/*============================================================================
|   Copyright (C) 2001  Jonathan Harm                                          
|
|
|   This program is free software; you can redistribute it and/or
|   modify it under the terms of the GNU General Public License
|   as published by the Free Software Foundation; either version 2
|   of the License, or (at your option) any later version.
|   This program is distributed in the hope that it will be useful,
|   but WITHOUT ANY WARRANTY; without even the implied warranty of
|   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
|   GNU General Public License for more details.
|   You should have received a copy of the GNU General Public License
|   along with this program; if not, write to the Free Software
|   
|   Foundation, Inc., 
|   59 Temple Place - Suite 330
|   Boston, MA  02111-1307, USA.
|
|  
|
|                  portscan  version 1
|
|  This program is under the GPL see http://www.gnu.org for more info
|
|  
|                   http://change.to/opensource
|                   110983@lycos.com
|
\============================================================================*/

//TODO:  add more error checking
//       tell what is probably on that port(i.e. 21 ftp   6699 napster  etc...)

#include <stdio.h>      /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket(), connect(), send(), and recv() */
#include <arpa/inet.h>  /* for sockaddr_in and inet_addr() */
#include <stdlib.h>     /* for atoi() */
#include <string.h>     /* for memset() */
#include <unistd.h>     /* for close() */


int main(int argc, char *argv[])
{
	
	
	int scansock;					              		//the actuall socket
	unsigned short portend, i;		                         //the variables to hold the beginning and ending port numbers
	char *remote_ip_p, remote_ip[16];		        //remote ip number, the 16 is there because an ip number can't
	               										//take up more than 16 characters including dots
	
	struct sockaddr_in p_scan;					//struct to hold data about remote pc

	unsigned short portbegin;     /* Echo server port */
	
	
	remote_ip_p = remote_ip_p;
	
	
	//check for correct number of arguments
	if(( argc < 3 || argc > 4)) {
		printf("Usage: %s <ip> <beginning port> <end port>\n", argv[0]);
		exit(1);
	}
	
	
	if( (scansock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
		fprintf(stderr, "Error Creating socket.\n\n");
		exit(1);
	}
	
	//now that we have all the arguments, put them in the variables
	remote_ip_p	= argv[1];
        portbegin      = atoi(argv[2]);
	portend		= atoi(argv[3]);  
	++portend;  //this is for the loop so it will increment all the way to the end port
	

        //fill in struct with data that isn't going to change
	memset(&p_scan, 0, sizeof(struct sockaddr_in));  
	p_scan.sin_family			= AF_INET;
	p_scan.sin_addr.s_addr		= inet_addr(remote_ip_p);
	
	for(i = portbegin; i < portend; i++) {
		
		p_scan.sin_port = htons(i);   //now that the port number has changed, put it in the struct
		
           //now try to connect to that port
    	     if (  connect(scansock, (struct sockaddr *) &p_scan, sizeof(p_scan)) == 0 ) {
		     printf("open: %d\n", i);
	     }
		
	     
     }
     
     close(scansock);
     
     return 0;
}