1 /* $OpenBSD: netcat.c,v 1.98 2010/07/03 04:44:51 guenther 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 rtableid; 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 ret = 1; 143 ipsec_count = 0; 144 s = 0; 145 socksv = 5; 146 host = NULL; 147 uport = NULL; 148 sv = NULL; 149 150 while ((ch = getopt_long(argc, argv, 151 "46DdEe:hI:i:jklnoO:P:p:rSs:tT:UuV:vw:X:x:z", 152 longopts, NULL)) != -1) { 153 switch (ch) { 154 case '4': 155 family = AF_INET; 156 break; 157 case '6': 158 family = AF_INET6; 159 break; 160 case 'U': 161 family = AF_UNIX; 162 break; 163 case 'X': 164 if (strcasecmp(optarg, "connect") == 0) 165 socksv = -1; /* HTTP proxy CONNECT */ 166 else if (strcmp(optarg, "4") == 0) 167 socksv = 4; /* SOCKS v.4 */ 168 else if (strcmp(optarg, "5") == 0) 169 socksv = 5; /* SOCKS v.5 */ 170 else 171 errx(1, "unsupported proxy protocol"); 172 break; 173 case 'd': 174 dflag = 1; 175 break; 176 case 'e': 177 #ifdef IPSEC 178 ipsec_policy[ipsec_count++ % 2] = optarg; 179 #else 180 errx(1, "IPsec support unavailable."); 181 #endif 182 break; 183 case 'E': 184 #ifdef IPSEC 185 ipsec_policy[0] = "in ipsec esp/transport//require"; 186 ipsec_policy[1] = "out ipsec esp/transport//require"; 187 #else 188 errx(1, "IPsec support unavailable."); 189 #endif 190 break; 191 case 'h': 192 help(); 193 break; 194 case 'i': 195 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 196 if (errstr) 197 errx(1, "interval %s: %s", errstr, optarg); 198 break; 199 #ifdef SO_JUMBO 200 case 'j': 201 jflag = 1; 202 break; 203 #endif 204 case 'k': 205 kflag = 1; 206 break; 207 case 'l': 208 lflag = 1; 209 break; 210 case 'n': 211 nflag = 1; 212 break; 213 case 'o': 214 fprintf(stderr, "option -o is deprecated.\n"); 215 break; 216 case 'P': 217 Pflag = optarg; 218 break; 219 case 'p': 220 pflag = optarg; 221 break; 222 case 'r': 223 rflag = 1; 224 break; 225 case 's': 226 sflag = optarg; 227 break; 228 case 't': 229 tflag = 1; 230 break; 231 case 'u': 232 uflag = 1; 233 break; 234 case 'V': 235 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 236 errx(1, "Multiple FIBS not supported"); 237 rtableid = (unsigned int)strtonum(optarg, 0, 238 numfibs - 1, &errstr); 239 if (errstr) 240 errx(1, "rtable %s: %s", errstr, optarg); 241 break; 242 case 'v': 243 vflag = 1; 244 break; 245 case 'w': 246 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 247 if (errstr) 248 errx(1, "timeout %s: %s", errstr, optarg); 249 timeout *= 1000; 250 break; 251 case 'x': 252 xflag = 1; 253 if ((proxy = strdup(optarg)) == NULL) 254 err(1, NULL); 255 break; 256 case 'z': 257 zflag = 1; 258 break; 259 case 'D': 260 Dflag = 1; 261 break; 262 case 'I': 263 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 264 if (errstr != NULL) 265 errx(1, "TCP receive window %s: %s", 266 errstr, optarg); 267 break; 268 case 'O': 269 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 270 if (errstr != NULL) { 271 if (strcmp(errstr, "invalid") != 0) 272 errx(1, "TCP send window %s: %s", 273 errstr, optarg); 274 } 275 break; 276 case 'S': 277 Sflag = 1; 278 break; 279 case 'T': 280 Tflag = parse_iptos(optarg); 281 break; 282 default: 283 usage(1); 284 } 285 } 286 argc -= optind; 287 argv += optind; 288 289 /* Cruft to make sure options are clean, and used properly. */ 290 if (argv[0] && !argv[1] && family == AF_UNIX) { 291 if (uflag) 292 errx(1, "cannot use -u and -U"); 293 host = argv[0]; 294 uport = NULL; 295 } else if (argv[0] && !argv[1]) { 296 if (!lflag) 297 usage(1); 298 uport = argv[0]; 299 host = NULL; 300 } else if (argv[0] && argv[1]) { 301 host = argv[0]; 302 uport = argv[1]; 303 } else 304 usage(1); 305 306 if (lflag && sflag) 307 errx(1, "cannot use -s and -l"); 308 if (lflag && pflag) 309 errx(1, "cannot use -p and -l"); 310 if (lflag && zflag) 311 errx(1, "cannot use -z and -l"); 312 if (!lflag && kflag) 313 errx(1, "must use -l with -k"); 314 315 /* Initialize addrinfo structure. */ 316 if (family != AF_UNIX) { 317 memset(&hints, 0, sizeof(struct addrinfo)); 318 hints.ai_family = family; 319 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 320 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 321 if (nflag) 322 hints.ai_flags |= AI_NUMERICHOST; 323 } 324 325 if (xflag) { 326 if (uflag) 327 errx(1, "no proxy support for UDP mode"); 328 329 if (lflag) 330 errx(1, "no proxy support for listen"); 331 332 if (family == AF_UNIX) 333 errx(1, "no proxy support for unix sockets"); 334 335 /* XXX IPv6 transport to proxy would probably work */ 336 if (family == AF_INET6) 337 errx(1, "no proxy support for IPv6"); 338 339 if (sflag) 340 errx(1, "no proxy support for local source address"); 341 342 proxyhost = strsep(&proxy, ":"); 343 proxyport = proxy; 344 345 memset(&proxyhints, 0, sizeof(struct addrinfo)); 346 proxyhints.ai_family = family; 347 proxyhints.ai_socktype = SOCK_STREAM; 348 proxyhints.ai_protocol = IPPROTO_TCP; 349 if (nflag) 350 proxyhints.ai_flags |= AI_NUMERICHOST; 351 } 352 353 if (lflag) { 354 int connfd; 355 ret = 0; 356 357 if (family == AF_UNIX) 358 s = unix_listen(host); 359 360 /* Allow only one connection at a time, but stay alive. */ 361 for (;;) { 362 if (family != AF_UNIX) 363 s = local_listen(host, uport, hints); 364 if (s < 0) 365 err(1, NULL); 366 /* 367 * For UDP, we will use recvfrom() initially 368 * to wait for a caller, then use the regular 369 * functions to talk to the caller. 370 */ 371 if (uflag) { 372 int rv, plen; 373 char buf[16384]; 374 struct sockaddr_storage z; 375 376 len = sizeof(z); 377 plen = jflag ? 16384 : 2048; 378 rv = recvfrom(s, buf, plen, MSG_PEEK, 379 (struct sockaddr *)&z, &len); 380 if (rv < 0) 381 err(1, "recvfrom"); 382 383 rv = connect(s, (struct sockaddr *)&z, len); 384 if (rv < 0) 385 err(1, "connect"); 386 387 connfd = s; 388 } else { 389 len = sizeof(cliaddr); 390 connfd = accept(s, (struct sockaddr *)&cliaddr, 391 &len); 392 } 393 394 readwrite(connfd); 395 close(connfd); 396 if (family != AF_UNIX) 397 close(s); 398 399 if (!kflag) 400 break; 401 } 402 } else if (family == AF_UNIX) { 403 ret = 0; 404 405 if ((s = unix_connect(host)) > 0 && !zflag) { 406 readwrite(s); 407 close(s); 408 } else 409 ret = 1; 410 411 exit(ret); 412 413 } else { 414 int i = 0; 415 416 /* Construct the portlist[] array. */ 417 build_ports(uport); 418 419 /* Cycle through portlist, connecting to each port. */ 420 for (i = 0; portlist[i] != NULL; i++) { 421 if (s) 422 close(s); 423 424 if (xflag) 425 s = socks_connect(host, portlist[i], hints, 426 proxyhost, proxyport, proxyhints, socksv, 427 Pflag); 428 else 429 s = remote_connect(host, portlist[i], hints); 430 431 if (s < 0) 432 continue; 433 434 ret = 0; 435 if (vflag || zflag) { 436 /* For UDP, make sure we are connected. */ 437 if (uflag) { 438 if (udptest(s) == -1) { 439 ret = 1; 440 continue; 441 } 442 } 443 444 /* Don't look up port if -n. */ 445 if (nflag) 446 sv = NULL; 447 else { 448 sv = getservbyport( 449 ntohs(atoi(portlist[i])), 450 uflag ? "udp" : "tcp"); 451 } 452 453 fprintf(stderr, 454 "Connection to %s %s port [%s/%s] " 455 "succeeded!\n", host, portlist[i], 456 uflag ? "udp" : "tcp", 457 sv ? sv->s_name : "*"); 458 } 459 if (!zflag) 460 readwrite(s); 461 } 462 } 463 464 if (s) 465 close(s); 466 467 exit(ret); 468 } 469 470 /* 471 * unix_connect() 472 * Returns a socket connected to a local unix socket. Returns -1 on failure. 473 */ 474 int 475 unix_connect(char *path) 476 { 477 struct sockaddr_un sun; 478 int s; 479 480 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 481 return (-1); 482 (void)fcntl(s, F_SETFD, 1); 483 484 memset(&sun, 0, sizeof(struct sockaddr_un)); 485 sun.sun_family = AF_UNIX; 486 487 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 488 sizeof(sun.sun_path)) { 489 close(s); 490 errno = ENAMETOOLONG; 491 return (-1); 492 } 493 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 494 close(s); 495 return (-1); 496 } 497 return (s); 498 499 } 500 501 /* 502 * unix_listen() 503 * Create a unix domain socket, and listen on it. 504 */ 505 int 506 unix_listen(char *path) 507 { 508 struct sockaddr_un sun; 509 int s; 510 511 /* Create unix domain socket. */ 512 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 513 return (-1); 514 515 memset(&sun, 0, sizeof(struct sockaddr_un)); 516 sun.sun_family = AF_UNIX; 517 518 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 519 sizeof(sun.sun_path)) { 520 close(s); 521 errno = ENAMETOOLONG; 522 return (-1); 523 } 524 525 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 526 close(s); 527 return (-1); 528 } 529 530 if (listen(s, 5) < 0) { 531 close(s); 532 return (-1); 533 } 534 return (s); 535 } 536 537 /* 538 * remote_connect() 539 * Returns a socket connected to a remote host. Properly binds to a local 540 * port or source address if needed. Returns -1 on failure. 541 */ 542 int 543 remote_connect(const char *host, const char *port, struct addrinfo hints) 544 { 545 struct addrinfo *res, *res0; 546 int s, error, on = 1; 547 548 if ((error = getaddrinfo(host, port, &hints, &res))) 549 errx(1, "getaddrinfo: %s", gai_strerror(error)); 550 551 res0 = res; 552 do { 553 if ((s = socket(res0->ai_family, res0->ai_socktype, 554 res0->ai_protocol)) < 0) 555 continue; 556 #ifdef IPSEC 557 if (ipsec_policy[0] != NULL) 558 add_ipsec_policy(s, ipsec_policy[0]); 559 if (ipsec_policy[1] != NULL) 560 add_ipsec_policy(s, ipsec_policy[1]); 561 #endif 562 563 if (rtableid) { 564 if (setfib(rtableid) == -1) 565 err(1, "setfib"); 566 } 567 568 /* Bind to a local port or source address if specified. */ 569 if (sflag || pflag) { 570 struct addrinfo ahints, *ares; 571 572 /* try IP_BINDANY, but don't insist */ 573 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 574 memset(&ahints, 0, sizeof(struct addrinfo)); 575 ahints.ai_family = res0->ai_family; 576 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 577 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 578 ahints.ai_flags = AI_PASSIVE; 579 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 580 errx(1, "getaddrinfo: %s", gai_strerror(error)); 581 582 if (bind(s, (struct sockaddr *)ares->ai_addr, 583 ares->ai_addrlen) < 0) 584 errx(1, "bind failed: %s", strerror(errno)); 585 freeaddrinfo(ares); 586 } 587 588 set_common_sockopts(s); 589 590 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 591 break; 592 else if (vflag) 593 warn("connect to %s port %s (%s) failed", host, port, 594 uflag ? "udp" : "tcp"); 595 596 close(s); 597 s = -1; 598 } while ((res0 = res0->ai_next) != NULL); 599 600 freeaddrinfo(res); 601 602 return (s); 603 } 604 605 /* 606 * local_listen() 607 * Returns a socket listening on a local port, binds to specified source 608 * address. Returns -1 on failure. 609 */ 610 int 611 local_listen(char *host, char *port, struct addrinfo hints) 612 { 613 struct addrinfo *res, *res0; 614 int s, ret, x = 1; 615 int error; 616 617 /* Allow nodename to be null. */ 618 hints.ai_flags |= AI_PASSIVE; 619 620 /* 621 * In the case of binding to a wildcard address 622 * default to binding to an ipv4 address. 623 */ 624 if (host == NULL && hints.ai_family == AF_UNSPEC) 625 hints.ai_family = AF_INET; 626 627 if ((error = getaddrinfo(host, port, &hints, &res))) 628 errx(1, "getaddrinfo: %s", gai_strerror(error)); 629 630 res0 = res; 631 do { 632 if ((s = socket(res0->ai_family, res0->ai_socktype, 633 res0->ai_protocol)) < 0) 634 continue; 635 636 if (rtableid) { 637 if (setfib(rtableid) == -1) 638 err(1, "setfib"); 639 } 640 641 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 642 if (ret == -1) 643 err(1, NULL); 644 #ifdef IPSEC 645 if (ipsec_policy[0] != NULL) 646 add_ipsec_policy(s, ipsec_policy[0]); 647 if (ipsec_policy[1] != NULL) 648 add_ipsec_policy(s, ipsec_policy[1]); 649 #endif 650 if (FreeBSD_Oflag) { 651 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 652 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 653 err(1, "disable TCP options"); 654 } 655 656 if (bind(s, (struct sockaddr *)res0->ai_addr, 657 res0->ai_addrlen) == 0) 658 break; 659 660 close(s); 661 s = -1; 662 } while ((res0 = res0->ai_next) != NULL); 663 664 if (!uflag && s != -1) { 665 if (listen(s, 1) < 0) 666 err(1, "listen"); 667 } 668 669 freeaddrinfo(res); 670 671 return (s); 672 } 673 674 /* 675 * readwrite() 676 * Loop that polls on the network file descriptor and stdin. 677 */ 678 void 679 readwrite(int nfd) 680 { 681 struct pollfd pfd[2]; 682 unsigned char buf[16384]; 683 int n, wfd = fileno(stdin); 684 int lfd = fileno(stdout); 685 int plen; 686 687 plen = jflag ? 16384 : 2048; 688 689 /* Setup Network FD */ 690 pfd[0].fd = nfd; 691 pfd[0].events = POLLIN; 692 693 /* Set up STDIN FD. */ 694 pfd[1].fd = wfd; 695 pfd[1].events = POLLIN; 696 697 while (pfd[0].fd != -1) { 698 if (iflag) 699 sleep(iflag); 700 701 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 702 close(nfd); 703 err(1, "Polling Error"); 704 } 705 706 if (n == 0) 707 return; 708 709 if (pfd[0].revents & POLLIN) { 710 if ((n = read(nfd, buf, plen)) < 0) 711 return; 712 else if (n == 0) { 713 shutdown(nfd, SHUT_RD); 714 pfd[0].fd = -1; 715 pfd[0].events = 0; 716 } else { 717 if (tflag) 718 atelnet(nfd, buf, n); 719 if (atomicio(vwrite, lfd, buf, n) != n) 720 return; 721 } 722 } 723 724 if (!dflag && pfd[1].revents & POLLIN) { 725 if ((n = read(wfd, buf, plen)) < 0) 726 return; 727 else if (n == 0) { 728 shutdown(nfd, SHUT_WR); 729 pfd[1].fd = -1; 730 pfd[1].events = 0; 731 } else { 732 if (atomicio(vwrite, nfd, buf, n) != n) 733 return; 734 } 735 } 736 } 737 } 738 739 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 740 void 741 atelnet(int nfd, unsigned char *buf, unsigned int size) 742 { 743 unsigned char *p, *end; 744 unsigned char obuf[4]; 745 746 if (size < 3) 747 return; 748 end = buf + size - 2; 749 750 for (p = buf; p < end; p++) { 751 if (*p != IAC) 752 continue; 753 754 obuf[0] = IAC; 755 p++; 756 if ((*p == WILL) || (*p == WONT)) 757 obuf[1] = DONT; 758 else if ((*p == DO) || (*p == DONT)) 759 obuf[1] = WONT; 760 else 761 continue; 762 763 p++; 764 obuf[2] = *p; 765 if (atomicio(vwrite, nfd, obuf, 3) != 3) 766 warn("Write Error!"); 767 } 768 } 769 770 /* 771 * build_ports() 772 * Build an array or ports in portlist[], listing each port 773 * that we should try to connect to. 774 */ 775 void 776 build_ports(char *p) 777 { 778 const char *errstr; 779 char *n; 780 int hi, lo, cp; 781 int x = 0; 782 783 if ((n = strchr(p, '-')) != NULL) { 784 if (lflag) 785 errx(1, "Cannot use -l with multiple ports!"); 786 787 *n = '\0'; 788 n++; 789 790 /* Make sure the ports are in order: lowest->highest. */ 791 hi = strtonum(n, 1, PORT_MAX, &errstr); 792 if (errstr) 793 errx(1, "port number %s: %s", errstr, n); 794 lo = strtonum(p, 1, PORT_MAX, &errstr); 795 if (errstr) 796 errx(1, "port number %s: %s", errstr, p); 797 798 if (lo > hi) { 799 cp = hi; 800 hi = lo; 801 lo = cp; 802 } 803 804 /* Load ports sequentially. */ 805 for (cp = lo; cp <= hi; cp++) { 806 portlist[x] = calloc(1, PORT_MAX_LEN); 807 if (portlist[x] == NULL) 808 err(1, NULL); 809 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 810 x++; 811 } 812 813 /* Randomly swap ports. */ 814 if (rflag) { 815 int y; 816 char *c; 817 818 for (x = 0; x <= (hi - lo); x++) { 819 y = (arc4random() & 0xFFFF) % (hi - lo); 820 c = portlist[x]; 821 portlist[x] = portlist[y]; 822 portlist[y] = c; 823 } 824 } 825 } else { 826 hi = strtonum(p, 1, PORT_MAX, &errstr); 827 if (errstr) 828 errx(1, "port number %s: %s", errstr, p); 829 portlist[0] = strdup(p); 830 if (portlist[0] == NULL) 831 err(1, NULL); 832 } 833 } 834 835 /* 836 * udptest() 837 * Do a few writes to see if the UDP port is there. 838 * XXX - Better way of doing this? Doesn't work for IPv6. 839 * Also fails after around 100 ports checked. 840 */ 841 int 842 udptest(int s) 843 { 844 int i, ret; 845 846 for (i = 0; i <= 3; i++) { 847 if (write(s, "X", 1) == 1) 848 ret = 1; 849 else 850 ret = -1; 851 } 852 return (ret); 853 } 854 855 void 856 set_common_sockopts(int s) 857 { 858 int x = 1; 859 860 if (Sflag) { 861 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 862 &x, sizeof(x)) == -1) 863 err(1, NULL); 864 } 865 if (Dflag) { 866 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 867 &x, sizeof(x)) == -1) 868 err(1, NULL); 869 } 870 #ifdef SO_JUMBO 871 if (jflag) { 872 if (setsockopt(s, SOL_SOCKET, SO_JUMBO, 873 &x, sizeof(x)) == -1) 874 err(1, NULL); 875 } 876 #endif 877 if (Tflag != -1) { 878 if (setsockopt(s, IPPROTO_IP, IP_TOS, 879 &Tflag, sizeof(Tflag)) == -1) 880 err(1, "set IP ToS"); 881 } 882 if (Iflag) { 883 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 884 &Iflag, sizeof(Iflag)) == -1) 885 err(1, "set TCP receive buffer size"); 886 } 887 if (Oflag) { 888 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 889 &Oflag, sizeof(Oflag)) == -1) 890 err(1, "set TCP send buffer size"); 891 } 892 if (FreeBSD_Oflag) { 893 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 894 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 895 err(1, "disable TCP options"); 896 } 897 } 898 899 int 900 parse_iptos(char *s) 901 { 902 int tos = -1; 903 904 if (strcmp(s, "lowdelay") == 0) 905 return (IPTOS_LOWDELAY); 906 if (strcmp(s, "throughput") == 0) 907 return (IPTOS_THROUGHPUT); 908 if (strcmp(s, "reliability") == 0) 909 return (IPTOS_RELIABILITY); 910 911 if (sscanf(s, "0x%x", &tos) != 1 || tos < 0 || tos > 0xff) 912 errx(1, "invalid IP Type of Service"); 913 return (tos); 914 } 915 916 void 917 help(void) 918 { 919 usage(0); 920 fprintf(stderr, "\tCommand Summary:\n\ 921 \t-4 Use IPv4\n\ 922 \t-6 Use IPv6\n\ 923 \t-D Enable the debug socket option\n\ 924 \t-d Detach from stdin\n"); 925 #ifdef IPSEC 926 fprintf(stderr, "\ 927 \t-E Use IPsec ESP\n\ 928 \t-e policy Use specified IPsec policy\n"); 929 #endif 930 fprintf(stderr, "\ 931 \t-h This help text\n\ 932 \t-I length TCP receive buffer length\n\ 933 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 934 \t-k Keep inbound sockets open for multiple connects\n\ 935 \t-l Listen mode, for inbound connects\n\ 936 \t-n Suppress name/port resolutions\n\ 937 \t--no-tcpopt Disable TCP options\n\ 938 \t-O length TCP send buffer length\n\ 939 \t-P proxyuser\tUsername for proxy authentication\n\ 940 \t-p port\t Specify local port for remote connects\n\ 941 \t-r Randomize remote ports\n\ 942 \t-S Enable the TCP MD5 signature option\n\ 943 \t-s addr\t Local source address\n\ 944 \t-T ToS\t Set IP Type of Service\n\ 945 \t-t Answer TELNET negotiation\n\ 946 \t-U Use UNIX domain socket\n\ 947 \t-u UDP mode\n\ 948 \t-V rtable Specify alternate routing table\n\ 949 \t-v Verbose\n\ 950 \t-w secs\t Timeout for connects and final net reads\n\ 951 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 952 \t-x addr[:port]\tSpecify proxy address and port\n\ 953 \t-z Zero-I/O mode [used for scanning]\n\ 954 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 955 #ifdef IPSEC 956 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 957 #endif 958 exit(1); 959 } 960 961 #ifdef IPSEC 962 void 963 add_ipsec_policy(int s, char *policy) 964 { 965 char *raw; 966 int e; 967 968 raw = ipsec_set_policy(policy, strlen(policy)); 969 if (raw == NULL) 970 errx(1, "ipsec_set_policy `%s': %s", policy, 971 ipsec_strerror()); 972 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 973 ipsec_get_policylen(raw)); 974 if (e < 0) 975 err(1, "ipsec policy cannot be configured"); 976 free(raw); 977 if (vflag) 978 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 979 return; 980 } 981 #endif /* IPSEC */ 982 983 void 984 usage(int ret) 985 { 986 fprintf(stderr, 987 #ifdef IPSEC 988 "usage: nc [-46DdEhklnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 989 #else 990 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n" 991 #endif 992 "\t [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS]\n" 993 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 994 "\t [-x proxy_address[:port]] [hostname] [port]\n"); 995 if (ret) 996 exit(1); 997 } 998