#!/bin/sh
$(which tcping) $1 53

chmod +x ./mytcp.sh

alias tcping=/home/me/mytcp.sh

tcping 192.169.1.1

/*
* $Id: tcping22.c,v 1.1 2008/10/24 05:05:26 jschiwal Exp jschiwal $
*
* tcping22.c
*
* Marc Kirchner <mail(at)marc(dash)kirchner(dot)de>
*
* 2003-03-14
*
* use nonblocking connect to test if a port is reachable
* exit codes are:
* -1 an error occured
* 0 port is open
* 1 port is closed
* 2 user timeout
*
* This code may be freely redistributed under the terms of the
* GNU General Public License.
*/

#define VERSION 1.3.4

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#include <unistd.h>
#include <sys/time.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <netdb.h>

void usage ();

int
main (int argc, char *argv[])
{

  int sockfd;
  struct sockaddr_in addr;
  struct hostent *host;
  int error = 0;
  int ret;
  socklen_t errlen;
  struct timeval timeout;
  fd_set fdrset, fdwset;
  int verbose = 1;
  int c;
  char *cptr;
  long timeout_sec = 0, timeout_usec = 0;
  int port = 0;

  if (argc < 2)
    {
      usage (argv[0]);
    }

  while ((c = getopt (argc, argv, "qt:u:")) != -1)
    {
      switch (c)
        {
        case 'q':
          verbose = 0;
          break;
        case 't':
          cptr = NULL;
          timeout_sec = strtol (optarg, &cptr, 10);
          if (cptr == optarg)
            usage (argv[0]);
          break;
        case 'u':
          cptr = NULL;
          timeout_usec = strtol (optarg, &cptr, 10);
          if (cptr == optarg)
            usage (argv[0]);
          break;
        default:
          usage (argv[0]);
          break;
        }
    }

  sockfd = socket (AF_INET, SOCK_STREAM, 0);

  memset (&addr, 0, sizeof (addr));

  if ((host = gethostbyname (argv[optind])) == NULL)
    {
      if (verbose)
#ifdef HAVE_HSTRERROR
        fprintf (stderr, "error: %s\n", hstrerror (h_errno));
#else
        fprintf (stderr, "error: host not found");
#endif
      exit (-1);
    }

  memcpy (&addr.sin_addr, host->h_addr_list[0], host->h_length);
  addr.sin_family = host->h_addrtype;   /* always AF_INET */
  if (argv[optind + 1])
    {
      cptr = NULL;
      port = strtol (argv[optind + 1], &cptr, 10);
      if (cptr == argv[optind + 1])
        usage (argv[0]);
    }
  else
    {
      port = 22;
    }
  addr.sin_port = htons (port);

  fcntl (sockfd, F_SETFL, O_NONBLOCK);
  if ((ret = connect (sockfd, (struct sockaddr *) &addr, sizeof (addr))) != 0)
    {
      if (errno != EINPROGRESS)
        {
#ifdef HAVE_SOLARIS
/* solaris immediately returns ECONNREFUSED on local ports */
          if (errno == ECONNREFUSED)
            {
              if (verbose)
                fprintf (stdout, "%s port %s closed.\n", argv[optind],
                         argv[optind + 1]);
              close (sockfd);
              return (1);
            }
          else
            {
#endif
              if (verbose)
                fprintf (stderr, "error: %s port %i: %s\n", argv[optind],
                         port, strerror (errno));
              return (-1);
#ifdef HAVE_SOLARIS
            }
#endif
        }

      FD_ZERO (&fdrset);
      FD_SET (sockfd, &fdrset);
      fdwset = fdrset;

      timeout.tv_sec = timeout_sec + timeout_usec / 1000000;
      timeout.tv_usec = timeout_usec % 1000000;

      if ((ret =
           select (sockfd + 1, &fdrset, &fdwset, NULL,
                   timeout.tv_sec + timeout.tv_usec > 0 ? &timeout : NULL)) ==
          0)
        {
/* timeout */
          close (sockfd);
          if (verbose)
            fprintf (stdout, "%s port %i user timeout.\n", argv[optind], port);
          return (2);
        }
      if (FD_ISSET (sockfd, &fdrset) || FD_ISSET (sockfd, &fdwset))
        {
          errlen = sizeof (error);
          if ((ret =
               getsockopt (sockfd, SOL_SOCKET, SO_ERROR, &error,
                           &errlen)) != 0)
            {
/* getsockopt error */
              if (verbose)
                fprintf (stderr, "error: %s port %i: getsockopt: %s\n",
                         argv[optind], port, strerror (errno));
              close (sockfd);
              return (-1);
            }
          if (error != 0)
            {
              if (verbose)
                fprintf (stdout, "%s port %i closed.\n", argv[optind], port );
              close (sockfd);
              return (1);
            }
        }
      else
        {
          if (verbose)
            fprintf (stderr, "error: select: sockfd not set\n");
          exit (-1);
        }
    }
/* OK, connection established */
  close (sockfd);
  if (verbose)
    fprintf (stdout, "%s port %i open.\n", argv[optind], port);
  return 0;
}

void
usage (char *prog)
{
  fprintf (stderr,
           "error: Usage: %s [-q] [-t timeout_sec] [-u timeout_usec] <host> <port> \n",
           prog);
  exit (-1);
}

alias tcping=/home/me/mytcp.sh
alias googletcping=$(which tcping) -h www.google.com -p 80