2 * Pscan is a mini port scanner implementation for busybox
4 * Copyright 2007 Tito Ragusa <farmatito@tiscali.it>
6 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
13 #define DMSG(...) bb_error_msg(__VA_ARGS__)
14 #define DERR(...) bb_perror_msg(__VA_ARGS__)
16 #define DMSG(...) ((void)0)
17 #define DERR(...) ((void)0)
20 static const char *port_name(unsigned port)
22 struct servent *server;
24 server = getservbyport(htons(port), NULL);
26 return server->s_name;
30 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
31 #define MONOTONIC_US() ((unsigned)monotonic_us())
33 int pscan_main(int argc, char **argv);
34 int pscan_main(int argc, char **argv)
36 const char *opt_max_port = "1024"; /* -P: default max port */
37 const char *opt_min_port = "1"; /* -p: default min port */
38 const char *opt_timeout = "5000"; /* -t: default timeout in msec */
39 /* We estimate rtt and wait rtt*4 before concluding that port is
40 * totally blocked. min rtt of 5 ms may be too low if you are
41 * scanning an Internet host behind saturated/traffic shaped link.
42 * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
43 * will take N seconds at absolute minimum */
44 const char *opt_min_rtt = "5"; /* -T: default min rtt in msec */
45 len_and_sockaddr *lsap;
47 unsigned port, max_port, nports;
48 unsigned closed_ports = 0;
49 unsigned open_ports = 0;
56 opt_complementary = "=1"; /* exactly one non-option */
57 getopt32(argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
59 max_port = xatou_range(opt_max_port, 1, 65535);
60 port = xatou_range(opt_min_port, 1, max_port);
61 nports = max_port - port + 1;
62 rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
63 min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
65 DMSG("min_rtt %u timeout %u", min_rtt, timeout);
67 lsap = xhost2sockaddr(*argv, port);
68 printf("Scanning %s ports %u to %u\n Port\tProto\tState\tService\n",
69 *argv, port, max_port);
71 for (; port <= max_port; port++) {
72 DMSG("rtt %u", rtt_4);
74 /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
75 set_nport(lsap, htons(port));
76 s = xsocket(lsap->sa.sa_family, SOCK_STREAM, 0);
78 /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
79 /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
81 DMSG("connect to port %u", port);
82 start = MONOTONIC_US();
83 if (connect(s, &lsap->sa, lsap->len) == 0) {
84 /* Unlikely, for me even localhost fails :) */
85 DMSG("connect succeeded");
88 /* Check for untypical errors... */
89 if (errno != EAGAIN && errno != EINPROGRESS
90 && errno != ECONNREFUSED
92 bb_perror_nomsg_and_die();
96 if (errno == ECONNREFUSED) {
97 DMSG("port %u: ECONNREFUSED", port);
101 DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
102 if ((MONOTONIC_US() - start) > rtt_4)
104 /* Can sleep (much) longer than specified delay.
105 * We check rtt BEFORE we usleep, otherwise
106 * on localhost we'll do zero writes done (!)
107 * before we exceed (rather small) rtt */
109 DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
110 if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
113 printf("%5u\ttcp\topen\t%s\n", port, port_name(port));
117 DMSG("out of loop @%u", MONOTONIC_US() - start);
119 /* Estimate new rtt - we don't want to wait entire timeout
120 * for each port. *4 allows for rise in net delay.
121 * We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
122 * because we don't want to accidentally miss ports. */
123 rtt_4 = (MONOTONIC_US() - start) * 4;
131 if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
133 printf("%d closed, %d open, %d timed out ports\n",
136 nports - (closed_ports + open_ports));