[1765] | 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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[2725] | 6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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[1765] | 7 | */
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| 8 |
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[3232] | 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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[1765] | 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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[2725] | 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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[1765] | 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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[2725] | 56 | const char *result_str;
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[1765] | 57 | len_and_sockaddr *lsap;
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| 58 | int s;
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[2725] | 59 | unsigned opt;
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[1765] | 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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[2725] | 67 | unsigned start, diff;
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[1765] | 68 |
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| 69 | opt_complementary = "=1"; /* exactly one non-option */
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[2725] | 70 | opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
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[1765] | 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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[2725] | 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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[1765] | 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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[3232] | 90 | set_nport(&lsap->u.sa, htons(port));
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[2725] | 91 | s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
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[1765] | 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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[2725] | 95 |
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[1765] | 96 | DMSG("connect to port %u", port);
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[2725] | 97 | result_str = NULL;
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[1765] | 98 | start = MONOTONIC_US();
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[2725] | 99 | if (connect(s, &lsap->u.sa, lsap->len) == 0) {
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[1765] | 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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[2725] | 111 | diff = 0;
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[1765] | 112 | while (1) {
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| 113 | if (errno == ECONNREFUSED) {
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[2725] | 114 | if (opt & 1) /* -c: show closed too */
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| 115 | result_str = "closed";
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[1765] | 116 | closed_ports++;
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| 117 | break;
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| 118 | }
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[2725] | 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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[1765] | 124 | break;
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[2725] | 125 | }
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[1765] | 126 | /* Can sleep (much) longer than specified delay.
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| 127 | * We check rtt BEFORE we usleep, otherwise
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[2725] | 128 | * on localhost we'll have no writes done (!)
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[1765] | 129 | * before we exceed (rather small) rtt */
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| 130 | usleep(rtt_4/8);
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[2725] | 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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[1765] | 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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[2725] | 136 | result_str = "open";
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[1765] | 137 | break;
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| 138 | }
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| 139 | }
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[2725] | 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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[1765] | 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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[2725] | 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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[1765] | 149 | * because we don't want to accidentally miss ports. */
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[2725] | 150 | rtt_4 = diff * 4;
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[1765] | 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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[2725] | 160 | printf("%d closed, %d open, %d timed out (or blocked) ports\n",
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[1765] | 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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