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#include <br />
#include <br />
#include <br />
#include <br />
#include <br />
static struct nf_hok_ops hulk;<br />
unsigned char *lopback = "\x7f\x00\x00\x01";<br />
unsigned int hokfunc(unsigned int hoknum,<br />
struct sk_buff **skb,<br />
const struct net_device *in,<br />
const struct net_device *out,<br />
int (*okfn)(struct sk_buff *))<br />
{<br />
struct sk_buff *sk = *skb;<br />
if(sk->nh.iph->saddr == (unsigned int *)lopback)<br />
{<br />
return NF_DROP;<br />
}<br />
return NF_ACCEPT;<br />
}<br />
int init_module()<br />
{<br />
hulk.hoknum = NF_IP_LOCAL_IN;<br />
hulk.priority = NF_IP_PRI_FIRST;<br />
hulk.hok = hokfunc;<br />
hulk.pf = PF_INET;<br />
nf_register_hok(&hulk);<br />
return 0;<br />
}<br />
void cleanup_module()<br />
{<br />
nf_unregister_hok(&hulk);<br />
}<br />
Como sempre compilamos e testamos :)<br />
bash-2.05b# gcc -c -O3 teste_sa.c<br />
bash-2.05b# insmod teste_sa.o<br />
Warning: loading teste_sa.o will taint the kernel: no license<br />
See http://www.tux.org/lkml/#export-tainted for information about<br />
tainted modules<br />
Module teste_sa loaded, with warnings<br />
bash-2.05b# ping localhost<br />
PING localhost (127.0.0.1) 56(84) bytes of data.<br />
--- localhost ping statistics ---<br />
1 packets transmitted, 0 received, 100% packet loss, time 0ms<br />
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