c * 2);
 593         if (ret < 0) {
 594                 pr_err("failed to register helpers\n");
 595                 return ret;
 596         }
 597
 598         return 0;
 599 }
 600
 601 module_init(nf_conntrack_ftp_init);
 602 module_exit(nf_conntrack_ftp_fini);