net/netfilter/nf_conntrack_standalone.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2005-2012 Patrick McHardy <kaber@trash.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/netfilter.h>
  12 #include <linux/slab.h>
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/percpu.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/security.h>
  20 #include <net/net_namespace.h>
  21 #ifdef CONFIG_SYSCTL
  22 #include <linux/sysctl.h>
  23 #endif
  24
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_core.h>
  27 #include <net/netfilter/nf_conntrack_l3proto.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_expect.h>
  30 #include <net/netfilter/nf_conntrack_helper.h>
  31 #include <net/netfilter/nf_conntrack_acct.h>
  32 #include <net/netfilter/nf_conntrack_zones.h>
  33 #include <net/netfilter/nf_conntrack_timestamp.h>
  34 #include <linux/rculist_nulls.h>
  35
  36 MODULE_LICENSE("GPL");
  37
  38 #ifdef CONFIG_NF_CONNTRACK_PROCFS
  39 void
  40 print_tuple(struct seq_file *s, const struct nf_conntrack_tuple *tuple,
  41             const struct nf_conntrack_l3proto *l3proto,
  42             const struct nf_conntrack_l4proto *l4proto)
  43 {
  44         l3proto->print_tuple(s, tuple);
  45         l4proto->print_tuple(s, tuple);
  46 }
  47 EXPORT_SYMBOL_GPL(print_tuple);
  48
  49 struct ct_iter_state {
  50         struct seq_net_private p;
  51         struct hlist_nulls_head *hash;
  52         unsigned int htable_size;
  53         unsigned int bucket;
  54         u_int64_t time_now;
  55 };
  56
  57 static struct hlist_nulls_node *ct_get_first(struct seq_file *seq)
  58 {
  59         struct ct_iter_state *st = seq->private;
  60         struct hlist_nulls_node *n;
  61
  62         for (st->bucket = 0;
  63              st->bucket < st->htable_size;
  64              st->bucket++) {
  65                 n = rcu_dereference(
  66                         hlist_nulls_first_rcu(&st->hash[st->bucket]));
  67                 if (!is_a_nulls(n))
  68                         return n;
  69         }
  70         return NULL;
  71 }
  72
  73 static struct hlist_nulls_node *ct_get_next(struct seq_file *seq,
  74                                       struct hlist_nulls_node *head)
  75 {
  76         struct ct_iter_state *st = seq->private;
  77
  78         head = rcu_dereference(hlist_nulls_next_rcu(head));
  79         while (is_a_nulls(head)) {
  80                 if (likely(get_nulls_value(head) == st->bucket)) {
  81                         if (++st->bucket >= st->htable_size)
  82                                 return NULL;
  83                 }
  84                 head = rcu_dereference(
  85                         hlist_nulls_first_rcu(&st->hash[st->bucket]));
  86         }
  87         return head;
  88 }
  89
  90 static struct hlist_nulls_node *ct_get_idx(struct seq_file *seq, loff_t pos)
  91 {
  92         struct hlist_nulls_node *head = ct_get_first(seq);
  93
  94         if (head)
  95                 while (pos && (head = ct_get_next(seq, head)))
  96                         pos--;
  97         return pos ? NULL : head;
  98 }
  99
 100 static void *ct_seq_start(struct seq_file *seq, loff_t *pos)
 101         __acquires(RCU)
 102 {
 103         struct ct_iter_state *st = seq->private;
 104
 105         st->time_now = ktime_get_real_ns();
 106         rcu_read_lock();
 107
 108         nf_conntrack_get_ht(&st->hash, &st->htable_size);
 109         return ct_get_idx(seq, *pos);
 110 }
 111
 112 static void *ct_seq_next(struct seq_file *s, void *v, loff_t *pos)
 113 {
 114         (*pos)++;
 115         return ct_get_next(s, v);
 116 }
 117
 118 static void ct_seq_stop(struct seq_file *s, void *v)
 119         __releases(RCU)
 120 {
 121         rcu_read_unlock();
 122 }
 123
 124 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 125 static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
 126 {
 127         int ret;
 128         u32 len;
 129         char *secctx;
 130
 131         ret = security_secid_to_secctx(ct->secmark, &secctx, &len);
 132         if (ret)
 133                 return;
 134
 135         seq_printf(s, "secctx=%s ", secctx);
 136
 137         security_release_secctx(secctx, len);
 138 }
 139 #else
 140 static inline void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
 141 {
 142 }
 143 #endif
 144
 145 #ifdef CONFIG_NF_CONNTRACK_ZONES
 146 static void ct_show_zone(struct seq_file *s, const struct nf_conn *ct,
 147                          int dir)
 148 {
 149         const struct nf_conntrack_zone *zone = nf_ct_zone(ct);
 150
 151         if (zone->dir != dir)
 152                 return;
 153         switch (zone->dir) {
 154         case NF_CT_DEFAULT_ZONE_DIR:
 155                 seq_printf(s, "zone=%u ", zone->id);
 156                 break;
 157         case NF_CT_ZONE_DIR_ORIG:
 158                 seq_printf(s, "zone-orig=%u ", zone->id);
 159                 break;
 160         case NF_CT_ZONE_DIR_REPL:
 161                 seq_printf(s, "zone-reply=%u ", zone->id);
 162                 break;
 163         default:
 164                 break;
 165         }
 166 }
 167 #else
 168 static inline void ct_show_zone(struct seq_file *s, const struct nf_conn *ct,
 169                                 int dir)
 170 {
 171 }
 172 #endif
 173
 174 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
 175 static void ct_show_delta_time(struct seq_file *s, const struct nf_conn *ct)
 176 {
 177         struct ct_iter_state *st = s->private;
 178         struct nf_conn_tstamp *tstamp;
 179         s64 delta_time;
 180
 181         tstamp = nf_conn_tstamp_find(ct);
 182         if (tstamp) {
 183                 delta_time = st->time_now - tstamp->start;
 184                 if (delta_time > 0)
 185                         delta_time = div_s64(delta_time, NSEC_PER_SEC);
 186                 else
 187                         delta_time = 0;
 188
 189                 seq_printf(s, "delta-time=%llu ",
 190                            (unsigned long long)delta_time);
 191         }
 192         return;
 193 }
 194 #else
 195 static inline void
 196 ct_show_delta_time(struct seq_file *s, const struct nf_conn *ct)
 197 {
 198 }
 199 #endif
 200
 201 /* return 0 on success, 1 in case of error */
 202 static int ct_seq_show(struct seq_file *s, void *v)
 203 {
 204         struct nf_conntrack_tuple_hash *hash = v;
 205         struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(hash);
 206         const struct nf_conntrack_l3proto *l3proto;
 207         const struct nf_conntrack_l4proto *l4proto;
 208         struct net *net = seq_file_net(s);
 209         int ret = 0;
 210
 211         NF_CT_ASSERT(ct);
 212         if (unlikely(!atomic_inc_not_zero(&ct->ct_general.use)))
 213                 return 0;
 214
 215         if (nf_ct_should_gc(ct)) {
 216                 nf_ct_kill(ct);
 217                 goto release;
 218         }
 219
 220         /* we only want to print DIR_ORIGINAL */
 221         if (NF_CT_DIRECTION(hash))
 222                 goto release;
 223
 224         if (!net_eq(nf_ct_net(ct), net))
 225                 goto release;
 226
 227         l3proto = __nf_ct_l3proto_find(nf_ct_l3num(ct));
 228         NF_CT_ASSERT(l3proto);
 229         l4proto = __nf_ct_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
 230         NF_CT_ASSERT(l4proto);
 231
 232         ret = -ENOSPC;
 233         seq_printf(s, "%-8s %u %-8s %u %ld ",
 234                    l3proto->name, nf_ct_l3num(ct),
 235                    l4proto->name, nf_ct_protonum(ct),
 236                    nf_ct_expires(ct)  / HZ);
 237
 238         if (l4proto->print_conntrack)
 239                 l4proto->print_conntrack(s, ct);
 240
 241         print_tuple(s, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
 242                     l3proto, l4proto);
 243
 244         ct_show_zone(s, ct, NF_CT_ZONE_DIR_ORIG);
 245
 246         if (seq_has_overflowed(s))
 247                 goto release;
 248
 249         if (seq_print_acct(s, ct, IP_CT_DIR_ORIGINAL))
 250                 goto release;
 251
 252         if (!(test_bit(IPS_SEEN_REPLY_BIT, &ct->status)))
 253                 seq_printf(s, "[UNREPLIED] ");
 254
 255         print_tuple(s, &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
 256                     l3proto, l4proto);
 257
 258         ct_show_zone(s, ct, NF_CT_ZONE_DIR_REPL);
 259
 260         if (seq_print_acct(s, ct, IP_CT_DIR_REPLY))
 261                 goto release;
 262
 263         if (test_bit(IPS_ASSURED_BIT, &ct->status))
 264                 seq_printf(s, "[ASSURED] ");
 265
 266         if (seq_has_overflowed(s))
 267                 goto release;
 268
 269 #if defined(CONFIG_NF_CONNTRACK_MARK)
 270         seq_printf(s, "mark=%u ", ct->mark);
 271 #endif
 272
 273         ct_show_secctx(s, ct);
 274         ct_show_zone(s, ct, NF_CT_DEFAULT_ZONE_DIR);
 275         ct_show_delta_time(s, ct);
 276
 277         seq_printf(s, "use=%u\n", atomic_read(&ct->ct_general.use));
 278
 279         if (seq_has_overflowed(s))
 280                 goto release;
 281
 282         ret = 0;
 283 release:
 284         nf_ct_put(ct);
 285         return ret;
 286 }
 287
 288 static const struct seq_operations ct_seq_ops = {
 289         .start = ct_seq_start,
 290         .next  = ct_seq_next,
 291         .stop  = ct_seq_stop,
 292         .show  = ct_seq_show
 293 };
 294
 295 static int ct_open(struct inode *inode, struct file *file)
 296 {
 297         return seq_open_net(inode, file, &ct_seq_ops,
 298                         sizeof(struct ct_iter_state));
 299 }
 300
 301 static const struct file_operations ct_file_ops = {
 302         .owner   = THIS_MODULE,
 303         .open    = ct_open,
 304         .read    = seq_read,
 305         .llseek  = seq_lseek,
 306         .release = seq_release_net,
 307 };
 308
 309 static void *ct_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 310 {
 311         struct net *net = seq_file_net(seq);
 312         int cpu;
 313
 314         if (*pos == 0)
 315                 return SEQ_START_TOKEN;
 316
 317         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
 318                 if (!cpu_possible(cpu))
 319                         continue;
 320                 *pos = cpu + 1;
 321                 return per_cpu_ptr(net->ct.stat, cpu);
 322         }
 323
 324         return NULL;
 325 }
 326
 327 static void *ct_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 328 {
 329         struct net *net = seq_file_net(seq);
 330         int cpu;
 331
 332         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
 333                 if (!cpu_possible(cpu))
 334                         continue;
 335                 *pos = cpu + 1;
 336                 return per_cpu_ptr(net->ct.stat, cpu);
 337         }
 338
 339         return NULL;
 340 }
 341
 342 static void ct_cpu_seq_stop(struct seq_file *seq, void *v)
 343 {
 344 }
 345
 346 static int ct_cpu_seq_show(struct seq_file *seq, void *v)
 347 {
 348         struct net *net = seq_file_net(seq);
 349         unsigned int nr_conntracks = atomic_read(&net->ct.count);
 350         const struct ip_conntrack_stat *st = v;
 351
 352         if (v == SEQ_START_TOKEN) {
 353                 seq_printf(seq, "entries  searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error  expect_new expect_create expect_delete search_restart\n");
 354                 return 0;
 355         }
 356
 357         seq_printf(seq, "%08x  %08x %08x %08x %08x %08x %08x %08x "
 358                         "%08x %08x %08x %08x %08x  %08x %08x %08x %08x\n",
 359                    nr_conntracks,
 360                    0,
 361                    st->found,
 362                    0,
 363                    st->invalid,
 364                    st->ignore,
 365                    0,
 366                    0,
 367                    st->insert,
 368                    st->insert_failed,
 369                    st->drop,
 370                    st->early_drop,
 371                    st->error,
 372
 373                    st->expect_new,
 374                    st->expect_create,
 375                    st->expect_delete,
 376                    st->search_restart
 377                 );
 378         return 0;
 379 }
 380
 381 static const struct seq_operations ct_cpu_seq_ops = {
 382         .start  = ct_cpu_seq_start,
 383         .next   = ct_cpu_seq_next,
 384         .stop   = ct_cpu_seq_stop,
 385         .show   = ct_cpu_seq_show,
 386 };
 387
 388 static int ct_cpu_seq_open(struct inode *inode, struct file *file)
 389 {
 390         return seq_open_net(inode, file, &ct_cpu_seq_ops,
 391                             sizeof(struct seq_net_private));
 392 }
 393
 394 static const struct file_operations ct_cpu_seq_fops = {
 395         .owner   = THIS_MODULE,
 396         .open    = ct_cpu_seq_open,
 397         .read    = seq_read,
 398         .llseek  = seq_lseek,
 399         .release = seq_release_net,
 400 };
 401
 402 static int nf_conntrack_standalone_init_proc(struct net *net)
 403 {
 404         struct proc_dir_entry *pde;
 405         kuid_t root_uid;
 406         kgid_t root_gid;
 407
 408         pde = proc_create("nf_conntrack", 0440, net->proc_net, &ct_file_ops);
 409         if (!pde)
 410                 goto out_nf_conntrack;
 411
 412         root_uid = make_kuid(net->user_ns, 0);
 413         root_gid = make_kgid(net->user_ns, 0);
 414         if (uid_valid(root_uid) && gid_valid(root_gid))
 415                 proc_set_user(pde, root_uid, root_gid);
 416
 417         pde = proc_create("nf_conntrack", S_IRUGO, net->proc_net_stat,
 418                           &ct_cpu_seq_fops);
 419         if (!pde)
 420                 goto out_stat_nf_conntrack;
 421         return 0;
 422
 423 out_stat_nf_conntrack:
 424         remove_proc_entry("nf_conntrack", net->proc_net);
 425 out_nf_conntrack:
 426         return -ENOMEM;
 427 }
 428
 429 static void nf_conntrack_standalone_fini_proc(struct net *net)
 430 {
 431         remove_proc_entry("nf_conntrack", net->proc_net_stat);
 432         remove_proc_entry("nf_conntrack", net->proc_net);
 433 }
 434 #else
 435 static int nf_conntrack_standalone_init_proc(struct net *net)
 436 {
 437         return 0;
 438 }
 439
 440 static void nf_conntrack_standalone_fini_proc(struct net *net)
 441 {
 442 }
 443 #endif /* CONFIG_NF_CONNTRACK_PROCFS */
 444
 445 /* Sysctl support */
 446
 447 #ifdef CONFIG_SYSCTL
 448 /* Log invalid packets of a given protocol */
 449 static int log_invalid_proto_min __read_mostly;
 450 static int log_invalid_proto_max __read_mostly = 255;
 451
 452 /* size the user *wants to set */
 453 static unsigned int nf_conntrack_htable_size_user __read_mostly;
 454
 455 static int
 456 nf_conntrack_hash_sysctl(struct ctl_table *table, int write,
 457                          void __user *buffer, size_t *lenp, loff_t *ppos)
 458 {
 459         int ret;
 460
 461         ret = proc_dointvec(table, write, buffer, lenp, ppos);
 462         if (ret < 0 || !write)
 463                 return ret;
 464
 465         /* update ret, we might not be able to satisfy request */
 466         ret = nf_conntrack_hash_resize(nf_conntrack_htable_size_user);
 467
 468         /* update it to the actual value used by conntrack */
 469         nf_conntrack_htable_size_user = nf_conntrack_htable_size;
 470         return ret;
 471 }
 472
 473 static struct ctl_table_header *nf_ct_netfilter_header;
 474
 475 static struct ctl_table nf_ct_sysctl_table[] = {
 476         {
 477                 .procname       = "nf_conntrack_max",
 478                 .data           = &nf_conntrack_max,
 479                 .maxlen         = sizeof(int),
 480                 .mode           = 0644,
 481                 .proc_handler   = proc_dointvec,
 482         },
 483         {
 484                 .procname       = "nf_conntrack_count",
 485                 .data           = &init_net.ct.count,
 486                 .maxlen         = sizeof(int),
 487                 .mode           = 0444,
 488                 .proc_handler   = proc_dointvec,
 489         },
 490         {
 491                 .procname       = "nf_conntrack_buckets",
 492                 .data           = &nf_conntrack_htable_size_user,
 493                 .maxlen         = sizeof(unsigned int),
 494                 .mode           = 0644,
 495                 .proc_handler   = nf_conntrack_hash_sysctl,
 496         },
 497         {
 498                 .procname       = "nf_conntrack_checksum",
 499                 .data           = &init_net.ct.sysctl_checksum,
 500                 .maxlen         = sizeof(unsigned int),
 501                 .mode           = 0644,
 502                 .proc_handler   = proc_dointvec,
 503         },
 504         {
 505                 .procname       = "nf_conntrack_log_invalid",
 506                 .data           = &init_net.ct.sysctl_log_invalid,
 507                 .maxlen         = sizeof(unsigned int),
 508                 .mode           = 0644,
 509                 .proc_handler   = proc_dointvec_minmax,
 510                 .extra1         = &log_invalid_proto_min,
 511                 .extra2         = &log_invalid_proto_max,
 512         },
 513         {
 514                 .procname       = "nf_conntrack_expect_max",
 515                 .data           = &nf_ct_expect_max,
 516                 .maxlen         = sizeof(int),
 517                 .mode           = 0644,
 518                 .proc_handler   = proc_dointvec,
 519         },
 520         { }
 521 };
 522
 523 static struct ctl_table nf_ct_netfilter_table[] = {
 524         {
 525                 .procname       = "nf_conntrack_max",
 526                 .data           = &nf_conntrack_max,
 527                 .maxlen         = sizeof(int),
 528                 .mode           = 0644,
 529                 .proc_handler   = proc_dointvec,
 530         },
 531         { }
 532 };
 533
 534 static int nf_conntrack_standalone_init_sysctl(struct net *net)
 535 {
 536         struct ctl_table *table;
 537
 538         table = kmemdup(nf_ct_sysctl_table, sizeof(nf_ct_sysctl_table),
 539                         GFP_KERNEL);
 540         if (!table)
 541                 goto out_kmemdup;
 542
 543         table[1].data = &net->ct.count;
 544         table[3].data = &net->ct.sysctl_checksum;
 545         table[4].data = &net->ct.sysctl_log_invalid;
 546
 547         /* Don't export sysctls to unprivileged users */
 548         if (net->user_ns != &init_user_ns)
 549                 table[0].procname = NULL;
 550
 551         if (!net_eq(&init_net, net))
 552                 table[2].mode = 0444;
 553
 554         net->ct.sysctl_header = register_net_sysctl(net, "net/netfilter", table);
 555         if (!net->ct.sysctl_header)
 556                 goto out_unregister_netfilter;
 557
 558         return 0;
 559
 560 out_unregister_netfilter:
 561         kfree(table);
 562 out_kmemdup:
 563         return -ENOMEM;
 564 }
 565
 566 static void nf_conntrack_standalone_fini_sysctl(struct net *net)
 567 {
 568         struct ctl_table *table;
 569
 570         table = net->ct.sysctl_header->ctl_table_arg;
 571         unregister_net_sysctl_table(net->ct.sysctl_header);
 572         kfree(table);
 573 }
 574 #else
 575 static int nf_conntrack_standalone_init_sysctl(struct net *net)
 576 {
 577         return 0;
 578 }
 579
 580 static void nf_conntrack_standalone_fini_sysctl(struct net *net)
 581 {
 582 }
 583 #endif /* CONFIG_SYSCTL */
 584
 585 static int nf_conntrack_pernet_init(struct net *net)
 586 {
 587         int ret;
 588
 589         ret = nf_conntrack_init_net(net);
 590         if (ret < 0)
 591                 goto out_init;
 592
 593         ret = nf_conntrack_standalone_init_proc(net);
 594         if (ret < 0)
 595                 goto out_proc;
 596
 597         net->ct.sysctl_checksum = 1;
 598         net->ct.sysctl_log_invalid = 0;
 599         ret = nf_conntrack_standalone_init_sysctl(net);
 600         if (ret < 0)
 601                 goto out_sysctl;
 602
 603         return 0;
 604
 605 out_sysctl:
 606         nf_conntrack_standalone_fini_proc(net);
 607 out_proc:
 608         nf_conntrack_cleanup_net(net);
 609 out_init:
 610         return ret;
 611 }
 612
 613 static void nf_conntrack_pernet_exit(struct list_head *net_exit_list)
 614 {
 615         struct net *net;
 616
 617         list_for_each_entry(net, net_exit_list, exit_list) {
 618                 nf_conntrack_standalone_fini_sysctl(net);
 619                 nf_conntrack_standalone_fini_proc(net);
 620         }
 621         nf_conntrack_cleanup_net_list(net_exit_list);
 622 }
 623
 624 static struct pernet_operations nf_conntrack_net_ops = {
 625         .init           = nf_conntrack_pernet_init,
 626         .exit_batch     = nf_conntrack_pernet_exit,
 627 };
 628
 629 static int __init nf_conntrack_standalone_init(void)
 630 {
 631         int ret = nf_conntrack_init_start();
 632         if (ret < 0)
 633                 goto out_start;
 634
 635 #ifdef CONFIG_SYSCTL
 636         nf_ct_netfilter_header =
 637                 register_net_sysctl(&init_net, "net", nf_ct_netfilter_table);
 638         if (!nf_ct_netfilter_header) {
 639                 pr_err("nf_conntrack: can't register to sysctl.\n");
 640                 ret = -ENOMEM;
 641                 goto out_sysctl;
 642         }
 643
 644         nf_conntrack_htable_size_user = nf_conntrack_htable_size;
 645 #endif
 646
 647         ret = register_pernet_subsys(&nf_conntrack_net_ops);
 648         if (ret < 0)
 649                 goto out_pernet;
 650
 651         nf_conntrack_init_end();
 652         return 0;
 653
 654 out_pernet:
 655 #ifdef CONFIG_SYSCTL
 656         unregister_net_sysctl_table(nf_ct_netfilter_header);
 657 out_sysctl:
 658 #endif
 659         nf_conntrack_cleanup_end();
 660 out_start:
 661         return ret;
 662 }
 663
 664 static void __exit nf_conntrack_standalone_fini(void)
 665 {
 666         nf_conntrack_cleanup_start();
 667         unregister_pernet_subsys(&nf_conntrack_net_ops);
 668 #ifdef CONFIG_SYSCTL
 669         unregister_net_sysctl_table(nf_ct_netfilter_header);
 670 #endif
 671         nf_conntrack_cleanup_end();
 672 }
 673
 674 module_init(nf_conntrack_standalone_init);
 675 module_exit(nf_conntrack_standalone_fini);
 676
 677 /* Some modules need us, but don't depend directly on any symbol.
 678    They should call this. */
 679 void need_conntrack(void)
 680 {
 681 }
 682 EXPORT_SYMBOL_GPL(need_conntrack);