1 | /*
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2 | * Pscan is a mini port scanner implementation for busybox
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3 | *
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4 | * Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
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5 | *
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6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | //usage:#define pscan_trivial_usage
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10 | //usage: "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
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11 | //usage:#define pscan_full_usage "\n\n"
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12 | //usage: "Scan a host, print all open ports\n"
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13 | //usage: "\n -c Show closed ports too"
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14 | //usage: "\n -b Show blocked ports too"
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15 | //usage: "\n -p Scan from this port (default 1)"
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16 | //usage: "\n -P Scan up to this port (default 1024)"
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17 | //usage: "\n -t Timeout (default 5000 ms)"
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18 | //usage: "\n -T Minimum rtt (default 5 ms, increase for congested hosts)"
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19 |
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20 | #include "libbb.h"
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21 |
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22 | /* debugging */
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23 | #ifdef DEBUG_PSCAN
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24 | #define DMSG(...) bb_error_msg(__VA_ARGS__)
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25 | #define DERR(...) bb_perror_msg(__VA_ARGS__)
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26 | #else
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27 | #define DMSG(...) ((void)0)
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28 | #define DERR(...) ((void)0)
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29 | #endif
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30 |
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31 | static const char *port_name(unsigned port)
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32 | {
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33 | struct servent *server;
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34 |
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35 | server = getservbyport(htons(port), NULL);
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36 | if (server)
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37 | return server->s_name;
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38 | return "unknown";
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39 | }
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40 |
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41 | /* We don't expect to see 1000+ seconds delay, unsigned is enough */
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42 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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43 |
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44 | int pscan_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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45 | int pscan_main(int argc UNUSED_PARAM, char **argv)
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46 | {
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47 | const char *opt_max_port = "1024"; /* -P: default max port */
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48 | const char *opt_min_port = "1"; /* -p: default min port */
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49 | const char *opt_timeout = "5000"; /* -t: default timeout in msec */
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50 | /* We estimate rtt and wait rtt*4 before concluding that port is
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51 | * totally blocked. min rtt of 5 ms may be too low if you are
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52 | * scanning an Internet host behind saturated/traffic shaped link.
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53 | * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
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54 | * will take N seconds at absolute minimum */
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55 | const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
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56 | const char *result_str;
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57 | len_and_sockaddr *lsap;
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58 | int s;
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59 | unsigned opt;
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60 | unsigned port, max_port, nports;
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61 | unsigned closed_ports = 0;
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62 | unsigned open_ports = 0;
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63 | /* all in usec */
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64 | unsigned timeout;
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65 | unsigned min_rtt;
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66 | unsigned rtt_4;
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67 | unsigned start, diff;
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68 |
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69 | opt_complementary = "=1"; /* exactly one non-option */
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70 | opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
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71 | argv += optind;
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72 | max_port = xatou_range(opt_max_port, 1, 65535);
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73 | port = xatou_range(opt_min_port, 1, max_port);
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74 | nports = max_port - port + 1;
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75 | min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
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76 | timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
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77 | /* Initial rtt is BIG: */
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78 | rtt_4 = timeout;
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79 |
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80 | DMSG("min_rtt %u timeout %u", min_rtt, timeout);
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81 |
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82 | lsap = xhost2sockaddr(*argv, port);
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83 | printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
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84 | *argv, port, max_port);
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85 |
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86 | for (; port <= max_port; port++) {
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87 | DMSG("rtt %u", rtt_4);
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88 |
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89 | /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
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90 | set_nport(&lsap->u.sa, htons(port));
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91 | s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
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92 | /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
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93 | /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
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94 | ndelay_on(s);
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95 |
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96 | DMSG("connect to port %u", port);
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97 | result_str = NULL;
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98 | start = MONOTONIC_US();
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99 | if (connect(s, &lsap->u.sa, lsap->len) == 0) {
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100 | /* Unlikely, for me even localhost fails :) */
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101 | DMSG("connect succeeded");
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102 | goto open;
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103 | }
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104 | /* Check for untypical errors... */
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105 | if (errno != EAGAIN && errno != EINPROGRESS
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106 | && errno != ECONNREFUSED
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107 | ) {
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108 | bb_perror_nomsg_and_die();
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109 | }
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110 |
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111 | diff = 0;
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112 | while (1) {
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113 | if (errno == ECONNREFUSED) {
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114 | if (opt & 1) /* -c: show closed too */
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115 | result_str = "closed";
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116 | closed_ports++;
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117 | break;
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118 | }
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119 | DERR("port %u errno %d @%u", port, errno, diff);
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120 |
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121 | if (diff > rtt_4) {
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122 | if (opt & 2) /* -b: show blocked too */
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123 | result_str = "blocked";
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124 | break;
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125 | }
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126 | /* Can sleep (much) longer than specified delay.
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127 | * We check rtt BEFORE we usleep, otherwise
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128 | * on localhost we'll have no writes done (!)
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129 | * before we exceed (rather small) rtt */
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130 | usleep(rtt_4/8);
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131 | open:
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132 | diff = MONOTONIC_US() - start;
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133 | DMSG("write to port %u @%u", port, diff - start);
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134 | if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
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135 | open_ports++;
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136 | result_str = "open";
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137 | break;
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138 | }
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139 | }
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140 | DMSG("out of loop @%u", diff);
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141 | if (result_str)
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142 | printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
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143 | port, result_str, port_name(port));
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144 |
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145 | /* Estimate new rtt - we don't want to wait entire timeout
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146 | * for each port. *4 allows for rise in net delay.
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147 | * We increase rtt quickly (rtt_4*4), decrease slowly
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148 | * (diff is at least rtt_4/8, *4 == rtt_4/2)
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149 | * because we don't want to accidentally miss ports. */
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150 | rtt_4 = diff * 4;
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151 | if (rtt_4 < min_rtt)
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152 | rtt_4 = min_rtt;
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153 | if (rtt_4 > timeout)
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154 | rtt_4 = timeout;
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155 | /* Clean up */
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156 | close(s);
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157 | }
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158 | if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
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159 |
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160 | printf("%d closed, %d open, %d timed out (or blocked) ports\n",
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161 | closed_ports,
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162 | open_ports,
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163 | nports - (closed_ports + open_ports));
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164 | return EXIT_SUCCESS;
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165 | }
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