Auto IP Update Script for Amazon EC2 Classic AND VPC instances

ip_update_amazon_ec2.sh

#!/bin/bash
#
# Auto IP Update Script for Amazon EC2 Classic AND VPC instances
#
# For detailed instructions, please see:
# https://blog.ls20.com/bash-script-for-automatic-ip-updates-on-amazon-ec2-or-digitalocean/
#
# Copyright (C) 2013 Lin Song
#
# This program 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 3 of the License, or (at your option) any later version.
#
# This program 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
# this program. If not, see http://www.gnu.org/licenses/.

MAC_ADDR=$(cat /sys/class/net/eth0/address)
LOCAL_IP=($(curl -s "http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC_ADDR}/local-ipv4s/"))
PUBLIC_IP=($(curl -s "http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC_ADDR}/public-ipv4s/"))
SUBNET_CIDR=$(curl -s "http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC_ADDR}/subnet-ipv4-cidr-block")

LOCAL_IP1=${LOCAL_IP[0]}; LOCAL_IP2=${LOCAL_IP[1]}
PUBLIC_IP1=${PUBLIC_IP[0]}; PUBLIC_IP2=${PUBLIC_IP[1]}
IP1_COMP=$(curl -s "http://169.254.169.254/latest/meta-data/network/interfaces/macs/${MAC_ADDR}/ipv4-associations/${PUBLIC_IP1}/")

IP_REGEX="^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"
CIDR_REGEX="^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])(\/(3[0-2]|[1-2]?[0-9]))$"

[ ! -f /root/IPADDR ] && { echo "IPADDR file does not exist! Aborting."; exit 1; }
. /root/IPADDR

[[ ! "${OLD_LOCAL_IP1}" =~ ${IP_REGEX} ]] && { echo "OLD LOCAL IP NOT FOUND OR INVALID! Aborting."; exit 1; }
[[ ! "${OLD_PUBLIC_IP1}" =~ ${IP_REGEX} ]] && { echo "OLD PUBLIC IP NOT FOUND OR INVALID! Aborting."; exit 1; }
[[ ! "${LOCAL_IP1}" =~ ${IP_REGEX} ]] && { echo "LOCAL IP NOT FOUND OR INVALID! Aborting."; exit 1; }
[[ ! "${PUBLIC_IP1}" =~ ${IP_REGEX} ]] && { echo "PUBLIC IP NOT FOUND OR INVALID! Aborting."; exit 1; }

TWOIP=0; SWAPIP=0
if [[ "${LOCAL_IP2}" =~ ${IP_REGEX} ]] && [[ "${PUBLIC_IP2}" =~ ${IP_REGEX} ]]; then
  TWOIP=1
  if [ "${IP1_COMP}" == "${LOCAL_IP2}" ]; then
    TEMPIP=${PUBLIC_IP1}; PUBLIC_IP1=${PUBLIC_IP2}; PUBLIC_IP2=${TEMPIP}
    SWAPIP=1
  fi
fi

# FOR PBX IN A FLASH (PIAF) USERS:
# FL1="/etc/asterisk/sip_general_additional.conf"
# FL2="/etc/asterisk/sip_general_custom.conf"

# FOR OPENSWAN/STRONGSWAN/LIBRESWAN VPN USERS:
# FL3="/etc/ipsec.conf"; FL4="/etc/ipsec.secrets"

if [[ "$OLD_LOCAL_IP1" != "$LOCAL_IP1" ]] || [[ "$OLD_PUBLIC_IP1" != "$PUBLIC_IP1" ]]; then
  sed -i "s/${OLD_LOCAL_IP1}/${LOCAL_IP1}/" YOUR_SOFTWARE_CONFIG_FILE
  sed -i "s/${OLD_PUBLIC_IP1}/${PUBLIC_IP1}/" YOUR_SOFTWARE_CONFIG_FILE
  
  sed -i "s/${OLD_LOCAL_IP1}/${LOCAL_IP1}/" YOUR_IPTABLES_RULES_FILE
  iptables -D ... ${OLD_LOCAL_IP1} ... # FILL IN YOUR DETAILS HERE
  iptables -A ... ${LOCAL_IP1} ...     # FILL IN YOUR DETAILS HERE

  # FOR PBX IN A FLASH (PIAF) USERS:
  # sed -i "s/${OLD_LOCAL_IP1}/${LOCAL_IP1}/" $FL1
  # sed -i "s/${OLD_PUBLIC_IP1}/${PUBLIC_IP1}/" $FL1
  
  # FOR OPENSWAN/STRONGSWAN/LIBRESWAN VPN USERS:
  # sed -i "s/${OLD_LOCAL_IP1}/${LOCAL_IP1}/" $FL3
  # sed -i "s/${OLD_PUBLIC_IP1}/${PUBLIC_IP1}/" $FL3
  # sed -i "s/${OLD_PUBLIC_IP1}/${PUBLIC_IP1}/" $FL4
fi

# FOR PBX IN A FLASH (PIAF) USERS:
# echo "tcpbindaddr=${LOCAL_IP1}" > $FL2; echo "bindaddr=${LOCAL_IP1}" >> $FL2
# echo "externip=${PUBLIC_IP1}" >> $FL2
# /usr/local/sbin/amportal kill
# /usr/local/sbin/amportal start

# FOR OPENSWAN/STRONGSWAN/LIBRESWAN VPN USERS:
# /sbin/service ipsec restart
# /sbin/service xl2tpd restart

echo "OLD_PUBLIC_IP1=${PUBLIC_IP1}" > /root/IPADDR
echo "OLD_LOCAL_IP1=${LOCAL_IP1}" >> /root/IPADDR

if [[ "${OLD_SUBNET_CIDR}" =~ ${CIDR_REGEX} ]] && [[ "${SUBNET_CIDR}" =~ ${CIDR_REGEX} ]]; then
  if [ "${OLD_SUBNET_CIDR}" != "${SUBNET_CIDR}" ]; then
    sed -i "s|${OLD_SUBNET_CIDR}|${SUBNET_CIDR}|" YOUR_SOFTWARE_CONFIG_FILE
  fi
  echo "OLD_SUBNET_CIDR=${SUBNET_CIDR}" >> /root/IPADDR
fi

[ "$SWAPIP" == "1" ] && echo "IP_SWAPPED=1" >> /root/IPADDR
if [ "$TWOIP" == "1" ]; then
  ip addr add dev eth0 "${LOCAL_IP2}/24"
  echo "OLD_PUBLIC_IP2=${PUBLIC_IP2}" >> /root/IPADDR
  echo "OLD_LOCAL_IP2=${LOCAL_IP2}" >> /root/IPADDR
fi