一个netfilter驱动的例子

netfilter例子

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4.h>
#include <linux/inet.h>
#include <linux/in.h>
#include <linux/ip.h>

MODULE_LICENSE("GPL");
#define NIPQUAD(addr) \
  ((unsigned char *)&addr)[0], \
  ((unsigned char *)&addr)[1], \
  ((unsigned char *)&addr)[2], \
  ((unsigned char *)&addr)[3]

static unsigned int sample(
unsigned int hooknum,
struct sk_buff * skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn) (struct sk_buff *))
{
    __be32 sip,dip;
 if(skb){
   struct sk_buff *sb = NULL;
   sb = skb;
   struct iphdr *iph;
   iph  = ip_hdr(sb);
   sip = iph->saddr;
   dip = iph->daddr;
   printk("Packet for source address: %d.%d.%d.%d\n destination address: %d.%d.%d.%d\n ", NIPQUAD(sip), NIPQUAD(dip));
    }
 return NF_ACCEPT;
}

 struct nf_hook_ops sample_ops = {
   .list =  {NULL,NULL},
   .hook = sample,
   .pf = PF_INET,
   .hooknum = NF_INET_PRE_ROUTING,
   .priority = NF_IP_PRI_FILTER+2
 };

static int __init sample_init(void) {
  nf_register_hook(&sample_ops);
  return 0;
}


static void __exit sample_exit(void) {
  nf_unregister_hook(&sample_ops);
}

 module_init(sample_init);
 module_exit(sample_exit);
 MODULE_AUTHOR("chenkangrui");
 MODULE_DESCRIPTION("sample");