1 /* $OpenBSD: netcat.c,v 1.94 2009/10/08 15:56:46 mpf 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 29 /* 30 * Re-written nc(1) for OpenBSD. Original implementation by 31 * *Hobbit* <hobbit@avian.org>. 32 */ 33 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 #include <sys/time.h> 37 #include <sys/un.h> 38 39 #include <netinet/in.h> 40 #include <netinet/in_systm.h> 41 #include <netinet/tcp.h> 42 #include <netinet/ip.h> 43 #include <arpa/telnet.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <netdb.h> 48 #include <poll.h> 49 #include <stdarg.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 #include <fcntl.h> 55 #include <limits.h> 56 #include "atomicio.h" 57 58 #ifndef SUN_LEN 59 #define SUN_LEN(su) \ 60 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 61 #endif 62 63 #define PORT_MAX 65535 64 #define PORT_MAX_LEN 6 65 66 /* Command Line Options */ 67 int dflag; /* detached, no stdin */ 68 unsigned int iflag; /* Interval Flag */ 69 int jflag; /* use jumbo frames if we can */ 70 int kflag; /* More than one connect */ 71 int lflag; /* Bind to local port */ 72 int nflag; /* Don't do name look up */ 73 char *Pflag; /* Proxy username */ 74 char *pflag; /* Localport flag */ 75 int rflag; /* Random ports flag */ 76 char *sflag; /* Source Address */ 77 int tflag; /* Telnet Emulation */ 78 int uflag; /* UDP - Default to TCP */ 79 int vflag; /* Verbosity */ 80 int xflag; /* Socks proxy */ 81 int zflag; /* Port Scan Flag */ 82 int Dflag; /* sodebug */ 83 int Iflag; /* TCP receive buffer size */ 84 int Oflag; /* TCP send buffer size */ 85 int Sflag; /* TCP MD5 signature option */ 86 int Tflag = -1; /* IP Type of Service */ 87 u_int rdomain; 88 89 int timeout = -1; 90 int family = AF_UNSPEC; 91 char *portlist[PORT_MAX+1]; 92 93 void atelnet(int, unsigned char *, unsigned int); 94 void build_ports(char *); 95 void help(void); 96 int local_listen(char *, char *, struct addrinfo); 97 void readwrite(int); 98 int remote_connect(const char *, const char *, struct addrinfo); 99 int socks_connect(const char *, const char *, struct addrinfo, 100 const char *, const char *, struct addrinfo, int, const char *); 101 int udptest(int); 102 int unix_connect(char *); 103 int unix_listen(char *); 104 void set_common_sockopts(int); 105 int parse_iptos(char *); 106 void usage(int); 107 108 int 109 main(int argc, char *argv[]) 110 { 111 int ch, s, ret, socksv; 112 char *host, *uport; 113 struct addrinfo hints; 114 struct servent *sv; 115 socklen_t len; 116 struct sockaddr_storage cliaddr; 117 char *proxy; 118 const char *errstr, *proxyhost = "", *proxyport = NULL; 119 struct addrinfo proxyhints; 120 121 ret = 1; 122 s = 0; 123 socksv = 5; 124 host = NULL; 125 uport = NULL; 126 sv = NULL; 127 128 while ((ch = getopt(argc, argv, 129 "46DdhI:i:jklnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) { 130 switch (ch) { 131 case '4': 132 family = AF_INET; 133 break; 134 case '6': 135 family = AF_INET6; 136 break; 137 case 'U': 138 family = AF_UNIX; 139 break; 140 case 'X': 141 if (strcasecmp(optarg, "connect") == 0) 142 socksv = -1; /* HTTP proxy CONNECT */ 143 else if (strcmp(optarg, "4") == 0) 144 socksv = 4; /* SOCKS v.4 */ 145 else if (strcmp(optarg, "5") == 0) 146 socksv = 5; /* SOCKS v.5 */ 147 else 148 errx(1, "unsupported proxy protocol"); 149 break; 150 case 'd': 151 dflag = 1; 152 break; 153 case 'h': 154 help(); 155 break; 156 case 'i': 157 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 158 if (errstr) 159 errx(1, "interval %s: %s", errstr, optarg); 160 break; 161 case 'j': 162 jflag = 1; 163 break; 164 case 'k': 165 kflag = 1; 166 break; 167 case 'l': 168 lflag = 1; 169 break; 170 case 'n': 171 nflag = 1; 172 break; 173 case 'P': 174 Pflag = optarg; 175 break; 176 case 'p': 177 pflag = optarg; 178 break; 179 case 'r': 180 rflag = 1; 181 break; 182 case 's': 183 sflag = optarg; 184 break; 185 case 't': 186 tflag = 1; 187 break; 188 case 'u': 189 uflag = 1; 190 break; 191 case 'V': 192 rdomain = (unsigned int)strtonum(optarg, 0, 193 RT_TABLEID_MAX, &errstr); 194 if (errstr) 195 errx(1, "rdomain %s: %s", errstr, optarg); 196 break; 197 case 'v': 198 vflag = 1; 199 break; 200 case 'w': 201 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 202 if (errstr) 203 errx(1, "timeout %s: %s", errstr, optarg); 204 timeout *= 1000; 205 break; 206 case 'x': 207 xflag = 1; 208 if ((proxy = strdup(optarg)) == NULL) 209 err(1, NULL); 210 break; 211 case 'z': 212 zflag = 1; 213 break; 214 case 'D': 215 Dflag = 1; 216 break; 217 case 'I': 218 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 219 if (errstr != NULL) 220 errx(1, "TCP receive window %s: %s", 221 errstr, optarg); 222 break; 223 case 'O': 224 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 225 if (errstr != NULL) 226 errx(1, "TCP send window %s: %s", 227 errstr, optarg); 228 break; 229 case 'S': 230 Sflag = 1; 231 break; 232 case 'T': 233 Tflag = parse_iptos(optarg); 234 break; 235 default: 236 usage(1); 237 } 238 } 239 argc -= optind; 240 argv += optind; 241 242 /* Cruft to make sure options are clean, and used properly. */ 243 if (argv[0] && !argv[1] && family == AF_UNIX) { 244 if (uflag) 245 errx(1, "cannot use -u and -U"); 246 host = argv[0]; 247 uport = NULL; 248 } else if (argv[0] && !argv[1]) { 249 if (!lflag) 250 usage(1); 251 uport = argv[0]; 252 host = NULL; 253 } else if (argv[0] && argv[1]) { 254 host = argv[0]; 255 uport = argv[1]; 256 } else 257 usage(1); 258 259 if (lflag && sflag) 260 errx(1, "cannot use -s and -l"); 261 if (lflag && pflag) 262 errx(1, "cannot use -p and -l"); 263 if (lflag && zflag) 264 errx(1, "cannot use -z and -l"); 265 if (!lflag && kflag) 266 errx(1, "must use -l with -k"); 267 268 /* Initialize addrinfo structure. */ 269 if (family != AF_UNIX) { 270 memset(&hints, 0, sizeof(struct addrinfo)); 271 hints.ai_family = family; 272 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 273 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 274 if (nflag) 275 hints.ai_flags |= AI_NUMERICHOST; 276 } 277 278 if (xflag) { 279 if (uflag) 280 errx(1, "no proxy support for UDP mode"); 281 282 if (lflag) 283 errx(1, "no proxy support for listen"); 284 285 if (family == AF_UNIX) 286 errx(1, "no proxy support for unix sockets"); 287 288 /* XXX IPv6 transport to proxy would probably work */ 289 if (family == AF_INET6) 290 errx(1, "no proxy support for IPv6"); 291 292 if (sflag) 293 errx(1, "no proxy support for local source address"); 294 295 proxyhost = strsep(&proxy, ":"); 296 proxyport = proxy; 297 298 memset(&proxyhints, 0, sizeof(struct addrinfo)); 299 proxyhints.ai_family = family; 300 proxyhints.ai_socktype = SOCK_STREAM; 301 proxyhints.ai_protocol = IPPROTO_TCP; 302 if (nflag) 303 proxyhints.ai_flags |= AI_NUMERICHOST; 304 } 305 306 if (lflag) { 307 int connfd; 308 ret = 0; 309 310 if (family == AF_UNIX) 311 s = unix_listen(host); 312 313 /* Allow only one connection at a time, but stay alive. */ 314 for (;;) { 315 if (family != AF_UNIX) 316 s = local_listen(host, uport, hints); 317 if (s < 0) 318 err(1, NULL); 319 /* 320 * For UDP, we will use recvfrom() initially 321 * to wait for a caller, then use the regular 322 * functions to talk to the caller. 323 */ 324 if (uflag) { 325 int rv, plen; 326 char buf[8192]; 327 struct sockaddr_storage z; 328 329 len = sizeof(z); 330 plen = jflag ? 8192 : 1024; 331 rv = recvfrom(s, buf, plen, MSG_PEEK, 332 (struct sockaddr *)&z, &len); 333 if (rv < 0) 334 err(1, "recvfrom"); 335 336 rv = connect(s, (struct sockaddr *)&z, len); 337 if (rv < 0) 338 err(1, "connect"); 339 340 connfd = s; 341 } else { 342 len = sizeof(cliaddr); 343 connfd = accept(s, (struct sockaddr *)&cliaddr, 344 &len); 345 } 346 347 readwrite(connfd); 348 close(connfd); 349 if (family != AF_UNIX) 350 close(s); 351 352 if (!kflag) 353 break; 354 } 355 } else if (family == AF_UNIX) { 356 ret = 0; 357 358 if ((s = unix_connect(host)) > 0 && !zflag) { 359 readwrite(s); 360 close(s); 361 } else 362 ret = 1; 363 364 exit(ret); 365 366 } else { 367 int i = 0; 368 369 /* Construct the portlist[] array. */ 370 build_ports(uport); 371 372 /* Cycle through portlist, connecting to each port. */ 373 for (i = 0; portlist[i] != NULL; i++) { 374 if (s) 375 close(s); 376 377 if (xflag) 378 s = socks_connect(host, portlist[i], hints, 379 proxyhost, proxyport, proxyhints, socksv, 380 Pflag); 381 else 382 s = remote_connect(host, portlist[i], hints); 383 384 if (s < 0) 385 continue; 386 387 ret = 0; 388 if (vflag || zflag) { 389 /* For UDP, make sure we are connected. */ 390 if (uflag) { 391 if (udptest(s) == -1) { 392 ret = 1; 393 continue; 394 } 395 } 396 397 /* Don't look up port if -n. */ 398 if (nflag) 399 sv = NULL; 400 else { 401 sv = getservbyport( 402 ntohs(atoi(portlist[i])), 403 uflag ? "udp" : "tcp"); 404 } 405 406 fprintf(stderr, 407 "Connection to %s %s port [%s/%s] " 408 "succeeded!\n", host, portlist[i], 409 uflag ? "udp" : "tcp", 410 sv ? sv->s_name : "*"); 411 } 412 if (!zflag) 413 readwrite(s); 414 } 415 } 416 417 if (s) 418 close(s); 419 420 exit(ret); 421 } 422 423 /* 424 * unix_connect() 425 * Returns a socket connected to a local unix socket. Returns -1 on failure. 426 */ 427 int 428 unix_connect(char *path) 429 { 430 struct sockaddr_un sun; 431 int s; 432 433 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 434 return (-1); 435 (void)fcntl(s, F_SETFD, 1); 436 437 memset(&sun, 0, sizeof(struct sockaddr_un)); 438 sun.sun_family = AF_UNIX; 439 440 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 441 sizeof(sun.sun_path)) { 442 close(s); 443 errno = ENAMETOOLONG; 444 return (-1); 445 } 446 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 447 close(s); 448 return (-1); 449 } 450 return (s); 451 452 } 453 454 /* 455 * unix_listen() 456 * Create a unix domain socket, and listen on it. 457 */ 458 int 459 unix_listen(char *path) 460 { 461 struct sockaddr_un sun; 462 int s; 463 464 /* Create unix domain socket. */ 465 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 466 return (-1); 467 468 memset(&sun, 0, sizeof(struct sockaddr_un)); 469 sun.sun_family = AF_UNIX; 470 471 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 472 sizeof(sun.sun_path)) { 473 close(s); 474 errno = ENAMETOOLONG; 475 return (-1); 476 } 477 478 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 479 close(s); 480 return (-1); 481 } 482 483 if (listen(s, 5) < 0) { 484 close(s); 485 return (-1); 486 } 487 return (s); 488 } 489 490 /* 491 * remote_connect() 492 * Returns a socket connected to a remote host. Properly binds to a local 493 * port or source address if needed. Returns -1 on failure. 494 */ 495 int 496 remote_connect(const char *host, const char *port, struct addrinfo hints) 497 { 498 struct addrinfo *res, *res0; 499 int s, error, on = 1; 500 501 if ((error = getaddrinfo(host, port, &hints, &res))) 502 errx(1, "getaddrinfo: %s", gai_strerror(error)); 503 504 res0 = res; 505 do { 506 if ((s = socket(res0->ai_family, res0->ai_socktype, 507 res0->ai_protocol)) < 0) 508 continue; 509 510 if (rdomain) { 511 if (setsockopt(s, IPPROTO_IP, SO_RDOMAIN, &rdomain, 512 sizeof(rdomain)) == -1) 513 err(1, "setsockopt SO_RDOMAIN"); 514 } 515 516 /* Bind to a local port or source address if specified. */ 517 if (sflag || pflag) { 518 struct addrinfo ahints, *ares; 519 520 /* try SO_BINDANY, but don't insist */ 521 setsockopt(s, SOL_SOCKET, SO_BINDANY, &on, sizeof(on)); 522 memset(&ahints, 0, sizeof(struct addrinfo)); 523 ahints.ai_family = res0->ai_family; 524 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 525 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 526 ahints.ai_flags = AI_PASSIVE; 527 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 528 errx(1, "getaddrinfo: %s", gai_strerror(error)); 529 530 if (bind(s, (struct sockaddr *)ares->ai_addr, 531 ares->ai_addrlen) < 0) 532 errx(1, "bind failed: %s", strerror(errno)); 533 freeaddrinfo(ares); 534 } 535 536 set_common_sockopts(s); 537 538 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 539 break; 540 else if (vflag) 541 warn("connect to %s port %s (%s) failed", host, port, 542 uflag ? "udp" : "tcp"); 543 544 close(s); 545 s = -1; 546 } while ((res0 = res0->ai_next) != NULL); 547 548 freeaddrinfo(res); 549 550 return (s); 551 } 552 553 /* 554 * local_listen() 555 * Returns a socket listening on a local port, binds to specified source 556 * address. Returns -1 on failure. 557 */ 558 int 559 local_listen(char *host, char *port, struct addrinfo hints) 560 { 561 struct addrinfo *res, *res0; 562 int s, ret, x = 1; 563 int error; 564 565 /* Allow nodename to be null. */ 566 hints.ai_flags |= AI_PASSIVE; 567 568 /* 569 * In the case of binding to a wildcard address 570 * default to binding to an ipv4 address. 571 */ 572 if (host == NULL && hints.ai_family == AF_UNSPEC) 573 hints.ai_family = AF_INET; 574 575 if ((error = getaddrinfo(host, port, &hints, &res))) 576 errx(1, "getaddrinfo: %s", gai_strerror(error)); 577 578 res0 = res; 579 do { 580 if ((s = socket(res0->ai_family, res0->ai_socktype, 581 res0->ai_protocol)) < 0) 582 continue; 583 584 if (rdomain) { 585 if (setsockopt(s, IPPROTO_IP, SO_RDOMAIN, &rdomain, 586 sizeof(rdomain)) == -1) 587 err(1, "setsockopt SO_RDOMAIN"); 588 } 589 590 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 591 if (ret == -1) 592 err(1, NULL); 593 594 set_common_sockopts(s); 595 596 if (bind(s, (struct sockaddr *)res0->ai_addr, 597 res0->ai_addrlen) == 0) 598 break; 599 600 close(s); 601 s = -1; 602 } while ((res0 = res0->ai_next) != NULL); 603 604 if (!uflag && s != -1) { 605 if (listen(s, 1) < 0) 606 err(1, "listen"); 607 } 608 609 freeaddrinfo(res); 610 611 return (s); 612 } 613 614 /* 615 * readwrite() 616 * Loop that polls on the network file descriptor and stdin. 617 */ 618 void 619 readwrite(int nfd) 620 { 621 struct pollfd pfd[2]; 622 unsigned char buf[8192]; 623 int n, wfd = fileno(stdin); 624 int lfd = fileno(stdout); 625 int plen; 626 627 plen = jflag ? 8192 : 1024; 628 629 /* Setup Network FD */ 630 pfd[0].fd = nfd; 631 pfd[0].events = POLLIN; 632 633 /* Set up STDIN FD. */ 634 pfd[1].fd = wfd; 635 pfd[1].events = POLLIN; 636 637 while (pfd[0].fd != -1) { 638 if (iflag) 639 sleep(iflag); 640 641 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 642 close(nfd); 643 err(1, "Polling Error"); 644 } 645 646 if (n == 0) 647 return; 648 649 if (pfd[0].revents & POLLIN) { 650 if ((n = read(nfd, buf, plen)) < 0) 651 return; 652 else if (n == 0) { 653 shutdown(nfd, SHUT_RD); 654 pfd[0].fd = -1; 655 pfd[0].events = 0; 656 } else { 657 if (tflag) 658 atelnet(nfd, buf, n); 659 if (atomicio(vwrite, lfd, buf, n) != n) 660 return; 661 } 662 } 663 664 if (!dflag && pfd[1].revents & POLLIN) { 665 if ((n = read(wfd, buf, plen)) < 0) 666 return; 667 else if (n == 0) { 668 shutdown(nfd, SHUT_WR); 669 pfd[1].fd = -1; 670 pfd[1].events = 0; 671 } else { 672 if (atomicio(vwrite, nfd, buf, n) != n) 673 return; 674 } 675 } 676 } 677 } 678 679 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 680 void 681 atelnet(int nfd, unsigned char *buf, unsigned int size) 682 { 683 unsigned char *p, *end; 684 unsigned char obuf[4]; 685 686 end = buf + size; 687 obuf[0] = '\0'; 688 689 for (p = buf; p < end; p++) { 690 if (*p != IAC) 691 break; 692 693 obuf[0] = IAC; 694 p++; 695 if ((*p == WILL) || (*p == WONT)) 696 obuf[1] = DONT; 697 if ((*p == DO) || (*p == DONT)) 698 obuf[1] = WONT; 699 if (obuf) { 700 p++; 701 obuf[2] = *p; 702 obuf[3] = '\0'; 703 if (atomicio(vwrite, nfd, obuf, 3) != 3) 704 warn("Write Error!"); 705 obuf[0] = '\0'; 706 } 707 } 708 } 709 710 /* 711 * build_ports() 712 * Build an array or ports in portlist[], listing each port 713 * that we should try to connect to. 714 */ 715 void 716 build_ports(char *p) 717 { 718 const char *errstr; 719 char *n; 720 int hi, lo, cp; 721 int x = 0; 722 723 if ((n = strchr(p, '-')) != NULL) { 724 if (lflag) 725 errx(1, "Cannot use -l with multiple ports!"); 726 727 *n = '\0'; 728 n++; 729 730 /* Make sure the ports are in order: lowest->highest. */ 731 hi = strtonum(n, 1, PORT_MAX, &errstr); 732 if (errstr) 733 errx(1, "port number %s: %s", errstr, n); 734 lo = strtonum(p, 1, PORT_MAX, &errstr); 735 if (errstr) 736 errx(1, "port number %s: %s", errstr, p); 737 738 if (lo > hi) { 739 cp = hi; 740 hi = lo; 741 lo = cp; 742 } 743 744 /* Load ports sequentially. */ 745 for (cp = lo; cp <= hi; cp++) { 746 portlist[x] = calloc(1, PORT_MAX_LEN); 747 if (portlist[x] == NULL) 748 err(1, NULL); 749 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 750 x++; 751 } 752 753 /* Randomly swap ports. */ 754 if (rflag) { 755 int y; 756 char *c; 757 758 for (x = 0; x <= (hi - lo); x++) { 759 y = (arc4random() & 0xFFFF) % (hi - lo); 760 c = portlist[x]; 761 portlist[x] = portlist[y]; 762 portlist[y] = c; 763 } 764 } 765 } else { 766 hi = strtonum(p, 1, PORT_MAX, &errstr); 767 if (errstr) 768 errx(1, "port number %s: %s", errstr, p); 769 portlist[0] = calloc(1, PORT_MAX_LEN); 770 if (portlist[0] == NULL) 771 err(1, NULL); 772 portlist[0] = p; 773 } 774 } 775 776 /* 777 * udptest() 778 * Do a few writes to see if the UDP port is there. 779 * XXX - Better way of doing this? Doesn't work for IPv6. 780 * Also fails after around 100 ports checked. 781 */ 782 int 783 udptest(int s) 784 { 785 int i, ret; 786 787 for (i = 0; i <= 3; i++) { 788 if (write(s, "X", 1) == 1) 789 ret = 1; 790 else 791 ret = -1; 792 } 793 return (ret); 794 } 795 796 void 797 set_common_sockopts(int s) 798 { 799 int x = 1; 800 801 if (Sflag) { 802 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 803 &x, sizeof(x)) == -1) 804 err(1, NULL); 805 } 806 if (Dflag) { 807 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 808 &x, sizeof(x)) == -1) 809 err(1, NULL); 810 } 811 if (jflag) { 812 if (setsockopt(s, SOL_SOCKET, SO_JUMBO, 813 &x, sizeof(x)) == -1) 814 err(1, NULL); 815 } 816 if (Tflag != -1) { 817 if (setsockopt(s, IPPROTO_IP, IP_TOS, 818 &Tflag, sizeof(Tflag)) == -1) 819 err(1, "set IP ToS"); 820 } 821 if (Iflag) { 822 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 823 &Iflag, sizeof(Iflag)) == -1) 824 err(1, "set TCP receive buffer size"); 825 } 826 if (Oflag) { 827 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 828 &Oflag, sizeof(Oflag)) == -1) 829 err(1, "set TCP send buffer size"); 830 } 831 } 832 833 int 834 parse_iptos(char *s) 835 { 836 int tos = -1; 837 838 if (strcmp(s, "lowdelay") == 0) 839 return (IPTOS_LOWDELAY); 840 if (strcmp(s, "throughput") == 0) 841 return (IPTOS_THROUGHPUT); 842 if (strcmp(s, "reliability") == 0) 843 return (IPTOS_RELIABILITY); 844 845 if (sscanf(s, "0x%x", &tos) != 1 || tos < 0 || tos > 0xff) 846 errx(1, "invalid IP Type of Service"); 847 return (tos); 848 } 849 850 void 851 help(void) 852 { 853 usage(0); 854 fprintf(stderr, "\tCommand Summary:\n\ 855 \t-4 Use IPv4\n\ 856 \t-6 Use IPv6\n\ 857 \t-D Enable the debug socket option\n\ 858 \t-d Detach from stdin\n\ 859 \t-h This help text\n\ 860 \t-I length TCP receive buffer length\n\ 861 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 862 \t-k Keep inbound sockets open for multiple connects\n\ 863 \t-l Listen mode, for inbound connects\n\ 864 \t-n Suppress name/port resolutions\n\ 865 \t-O length TCP send buffer length\n\ 866 \t-P proxyuser\tUsername for proxy authentication\n\ 867 \t-p port\t Specify local port for remote connects\n\ 868 \t-r Randomize remote ports\n\ 869 \t-S Enable the TCP MD5 signature option\n\ 870 \t-s addr\t Local source address\n\ 871 \t-T ToS\t Set IP Type of Service\n\ 872 \t-t Answer TELNET negotiation\n\ 873 \t-U Use UNIX domain socket\n\ 874 \t-u UDP mode\n\ 875 \t-V rdomain Specify alternate routing domain\n\ 876 \t-v Verbose\n\ 877 \t-w secs\t Timeout for connects and final net reads\n\ 878 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 879 \t-x addr[:port]\tSpecify proxy address and port\n\ 880 \t-z Zero-I/O mode [used for scanning]\n\ 881 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 882 exit(1); 883 } 884 885 void 886 usage(int ret) 887 { 888 fprintf(stderr, 889 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n" 890 "\t [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS]\n" 891 "\t [-V rdomain] [-w timeout] [-X proxy_protocol]\n" 892 "\t [-x proxy_address[:port]] [hostname] [port]\n"); 893 if (ret) 894 exit(1); 895 } 896