ip/iptunnel.c

   1 /*
   2  * iptunnel.c          "ip tunnel"
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  *
  12  * Changes:
  13  *
  14  * Rani Assaf <rani@magic.metawire.com> 980929: resolve addresses
  15  * Rani Assaf <rani@magic.metawire.com> 980930: do not allow key for ipip/sit
  16  * Phil Karn <karn@ka9q.ampr.org>       990408: "pmtudisc" flag
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <syslog.h>
  24 #include <fcntl.h>
  25 #include <sys/socket.h>
  26 #include <netinet/in.h>
  27 #include <arpa/inet.h>
  28 #include <sys/ioctl.h>
  29 #include <linux/if.h>
  30 #include <linux/if_arp.h>
  31 #include <linux/ip.h>
  32 #include <linux/if_tunnel.h>
  33
  34 #include "rt_names.h"
  35 #include "utils.h"
  36
  37 static void usage(void) __attribute__((noreturn));
  38
  39 static void usage(void)
  40 {
  41         fprintf(stderr, "Usage: ip tunnel { add | change | del | show } [ NAME ]\n");
  42         fprintf(stderr, "          [ mode { ipip | gre | sit } ] [ remote ADDR ] [ local ADDR ]\n");
  43         fprintf(stderr, "          [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
  44         fprintf(stderr, "          [ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ] [ dev PHYS_DEV ]\n");
  45         fprintf(stderr, "\n");
  46         fprintf(stderr, "Where: NAME := STRING\n");
  47         fprintf(stderr, "       ADDR := { IP_ADDRESS | any }\n");
  48         fprintf(stderr, "       TOS  := { NUMBER | inherit }\n");
  49         fprintf(stderr, "       TTL  := { 1..255 | inherit }\n");
  50         fprintf(stderr, "       KEY  := { DOTTED_QUAD | NUMBER }\n");
  51         exit(-1);
  52 }
  53
  54 static int do_ioctl_get_ifindex(const char *dev)
  55 {
  56         struct ifreq ifr;
  57         int fd;
  58         int err;
  59
  60         strncpy(ifr.ifr_name, dev, IFNAMSIZ);
  61         fd = socket(AF_INET, SOCK_DGRAM, 0);
  62         err = ioctl(fd, SIOCGIFINDEX, &ifr);
  63         if (err) {
  64                 perror("ioctl");
  65                 return 0;
  66         }
  67         close(fd);
  68         return ifr.ifr_ifindex;
  69 }
  70
  71 static int do_ioctl_get_iftype(const char *dev)
  72 {
  73         struct ifreq ifr;
  74         int fd;
  75         int err;
  76
  77         strncpy(ifr.ifr_name, dev, IFNAMSIZ);
  78         fd = socket(AF_INET, SOCK_DGRAM, 0);
  79         err = ioctl(fd, SIOCGIFHWADDR, &ifr);
  80         if (err) {
  81                 perror("ioctl");
  82                 return -1;
  83         }
  84         close(fd);
  85         return ifr.ifr_addr.sa_family;
  86 }
  87
  88
  89 static char * do_ioctl_get_ifname(int idx)
  90 {
  91         static struct ifreq ifr;
  92         int fd;
  93         int err;
  94
  95         ifr.ifr_ifindex = idx;
  96         fd = socket(AF_INET, SOCK_DGRAM, 0);
  97         err = ioctl(fd, SIOCGIFNAME, &ifr);
  98         if (err) {
  99                 perror("ioctl");
 100                 return NULL;
 101         }
 102         close(fd);
 103         return ifr.ifr_name;
 104 }
 105
 106
 107 static int do_get_ioctl(const char *basedev, struct ip_tunnel_parm *p)
 108 {
 109         struct ifreq ifr;
 110         int fd;
 111         int err;
 112
 113         strncpy(ifr.ifr_name, basedev, IFNAMSIZ);
 114         ifr.ifr_ifru.ifru_data = (void*)p;
 115         fd = socket(AF_INET, SOCK_DGRAM, 0);
 116         err = ioctl(fd, SIOCGETTUNNEL, &ifr);
 117         if (err)
 118                 perror("ioctl");
 119         close(fd);
 120         return err;
 121 }
 122
 123 static int do_add_ioctl(int cmd, const char *basedev, struct ip_tunnel_parm *p)
 124 {
 125         struct ifreq ifr;
 126         int fd;
 127         int err;
 128
 129         if (cmd == SIOCCHGTUNNEL && p->name[0])
 130                 strncpy(ifr.ifr_name, p->name, IFNAMSIZ);
 131         else
 132                 strncpy(ifr.ifr_name, basedev, IFNAMSIZ);
 133         ifr.ifr_ifru.ifru_data = (void*)p;
 134         fd = socket(AF_INET, SOCK_DGRAM, 0);
 135         err = ioctl(fd, cmd, &ifr);
 136         if (err)
 137                 perror("ioctl");
 138         close(fd);
 139         return err;
 140 }
 141
 142 static int do_del_ioctl(const char *basedev, struct ip_tunnel_parm *p)
 143 {
 144         struct ifreq ifr;
 145         int fd;
 146         int err;
 147
 148         if (p->name[0])
 149                 strncpy(ifr.ifr_name, p->name, IFNAMSIZ);
 150         else
 151                 strncpy(ifr.ifr_name, basedev, IFNAMSIZ);
 152         ifr.ifr_ifru.ifru_data = (void*)p;
 153         fd = socket(AF_INET, SOCK_DGRAM, 0);
 154         err = ioctl(fd, SIOCDELTUNNEL, &ifr);
 155         if (err)
 156                 perror("ioctl");
 157         close(fd);
 158         return err;
 159 }
 160
 161 static int parse_args(int argc, char **argv, int cmd, struct ip_tunnel_parm *p)
 162 {
 163         int count = 0;
 164         char medium[IFNAMSIZ];
 165
 166         memset(p, 0, sizeof(*p));
 167         memset(&medium, 0, sizeof(medium));
 168
 169         p->iph.version = 4;
 170         p->iph.ihl = 5;
 171 #ifndef IP_DF
 172 #define IP_DF           0x4000          /* Flag: "Don't Fragment"       */
 173 #endif
 174         p->iph.frag_off = htons(IP_DF);
 175
 176         while (argc > 0) {
 177                 if (strcmp(*argv, "mode") == 0) {
 178                         NEXT_ARG();
 179                         if (strcmp(*argv, "ipip") == 0 ||
 180                             strcmp(*argv, "ip/ip") == 0) {
 181                                 if (p->iph.protocol && p->iph.protocol != IPPROTO_IPIP) {
 182                                         fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
 183                                         exit(-1);
 184                                 }
 185                                 p->iph.protocol = IPPROTO_IPIP;
 186                         } else if (strcmp(*argv, "gre") == 0 ||
 187                                    strcmp(*argv, "gre/ip") == 0) {
 188                                 if (p->iph.protocol && p->iph.protocol != IPPROTO_GRE) {
 189                                         fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
 190                                         exit(-1);
 191                                 }
 192                                 p->iph.protocol = IPPROTO_GRE;
 193                         } else if (strcmp(*argv, "sit") == 0 ||
 194                                    strcmp(*argv, "ipv6/ip") == 0) {
 195                                 if (p->iph.protocol && p->iph.protocol != IPPROTO_IPV6) {
 196                                         fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
 197                                         exit(-1);
 198                                 }
 199                                 p->iph.protocol = IPPROTO_IPV6;
 200                         } else {
 201                                 fprintf(stderr,"Cannot guess tunnel mode.\n");
 202                                 exit(-1);
 203                         }
 204                 } else if (strcmp(*argv, "key") == 0) {
 205                         unsigned uval;
 206                         NEXT_ARG();
 207                         p->i_flags |= GRE_KEY;
 208                         p->o_flags |= GRE_KEY;
 209                         if (strchr(*argv, '.'))
 210                                 p->i_key = p->o_key = get_addr32(*argv);
 211                         else {
 212                                 if (get_unsigned(&uval, *argv, 0)<0) {
 213                                         fprintf(stderr, "invalid value of \"key\"\n");
 214                                         exit(-1);
 215                                 }
 216                                 p->i_key = p->o_key = htonl(uval);
 217                         }
 218                 } else if (strcmp(*argv, "ikey") == 0) {
 219                         unsigned uval;
 220                         NEXT_ARG();
 221                         p->i_flags |= GRE_KEY;
 222                         if (strchr(*argv, '.'))
 223                                 p->o_key = get_addr32(*argv);
 224                         else {
 225                                 if (get_unsigned(&uval, *argv, 0)<0) {
 226                                         fprintf(stderr, "invalid value of \"ikey\"\n");
 227                                         exit(-1);
 228                                 }
 229                                 p->i_key = htonl(uval);
 230                         }
 231                 } else if (strcmp(*argv, "okey") == 0) {
 232                         unsigned uval;
 233                         NEXT_ARG();
 234                         p->o_flags |= GRE_KEY;
 235                         if (strchr(*argv, '.'))
 236                                 p->o_key = get_addr32(*argv);
 237                         else {
 238                                 if (get_unsigned(&uval, *argv, 0)<0) {
 239                                         fprintf(stderr, "invalid value of \"okey\"\n");
 240                                         exit(-1);
 241                                 }
 242                                 p->o_key = htonl(uval);
 243                         }
 244                 } else if (strcmp(*argv, "seq") == 0) {
 245                         p->i_flags |= GRE_SEQ;
 246                         p->o_flags |= GRE_SEQ;
 247                 } else if (strcmp(*argv, "iseq") == 0) {
 248                         p->i_flags |= GRE_SEQ;
 249                 } else if (strcmp(*argv, "oseq") == 0) {
 250                         p->o_flags |= GRE_SEQ;
 251                 } else if (strcmp(*argv, "csum") == 0) {
 252                         p->i_flags |= GRE_CSUM;
 253                         p->o_flags |= GRE_CSUM;
 254                 } else if (strcmp(*argv, "icsum") == 0) {
 255                         p->i_flags |= GRE_CSUM;
 256                 } else if (strcmp(*argv, "ocsum") == 0) {
 257                         p->o_flags |= GRE_CSUM;
 258                 } else if (strcmp(*argv, "nopmtudisc") == 0) {
 259                         p->iph.frag_off = 0;
 260                 } else if (strcmp(*argv, "pmtudisc") == 0) {
 261                         p->iph.frag_off = htons(IP_DF);
 262                 } else if (strcmp(*argv, "remote") == 0) {
 263                         NEXT_ARG();
 264                         if (strcmp(*argv, "any"))
 265                                 p->iph.daddr = get_addr32(*argv);
 266                 } else if (strcmp(*argv, "local") == 0) {
 267                         NEXT_ARG();
 268                         if (strcmp(*argv, "any"))
 269                                 p->iph.saddr = get_addr32(*argv);
 270                 } else if (strcmp(*argv, "dev") == 0) {
 271                         NEXT_ARG();
 272                         strncpy(medium, *argv, IFNAMSIZ-1);
 273                 } else if (strcmp(*argv, "ttl") == 0) {
 274                         unsigned uval;
 275                         NEXT_ARG();
 276                         if (strcmp(*argv, "inherit") != 0) {
 277                                 if (get_unsigned(&uval, *argv, 0))
 278                                         invarg("invalid TTL\n", *argv);
 279                                 if (uval > 255)
 280                                         invarg("TTL must be <=255\n", *argv);
 281                                 p->iph.ttl = uval;
 282                         }
 283                 } else if (strcmp(*argv, "tos") == 0 ||
 284                            matches(*argv, "dsfield") == 0) {
 285                         __u32 uval;
 286                         NEXT_ARG();
 287                         if (strcmp(*argv, "inherit") != 0) {
 288                                 if (rtnl_dsfield_a2n(&uval, *argv))
 289                                         invarg("bad TOS value", *argv);
 290                                 p->iph.tos = uval;
 291                         } else
 292                                 p->iph.tos = 1;
 293                 } else {
 294                         if (strcmp(*argv, "name") == 0) {
 295                                 NEXT_ARG();
 296                         }
 297                         if (matches(*argv, "help") == 0)
 298                                 usage();
 299                         if (p->name[0])
 300                                 duparg2("name", *argv);
 301                         strncpy(p->name, *argv, IFNAMSIZ);
 302                         if (cmd == SIOCCHGTUNNEL && count == 0) {
 303                                 struct ip_tunnel_parm old_p;
 304                                 memset(&old_p, 0, sizeof(old_p));
 305                                 if (do_get_ioctl(*argv, &old_p))
 306                                         return -1;
 307                                 *p = old_p;
 308                         }
 309                 }
 310                 count++;
 311                 argc--; argv++;
 312         }
 313
 314
 315         if (p->iph.protocol == 0) {
 316                 if (memcmp(p->name, "gre", 3) == 0)
 317                         p->iph.protocol = IPPROTO_GRE;
 318                 else if (memcmp(p->name, "ipip", 4) == 0)
 319                         p->iph.protocol = IPPROTO_IPIP;
 320                 else if (memcmp(p->name, "sit", 3) == 0)
 321                         p->iph.protocol = IPPROTO_IPV6;
 322         }
 323
 324         if (p->iph.protocol == IPPROTO_IPIP || p->iph.protocol == IPPROTO_IPV6) {
 325                 if ((p->i_flags & GRE_KEY) || (p->o_flags & GRE_KEY)) {
 326                         fprintf(stderr, "Keys are not allowed with ipip and sit.\n");
 327                         return -1;
 328                 }
 329         }
 330
 331         if (medium[0]) {
 332                 p->link = do_ioctl_get_ifindex(medium);
 333                 if (p->link == 0)
 334                         return -1;
 335         }
 336
 337         if (p->i_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
 338                 p->i_key = p->iph.daddr;
 339                 p->i_flags |= GRE_KEY;
 340         }
 341         if (p->o_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
 342                 p->o_key = p->iph.daddr;
 343                 p->o_flags |= GRE_KEY;
 344         }
 345         if (IN_MULTICAST(ntohl(p->iph.daddr)) && !p->iph.saddr) {
 346                 fprintf(stderr, "Broadcast tunnel requires a source address.\n");
 347                 return -1;
 348         }
 349         return 0;
 350 }
 351
 352
 353 static int do_add(int cmd, int argc, char **argv)
 354 {
 355         struct ip_tunnel_parm p;
 356
 357         if (parse_args(argc, argv, cmd, &p) < 0)
 358                 return -1;
 359
 360         if (p.iph.ttl && p.iph.frag_off == 0) {
 361                 fprintf(stderr, "ttl != 0 and noptmudisc are incompatible\n");
 362                 return -1;
 363         }
 364
 365         switch (p.iph.protocol) {
 366         case IPPROTO_IPIP:
 367                 return do_add_ioctl(cmd, "tunl0", &p);
 368         case IPPROTO_GRE:
 369                 return do_add_ioctl(cmd, "gre0", &p);
 370         case IPPROTO_IPV6:
 371                 return do_add_ioctl(cmd, "sit0", &p);
 372         default:
 373                 fprintf(stderr, "cannot determine tunnel mode (ipip, gre or sit)\n");
 374                 return -1;
 375         }
 376         return -1;
 377 }
 378
 379 int do_del(int argc, char **argv)
 380 {
 381         struct ip_tunnel_parm p;
 382
 383         if (parse_args(argc, argv, SIOCDELTUNNEL, &p) < 0)
 384                 return -1;
 385
 386         switch (p.iph.protocol) {
 387         case IPPROTO_IPIP:
 388                 return do_del_ioctl("tunl0", &p);
 389         case IPPROTO_GRE:
 390                 return do_del_ioctl("gre0", &p);
 391         case IPPROTO_IPV6:
 392                 return do_del_ioctl("sit0", &p);
 393         default:
 394                 return do_del_ioctl(p.name, &p);
 395         }
 396         return -1;
 397 }
 398
 399 void print_tunnel(struct ip_tunnel_parm *p)
 400 {
 401         char s1[1024];
 402         char s2[1024];
 403         char s3[64];
 404         char s4[64];
 405
 406         inet_ntop(AF_INET, &p->i_key, s3, sizeof(s3));
 407         inet_ntop(AF_INET, &p->o_key, s4, sizeof(s4));
 408
 409         /* Do not use format_host() for local addr,
 410          * symbolic name will not be useful.
 411          */
 412         printf("%s: %s/ip  remote %s  local %s ",
 413                p->name,
 414                p->iph.protocol == IPPROTO_IPIP ? "ip" :
 415                (p->iph.protocol == IPPROTO_GRE ? "gre" :
 416                 (p->iph.protocol == IPPROTO_IPV6 ? "ipv6" : "unknown")),
 417                p->iph.daddr ? format_host(AF_INET, 4, &p->iph.daddr, s1, sizeof(s1))  : "any",
 418                p->iph.saddr ? rt_addr_n2a(AF_INET, 4, &p->iph.saddr, s2, sizeof(s2)) : "any");
 419
 420         if (p->link) {
 421                 char *n = do_ioctl_get_ifname(p->link);
 422                 if (n)
 423                         printf(" dev %s ", n);
 424         }
 425
 426         if (p->iph.ttl)
 427                 printf(" ttl %d ", p->iph.ttl);
 428         else
 429                 printf(" ttl inherit ");
 430
 431         if (p->iph.tos) {
 432                 SPRINT_BUF(b1);
 433                 printf(" tos");
 434                 if (p->iph.tos&1)
 435                         printf(" inherit");
 436                 if (p->iph.tos&~1)
 437                         printf("%c%s ", p->iph.tos&1 ? '/' : ' ',
 438                                rtnl_dsfield_n2a(p->iph.tos&~1, b1, sizeof(b1)));
 439         }
 440
 441         if (!(p->iph.frag_off&htons(IP_DF)))
 442                 printf(" nopmtudisc");
 443
 444         if ((p->i_flags&GRE_KEY) && (p->o_flags&GRE_KEY) && p->o_key == p->i_key)
 445                 printf(" key %s", s3);
 446         else if ((p->i_flags|p->o_flags)&GRE_KEY) {
 447                 if (p->i_flags&GRE_KEY)
 448                         printf(" ikey %s ", s3);
 449                 if (p->o_flags&GRE_KEY)
 450                         printf(" okey %s ", s4);
 451         }
 452
 453         if (p->i_flags&GRE_SEQ)
 454                 printf("%s  Drop packets out of sequence.\n", _SL_);
 455         if (p->i_flags&GRE_CSUM)
 456                 printf("%s  Checksum in received packet is required.", _SL_);
 457         if (p->o_flags&GRE_SEQ)
 458                 printf("%s  Sequence packets on output.", _SL_);
 459         if (p->o_flags&GRE_CSUM)
 460                 printf("%s  Checksum output packets.", _SL_);
 461 }
 462
 463 static int do_tunnels_list(struct ip_tunnel_parm *p)
 464 {
 465         char name[IFNAMSIZ];
 466         unsigned long  rx_bytes, rx_packets, rx_errs, rx_drops,
 467         rx_fifo, rx_frame,
 468         tx_bytes, tx_packets, tx_errs, tx_drops,
 469         tx_fifo, tx_colls, tx_carrier, rx_multi;
 470         int type;
 471         struct ip_tunnel_parm p1;
 472
 473         char buf[512];
 474         FILE *fp = fopen("/proc/net/dev", "r");
 475         if (fp == NULL) {
 476                 perror("fopen");
 477                 return -1;
 478         }
 479
 480         fgets(buf, sizeof(buf), fp);
 481         fgets(buf, sizeof(buf), fp);
 482
 483         while (fgets(buf, sizeof(buf), fp) != NULL) {
 484                 char *ptr;
 485                 buf[sizeof(buf) - 1] = 0;
 486                 if ((ptr = strchr(buf, ':')) == NULL ||
 487                     (*ptr++ = 0, sscanf(buf, "%s", name) != 1)) {
 488                         fprintf(stderr, "Wrong format of /proc/net/dev. Sorry.\n");
 489                         return -1;
 490                 }
 491                 if (sscanf(ptr, "%ld%ld%ld%ld%ld%ld%ld%*d%ld%ld%ld%ld%ld%ld%ld",
 492                            &rx_bytes, &rx_packets, &rx_errs, &rx_drops,
 493                            &rx_fifo, &rx_frame, &rx_multi,
 494                            &tx_bytes, &tx_packets, &tx_errs, &tx_drops,
 495                            &tx_fifo, &tx_colls, &tx_carrier) != 14)
 496                         continue;
 497                 if (p->name[0] && strcmp(p->name, name))
 498                         continue;
 499                 type = do_ioctl_get_iftype(name);
 500                 if (type == -1) {
 501                         fprintf(stderr, "Failed to get type of [%s]\n", name);
 502                         continue;
 503                 }
 504                 if (type != ARPHRD_TUNNEL && type != ARPHRD_IPGRE && type != ARPHRD_SIT)
 505                         continue;
 506                 memset(&p1, 0, sizeof(p1));
 507                 if (do_get_ioctl(name, &p1))
 508                         continue;
 509                 if ((p->link && p1.link != p->link) ||
 510                     (p->name[0] && strcmp(p1.name, p->name)) ||
 511                     (p->iph.daddr && p1.iph.daddr != p->iph.daddr) ||
 512                     (p->iph.saddr && p1.iph.saddr != p->iph.saddr) ||
 513                     (p->i_key && p1.i_key != p->i_key))
 514                         continue;
 515                 print_tunnel(&p1);
 516                 if (show_stats) {
 517                         printf("%s", _SL_);
 518                         printf("RX: Packets    Bytes        Errors CsumErrs OutOfSeq Mcasts%s", _SL_);
 519                         printf("    %-10ld %-12ld %-6ld %-8ld %-8ld %-8ld%s",
 520                                rx_packets, rx_bytes, rx_errs, rx_frame, rx_fifo, rx_multi, _SL_);
 521                         printf("TX: Packets    Bytes        Errors DeadLoop NoRoute  NoBufs%s", _SL_);
 522                         printf("    %-10ld %-12ld %-6ld %-8ld %-8ld %-6ld",
 523                                tx_packets, tx_bytes, tx_errs, tx_colls, tx_carrier, tx_drops);
 524                 }
 525                 printf("\n");
 526         }
 527         return 0;
 528 }
 529
 530 static int do_show(int argc, char **argv)
 531 {
 532         int err;
 533         struct ip_tunnel_parm p;
 534
 535         if (parse_args(argc, argv, SIOCGETTUNNEL, &p) < 0)
 536                 return -1;
 537
 538         switch (p.iph.protocol) {
 539         case IPPROTO_IPIP:
 540                 err = do_get_ioctl(p.name[0] ? p.name : "tunl0", &p);
 541                 break;
 542         case IPPROTO_GRE:
 543                 err = do_get_ioctl(p.name[0] ? p.name : "gre0", &p);
 544                 break;
 545         case IPPROTO_IPV6:
 546                 err = do_get_ioctl(p.name[0] ? p.name : "sit0", &p);
 547                 break;
 548         default:
 549                 do_tunnels_list(&p);
 550                 return 0;
 551         }
 552         if (err)
 553                 return -1;
 554
 555         print_tunnel(&p);
 556         printf("\n");
 557         return 0;
 558 }
 559
 560 int do_iptunnel(int argc, char **argv)
 561 {
 562         if (argc > 0) {
 563                 if (matches(*argv, "add") == 0)
 564                         return do_add(SIOCADDTUNNEL, argc-1, argv+1);
 565                 if (matches(*argv, "change") == 0)
 566                         return do_add(SIOCCHGTUNNEL, argc-1, argv+1);
 567                 if (matches(*argv, "del") == 0)
 568                         return do_del(argc-1, argv+1);
 569                 if (matches(*argv, "show") == 0 ||
 570                     matches(*argv, "lst") == 0 ||
 571                     matches(*argv, "list") == 0)
 572                         return do_show(argc-1, argv+1);
 573                 if (matches(*argv, "help") == 0)
 574                         usage();
 575         } else
 576                 return do_show(0, NULL);
 577
 578         fprintf(stderr, "Command \"%s\" is unknown, try \"ip tunnel help\".\n", *argv);
 579         exit(-1);
 580 }