1 /* $OpenBSD: ssh-keyscan.c,v 1.92 2014/04/29 18:01:49 markus Exp $ */ 2 /* 3 * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>. 4 * 5 * Modification and redistribution in source and binary forms is 6 * permitted provided that due credit is given to the author and the 7 * OpenBSD project by leaving this copyright notice intact. 8 */ 9 10 #include <sys/types.h> 11 #include <sys/socket.h> 12 #include <sys/queue.h> 13 #include <sys/time.h> 14 #include <sys/resource.h> 15 16 #include <openssl/bn.h> 17 18 #include <errno.h> 19 #include <netdb.h> 20 #include <setjmp.h> 21 #include <stdarg.h> 22 #include <stdio.h> 23 #include <stdlib.h> 24 #include <signal.h> 25 #include <string.h> 26 #include <unistd.h> 27 28 #include "xmalloc.h" 29 #include "ssh.h" 30 #include "ssh1.h" 31 #include "buffer.h" 32 #include "key.h" 33 #include "cipher.h" 34 #include "kex.h" 35 #include "compat.h" 36 #include "myproposal.h" 37 #include "packet.h" 38 #include "dispatch.h" 39 #include "log.h" 40 #include "atomicio.h" 41 #include "misc.h" 42 #include "hostfile.h" 43 44 /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. 45 Default value is AF_UNSPEC means both IPv4 and IPv6. */ 46 int IPv4or6 = AF_UNSPEC; 47 48 int ssh_port = SSH_DEFAULT_PORT; 49 50 #define KT_RSA1 1 51 #define KT_DSA 2 52 #define KT_RSA 4 53 #define KT_ECDSA 8 54 #define KT_ED25519 16 55 56 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519; 57 58 int hash_hosts = 0; /* Hash hostname on output */ 59 60 #define MAXMAXFD 256 61 62 /* The number of seconds after which to give up on a TCP connection */ 63 int timeout = 5; 64 65 int maxfd; 66 #define MAXCON (maxfd - 10) 67 68 extern char *__progname; 69 fd_set *read_wait; 70 size_t read_wait_nfdset; 71 int ncon; 72 int nonfatal_fatal = 0; 73 jmp_buf kexjmp; 74 Key *kexjmp_key; 75 76 /* 77 * Keep a connection structure for each file descriptor. The state 78 * associated with file descriptor n is held in fdcon[n]. 79 */ 80 typedef struct Connection { 81 u_char c_status; /* State of connection on this file desc. */ 82 #define CS_UNUSED 0 /* File descriptor unused */ 83 #define CS_CON 1 /* Waiting to connect/read greeting */ 84 #define CS_SIZE 2 /* Waiting to read initial packet size */ 85 #define CS_KEYS 3 /* Waiting to read public key packet */ 86 int c_fd; /* Quick lookup: c->c_fd == c - fdcon */ 87 int c_plen; /* Packet length field for ssh packet */ 88 int c_len; /* Total bytes which must be read. */ 89 int c_off; /* Length of data read so far. */ 90 int c_keytype; /* Only one of KT_RSA1, KT_DSA, or KT_RSA */ 91 char *c_namebase; /* Address to free for c_name and c_namelist */ 92 char *c_name; /* Hostname of connection for errors */ 93 char *c_namelist; /* Pointer to other possible addresses */ 94 char *c_output_name; /* Hostname of connection for output */ 95 char *c_data; /* Data read from this fd */ 96 Kex *c_kex; /* The key-exchange struct for ssh2 */ 97 struct timeval c_tv; /* Time at which connection gets aborted */ 98 TAILQ_ENTRY(Connection) c_link; /* List of connections in timeout order. */ 99 } con; 100 101 TAILQ_HEAD(conlist, Connection) tq; /* Timeout Queue */ 102 con *fdcon; 103 104 static int 105 fdlim_get(int hard) 106 { 107 struct rlimit rlfd; 108 109 if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0) 110 return (-1); 111 if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY) 112 return sysconf(_SC_OPEN_MAX); 113 else 114 return hard ? rlfd.rlim_max : rlfd.rlim_cur; 115 } 116 117 static int 118 fdlim_set(int lim) 119 { 120 struct rlimit rlfd; 121 122 if (lim <= 0) 123 return (-1); 124 if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0) 125 return (-1); 126 rlfd.rlim_cur = lim; 127 if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0) 128 return (-1); 129 return (0); 130 } 131 132 /* 133 * This is an strsep function that returns a null field for adjacent 134 * separators. This is the same as the 4.4BSD strsep, but different from the 135 * one in the GNU libc. 136 */ 137 static char * 138 xstrsep(char **str, const char *delim) 139 { 140 char *s, *e; 141 142 if (!**str) 143 return (NULL); 144 145 s = *str; 146 e = s + strcspn(s, delim); 147 148 if (*e != '\0') 149 *e++ = '\0'; 150 *str = e; 151 152 return (s); 153 } 154 155 /* 156 * Get the next non-null token (like GNU strsep). Strsep() will return a 157 * null token for two adjacent separators, so we may have to loop. 158 */ 159 static char * 160 strnnsep(char **stringp, char *delim) 161 { 162 char *tok; 163 164 do { 165 tok = xstrsep(stringp, delim); 166 } while (tok && *tok == '\0'); 167 return (tok); 168 } 169 170 #ifdef WITH_SSH1 171 static Key * 172 keygrab_ssh1(con *c) 173 { 174 static Key *rsa; 175 static Buffer msg; 176 177 if (rsa == NULL) { 178 buffer_init(&msg); 179 rsa = key_new(KEY_RSA1); 180 } 181 buffer_append(&msg, c->c_data, c->c_plen); 182 buffer_consume(&msg, 8 - (c->c_plen & 7)); /* padding */ 183 if (buffer_get_char(&msg) != (int) SSH_SMSG_PUBLIC_KEY) { 184 error("%s: invalid packet type", c->c_name); 185 buffer_clear(&msg); 186 return NULL; 187 } 188 buffer_consume(&msg, 8); /* cookie */ 189 190 /* server key */ 191 (void) buffer_get_int(&msg); 192 buffer_get_bignum(&msg, rsa->rsa->e); 193 buffer_get_bignum(&msg, rsa->rsa->n); 194 195 /* host key */ 196 (void) buffer_get_int(&msg); 197 buffer_get_bignum(&msg, rsa->rsa->e); 198 buffer_get_bignum(&msg, rsa->rsa->n); 199 200 buffer_clear(&msg); 201 202 return (rsa); 203 } 204 #endif 205 206 static int 207 hostjump(Key *hostkey) 208 { 209 kexjmp_key = hostkey; 210 longjmp(kexjmp, 1); 211 } 212 213 static int 214 ssh2_capable(int remote_major, int remote_minor) 215 { 216 switch (remote_major) { 217 case 1: 218 if (remote_minor == 99) 219 return 1; 220 break; 221 case 2: 222 return 1; 223 default: 224 break; 225 } 226 return 0; 227 } 228 229 static Key * 230 keygrab_ssh2(con *c) 231 { 232 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; 233 int j; 234 235 packet_set_connection(c->c_fd, c->c_fd); 236 enable_compat20(); 237 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 238 c->c_keytype == KT_DSA ? "ssh-dss" : 239 (c->c_keytype == KT_RSA ? "ssh-rsa" : 240 (c->c_keytype == KT_ED25519 ? "ssh-ed25519" : 241 "ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521")); 242 c->c_kex = kex_setup(myproposal); 243 #ifdef WITH_OPENSSL 244 c->c_kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; 245 c->c_kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; 246 c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; 247 c->c_kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; 248 c->c_kex->kex[KEX_ECDH_SHA2] = kexecdh_client; 249 #endif 250 c->c_kex->kex[KEX_C25519_SHA256] = kexc25519_client; 251 c->c_kex->verify_host_key = hostjump; 252 253 if (!(j = setjmp(kexjmp))) { 254 nonfatal_fatal = 1; 255 dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex); 256 fprintf(stderr, "Impossible! dispatch_run() returned!\n"); 257 exit(1); 258 } 259 nonfatal_fatal = 0; 260 free(c->c_kex); 261 c->c_kex = NULL; 262 packet_close(); 263 264 return j < 0? NULL : kexjmp_key; 265 } 266 267 static void 268 keyprint(con *c, Key *key) 269 { 270 char *host = c->c_output_name ? c->c_output_name : c->c_name; 271 272 if (!key) 273 return; 274 if (hash_hosts && (host = host_hash(host, NULL, 0)) == NULL) 275 fatal("host_hash failed"); 276 277 fprintf(stdout, "%s ", host); 278 key_write(key, stdout); 279 fputs("\n", stdout); 280 } 281 282 static int 283 tcpconnect(char *host) 284 { 285 struct addrinfo hints, *ai, *aitop; 286 char strport[NI_MAXSERV]; 287 int gaierr, s = -1; 288 289 snprintf(strport, sizeof strport, "%d", ssh_port); 290 memset(&hints, 0, sizeof(hints)); 291 hints.ai_family = IPv4or6; 292 hints.ai_socktype = SOCK_STREAM; 293 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) 294 fatal("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr)); 295 for (ai = aitop; ai; ai = ai->ai_next) { 296 s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 297 if (s < 0) { 298 error("socket: %s", strerror(errno)); 299 continue; 300 } 301 if (set_nonblock(s) == -1) 302 fatal("%s: set_nonblock(%d)", __func__, s); 303 if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 && 304 errno != EINPROGRESS) 305 error("connect (`%s'): %s", host, strerror(errno)); 306 else 307 break; 308 close(s); 309 s = -1; 310 } 311 freeaddrinfo(aitop); 312 return s; 313 } 314 315 static int 316 conalloc(char *iname, char *oname, int keytype) 317 { 318 char *namebase, *name, *namelist; 319 int s; 320 321 namebase = namelist = xstrdup(iname); 322 323 do { 324 name = xstrsep(&namelist, ","); 325 if (!name) { 326 free(namebase); 327 return (-1); 328 } 329 } while ((s = tcpconnect(name)) < 0); 330 331 if (s >= maxfd) 332 fatal("conalloc: fdno %d too high", s); 333 if (fdcon[s].c_status) 334 fatal("conalloc: attempt to reuse fdno %d", s); 335 336 fdcon[s].c_fd = s; 337 fdcon[s].c_status = CS_CON; 338 fdcon[s].c_namebase = namebase; 339 fdcon[s].c_name = name; 340 fdcon[s].c_namelist = namelist; 341 fdcon[s].c_output_name = xstrdup(oname); 342 fdcon[s].c_data = (char *) &fdcon[s].c_plen; 343 fdcon[s].c_len = 4; 344 fdcon[s].c_off = 0; 345 fdcon[s].c_keytype = keytype; 346 gettimeofday(&fdcon[s].c_tv, NULL); 347 fdcon[s].c_tv.tv_sec += timeout; 348 TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link); 349 FD_SET(s, read_wait); 350 ncon++; 351 return (s); 352 } 353 354 static void 355 confree(int s) 356 { 357 if (s >= maxfd || fdcon[s].c_status == CS_UNUSED) 358 fatal("confree: attempt to free bad fdno %d", s); 359 close(s); 360 free(fdcon[s].c_namebase); 361 free(fdcon[s].c_output_name); 362 if (fdcon[s].c_status == CS_KEYS) 363 free(fdcon[s].c_data); 364 fdcon[s].c_status = CS_UNUSED; 365 fdcon[s].c_keytype = 0; 366 TAILQ_REMOVE(&tq, &fdcon[s], c_link); 367 FD_CLR(s, read_wait); 368 ncon--; 369 } 370 371 static void 372 contouch(int s) 373 { 374 TAILQ_REMOVE(&tq, &fdcon[s], c_link); 375 gettimeofday(&fdcon[s].c_tv, NULL); 376 fdcon[s].c_tv.tv_sec += timeout; 377 TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link); 378 } 379 380 static int 381 conrecycle(int s) 382 { 383 con *c = &fdcon[s]; 384 int ret; 385 386 ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype); 387 confree(s); 388 return (ret); 389 } 390 391 static void 392 congreet(int s) 393 { 394 int n = 0, remote_major = 0, remote_minor = 0; 395 char buf[256], *cp; 396 char remote_version[sizeof buf]; 397 size_t bufsiz; 398 con *c = &fdcon[s]; 399 400 for (;;) { 401 memset(buf, '\0', sizeof(buf)); 402 bufsiz = sizeof(buf); 403 cp = buf; 404 while (bufsiz-- && 405 (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') { 406 if (*cp == '\r') 407 *cp = '\n'; 408 cp++; 409 } 410 if (n != 1 || strncmp(buf, "SSH-", 4) == 0) 411 break; 412 } 413 if (n == 0) { 414 switch (errno) { 415 case EPIPE: 416 error("%s: Connection closed by remote host", c->c_name); 417 break; 418 case ECONNREFUSED: 419 break; 420 default: 421 error("read (%s): %s", c->c_name, strerror(errno)); 422 break; 423 } 424 conrecycle(s); 425 return; 426 } 427 if (*cp != '\n' && *cp != '\r') { 428 error("%s: bad greeting", c->c_name); 429 confree(s); 430 return; 431 } 432 *cp = '\0'; 433 if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", 434 &remote_major, &remote_minor, remote_version) == 3) 435 compat_datafellows(remote_version); 436 else 437 datafellows = 0; 438 if (c->c_keytype != KT_RSA1) { 439 if (!ssh2_capable(remote_major, remote_minor)) { 440 debug("%s doesn't support ssh2", c->c_name); 441 confree(s); 442 return; 443 } 444 } else if (remote_major != 1) { 445 debug("%s doesn't support ssh1", c->c_name); 446 confree(s); 447 return; 448 } 449 fprintf(stderr, "# %s %s\n", c->c_name, chop(buf)); 450 n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n", 451 c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2, 452 c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2); 453 if (n < 0 || (size_t)n >= sizeof(buf)) { 454 error("snprintf: buffer too small"); 455 confree(s); 456 return; 457 } 458 if (atomicio(vwrite, s, buf, n) != (size_t)n) { 459 error("write (%s): %s", c->c_name, strerror(errno)); 460 confree(s); 461 return; 462 } 463 if (c->c_keytype != KT_RSA1) { 464 keyprint(c, keygrab_ssh2(c)); 465 confree(s); 466 return; 467 } 468 c->c_status = CS_SIZE; 469 contouch(s); 470 } 471 472 static void 473 conread(int s) 474 { 475 con *c = &fdcon[s]; 476 size_t n; 477 478 if (c->c_status == CS_CON) { 479 congreet(s); 480 return; 481 } 482 n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off); 483 if (n == 0) { 484 error("read (%s): %s", c->c_name, strerror(errno)); 485 confree(s); 486 return; 487 } 488 c->c_off += n; 489 490 if (c->c_off == c->c_len) 491 switch (c->c_status) { 492 case CS_SIZE: 493 c->c_plen = htonl(c->c_plen); 494 c->c_len = c->c_plen + 8 - (c->c_plen & 7); 495 c->c_off = 0; 496 c->c_data = xmalloc(c->c_len); 497 c->c_status = CS_KEYS; 498 break; 499 #ifdef WITH_SSH1 500 case CS_KEYS: 501 keyprint(c, keygrab_ssh1(c)); 502 confree(s); 503 return; 504 #endif 505 default: 506 fatal("conread: invalid status %d", c->c_status); 507 break; 508 } 509 510 contouch(s); 511 } 512 513 static void 514 conloop(void) 515 { 516 struct timeval seltime, now; 517 fd_set *r, *e; 518 con *c; 519 int i; 520 521 gettimeofday(&now, NULL); 522 c = TAILQ_FIRST(&tq); 523 524 if (c && (c->c_tv.tv_sec > now.tv_sec || 525 (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) { 526 seltime = c->c_tv; 527 seltime.tv_sec -= now.tv_sec; 528 seltime.tv_usec -= now.tv_usec; 529 if (seltime.tv_usec < 0) { 530 seltime.tv_usec += 1000000; 531 seltime.tv_sec--; 532 } 533 } else 534 timerclear(&seltime); 535 536 r = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 537 e = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 538 memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask)); 539 memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask)); 540 541 while (select(maxfd, r, NULL, e, &seltime) == -1 && 542 (errno == EAGAIN || errno == EINTR)) 543 ; 544 545 for (i = 0; i < maxfd; i++) { 546 if (FD_ISSET(i, e)) { 547 error("%s: exception!", fdcon[i].c_name); 548 confree(i); 549 } else if (FD_ISSET(i, r)) 550 conread(i); 551 } 552 free(r); 553 free(e); 554 555 c = TAILQ_FIRST(&tq); 556 while (c && (c->c_tv.tv_sec < now.tv_sec || 557 (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) { 558 int s = c->c_fd; 559 560 c = TAILQ_NEXT(c, c_link); 561 conrecycle(s); 562 } 563 } 564 565 static void 566 do_host(char *host) 567 { 568 char *name = strnnsep(&host, " \t\n"); 569 int j; 570 571 if (name == NULL) 572 return; 573 for (j = KT_RSA1; j <= KT_ED25519; j *= 2) { 574 if (get_keytypes & j) { 575 while (ncon >= MAXCON) 576 conloop(); 577 conalloc(name, *host ? host : name, j); 578 } 579 } 580 } 581 582 void 583 fatal(const char *fmt,...) 584 { 585 va_list args; 586 587 va_start(args, fmt); 588 do_log(SYSLOG_LEVEL_FATAL, fmt, args); 589 va_end(args); 590 if (nonfatal_fatal) 591 longjmp(kexjmp, -1); 592 else 593 exit(255); 594 } 595 596 static void 597 usage(void) 598 { 599 fprintf(stderr, 600 "usage: %s [-46Hv] [-f file] [-p port] [-T timeout] [-t type]\n" 601 "\t\t [host | addrlist namelist] ...\n", 602 __progname); 603 exit(1); 604 } 605 606 int 607 main(int argc, char **argv) 608 { 609 int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO; 610 int opt, fopt_count = 0, j; 611 char *tname, *cp, line[NI_MAXHOST]; 612 FILE *fp; 613 u_long linenum; 614 615 extern int optind; 616 extern char *optarg; 617 618 TAILQ_INIT(&tq); 619 620 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 621 sanitise_stdfd(); 622 623 if (argc <= 1) 624 usage(); 625 626 while ((opt = getopt(argc, argv, "Hv46p:T:t:f:")) != -1) { 627 switch (opt) { 628 case 'H': 629 hash_hosts = 1; 630 break; 631 case 'p': 632 ssh_port = a2port(optarg); 633 if (ssh_port <= 0) { 634 fprintf(stderr, "Bad port '%s'\n", optarg); 635 exit(1); 636 } 637 break; 638 case 'T': 639 timeout = convtime(optarg); 640 if (timeout == -1 || timeout == 0) { 641 fprintf(stderr, "Bad timeout '%s'\n", optarg); 642 usage(); 643 } 644 break; 645 case 'v': 646 if (!debug_flag) { 647 debug_flag = 1; 648 log_level = SYSLOG_LEVEL_DEBUG1; 649 } 650 else if (log_level < SYSLOG_LEVEL_DEBUG3) 651 log_level++; 652 else 653 fatal("Too high debugging level."); 654 break; 655 case 'f': 656 if (strcmp(optarg, "-") == 0) 657 optarg = NULL; 658 argv[fopt_count++] = optarg; 659 break; 660 case 't': 661 get_keytypes = 0; 662 tname = strtok(optarg, ","); 663 while (tname) { 664 int type = key_type_from_name(tname); 665 switch (type) { 666 case KEY_RSA1: 667 get_keytypes |= KT_RSA1; 668 break; 669 case KEY_DSA: 670 get_keytypes |= KT_DSA; 671 break; 672 case KEY_ECDSA: 673 get_keytypes |= KT_ECDSA; 674 break; 675 case KEY_RSA: 676 get_keytypes |= KT_RSA; 677 break; 678 case KEY_ED25519: 679 get_keytypes |= KT_ED25519; 680 break; 681 case KEY_UNSPEC: 682 fatal("unknown key type %s", tname); 683 } 684 tname = strtok(NULL, ","); 685 } 686 break; 687 case '4': 688 IPv4or6 = AF_INET; 689 break; 690 case '6': 691 IPv4or6 = AF_INET6; 692 break; 693 case '?': 694 default: 695 usage(); 696 } 697 } 698 if (optind == argc && !fopt_count) 699 usage(); 700 701 log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1); 702 703 maxfd = fdlim_get(1); 704 if (maxfd < 0) 705 fatal("%s: fdlim_get: bad value", __progname); 706 if (maxfd > MAXMAXFD) 707 maxfd = MAXMAXFD; 708 if (MAXCON <= 0) 709 fatal("%s: not enough file descriptors", __progname); 710 if (maxfd > fdlim_get(0)) 711 fdlim_set(maxfd); 712 fdcon = xcalloc(maxfd, sizeof(con)); 713 714 read_wait_nfdset = howmany(maxfd, NFDBITS); 715 read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask)); 716 717 for (j = 0; j < fopt_count; j++) { 718 if (argv[j] == NULL) 719 fp = stdin; 720 else if ((fp = fopen(argv[j], "r")) == NULL) 721 fatal("%s: %s: %s", __progname, argv[j], 722 strerror(errno)); 723 linenum = 0; 724 725 while (read_keyfile_line(fp, 726 argv[j] == NULL ? "(stdin)" : argv[j], line, sizeof(line), 727 &linenum) != -1) { 728 /* Chomp off trailing whitespace and comments */ 729 if ((cp = strchr(line, '#')) == NULL) 730 cp = line + strlen(line) - 1; 731 while (cp >= line) { 732 if (*cp == ' ' || *cp == '\t' || 733 *cp == '\n' || *cp == '#') 734 *cp-- = '\0'; 735 else 736 break; 737 } 738 739 /* Skip empty lines */ 740 if (*line == '\0') 741 continue; 742 743 do_host(line); 744 } 745 746 if (ferror(fp)) 747 fatal("%s: %s: %s", __progname, argv[j], 748 strerror(errno)); 749 750 fclose(fp); 751 } 752 753 while (optind < argc) 754 do_host(argv[optind++]); 755 756 while (ncon > 0) 757 conloop(); 758 759 return (0); 760 } 761