diff --git a/lib/if.h b/lib/if.h
new file mode 100644
index 0000000..3896d18
--- /dev/null
+++ b/lib/if.h
@@ -0,0 +1,222 @@
+/* Interface related header.
+   Copyright (C) 1997, 98, 99 Kunihiro Ishiguro
+
+This file is part of GNU Zebra.
+
+GNU Zebra is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published
+by the Free Software Foundation; either version 2, or (at your
+option) any later version.
+
+GNU Zebra is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Zebra; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#ifndef _ZEBRA_IF_H
+#define _ZEBRA_IF_H
+
+#include "linklist.h"
+
+/*
+  Interface name length.
+
+   Linux define value in /usr/include/linux/if.h.
+   #define IFNAMSIZ        16
+
+   FreeBSD define value in /usr/include/net/if.h.
+   #define IFNAMSIZ        16
+*/
+
+#define INTERFACE_NAMSIZ      20
+#define INTERFACE_HWADDR_MAX  20
+
+/* Internal If indexes start at 0xFFFFFFFF and go down to 1 greater
+   than this */
+#define IFINDEX_INTERNBASE 0x80000000
+
+#ifdef HAVE_PROC_NET_DEV
+struct if_stats
+{
+  unsigned long rx_packets;   /* total packets received       */
+  unsigned long tx_packets;   /* total packets transmitted    */
+  unsigned long rx_bytes;     /* total bytes received         */
+  unsigned long tx_bytes;     /* total bytes transmitted      */
+  unsigned long rx_errors;    /* bad packets received         */
+  unsigned long tx_errors;    /* packet transmit problems     */
+  unsigned long rx_dropped;   /* no space in linux buffers    */
+  unsigned long tx_dropped;   /* no space available in linux  */
+  unsigned long rx_multicast; /* multicast packets received   */
+  unsigned long rx_compressed;
+  unsigned long tx_compressed;
+  unsigned long collisions;
+
+  /* detailed rx_errors: */
+  unsigned long rx_length_errors;
+  unsigned long rx_over_errors;       /* receiver ring buff overflow  */
+  unsigned long rx_crc_errors;        /* recved pkt with crc error    */
+  unsigned long rx_frame_errors;      /* recv'd frame alignment error */
+  unsigned long rx_fifo_errors;       /* recv'r fifo overrun          */
+  unsigned long rx_missed_errors;     /* receiver missed packet     */
+  /* detailed tx_errors */
+  unsigned long tx_aborted_errors;
+  unsigned long tx_carrier_errors;
+  unsigned long tx_fifo_errors;
+  unsigned long tx_heartbeat_errors;
+  unsigned long tx_window_errors;
+};
+#endif /* HAVE_PROC_NET_DEV */
+
+/* Interface structure */
+struct interface 
+{
+  /* Interface name. */
+  char name[INTERFACE_NAMSIZ + 1];
+
+  /* Interface index. */
+  unsigned int ifindex;
+
+  /* Zebra internal interface status */
+  u_char status;
+#define ZEBRA_INTERFACE_ACTIVE     (1 << 0)
+#define ZEBRA_INTERFACE_SUB        (1 << 1)
+  
+  /* Interface flags. */
+  unsigned long flags;
+
+  /* Interface metric */
+  int metric;
+
+  /* Interface MTU. */
+  int mtu;
+
+  /* Hardware address. */
+#ifdef HAVE_SOCKADDR_DL
+  struct sockaddr_dl sdl;
+#else
+  unsigned short hw_type;
+  u_char hw_addr[INTERFACE_HWADDR_MAX];
+  int hw_addr_len;
+#endif /* HAVE_SOCKADDR_DL */
+
+  /* interface bandwidth, kbits */
+  unsigned int bandwidth;
+  
+  /* description of the interface. */
+  char *desc;			
+
+  /* Distribute list. */
+  void *distribute_in;
+  void *distribute_out;
+
+  /* Connected address list. */
+  list connected;
+
+  /* Daemon specific interface data pointer. */
+  void *info;
+
+  /* Statistics fileds. */
+#ifdef HAVE_PROC_NET_DEV
+  struct if_stats stats;
+#endif /* HAVE_PROC_NET_DEV */  
+#ifdef HAVE_NET_RT_IFLIST
+  struct if_data stats;
+#endif /* HAVE_NET_RT_IFLIST */
+};
+
+/* Connected address structure. */
+struct connected
+{
+  /* Attached interface. */
+  struct interface *ifp;
+
+  /* Flags for configuration. */
+  u_char conf;
+#define ZEBRA_IFC_REAL         (1 << 0)
+#define ZEBRA_IFC_CONFIGURED   (1 << 1)
+
+  /* Flags for connected address. */
+  u_char flags;
+#define ZEBRA_IFA_SECONDARY   (1 << 0)
+
+  /* Address of connected network. */
+  struct prefix *address;
+  struct prefix *destination;
+
+  /* Label for Linux 2.2.X and upper. */
+  char *label;
+};
+
+/* Interface hook sort. */
+#define IF_NEW_HOOK   0
+#define IF_DELETE_HOOK 1
+
+/* There are some interface flags which are only supported by some
+   operating system. */
+
+#ifndef IFF_NOTRAILERS
+#define IFF_NOTRAILERS 0x0
+#endif /* IFF_NOTRAILERS */
+#ifndef IFF_OACTIVE
+#define IFF_OACTIVE 0x0
+#endif /* IFF_OACTIVE */
+#ifndef IFF_SIMPLEX
+#define IFF_SIMPLEX 0x0
+#endif /* IFF_SIMPLEX */
+#ifndef IFF_LINK0
+#define IFF_LINK0 0x0
+#endif /* IFF_LINK0 */
+#ifndef IFF_LINK1
+#define IFF_LINK1 0x0
+#endif /* IFF_LINK1 */
+#ifndef IFF_LINK2
+#define IFF_LINK2 0x0
+#endif /* IFF_LINK2 */
+
+/* Prototypes. */
+struct interface *if_new (void);
+struct interface *if_create (void);
+struct interface *if_lookup_by_index (unsigned int);
+struct interface *if_lookup_by_name (char *);
+struct interface *if_lookup_exact_address (struct in_addr);
+struct interface *if_lookup_address (struct in_addr);
+struct interface *if_get_by_name (char *);
+void if_delete (struct interface *);
+int if_is_up (struct interface *);
+int if_is_loopback (struct interface *);
+int if_is_broadcast (struct interface *);
+int if_is_pointopoint (struct interface *);
+int if_is_multicast (struct interface *);
+void if_add_hook (int, int (*)(struct interface *));
+void if_init ();
+void if_dump_all ();
+char *ifindex2ifname (unsigned int);
+
+/* Connected address functions. */
+struct connected *connected_new ();
+void connected_free (struct connected *);
+void connected_add (struct interface *, struct connected *);
+struct connected  *connected_delete_by_prefix (struct interface *, struct prefix *);
+int ifc_pointopoint (struct connected *);
+
+#ifndef HAVE_IF_NAMETOINDEX
+unsigned int if_nametoindex (const char *);
+#endif
+#ifndef HAVE_IF_INDEXTONAME
+char *if_indextoname (unsigned int, char *);
+#endif
+
+/* Exported variables. */
+extern list iflist;
+extern struct cmd_element interface_desc_cmd;
+extern struct cmd_element no_interface_desc_cmd;
+extern struct cmd_element interface_cmd;
+extern struct cmd_element interface_pseudo_cmd;
+extern struct cmd_element no_interface_pseudo_cmd;
+
+#endif /* _ZEBRA_IF_H */