多核系统上的Netfilter钩子

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/inet.h>

static struct nf_hook_ops nfho;

static int prerouting_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) {
    struct iphdr *iph = ip_hdr(skb);
    printk(KERN_INFO "PREROUTING: src=%pI4, dst=%pI4, protocol=%d\n", &iph->saddr, &iph->daddr, iph->protocol);
    return NF_ACCEPT;
}

static int __init netfilter_init(void) {
    nfho.hook = prerouting_hook;
    nfho.hooknum = NF_INET_PRE_ROUTING;
    nfho.pf = PF_INET;
    nfho.priority = NF_IP_PRI_FIRST;

    nf_register_hook(&nfho);
    printk(KERN_INFO "Netfilter hook registered\n");
    return 0;
}

static void __exit netfilter_exit(void) {
    nf_unregister_hook(&nfho);
    printk(KERN_INFO "Netfilter hook unregistered\n");
}

module_init(netfilter_init);
module_exit(netfilter_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple Netfilter hook module");