IPIP Tunnel Maker

ipip.sh

#!/bin/bash
# this script creates an IPIP Tunnel
# tested for CENTOS 6 & 7

#----------------------------
#        CONFIGURATION 
#----------------------------

# name of tunnel
name='tun_test'   

# local virtual ipv4 address for the tunnel
# example:  hostA 192.168.5.1,  hostB 192.168.5.2
inner='192.168.5.1'

# local ipv4 address
# example: hostA 192.168.30.10,  hostB: 145.30.200.5
outer='192.168.30.10'

# partner tunnel ipv4 address
# example: hostA 145.30.200.5,  hostB: 192.168.30.10
peer='145.30.200.5'

#------------------------

# check if Redhat or Centos
OSVER=$(awk -F= '/^NAME/{print $2}' /etc/os-release | tr -d '"')
[ "${OSVER}" != "CentOS Linux" ] && echo "Host is not Centos or Redhat, exiting" && exit 1

# IP packet forwarding
sysctl -w net.ipv4.ip_forward=1

# enable tunnel mods
modprobe ip_tunnel
modprobe tun

ARG=${1:?"No argument was passed: ./ipip.sh up / down"}
SYSCFGDIR='/etc/sysconfig/network-scripts'

if [[ $ARG == 'up' ]]
then
    # bring up the tunnel
    ip tunnel add $name mode ipip remote $peer local $outer
    ip link set $name up
    ip addr add $inner/30 dev $name

    # create permanent tunnel
    echo -e "TYPE=IPIP
BOOTPROTO=none
DEVICE=$name
ONBOOT=yes
MY_INNER_IPADDR=$inner
MY_OUTER_IPADDR=$outer
PEER_OUTER_IPADDR=$peer" > $SYSCFGDIR/ifcfg-$name
fi

if [[ $ARG == 'down' ]]
then
    ip link set dev $name down
    ip link delete $name
    [ -f $SYSCFGDIR/ifcfg-$name ] && rm -f $SYSCFGDIR/ifcfg-$name
fi