#ifndef __LINUX_IP_NETFILTER_H
  #define __LINUX_IP_NETFILTER_H
  
  /* IPv4-specific defines for netfilter. 
   * (C)1998 Rusty Russell -- This code is GPL.
   */

  #include <linux/netfilter.h>

  /* only for userspace compatibility */
  #ifndef __KERNEL__

  
  #include <limits.h> /* for INT_MIN, INT_MAX */

  /* IP Cache bits. */
  /* Src IP address. */
  #define NFC_IP_SRC		0x0001
  /* Dest IP address. */
  #define NFC_IP_DST		0x0002
  /* Input device. */
  #define NFC_IP_IF_IN		0x0004
  /* Output device. */
  #define NFC_IP_IF_OUT		0x0008
  /* TOS. */
  #define NFC_IP_TOS		0x0010
  /* Protocol. */
  #define NFC_IP_PROTO		0x0020
  /* IP options. */
  #define NFC_IP_OPTIONS		0x0040
  /* Frag & flags. */
  #define NFC_IP_FRAG		0x0080
  
  /* Per-protocol information: only matters if proto match. */
  /* TCP flags. */
  #define NFC_IP_TCPFLAGS		0x0100
  /* Source port. */
  #define NFC_IP_SRC_PT		0x0200
  /* Dest port. */
  #define NFC_IP_DST_PT		0x0400
  /* Something else about the proto */
  #define NFC_IP_PROTO_UNKNOWN	0x2000
  
  /* IP Hooks */
  /* After promisc drops, checksum checks. */
  #define NF_IP_PRE_ROUTING	0
  /* If the packet is destined for this box. */
  #define NF_IP_LOCAL_IN		1
  /* If the packet is destined for another interface. */
  #define NF_IP_FORWARD		2
  /* Packets coming from a local process. */
  #define NF_IP_LOCAL_OUT		3
  /* Packets about to hit the wire. */
  #define NF_IP_POST_ROUTING	4
  #define NF_IP_NUMHOOKS		5

  #endif /* ! __KERNEL__ */

  
  enum nf_ip_hook_priorities {
  	NF_IP_PRI_FIRST = INT_MIN,
  	NF_IP_PRI_CONNTRACK_DEFRAG = -400,
  	NF_IP_PRI_RAW = -300,
  	NF_IP_PRI_SELINUX_FIRST = -225,
  	NF_IP_PRI_CONNTRACK = -200,

  	NF_IP_PRI_MANGLE = -150,
  	NF_IP_PRI_NAT_DST = -100,

  	NF_IP_PRI_FILTER = 0,

  	NF_IP_PRI_SECURITY = 50,

  	NF_IP_PRI_NAT_SRC = 100,
  	NF_IP_PRI_SELINUX_LAST = 225,

  	NF_IP_PRI_CONNTRACK_CONFIRM = INT_MAX,

  	NF_IP_PRI_LAST = INT_MAX,
  };
  
  /* Arguments for setsockopt SOL_IP: */
  /* 2.0 firewalling went from 64 through 71 (and +256, +512, etc). */
  /* 2.2 firewalling (+ masq) went from 64 through 76 */
  /* 2.4 firewalling went 64 through 67. */
  #define SO_ORIGINAL_DST 80
  
  #ifdef __KERNEL__

  extern int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type);
  extern int ip_xfrm_me_harder(struct sk_buff *skb);

  extern __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,

  				   unsigned int dataoff, u_int8_t protocol);

  #endif /*__KERNEL__*/
  
  #endif /*__LINUX_IP_NETFILTER_H*/