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ntp.c
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ntp.c
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/*
* $Id: ntp.c,v 1.3 2004/02/20 18:53:49 mike Exp $
*
* libnet 1.1
* Build an NTP Packet
*
* Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#if (HAVE_CONFIG_H)
#include "../include/config.h"
#endif
#include "./libnet_test.h"
int
main(int argc, char **argv)
{
int c;
libnet_t *l;
u_long dst_ip;
libnet_ptag_t t;
char errbuf[LIBNET_ERRBUF_SIZE];
printf("libnet 1.1 NTP packet shaping[raw -- autobuilding IP]\n");
/*
* Initialize the library. Root priviledges are required.
*/
l = libnet_init(
LIBNET_RAW4, /* injection type */
NULL, /* network interface */
errbuf); /* error buf */
if (l == NULL)
{
fprintf(stderr, "libnet_init() failed: %s", errbuf);
exit(EXIT_FAILURE);
}
dst_ip = 0;
while((c = getopt(argc, argv, "d:")) != EOF)
{
switch (c)
{
/*
* We expect the input to be of the form `ip.ip.ip.ip.port`. We
* point cp to the last dot of the IP address/port string and
* then separate them with a NULL byte. The optarg now points to
* just the IP address, and cp points to the port.
*/
case 'd':
if ((dst_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
{
fprintf(stderr, "Bad destination IP address: %s\n", optarg);
exit(1);
}
break;
}
}
if (!dst_ip)
{
usage(argv[0]);
exit(EXIT_FAILURE);
}
/*
* Build the packet, remmebering that order IS important. We must
* build the packet from lowest protocol type on up as it would
* appear on the wire. So for our NTP packet:
*
* --------------------------------------------------------------------
* | IP | UDP | NTP |
* --------------------------------------------------------------------
* ^ ^ ^
* |-------------- | |
* libnet_build_ipv4()--| | |
* | |
* libnet_build_udp()-------| |
* |
* libnet_build_ntp()------------------------------|
*/
t = libnet_build_ntp(
LIBNET_NTP_LI_AC, /* leap indicator */
LIBNET_NTP_VN_4, /* version */
LIBNET_NTP_MODE_S, /* mode */
LIBNET_NTP_STRATUM_PRIMARY, /* stratum */
4, /* poll interval */
1, /* precision */
0xffff, /* delay interval */
0xffff, /* delay fraction */
0xffff, /* dispersion interval */
0xffff, /* dispersion fraction */
LIBNET_NTP_REF_PPS, /* reference id */
0x11, /* reference ts int */
0x22, /* reference ts frac */
0x33, /* originate ts int */
0x44, /* originate ts frac */
0x55, /* receive ts int */
0x66, /* receive ts frac */
0x77, /* transmit ts interval */
0x88, /* transmit ts fraction */
NULL, /* payload */
0, /* payload size */
l, /* libnet handle */
0); /* libnet id */
if (t == -1)
{
fprintf(stderr, "Can't build NTP header: %s\n", libnet_geterror(l));
goto bad;
}
libnet_seed_prand(l);
t = libnet_build_udp(
libnet_get_prand(LIBNET_PRu16), /* source port */
123, /* NTP port */
LIBNET_UDP_H + LIBNET_NTP_H, /* UDP packet length */
0, /* checksum */
NULL, /* payload */
0, /* payload size */
l, /* libnet handle */
0); /* libnet id */
if (t == -1)
{
fprintf(stderr, "Can't build UDP header: %s\n", libnet_geterror(l));
goto bad;
}
t = libnet_autobuild_ipv4(
LIBNET_IPV4_H + LIBNET_UDP_H + LIBNET_NTP_H,/* packet length */
IPPROTO_UDP,
dst_ip,
l);
if (t == -1)
{
fprintf(stderr, "Can't build IP header: %s\n", libnet_geterror(l));
goto bad;
}
/*
* Write it to the wire.
*/
fprintf(stderr, "l contains a %d byte packet\n", libnet_getpacket_size(l));
c = libnet_write(l);
if (c == -1)
{
fprintf(stderr, "Write error: %s\n", libnet_geterror(l));
goto bad;
}
else
{
fprintf(stderr, "Wrote %d byte NTP packet; check the wire.\n", c);
}
libnet_destroy(l);
return (EXIT_SUCCESS);
bad:
libnet_destroy(l);
return (EXIT_FAILURE);
}
void
usage(char *name)
{
fprintf(stderr,
"usage: %s -d destination_ip\n",
name);
}