帮忙看段小程序， 我帮朋友的，我也不会，分析一下是做什么，具体是干吗的？ [复制链接]

#ifndef __KERNEL__
#define __KERNEL__
#endif

#ifndef MODULE
#define MODULE
#endif

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/netfilter_arp.h>
#include <linux/if_arp.h>

#define NF_ARP_PRI 0

static struct nf_hook_ops sArpHookOps;

int arp_request_defend(arg1,...)
{

    //arp请求攻击的防范

}
int arp_reply_defend(arg1,...)
{

    //arp应答攻击的防范

}
unsigned int arp_in(unsigned int hooknum,
                    struct sk_buff *skb,
                    const struct net_device *in,
                    const struct net_device *out,
                    int (*okfn)(struct sk_buff *))
{
    struct arphdr *psArpHead = arp_hdr(skb);
    
    if(psArpHead->ar_op == htons(ARPOP_REQUEST))
    {
        printk("Receive ARP REQUEST\n");  //just for test
        arp_request_defend();
    }
    else if(psArpHead->ar_op == htons(ARPOP_REPLY))
    {
        printk("Receive ARP REPLY\n");    //just for test
        arp_reply_defend();
    }
    else
    {
        printk("Not an ARP packet!\n");
    }
      
    //return NF_ACCEPT;
    
}

int __init ArpDefendInit(void)
{

    int ret;

    sArpHookOps.hook = arp_in;
    sArpHookOps.hooknum = NF_ARP_IN;
    sArpHookOps.pf = NF_ARP;
    sArpHookOps.priority = NF_ARP_PRI;

    ret = nf_register_hook(&sArpHookOps);
    if( ret != 0)
    {
        printk("arp hook register fail!\n");     //just for test
    }

    return ret;
}

void __exit ArpDefendExit(void)
{
    int ret;

    ret = nf_unregister_hook(&sArpHookOps);
    if( ret != 0)
    {
        printk("arp hook unregister fail!\n");
    }

    return ret;
}


module_init(ArpDefendInit);
module_exit(ArpDefendExit);

MODULE_LICENSE("GPL");