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/*
* Copyright (c) 2003+ Evgeniy Polyakov <zbr@ioremap.net>
*
*
* 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
*/
/*
* xtables interface for OS fingerprint matching module.
*/
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <ctype.h>
#include <linux/types.h>
#include <xtables.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <linux/netfilter/xt_osf.h>
static void osf_help(void)
{
printf("OS fingerprint match options:\n"
"[!] --genre string Match a OS genre by passive fingerprinting.\n"
"--ttl level Use some TTL check extensions to determine OS:\n"
" 0 true ip and fingerprint TTL comparison. Works for LAN.\n"
" 1 check if ip TTL is less than fingerprint one. Works for global addresses.\n"
" 2 do not compare TTL at all. Allows to detect NMAP, but can produce false results.\n"
"--log level Log determined genres into dmesg even if they do not match desired one:\n"
" 0 log all matched or unknown signatures.\n"
" 1 log only first one.\n"
" 2 log all known matched signatures.\n"
);
}
static const struct option osf_opts[] = {
{ .name = "genre", .has_arg = true, .val = '1' },
{ .name = "ttl", .has_arg = true, .val = '2' },
{ .name = "log", .has_arg = true, .val = '3' },
{ .name = NULL }
};
static void osf_parse_string(const char *s, struct xt_osf_info *info)
{
if (strlen(s) < MAXGENRELEN)
strcpy(info->genre, s);
else
xtables_error(PARAMETER_PROBLEM,
"Genre string too long `%s' [%zd], max=%d",
s, strlen(s), MAXGENRELEN);
}
static int osf_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry,
struct xt_entry_match **match)
{
struct xt_osf_info *info = (struct xt_osf_info *)(*match)->data;
switch(c) {
case '1': /* --genre */
if (*flags & XT_OSF_GENRE)
xtables_error(PARAMETER_PROBLEM,
"Can't specify multiple genre parameter");
xtables_check_inverse(optarg, &invert, &optind, 0, argv);
osf_parse_string(argv[optind-1], info);
if (invert)
info->flags |= XT_OSF_INVERT;
info->len=strlen(info->genre);
*flags |= XT_OSF_GENRE;
break;
case '2': /* --ttl */
if (*flags & XT_OSF_TTL)
xtables_error(PARAMETER_PROBLEM,
"Can't specify multiple ttl parameter");
*flags |= XT_OSF_TTL;
info->flags |= XT_OSF_TTL;
if (!xtables_strtoui(argv[optind-1], NULL, &info->ttl, 0, 2))
xtables_error(PARAMETER_PROBLEM, "TTL parameter is too big");
break;
case '3': /* --log */
if (*flags & XT_OSF_LOG)
xtables_error(PARAMETER_PROBLEM,
"Can't specify multiple log parameter");
*flags |= XT_OSF_LOG;
if (!xtables_strtoui(argv[optind-1], NULL, &info->loglevel, 0, 2))
xtables_error(PARAMETER_PROBLEM, "Log level parameter is too big");
info->flags |= XT_OSF_LOG;
break;
default:
return 0;
}
return 1;
}
static void osf_final_check(unsigned int flags)
{
if (!flags)
xtables_error(PARAMETER_PROBLEM,
"OS fingerprint match: You must specify `--genre'");
}
static void osf_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
const struct xt_osf_info *info = (const struct xt_osf_info*) match->data;
printf("OS fingerprint match %s%s ", (info->flags & XT_OSF_INVERT) ? "! " : "", info->genre);
}
static void osf_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_osf_info *info = (const struct xt_osf_info*) match->data;
printf("--genre %s%s ", (info->flags & XT_OSF_INVERT) ? "! ": "", info->genre);
}
static struct xtables_match osf_match = {
.name = "osf",
.version = XTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_osf_info)),
.userspacesize = XT_ALIGN(sizeof(struct xt_osf_info)),
.help = osf_help,
.parse = osf_parse,
.print = osf_print,
.final_check = osf_final_check,
.save = osf_save,
.extra_opts = osf_opts,
.family = NFPROTO_IPV4
};
void _init(void)
{
xtables_register_match(&osf_match);
}
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