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/* This is a module which is used for setting up fake conntracks
* on packets so that they are not seen by the conntrack/NAT code.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
static unsigned int
target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
/* Previously seen (loopback)? Ignore. */
if ((*pskb)->nfct != NULL)
return IPT_CONTINUE;
/* Attach fake conntrack entry.
If there is a real ct entry correspondig to this packet,
it'll hang aroun till timing out. We don't deal with it
for performance reasons. JK */
(*pskb)->nfct = &ip_conntrack_untracked.ct_general;
(*pskb)->nfctinfo = IP_CT_NEW;
nf_conntrack_get((*pskb)->nfct);
return IPT_CONTINUE;
}
static int
checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
if (targinfosize != 0) {
printk(KERN_WARNING "NOTRACK: targinfosize %u != 0\n",
targinfosize);
return 0;
}
if (strcmp(tablename, "raw") != 0) {
printk(KERN_WARNING "NOTRACK: can only be called from \"raw\" table, not \"%s\"\n", tablename);
return 0;
}
return 1;
}
static struct ipt_target ipt_notrack_reg = {
.name = "NOTRACK",
.target = target,
.checkentry = checkentry,
.me = THIS_MODULE
};
static int __init init(void)
{
if (ipt_register_target(&ipt_notrack_reg))
return -EINVAL;
return 0;
}
static void __exit fini(void)
{
ipt_unregister_target(&ipt_notrack_reg);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
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