ipip_tunnel.sh

#!/bin/bash

LOCAL_IP=$(hostname -i)
REMOTE_IP=$1
LOCAL_TUNNEL_IP=$2
REMOTE_TUNNEL_IP=$3

display_usage() {
    echo -e "\nUsage: $0 [remote ip address] [local tunnel ip] [remote tunnel ip] \n"
}

if [ $# -lt 3 ]
then
    display_usage
    exit 1
fi

if [[ $USER != "root" ]]; then
    echo "This script must be run as root!"
    exit 1
fi

modprobe ipip
ip tunnel add tunl1 mode ipip remote $REMOTE_IP local $LOCAL_IP ttl 255
ifconfig tunl1 $LOCAL_TUNNEL_IP
route add -host $REMOTE_TUNNEL_IP dev tunl1