#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define DEFAULT_PORT 80

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

  int sockfd, result, counter = 0;
  char host[15];
  char *ip;
  int port;

struct sockaddr_in address;
  if (argc < 2)
    {
      printf ("Usage: %s [X.X.X] <port>\n", argv[0]);
      exit (1);
   }

  if(argv[2] != NULL)   {   port = atoi(argv[2]); }
  else {    port = DEFAULT_PORT;  }

ip = argv[1];
sprintf(host, "%s.255", ip);
   if(!inet_aton(host, &address.sin_addr))
     { printf("error: invalid class c\n"); exit(1); }

  while (counter < 255)
    {
      ++counter;
      sprintf (host, "%s.%d\n", ip, counter);
      if ((fork ()) == 0)
        {
          address.sin_family = AF_INET;
          address.sin_port = htons (port);
          address.sin_addr.s_addr = inet_addr (host);
          sockfd = socket (AF_INET, SOCK_STREAM, 0);
          if (sockfd < 0)
            {
              perror ("Socket");
   exit (2);
            }
          alarm (3);
          result = connect (sockfd, (struct sockaddr *) &address, sizeof (addres
s));
          if (result == 0)
            {
              printf ("%s", host);
              close (sockfd);
              exit (0);
              continue;
            }
          exit (0);
        }
    }
  sleep(1);
  close (sockfd);
  exit (0);

}