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/* Shared library add-on to iptables to add recent matching support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ipt_recent.h>
/* Need these in order to not fail when compiling against an older kernel. */
#ifndef RECENT_NAME
#define RECENT_NAME "ipt_recent"
#endif /* RECENT_NAME */
#ifndef RECENT_VER
#define RECENT_VER "unknown"
#endif /* RECENT_VER */
#ifndef IPT_RECENT_NAME_LEN
#define IPT_RECENT_NAME_LEN 200
#endif /* IPT_RECENT_NAME_LEN */
/* Options for this module */
static struct option opts[] = {
{ .name = "set", .has_arg = 0, .flag = 0, .val = 201 },
{ .name = "rcheck", .has_arg = 0, .flag = 0, .val = 202 },
{ .name = "update", .has_arg = 0, .flag = 0, .val = 203 },
{ .name = "seconds", .has_arg = 1, .flag = 0, .val = 204 },
{ .name = "hitcount", .has_arg = 1, .flag = 0, .val = 205 },
{ .name = "remove", .has_arg = 0, .flag = 0, .val = 206 },
{ .name = "rttl", .has_arg = 0, .flag = 0, .val = 207 },
{ .name = "name", .has_arg = 1, .flag = 0, .val = 208 },
{ .name = "rsource", .has_arg = 0, .flag = 0, .val = 209 },
{ .name = "rdest", .has_arg = 0, .flag = 0, .val = 210 },
{ .name = 0, .has_arg = 0, .flag = 0, .val = 0 }
};
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"recent v%s options:\n"
"[!] --set Add source address to list, always matches.\n"
"[!] --rcheck Match if source address in list.\n"
"[!] --update Match if source address in list, also update last-seen time.\n"
"[!] --remove Match if source address in list, also removes that address from list.\n"
" --seconds seconds For check and update commands above.\n"
" Specifies that the match will only occur if source address last seen within\n"
" the last 'seconds' seconds.\n"
" --hitcount hits For check and update commands above.\n"
" Specifies that the match will only occur if source address seen hits times.\n"
" May be used in conjunction with the seconds option.\n"
" --rttl For check and update commands above.\n"
" Specifies that the match will only occur if the source address and the TTL\n"
" match between this packet and the one which was set.\n"
" Useful if you have problems with people spoofing their source address in order\n"
" to DoS you via this module.\n"
" --name name Name of the recent list to be used. DEFAULT used if none given.\n"
" --rsource Match/Save the source address of each packet in the recent list table (default).\n"
" --rdest Match/Save the destination address of each packet in the recent list table.\n"
RECENT_NAME " " RECENT_VER ": Stephen Frost <sfrost@snowman.net>. http://snowman.net/projects/ipt_recent/\n"
,
IPTABLES_VERSION);
}
/* Initialize the match. */
static void
init(struct xt_entry_match *match, unsigned int *nfcache)
{
struct ipt_recent_info *info = (struct ipt_recent_info *)(match)->data;
strncpy(info->name,"DEFAULT",IPT_RECENT_NAME_LEN);
/* eventhough IPT_RECENT_NAME_LEN is currently defined as 200,
* better be safe, than sorry */
info->name[IPT_RECENT_NAME_LEN-1] = '\0';
info->side = IPT_RECENT_SOURCE;
}
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct xt_entry_match **match)
{
struct ipt_recent_info *info = (struct ipt_recent_info *)(*match)->data;
switch (c) {
case 201:
if (*flags) exit_error(PARAMETER_PROBLEM,
"recent: only one of `--set', `--rcheck' "
"`--update' or `--remove' may be set");
check_inverse(optarg, &invert, &optind, 0);
info->check_set |= IPT_RECENT_SET;
if (invert) info->invert = 1;
*flags = 1;
break;
case 202:
if (*flags) exit_error(PARAMETER_PROBLEM,
"recent: only one of `--set', `--rcheck' "
"`--update' or `--remove' may be set");
check_inverse(optarg, &invert, &optind, 0);
info->check_set |= IPT_RECENT_CHECK;
if(invert) info->invert = 1;
*flags = 1;
break;
case 203:
if (*flags) exit_error(PARAMETER_PROBLEM,
"recent: only one of `--set', `--rcheck' "
"`--update' or `--remove' may be set");
check_inverse(optarg, &invert, &optind, 0);
info->check_set |= IPT_RECENT_UPDATE;
if (invert) info->invert = 1;
*flags = 1;
break;
case 206:
if (*flags) exit_error(PARAMETER_PROBLEM,
"recent: only one of `--set', `--rcheck' "
"`--update' or `--remove' may be set");
check_inverse(optarg, &invert, &optind, 0);
info->check_set |= IPT_RECENT_REMOVE;
if (invert) info->invert = 1;
*flags = 1;
break;
case 204:
info->seconds = atoi(optarg);
break;
case 205:
info->hit_count = atoi(optarg);
break;
case 207:
info->check_set |= IPT_RECENT_TTL;
break;
case 208:
strncpy(info->name,optarg,IPT_RECENT_NAME_LEN);
info->name[IPT_RECENT_NAME_LEN-1] = '\0';
break;
case 209:
info->side = IPT_RECENT_SOURCE;
break;
case 210:
info->side = IPT_RECENT_DEST;
break;
default:
return 0;
}
return 1;
}
/* Final check; must have specified a specific option. */
static void
final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"recent: you must specify one of `--set', `--rcheck' "
"`--update' or `--remove'");
}
/* Prints out the matchinfo. */
static void
print(const struct ipt_ip *ip,
const struct xt_entry_match *match,
int numeric)
{
struct ipt_recent_info *info = (struct ipt_recent_info *)match->data;
if (info->invert)
fputc('!', stdout);
printf("recent: ");
if(info->check_set & IPT_RECENT_SET) printf("SET ");
if(info->check_set & IPT_RECENT_CHECK) printf("CHECK ");
if(info->check_set & IPT_RECENT_UPDATE) printf("UPDATE ");
if(info->check_set & IPT_RECENT_REMOVE) printf("REMOVE ");
if(info->seconds) printf("seconds: %d ",info->seconds);
if(info->hit_count) printf("hit_count: %d ",info->hit_count);
if(info->check_set & IPT_RECENT_TTL) printf("TTL-Match ");
if(info->name) printf("name: %s ",info->name);
if(info->side == IPT_RECENT_SOURCE) printf("side: source ");
if(info->side == IPT_RECENT_DEST) printf("side: dest");
}
/* Saves the union ipt_matchinfo in parsable form to stdout. */
static void
save(const struct ipt_ip *ip, const struct xt_entry_match *match)
{
struct ipt_recent_info *info = (struct ipt_recent_info *)match->data;
if (info->invert)
printf("! ");
if(info->check_set & IPT_RECENT_SET) printf("--set ");
if(info->check_set & IPT_RECENT_CHECK) printf("--rcheck ");
if(info->check_set & IPT_RECENT_UPDATE) printf("--update ");
if(info->check_set & IPT_RECENT_REMOVE) printf("--remove ");
if(info->seconds) printf("--seconds %d ",info->seconds);
if(info->hit_count) printf("--hitcount %d ",info->hit_count);
if(info->check_set & IPT_RECENT_TTL) printf("--rttl ");
if(info->name) printf("--name %s ",info->name);
if(info->side == IPT_RECENT_SOURCE) printf("--rsource ");
if(info->side == IPT_RECENT_DEST) printf("--rdest ");
}
/* Structure for iptables to use to communicate with module */
static struct iptables_match recent = {
.next = NULL,
.name = "recent",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ipt_recent_info)),
.userspacesize = IPT_ALIGN(sizeof(struct ipt_recent_info)),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
register_match(&recent);
}
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