1 /* This is a module which is used for setting up fake conntracks
2  * on packets so that they are not seen by the conntrack/NAT code.
3  */
4 #include <linux/module.h>
5 #include <linux/skbuff.h>
6 
7 #include <linux/netfilter/x_tables.h>
8 #include <net/netfilter/nf_conntrack.h>
9 
10 MODULE_DESCRIPTION("Xtables: Disabling connection tracking for packets");
11 MODULE_LICENSE("GPL");
12 MODULE_ALIAS("ipt_NOTRACK");
13 MODULE_ALIAS("ip6t_NOTRACK");
14 
15 static unsigned int
notrack_tg(struct sk_buff * skb,const struct xt_action_param * par)16 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
17 {
18 	/* Previously seen (loopback)? Ignore. */
19 	if (skb->nfct != NULL)
20 		return XT_CONTINUE;
21 
22 	/* Attach fake conntrack entry.
23 	   If there is a real ct entry correspondig to this packet,
24 	   it'll hang aroun till timing out. We don't deal with it
25 	   for performance reasons. JK */
26 	skb->nfct = &nf_ct_untracked_get()->ct_general;
27 	skb->nfctinfo = IP_CT_NEW;
28 	nf_conntrack_get(skb->nfct);
29 
30 	return XT_CONTINUE;
31 }
32 
33 static struct xt_target notrack_tg_reg __read_mostly = {
34 	.name     = "NOTRACK",
35 	.revision = 0,
36 	.family   = NFPROTO_UNSPEC,
37 	.target   = notrack_tg,
38 	.table    = "raw",
39 	.me       = THIS_MODULE,
40 };
41 
notrack_tg_init(void)42 static int __init notrack_tg_init(void)
43 {
44 	return xt_register_target(&notrack_tg_reg);
45 }
46 
notrack_tg_exit(void)47 static void __exit notrack_tg_exit(void)
48 {
49 	xt_unregister_target(&notrack_tg_reg);
50 }
51 
52 module_init(notrack_tg_init);
53 module_exit(notrack_tg_exit);
54