1. 根目录:
2. net
3. netfilter
4. nf_internals.h

#ifndef _NF_INTERNALS_H
#define _NF_INTERNALS_H

#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>

#ifdef CONFIG_NETFILTER_DEBUG
#define NFDEBUG(format, args...)  printk(KERN_DEBUG format , ## args)
#else
#define NFDEBUG(format, args...)
#endif


/* core.c */
extern unsigned int nf_iterate(struct list_head *head,
				struct sk_buff *skb,
				unsigned int hook,
				const struct net_device *indev,
				const struct net_device *outdev,
				struct list_head **i,
				int (*okfn)(struct sk_buff *),
				int hook_thresh);

/* nf_queue.c */
extern int nf_queue(struct sk_buff *skb,
		    struct list_head *elem,
		    u_int8_t pf, unsigned int hook,
		    struct net_device *indev,
		    struct net_device *outdev,
		    int (*okfn)(struct sk_buff *),
		    unsigned int queuenum);
extern int __init netfilter_queue_init(void);

/* nf_log.c */
extern int __init netfilter_log_init(void);

#endif