/* 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 inttarget(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.infos[IP_CT_NEW];	nf_conntrack_get((*pskb)->nfct);	return IPT_CONTINUE;}static intcheckentry(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");