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/*
nast
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.
*/
/* try to find lan-gateway
*
* return 1 if lan-gw is found
* return 0 if lan-gw is not found
* return -1 on error
*
*/
/* This version is limitated:
* Max 255 hosts to search gateway for ...
*/
#include "include/nast.h"
int fgw (u_char *dev)
{
/* an "external" ip (www.google.com) */
u_char *extip =
{
"66.102.11.99"
};
u_long myip;
struct libnet_ether_addr *tmpmac;
u_char mymac[6];
u_short i, k, pcount;
u_short n; /* n=number of up hosts */
int line,col;
libnet_t *l;
u_char ebuf[LIBNET_ERRBUF_SIZE];
libnet_ptag_t ptag;
/* to be implemented*/
int lg;
pcap_t *p;
struct host * uphost;
/* pcap options */
u_int16_t type;
struct libnet_ipv4_hdr *ip;
struct libnet_tcp_hdr *tcp;
int sd;
struct timeval tv;
fd_set rfsd;
n = k = ptag = pcount = lg = 0;
line = col = 1;
/* query device to find MAC / IP / NETMASK */
if (!dev)
{
w_error(1, "Device is null!\n");
}
#ifdef HAVE_LIBNCURSES
if (graph)
init_scr();
#endif
if (demonize)
{
w_error(0, "Is very useless demonize me in finding gateway! Omit");
demonize = 0;
}
l = libnet_init (LIBNET_LINK, dev, ebuf);
myip = libnet_get_ipaddr4(l);
tmpmac = libnet_get_hwaddr(l);
for (i=0; i<6; i++) mymac[i]=tmpmac->ether_addr_octet[i];
/* init libnet_t *l */
l = libnet_init (LIBNET_LINK, dev, ebuf);
/* build tcp and ip header (this doesn't change */
if (libnet_build_tcp (2500, 80, 847930886, 524972923, 0x02, 32767, 0, 0, LIBNET_TCP_H, NULL, 0, l, 0)==-1)
{
libnet_destroy (l);
w_error(1, "Error building tcp header : %s\n" ,libnet_geterror(l));
}
if (libnet_build_ipv4 (LIBNET_TCP_H + LIBNET_IPV4_H, 0x08, 35320, 0, 64, IPPROTO_TCP, 0, myip, libnet_name2addr4(l, extip, LIBNET_DONT_RESOLVE), NULL, 0, l, 0)==-1)
{
libnet_destroy(l);
w_error(1, "Error building ip header : %s\n", libnet_geterror(l));
}
n_print ("princ",line,col,lg,"Finding suitable hosts (excluding localhost) -> ");
fflush (stdout);
/* find up possible hosts */
if ((uphost = map_lan(dev, 0, &n))==NULL)
{
if(w_error(0, "\nCan't build truly host list! mmhhh!\nReport bug to author please\n\n")==-1)
return -1;
}
if (n==0)
{
if(w_error(0,"What are you doing? You are alone in this network!\n\n")==-1)
return -1;
}
n_print ("princ",line,50,lg,"Done\n\n");
line = line+2;
/* set gwip and increment within for cicle */
while (k < n)
{
n_print ("princ",line,col,lg,"Trying %d.%d.%d.%d (%s)-> ",uphost[k].ip[0], uphost[k].ip[1], uphost[k].ip[2], uphost[k].ip[3], nast_hex_ntoa (uphost[k].mac));
fflush (stdout);
if ((ptag = libnet_build_ethernet (uphost[k].mac, mymac, 0x0800, NULL, 0, l, ptag))==-1)
{
libnet_destroy(l);
w_error(1, "Error rebuilding ethernet frame : %s\n", libnet_geterror(l));
}
if (libnet_write (l) == -1)
{
libnet_destroy(l);
w_error(1, "Error writing packet on wire : %s\n", libnet_geterror(l));
}
pcap_lookupnet(dev,&netp,&maskp,ebuf);
if ((p = pcap_open_live (dev, BUFSIZ, NOT_PROMISC, 10, ebuf))==NULL)
{
libnet_destroy(l);
w_error(1, "pcap_open_live() error : %s\n", ebuf);
}
/* to better work with many traffic */
pcap_compile(p,&fp,"src port 80 and dst port 2500",0,netp);
pcap_setfilter(p,&fp);
sd = pcap_fileno(p);
/* try to sniff */
for (;;)
{
/* set 2 secondz delay | DONT TOUCH! */
FD_ZERO (&rfsd);
FD_SET (sd ,&rfsd);
tv.tv_sec = 2;
tv.tv_usec = 0;
/* 30 packet max for delay */
if (pcount == 30)
{
n_print ("princ",line,2,lg,"Bad (timeout due to high traffic to your host, try again later to make sure)\n");
break;
}
if (!select(sd+1, &rfsd, NULL, NULL, &tv))
{
n_print ("princ",line,50,lg,"Bad\n");
break;
}
/* capture packet (packet) and pcap_header (hdr) */
packet = (u_char *) pcap_next (p, &hdr);
if (packet==NULL)
{
//fprintf (stderr, "Null packet!\n");
break;
}
type = handle_ethernet (packet);
if (type==ETHERTYPE_IP)
{
ip = (struct libnet_ipv4_hdr *) (packet + offset);
tcp = (struct libnet_tcp_hdr *) (packet + offset + sizeof(struct libnet_ipv4_hdr));
/* verify packet : ports and source ip*/
if ((ntohs(tcp->th_sport)==80) && (ntohs(tcp->th_dport)==2500) && (!strcmp(inet_ntoa(ip->ip_src), extip)))
{
n_print ("princ",line,50,lg,"Yep!\n");
break;
}
}
pcount ++;
}
pcap_close(p);
pcount = 1;
k++;
++line;
}
if(!graph)
printf("\n");
n_print("winfo",2,1,lg," ");
n_print("winfo",2,2,lg,"\nFinished\n");
if (l) libnet_destroy(l);
//printf ("\n");
return 0;
}
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