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/* Shared library add-on to iptables to add customized REJECT support.
*
* (C) 2000 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_REJECT.h>
#include <linux/version.h>
/* If we are compiling against a kernel that does not support
* IPT_ICMP_ADMIN_PROHIBITED, we are emulating it.
* The result will be a plain DROP of the packet instead of
* reject. -- Maciej Soltysiak <solt@dns.toxicfilms.tv>
*/
#ifndef IPT_ICMP_ADMIN_PROHIBITED
#define IPT_ICMP_ADMIN_PROHIBITED IPT_TCP_RESET + 1
#endif
struct reject_names {
const char *name;
const char *alias;
enum ipt_reject_with with;
const char *desc;
};
static const struct reject_names reject_table[] = {
{"icmp-net-unreachable", "net-unreach",
IPT_ICMP_NET_UNREACHABLE, "ICMP network unreachable"},
{"icmp-host-unreachable", "host-unreach",
IPT_ICMP_HOST_UNREACHABLE, "ICMP host unreachable"},
{"icmp-proto-unreachable", "proto-unreach",
IPT_ICMP_PROT_UNREACHABLE, "ICMP protocol unreachable"},
{"icmp-port-unreachable", "port-unreach",
IPT_ICMP_PORT_UNREACHABLE, "ICMP port unreachable (default)"},
#if 0
{"echo-reply", "echoreply",
IPT_ICMP_ECHOREPLY, "for ICMP echo only: faked ICMP echo reply"},
#endif
{"icmp-net-prohibited", "net-prohib",
IPT_ICMP_NET_PROHIBITED, "ICMP network prohibited"},
{"icmp-host-prohibited", "host-prohib",
IPT_ICMP_HOST_PROHIBITED, "ICMP host prohibited"},
{"tcp-reset", "tcp-rst",
IPT_TCP_RESET, "TCP RST packet"},
{"icmp-admin-prohibited", "admin-prohib",
IPT_ICMP_ADMIN_PROHIBITED, "ICMP administratively prohibited (*)"}
};
static void
print_reject_types()
{
unsigned int i;
printf("Valid reject types:\n");
for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) {
printf(" %-25s\t%s\n", reject_table[i].name, reject_table[i].desc);
printf(" %-25s\talias\n", reject_table[i].alias);
}
printf("\n");
}
/* Saves the union ipt_targinfo in parsable form to stdout. */
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"REJECT options:\n"
"--reject-with type drop input packet and send back\n"
" a reply packet according to type:\n");
print_reject_types();
printf("(*) See man page or read the INCOMPATIBILITES file for compatibility issues.\n");
}
static struct option opts[] = {
{ "reject-with", 1, 0, '1' },
{ 0 }
};
/* Allocate and initialize the target. */
static void
init(struct xt_entry_target *t, unsigned int *nfcache)
{
struct ipt_reject_info *reject = (struct ipt_reject_info *)t->data;
/* default */
reject->with = IPT_ICMP_PORT_UNREACHABLE;
}
/* 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 void *entry,
struct xt_entry_target **target)
{
struct ipt_reject_info *reject = (struct ipt_reject_info *)(*target)->data;
unsigned int limit = sizeof(reject_table)/sizeof(struct reject_names);
unsigned int i;
switch(c) {
case '1':
if (check_inverse(optarg, &invert, NULL, 0))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --reject-with");
for (i = 0; i < limit; i++) {
if ((strncasecmp(reject_table[i].name, optarg, strlen(optarg)) == 0)
|| (strncasecmp(reject_table[i].alias, optarg, strlen(optarg)) == 0)) {
reject->with = reject_table[i].with;
return 1;
}
}
/* This due to be dropped late in 2.4 pre-release cycle --RR */
if (strncasecmp("echo-reply", optarg, strlen(optarg)) == 0
|| strncasecmp("echoreply", optarg, strlen(optarg)) == 0)
fprintf(stderr, "--reject-with echo-reply no longer"
" supported\n");
exit_error(PARAMETER_PROBLEM, "unknown reject type `%s'",optarg);
default:
/* Fall through */
break;
}
return 0;
}
/* Final check; nothing. */
static void final_check(unsigned int flags)
{
}
/* Prints out ipt_reject_info. */
static void
print(const void *ip,
const struct xt_entry_target *target,
int numeric)
{
const struct ipt_reject_info *reject
= (const struct ipt_reject_info *)target->data;
unsigned int i;
for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) {
if (reject_table[i].with == reject->with)
break;
}
printf("reject-with %s ", reject_table[i].name);
}
/* Saves ipt_reject in parsable form to stdout. */
static void save(const void *ip, const struct xt_entry_target *target)
{
const struct ipt_reject_info *reject
= (const struct ipt_reject_info *)target->data;
unsigned int i;
for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++)
if (reject_table[i].with == reject->with)
break;
printf("--reject-with %s ", reject_table[i].name);
}
static struct iptables_target reject = {
.next = NULL,
.name = "REJECT",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ipt_reject_info)),
.userspacesize = IPT_ALIGN(sizeof(struct ipt_reject_info)),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
register_target(&reject);
}
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