1 /* $OpenBSD: netcat.c,v 1.95 2010/02/27 00:58:56 nicm Exp $ */ 2 /* 3 * Copyright (c) 2001 Eric Jackson <ericj@monkey.org> 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $FreeBSD$ 29 */ 30 31 /* 32 * Re-written nc(1) for OpenBSD. Original implementation by 33 * *Hobbit* <hobbit@avian.org>. 34 */ 35 36 #include <sys/limits.h> 37 #include <sys/types.h> 38 #include <sys/socket.h> 39 #include <sys/sysctl.h> 40 #include <sys/time.h> 41 #include <sys/un.h> 42 43 #include <netinet/in.h> 44 #include <netinet/in_systm.h> 45 #ifdef IPSEC 46 #include <netipsec/ipsec.h> 47 #endif 48 #include <netinet/tcp.h> 49 #include <netinet/ip.h> 50 #include <arpa/telnet.h> 51 52 #include <err.h> 53 #include <errno.h> 54 #include <getopt.h> 55 #include <netdb.h> 56 #include <poll.h> 57 #include <stdarg.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 #include <fcntl.h> 63 #include <limits.h> 64 #include "atomicio.h" 65 66 #ifndef SUN_LEN 67 #define SUN_LEN(su) \ 68 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 69 #endif 70 71 #define PORT_MAX 65535 72 #define PORT_MAX_LEN 6 73 74 /* Command Line Options */ 75 int dflag; /* detached, no stdin */ 76 unsigned int iflag; /* Interval Flag */ 77 int jflag; /* use jumbo frames if we can */ 78 int kflag; /* More than one connect */ 79 int lflag; /* Bind to local port */ 80 int nflag; /* Don't do name look up */ 81 int FreeBSD_Oflag; /* Do not use TCP options */ 82 char *Pflag; /* Proxy username */ 83 char *pflag; /* Localport flag */ 84 int rflag; /* Random ports flag */ 85 char *sflag; /* Source Address */ 86 int tflag; /* Telnet Emulation */ 87 int uflag; /* UDP - Default to TCP */ 88 int vflag; /* Verbosity */ 89 int xflag; /* Socks proxy */ 90 int zflag; /* Port Scan Flag */ 91 int Dflag; /* sodebug */ 92 int Iflag; /* TCP receive buffer size */ 93 int Oflag; /* TCP send buffer size */ 94 int Sflag; /* TCP MD5 signature option */ 95 int Tflag = -1; /* IP Type of Service */ 96 u_int rdomain; 97 98 int timeout = -1; 99 int family = AF_UNSPEC; 100 char *portlist[PORT_MAX+1]; 101 102 void atelnet(int, unsigned char *, unsigned int); 103 void build_ports(char *); 104 void help(void); 105 int local_listen(char *, char *, struct addrinfo); 106 void readwrite(int); 107 int remote_connect(const char *, const char *, struct addrinfo); 108 int socks_connect(const char *, const char *, struct addrinfo, 109 const char *, const char *, struct addrinfo, int, const char *); 110 int udptest(int); 111 int unix_connect(char *); 112 int unix_listen(char *); 113 void set_common_sockopts(int); 114 int parse_iptos(char *); 115 void usage(int); 116 117 #ifdef IPSEC 118 void add_ipsec_policy(int, char *); 119 120 char *ipsec_policy[2]; 121 #endif 122 123 int 124 main(int argc, char *argv[]) 125 { 126 int ch, s, ret, socksv, ipsec_count; 127 int numfibs; 128 size_t intsize = sizeof(int); 129 char *host, *uport; 130 struct addrinfo hints; 131 struct servent *sv; 132 socklen_t len; 133 struct sockaddr_storage cliaddr; 134 char *proxy; 135 const char *errstr, *proxyhost = "", *proxyport = NULL; 136 struct addrinfo proxyhints; 137 struct option longopts[] = { 138 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 139 { NULL, 0, NULL, 0 } 140 }; 141 142 rdomain = 0; 143 ret = 1; 144 ipsec_count = 0; 145 s = 0; 146 socksv = 5; 147 host = NULL; 148 uport = NULL; 149 sv = NULL; 150 151 while ((ch = getopt_long(argc, argv, 152 "46DdEe:hI:i:jklnoO:P:p:rSs:tT:UuV:vw:X:x:z", 153 longopts, NULL)) != -1) { 154 switch (ch) { 155 case '4': 156 family = AF_INET; 157 break; 158 case '6': 159 family = AF_INET6; 160 break; 161 case 'U': 162 family = AF_UNIX; 163 break; 164 case 'X': 165 if (strcasecmp(optarg, "connect") == 0) 166 socksv = -1; /* HTTP proxy CONNECT */ 167 else if (strcmp(optarg, "4") == 0) 168 socksv = 4; /* SOCKS v.4 */ 169 else if (strcmp(optarg, "5") == 0) 170 socksv = 5; /* SOCKS v.5 */ 171 else 172 errx(1, "unsupported proxy protocol"); 173 break; 174 case 'd': 175 dflag = 1; 176 break; 177 case 'e': 178 #ifdef IPSEC 179 ipsec_policy[ipsec_count++ % 2] = optarg; 180 #else 181 errx(1, "IPsec support unavailable."); 182 #endif 183 break; 184 case 'E': 185 #ifdef IPSEC 186 ipsec_policy[0] = "in ipsec esp/transport//require"; 187 ipsec_policy[1] = "out ipsec esp/transport//require"; 188 #else 189 errx(1, "IPsec support unavailable."); 190 #endif 191 break; 192 case 'h': 193 help(); 194 break; 195 case 'i': 196 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 197 if (errstr) 198 errx(1, "interval %s: %s", errstr, optarg); 199 break; 200 #ifdef SO_JUMBO 201 case 'j': 202 jflag = 1; 203 break; 204 #endif 205 case 'k': 206 kflag = 1; 207 break; 208 case 'l': 209 lflag = 1; 210 break; 211 case 'n': 212 nflag = 1; 213 break; 214 case 'o': 215 fprintf(stderr, "option -o is deprecated.\n"); 216 break; 217 case 'P': 218 Pflag = optarg; 219 break; 220 case 'p': 221 pflag = optarg; 222 break; 223 case 'r': 224 rflag = 1; 225 break; 226 case 's': 227 sflag = optarg; 228 break; 229 case 't': 230 tflag = 1; 231 break; 232 case 'u': 233 uflag = 1; 234 break; 235 case 'V': 236 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 237 errx(1, "Multiple FIBS not supported"); 238 rdomain = (unsigned int)strtonum(optarg, 0, 239 numfibs - 1, &errstr); 240 if (errstr) 241 errx(1, "FIB %s: %s", errstr, optarg); 242 break; 243 case 'v': 244 vflag = 1; 245 break; 246 case 'w': 247 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 248 if (errstr) 249 errx(1, "timeout %s: %s", errstr, optarg); 250 timeout *= 1000; 251 break; 252 case 'x': 253 xflag = 1; 254 if ((proxy = strdup(optarg)) == NULL) 255 err(1, NULL); 256 break; 257 case 'z': 258 zflag = 1; 259 break; 260 case 'D': 261 Dflag = 1; 262 break; 263 case 'I': 264 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 265 if (errstr != NULL) 266 errx(1, "TCP receive window %s: %s", 267 errstr, optarg); 268 break; 269 case 'O': 270 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 271 if (errstr != NULL) { 272 if (strcmp(errstr, "invalid") != 0) 273 errx(1, "TCP send window %s: %s", 274 errstr, optarg); 275 } 276 break; 277 case 'S': 278 Sflag = 1; 279 break; 280 case 'T': 281 Tflag = parse_iptos(optarg); 282 break; 283 default: 284 usage(1); 285 } 286 } 287 argc -= optind; 288 argv += optind; 289 290 /* Cruft to make sure options are clean, and used properly. */ 291 if (argv[0] && !argv[1] && family == AF_UNIX) { 292 if (uflag) 293 errx(1, "cannot use -u and -U"); 294 host = argv[0]; 295 uport = NULL; 296 } else if (argv[0] && !argv[1]) { 297 if (!lflag) 298 usage(1); 299 uport = argv[0]; 300 host = NULL; 301 } else if (argv[0] && argv[1]) { 302 host = argv[0]; 303 uport = argv[1]; 304 } else 305 usage(1); 306 307 if (lflag && sflag) 308 errx(1, "cannot use -s and -l"); 309 if (lflag && pflag) 310 errx(1, "cannot use -p and -l"); 311 if (lflag && zflag) 312 errx(1, "cannot use -z and -l"); 313 if (!lflag && kflag) 314 errx(1, "must use -l with -k"); 315 316 /* Initialize addrinfo structure. */ 317 if (family != AF_UNIX) { 318 memset(&hints, 0, sizeof(struct addrinfo)); 319 hints.ai_family = family; 320 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 321 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 322 if (nflag) 323 hints.ai_flags |= AI_NUMERICHOST; 324 } 325 326 if (xflag) { 327 if (uflag) 328 errx(1, "no proxy support for UDP mode"); 329 330 if (lflag) 331 errx(1, "no proxy support for listen"); 332 333 if (family == AF_UNIX) 334 errx(1, "no proxy support for unix sockets"); 335 336 /* XXX IPv6 transport to proxy would probably work */ 337 if (family == AF_INET6) 338 errx(1, "no proxy support for IPv6"); 339 340 if (sflag) 341 errx(1, "no proxy support for local source address"); 342 343 proxyhost = strsep(&proxy, ":"); 344 proxyport = proxy; 345 346 memset(&proxyhints, 0, sizeof(struct addrinfo)); 347 proxyhints.ai_family = family; 348 proxyhints.ai_socktype = SOCK_STREAM; 349 proxyhints.ai_protocol = IPPROTO_TCP; 350 if (nflag) 351 proxyhints.ai_flags |= AI_NUMERICHOST; 352 } 353 354 if (lflag) { 355 int connfd; 356 ret = 0; 357 358 if (family == AF_UNIX) 359 s = unix_listen(host); 360 361 /* Allow only one connection at a time, but stay alive. */ 362 for (;;) { 363 if (family != AF_UNIX) 364 s = local_listen(host, uport, hints); 365 if (s < 0) 366 err(1, NULL); 367 /* 368 * For UDP, we will use recvfrom() initially 369 * to wait for a caller, then use the regular 370 * functions to talk to the caller. 371 */ 372 if (uflag) { 373 int rv, plen; 374 char buf[8192]; 375 struct sockaddr_storage z; 376 377 len = sizeof(z); 378 plen = jflag ? 8192 : 1024; 379 rv = recvfrom(s, buf, plen, MSG_PEEK, 380 (struct sockaddr *)&z, &len); 381 if (rv < 0) 382 err(1, "recvfrom"); 383 384 rv = connect(s, (struct sockaddr *)&z, len); 385 if (rv < 0) 386 err(1, "connect"); 387 388 connfd = s; 389 } else { 390 len = sizeof(cliaddr); 391 connfd = accept(s, (struct sockaddr *)&cliaddr, 392 &len); 393 } 394 395 readwrite(connfd); 396 close(connfd); 397 if (family != AF_UNIX) 398 close(s); 399 400 if (!kflag) 401 break; 402 } 403 } else if (family == AF_UNIX) { 404 ret = 0; 405 406 if ((s = unix_connect(host)) > 0 && !zflag) { 407 readwrite(s); 408 close(s); 409 } else 410 ret = 1; 411 412 exit(ret); 413 414 } else { 415 int i = 0; 416 417 /* Construct the portlist[] array. */ 418 build_ports(uport); 419 420 /* Cycle through portlist, connecting to each port. */ 421 for (i = 0; portlist[i] != NULL; i++) { 422 if (s) 423 close(s); 424 425 if (xflag) 426 s = socks_connect(host, portlist[i], hints, 427 proxyhost, proxyport, proxyhints, socksv, 428 Pflag); 429 else 430 s = remote_connect(host, portlist[i], hints); 431 432 if (s < 0) 433 continue; 434 435 ret = 0; 436 if (vflag || zflag) { 437 /* For UDP, make sure we are connected. */ 438 if (uflag) { 439 if (udptest(s) == -1) { 440 ret = 1; 441 continue; 442 } 443 } 444 445 /* Don't look up port if -n. */ 446 if (nflag) 447 sv = NULL; 448 else { 449 sv = getservbyport( 450 ntohs(atoi(portlist[i])), 451 uflag ? "udp" : "tcp"); 452 } 453 454 fprintf(stderr, 455 "Connection to %s %s port [%s/%s] " 456 "succeeded!\n", host, portlist[i], 457 uflag ? "udp" : "tcp", 458 sv ? sv->s_name : "*"); 459 } 460 if (!zflag) 461 readwrite(s); 462 } 463 } 464 465 if (s) 466 close(s); 467 468 exit(ret); 469 } 470 471 /* 472 * unix_connect() 473 * Returns a socket connected to a local unix socket. Returns -1 on failure. 474 */ 475 int 476 unix_connect(char *path) 477 { 478 struct sockaddr_un sun; 479 int s; 480 481 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 482 return (-1); 483 (void)fcntl(s, F_SETFD, 1); 484 485 memset(&sun, 0, sizeof(struct sockaddr_un)); 486 sun.sun_family = AF_UNIX; 487 488 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 489 sizeof(sun.sun_path)) { 490 close(s); 491 errno = ENAMETOOLONG; 492 return (-1); 493 } 494 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 495 close(s); 496 return (-1); 497 } 498 return (s); 499 500 } 501 502 /* 503 * unix_listen() 504 * Create a unix domain socket, and listen on it. 505 */ 506 int 507 unix_listen(char *path) 508 { 509 struct sockaddr_un sun; 510 int s; 511 512 /* Create unix domain socket. */ 513 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 514 return (-1); 515 516 memset(&sun, 0, sizeof(struct sockaddr_un)); 517 sun.sun_family = AF_UNIX; 518 519 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 520 sizeof(sun.sun_path)) { 521 close(s); 522 errno = ENAMETOOLONG; 523 return (-1); 524 } 525 526 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 527 close(s); 528 return (-1); 529 } 530 531 if (listen(s, 5) < 0) { 532 close(s); 533 return (-1); 534 } 535 return (s); 536 } 537 538 /* 539 * remote_connect() 540 * Returns a socket connected to a remote host. Properly binds to a local 541 * port or source address if needed. Returns -1 on failure. 542 */ 543 int 544 remote_connect(const char *host, const char *port, struct addrinfo hints) 545 { 546 struct addrinfo *res, *res0; 547 int s, error, on = 1; 548 549 if ((error = getaddrinfo(host, port, &hints, &res))) 550 errx(1, "getaddrinfo: %s", gai_strerror(error)); 551 552 res0 = res; 553 do { 554 if ((s = socket(res0->ai_family, res0->ai_socktype, 555 res0->ai_protocol)) < 0) 556 continue; 557 #ifdef IPSEC 558 if (ipsec_policy[0] != NULL) 559 add_ipsec_policy(s, ipsec_policy[0]); 560 if (ipsec_policy[1] != NULL) 561 add_ipsec_policy(s, ipsec_policy[1]); 562 #endif 563 564 if (rdomain) { 565 if (setfib(rdomain) == -1) 566 err(1, "setfib"); 567 } 568 569 /* Bind to a local port or source address if specified. */ 570 if (sflag || pflag) { 571 struct addrinfo ahints, *ares; 572 573 /* try IP_BINDANY, but don't insist */ 574 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 575 memset(&ahints, 0, sizeof(struct addrinfo)); 576 ahints.ai_family = res0->ai_family; 577 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 578 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 579 ahints.ai_flags = AI_PASSIVE; 580 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 581 errx(1, "getaddrinfo: %s", gai_strerror(error)); 582 583 if (bind(s, (struct sockaddr *)ares->ai_addr, 584 ares->ai_addrlen) < 0) 585 errx(1, "bind failed: %s", strerror(errno)); 586 freeaddrinfo(ares); 587 } 588 589 set_common_sockopts(s); 590 591 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 592 break; 593 else if (vflag) 594 warn("connect to %s port %s (%s) failed", host, port, 595 uflag ? "udp" : "tcp"); 596 597 close(s); 598 s = -1; 599 } while ((res0 = res0->ai_next) != NULL); 600 601 freeaddrinfo(res); 602 603 return (s); 604 } 605 606 /* 607 * local_listen() 608 * Returns a socket listening on a local port, binds to specified source 609 * address. Returns -1 on failure. 610 */ 611 int 612 local_listen(char *host, char *port, struct addrinfo hints) 613 { 614 struct addrinfo *res, *res0; 615 int s, ret, x = 1; 616 int error; 617 618 /* Allow nodename to be null. */ 619 hints.ai_flags |= AI_PASSIVE; 620 621 /* 622 * In the case of binding to a wildcard address 623 * default to binding to an ipv4 address. 624 */ 625 if (host == NULL && hints.ai_family == AF_UNSPEC) 626 hints.ai_family = AF_INET; 627 628 if ((error = getaddrinfo(host, port, &hints, &res))) 629 errx(1, "getaddrinfo: %s", gai_strerror(error)); 630 631 res0 = res; 632 do { 633 if ((s = socket(res0->ai_family, res0->ai_socktype, 634 res0->ai_protocol)) < 0) 635 continue; 636 637 if (rdomain) { 638 if (setfib(rdomain) == -1) 639 err(1, "setfib"); 640 } 641 642 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 643 if (ret == -1) 644 err(1, NULL); 645 #ifdef IPSEC 646 if (ipsec_policy[0] != NULL) 647 add_ipsec_policy(s, ipsec_policy[0]); 648 if (ipsec_policy[1] != NULL) 649 add_ipsec_policy(s, ipsec_policy[1]); 650 #endif 651 if (FreeBSD_Oflag) { 652 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 653 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 654 err(1, "disable TCP options"); 655 } 656 657 if (bind(s, (struct sockaddr *)res0->ai_addr, 658 res0->ai_addrlen) == 0) 659 break; 660 661 close(s); 662 s = -1; 663 } while ((res0 = res0->ai_next) != NULL); 664 665 if (!uflag && s != -1) { 666 if (listen(s, 1) < 0) 667 err(1, "listen"); 668 } 669 670 freeaddrinfo(res); 671 672 return (s); 673 } 674 675 /* 676 * readwrite() 677 * Loop that polls on the network file descriptor and stdin. 678 */ 679 void 680 readwrite(int nfd) 681 { 682 struct pollfd pfd[2]; 683 unsigned char buf[8192]; 684 int n, wfd = fileno(stdin); 685 int lfd = fileno(stdout); 686 int plen; 687 688 plen = jflag ? 8192 : 1024; 689 690 /* Setup Network FD */ 691 pfd[0].fd = nfd; 692 pfd[0].events = POLLIN; 693 694 /* Set up STDIN FD. */ 695 pfd[1].fd = wfd; 696 pfd[1].events = POLLIN; 697 698 while (pfd[0].fd != -1) { 699 if (iflag) 700 sleep(iflag); 701 702 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 703 close(nfd); 704 err(1, "Polling Error"); 705 } 706 707 if (n == 0) 708 return; 709 710 if (pfd[0].revents & POLLIN) { 711 if ((n = read(nfd, buf, plen)) < 0) 712 return; 713 else if (n == 0) { 714 shutdown(nfd, SHUT_RD); 715 pfd[0].fd = -1; 716 pfd[0].events = 0; 717 } else { 718 if (tflag) 719 atelnet(nfd, buf, n); 720 if (atomicio(vwrite, lfd, buf, n) != n) 721 return; 722 } 723 } 724 725 if (!dflag && pfd[1].revents & POLLIN) { 726 if ((n = read(wfd, buf, plen)) < 0) 727 return; 728 else if (n == 0) { 729 shutdown(nfd, SHUT_WR); 730 pfd[1].fd = -1; 731 pfd[1].events = 0; 732 } else { 733 if (atomicio(vwrite, nfd, buf, n) != n) 734 return; 735 } 736 } 737 } 738 } 739 740 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 741 void 742 atelnet(int nfd, unsigned char *buf, unsigned int size) 743 { 744 unsigned char *p, *end; 745 unsigned char obuf[4]; 746 747 if (size < 3) 748 return; 749 end = buf + size - 2; 750 751 for (p = buf; p < end; p++) { 752 if (*p != IAC) 753 continue; 754 755 obuf[0] = IAC; 756 p++; 757 if ((*p == WILL) || (*p == WONT)) 758 obuf[1] = DONT; 759 else if ((*p == DO) || (*p == DONT)) 760 obuf[1] = WONT; 761 else 762 continue; 763 764 p++; 765 obuf[2] = *p; 766 if (atomicio(vwrite, nfd, obuf, 3) != 3) 767 warn("Write Error!"); 768 } 769 } 770 771 /* 772 * build_ports() 773 * Build an array or ports in portlist[], listing each port 774 * that we should try to connect to. 775 */ 776 void 777 build_ports(char *p) 778 { 779 const char *errstr; 780 char *n; 781 int hi, lo, cp; 782 int x = 0; 783 784 if ((n = strchr(p, '-')) != NULL) { 785 if (lflag) 786 errx(1, "Cannot use -l with multiple ports!"); 787 788 *n = '\0'; 789 n++; 790 791 /* Make sure the ports are in order: lowest->highest. */ 792 hi = strtonum(n, 1, PORT_MAX, &errstr); 793 if (errstr) 794 errx(1, "port number %s: %s", errstr, n); 795 lo = strtonum(p, 1, PORT_MAX, &errstr); 796 if (errstr) 797 errx(1, "port number %s: %s", errstr, p); 798 799 if (lo > hi) { 800 cp = hi; 801 hi = lo; 802 lo = cp; 803 } 804 805 /* Load ports sequentially. */ 806 for (cp = lo; cp <= hi; cp++) { 807 portlist[x] = calloc(1, PORT_MAX_LEN); 808 if (portlist[x] == NULL) 809 err(1, NULL); 810 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 811 x++; 812 } 813 814 /* Randomly swap ports. */ 815 if (rflag) { 816 int y; 817 char *c; 818 819 for (x = 0; x <= (hi - lo); x++) { 820 y = (arc4random() & 0xFFFF) % (hi - lo); 821 c = portlist[x]; 822 portlist[x] = portlist[y]; 823 portlist[y] = c; 824 } 825 } 826 } else { 827 hi = strtonum(p, 1, PORT_MAX, &errstr); 828 if (errstr) 829 errx(1, "port number %s: %s", errstr, p); 830 portlist[0] = calloc(1, PORT_MAX_LEN); 831 if (portlist[0] == NULL) 832 err(1, NULL); 833 portlist[0] = p; 834 } 835 } 836 837 /* 838 * udptest() 839 * Do a few writes to see if the UDP port is there. 840 * XXX - Better way of doing this? Doesn't work for IPv6. 841 * Also fails after around 100 ports checked. 842 */ 843 int 844 udptest(int s) 845 { 846 int i, ret; 847 848 for (i = 0; i <= 3; i++) { 849 if (write(s, "X", 1) == 1) 850 ret = 1; 851 else 852 ret = -1; 853 } 854 return (ret); 855 } 856 857 void 858 set_common_sockopts(int s) 859 { 860 int x = 1; 861 862 if (Sflag) { 863 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 864 &x, sizeof(x)) == -1) 865 err(1, NULL); 866 } 867 if (Dflag) { 868 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 869 &x, sizeof(x)) == -1) 870 err(1, NULL); 871 } 872 #ifdef SO_JUMBO 873 if (jflag) { 874 if (setsockopt(s, SOL_SOCKET, SO_JUMBO, 875 &x, sizeof(x)) == -1) 876 err(1, NULL); 877 } 878 #endif 879 if (Tflag != -1) { 880 if (setsockopt(s, IPPROTO_IP, IP_TOS, 881 &Tflag, sizeof(Tflag)) == -1) 882 err(1, "set IP ToS"); 883 } 884 if (Iflag) { 885 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 886 &Iflag, sizeof(Iflag)) == -1) 887 err(1, "set TCP receive buffer size"); 888 } 889 if (Oflag) { 890 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 891 &Oflag, sizeof(Oflag)) == -1) 892 err(1, "set TCP send buffer size"); 893 } 894 if (FreeBSD_Oflag) { 895 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 896 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 897 err(1, "disable TCP options"); 898 } 899 } 900 901 int 902 parse_iptos(char *s) 903 { 904 int tos = -1; 905 906 if (strcmp(s, "lowdelay") == 0) 907 return (IPTOS_LOWDELAY); 908 if (strcmp(s, "throughput") == 0) 909 return (IPTOS_THROUGHPUT); 910 if (strcmp(s, "reliability") == 0) 911 return (IPTOS_RELIABILITY); 912 913 if (sscanf(s, "0x%x", &tos) != 1 || tos < 0 || tos > 0xff) 914 errx(1, "invalid IP Type of Service"); 915 return (tos); 916 } 917 918 void 919 help(void) 920 { 921 usage(0); 922 fprintf(stderr, "\tCommand Summary:\n\ 923 \t-4 Use IPv4\n\ 924 \t-6 Use IPv6\n\ 925 \t-D Enable the debug socket option\n\ 926 \t-d Detach from stdin\n"); 927 #ifdef IPSEC 928 fprintf(stderr, "\ 929 \t-E Use IPsec ESP\n\ 930 \t-e policy Use specified IPsec policy\n"); 931 #endif 932 fprintf(stderr, "\ 933 \t-h This help text\n\ 934 \t-I length TCP receive buffer length\n\ 935 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 936 \t-k Keep inbound sockets open for multiple connects\n\ 937 \t-l Listen mode, for inbound connects\n\ 938 \t-n Suppress name/port resolutions\n\ 939 \t--no-tcpopt Disable TCP options\n\ 940 \t-O length TCP send buffer length\n\ 941 \t-P proxyuser\tUsername for proxy authentication\n\ 942 \t-p port\t Specify local port for remote connects\n\ 943 \t-r Randomize remote ports\n\ 944 \t-S Enable the TCP MD5 signature option\n\ 945 \t-s addr\t Local source address\n\ 946 \t-T ToS\t Set IP Type of Service\n\ 947 \t-t Answer TELNET negotiation\n\ 948 \t-U Use UNIX domain socket\n\ 949 \t-u UDP mode\n\ 950 \t-V fib Specify alternate routing table (FIB)\n\ 951 \t-v Verbose\n\ 952 \t-w secs\t Timeout for connects and final net reads\n\ 953 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 954 \t-x addr[:port]\tSpecify proxy address and port\n\ 955 \t-z Zero-I/O mode [used for scanning]\n\ 956 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 957 #ifdef IPSEC 958 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 959 #endif 960 exit(1); 961 } 962 963 #ifdef IPSEC 964 void 965 add_ipsec_policy(int s, char *policy) 966 { 967 char *raw; 968 int e; 969 970 raw = ipsec_set_policy(policy, strlen(policy)); 971 if (raw == NULL) 972 errx(1, "ipsec_set_policy `%s': %s", policy, 973 ipsec_strerror()); 974 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 975 ipsec_get_policylen(raw)); 976 if (e < 0) 977 err(1, "ipsec policy cannot be configured"); 978 free(raw); 979 if (vflag) 980 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 981 return; 982 } 983 #endif /* IPSEC */ 984 985 void 986 usage(int ret) 987 { 988 fprintf(stderr, 989 #ifdef IPSEC 990 "usage: nc [-46DdEhklnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 991 #else 992 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n" 993 #endif 994 "\t [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS]\n" 995 "\t [-V fib] [-w timeout] [-X proxy_protocol]\n" 996 "\t [-x proxy_address[:port]] [hostname] [port]\n"); 997 if (ret) 998 exit(1); 999 } 1000