text: #ifndef __LINUX_IP6_NETFILTER_H
  #define __LINUX_IP6_NETFILTER_H
  
  /* IPv6-specific defines for netfilter. 
   * (C)1998 Rusty Russell -- This code is GPL.
   * (C)1999 David Jeffery
   *   this header was blatantly ripped from netfilter_ipv4.h 
   *   it's amazing what adding a bunch of 6s can do =8^)
   */
  
  #include <linux/netfilter.h>
  
  /* only for userspace compatibility */
  #ifndef __KERNEL__
  /* IP Cache bits. */
  /* Src IP address. */
  #define NFC_IP6_SRC              0x0001
  /* Dest IP address. */
  #define NFC_IP6_DST              0x0002
  /* Input device. */
  #define NFC_IP6_IF_IN            0x0004
  /* Output device. */
  #define NFC_IP6_IF_OUT           0x0008
  /* TOS. */
  #define NFC_IP6_TOS              0x0010
  /* Protocol. */
  #define NFC_IP6_PROTO            0x0020
  /* IP options. */
  #define NFC_IP6_OPTIONS          0x0040
  /* Frag & flags. */
  #define NFC_IP6_FRAG             0x0080
  
  
  /* Per-protocol information: only matters if proto match. */
  /* TCP flags. */
  #define NFC_IP6_TCPFLAGS         0x0100
  /* Source port. */
  #define NFC_IP6_SRC_PT           0x0200
  /* Dest port. */
  #define NFC_IP6_DST_PT           0x0400
  /* Something else about the proto */
  #define NFC_IP6_PROTO_UNKNOWN    0x2000
  #endif /* ! __KERNEL__ */
  
  
  /* IP6 Hooks */
  /* After promisc drops, checksum checks. */
  #define NF_IP6_PRE_ROUTING	0
  /* If the packet is destined for this box. */
  #define NF_IP6_LOCAL_IN		1
  /* If the packet is destined for another interface. */
  #define NF_IP6_FORWARD		2
  /* Packets coming from a local process. */
  #define NF_IP6_LOCAL_OUT		3
  /* Packets about to hit the wire. */
  #define NF_IP6_POST_ROUTING	4
  #define NF_IP6_NUMHOOKS		5
  
  
  enum nf_ip6_hook_priorities {
  	NF_IP6_PRI_FIRST = INT_MIN,
  	NF_IP6_PRI_CONNTRACK_DEFRAG = -400,
  	NF_IP6_PRI_SELINUX_FIRST = -225,
  	NF_IP6_PRI_CONNTRACK = -200,
  	NF_IP6_PRI_MANGLE = -150,
  	NF_IP6_PRI_NAT_DST = -100,
  	NF_IP6_PRI_FILTER = 0,
  	NF_IP6_PRI_NAT_SRC = 100,
  	NF_IP6_PRI_SELINUX_LAST = 225,
  	NF_IP6_PRI_LAST = INT_MAX,
  };
  
  #ifdef CONFIG_NETFILTER
  extern int ip6_route_me_harder(struct sk_buff *skb);
  extern __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  				    unsigned int dataoff, u_int8_t protocol);
  
  extern int ipv6_netfilter_init(void);
  extern void ipv6_netfilter_fini(void);
  #else /* CONFIG_NETFILTER */
  static inline int ipv6_netfilter_init(void) { return 0; }
  static inline void ipv6_netfilter_fini(void) { return; }
  #endif /* CONFIG_NETFILTER */
  
  #endif /*__LINUX_IP6_NETFILTER_H*/
  