function update_static_routes () {
   local action static_routes destination gateway
   action=$1
   static_routes="$2 "   # add space for easy looping
   while [ "$static_routes" ]; do
     destination=${static_routes%% *}
     static_routes=${static_routes#* }
     gateway=${static_routes%% *}
     static_routes=${static_routes#* }
     route $action $destination gw $gateway
   done
}
if [ x$new_broadcast_address != x ]; then
  new_broadcast_arg="broadcast $new_broadcast_address"
fi
if [ x$old_broadcast_address != x ]; then
  old_broadcast_arg="broadcast $old_broadcast_address"
fi
if [ x$new_subnet_mask != x ]; then
  new_subnet_arg="netmask $new_subnet_mask"
fi
if [ x$old_subnet_mask != x ]; then
  old_subnet_arg="netmask $old_subnet_mask"
fi
if [ x$alias_subnet_mask != x ]; then
  alias_subnet_arg="netmask $alias_subnet_mask"
fi
if [ x$reason = xMEDIUM ]; then
  # Linux doesn't do mediums (ok, ok, media).
  exit 0
fi
if [ x$reason = xPREINIT ]; then
  if [ x$alias_ip_address != x ]; then
    # Bring down alias interface. Its routes will disappear too.
    ifconfig $interface:0- inet 0
  fi
  ifconfig $interface inet 0.0.0.0 netmask 0.0.0.0 \
                broadcast 255.255.255.255 up
  # Add route to make broadcast work. Do not omit netmask.
  route add default dev $interface netmask 0.0.0.0
  exit 0
fi
if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
  exit 0;
fi

if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then
  if [ x$old_ip_address != x ] && [ x$alias_ip_address != x ] && \
                [ x$alias_ip_address != x$old_ip_address ]; then
    # Possible new alias. Remove old alias.
    ifconfig $interface:0- inet 0
  fi
  if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
    # IP address changed. Bringing down the interface will delete all routes,
    # and clear the ARP cache.
    ifconfig $interface inet down
  fi
  if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
     [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then
    ifconfig $interface inet $new_ip_address $new_subnet_arg \
       $new_broadcast_arg
    # Add a network route to the computed network address.
    route add -net $new_network_number $new_subnet_arg dev $interface
    for router in $new_routers; do
      route add default gw $router
    done
    # don't need to test old values for domain/host
    # no problems if resetting them to identical value??
    if [ x$new_nis_domain != x ]; then
      echo $new_nis_domain >/etc/defaultdomain
      nisdomainname `cat /etc/defaultdomain`
    fi
    if [ x$new_host_name != x ]; then
      echo $new_host_name >/etc/hostname
      hostname --file /etc/hostname
    fi
    # old and new static routes different?
    if [ "x$old_static_routes" != "x$new_static_routes" ]; then
      # delete old static routes if they existed
      if [ "x$old_static_routes" != "x" ]; then
        update_static_routes "del -net" "$old_static_routes"
      fi
      # add new static routes if they exist
      if [ "x$new_static_routes" != "x" ]; then
        update_static_routes "add -net" "$new_static_routes"
      fi
    fi
  fi
  if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
   then
    ifconfig $interface:0- inet 0
    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
    route add -host $alias_ip_address $interface:0
  fi
  echo domain $new_domain_name >/etc/resolv.conf
  for nameserver in $new_domain_name_servers; do
    echo nameserver $nameserver >>/etc/resolv.conf
  done
  exit 0
fi
if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ]; then
  if [ x$alias_ip_address != x ]; then
    # Turn off alias interface.
    ifconfig $interface:0- inet 0
  fi
  if [ x$old_ip_address != x ]; then
    # Shut down interface, which will delete routes and clear arp cache.
    ifconfig $interface inet down
  fi
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
    route add -host $alias_ip_address $interface:0
  fi
  # dhclient will now try to restart itself: re-init the interface.
  reason=PREINIT exec $0
  #exit 0
fi
if [ x$reason = xTIMEOUT ]; then
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0- inet 0
  fi
  ifconfig $interface inet $new_ip_address $new_subnet_arg \
      $new_broadcast_arg
  set $new_routers
  ############## what is -w in ping?
  if ping -q -c 1 -w 1 $1; then
    if [ x$new_ip_address != x$alias_ip_address ] && \
       [ x$alias_ip_address != x ]; then
      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
      route add -host $alias_ip_address dev $interface:0
    fi
    route add -net $new_network_number
    for router in $new_routers; do
      route add default gw $router
    done
    # don't need to test old values for domain/host
    # no problems if resetting them to identical value??
    if [ x$new_nis_domain != x ]; then
      echo $new_nis_domain >/etc/defaultdomain
      nisdomainname `cat /etc/defaultdomain`
    fi
    if [ x$new_host_name != x ]; then
      echo $new_host_name >/etc/hostname
      hostname --file /etc/hostname
    fi
    # old and new static routes different?
    if [ "x$old_static_routes" != "x$new_static_routes" ]; then
      # delete old static routes if they existed
      if [ "x$old_static_routes" != "x" ]; then
        update_static_routes "del -net" "$old_static_routes"
      fi
      # add new static routes if they exist
      if [ "x$new_static_routes" != "x" ]; then
        update_static_routes "add -net" "$new_static_routes"
      fi
    fi
    echo domain $new_domain_name >/etc/resolv.conf.std
    for nameserver in $new_domain_name_servers; do
      echo nameserver $nameserver >>/etc/resolv.conf.std
    done
    if [ -f /etc/resolv.conf ]; then
      rm -f /etc/resolv.conf
      ln /etc/resolv.conf.std /etc/resolv.conf
    fi
    exit 0
  fi
  ifconfig $interface inet down
  exit 1
fi
exit 0

