#!/bin/sh

   ENDPOINT=129.100.33.20

   case "$2" in
   up|dhcp4-change)
       route=$(ip -4 route show default | awk 'NR==1')
       gateway=$(echo "$route" | awk '{for (i=1;i<=NF;i++) if ($i=="via") print $(i+1)}')
       device=$(echo "$route" | awk '{for (i=1;i<=NF;i++) if ($i=="dev") print $(i+1)}')

       if [ -n "$gateway" ] && [ -n "$device" ]; then
           ip -4 route replace "$ENDPOINT/32" via "$gateway" dev "$device"
       fi
       ;;
   esac