Restrict access to server from dyn ip

This script will configure the ufw of target host to allow HOSTNAME access.

• Your hostname should be resolvable by DNS

user@host ~ # mkdir -p scripts/dynip
user@host ~ # cd scripts/dynip

Dynip-ufw.sh

#!/usr/bin/bash
HOSTNAME=<HOSTNAME>          # <-- set this to your dynamic hostname
BASEDIR=$HOME/scripts/ufw    # <-- set this to the created directory
IPFILE=${BASEDIR}/currip
 
LOGFILE=${BASEDIR}/ufw.log
 
Current_IP=$(host ${HOSTNAME} | head -n1 | cut -f4 -d ' ')
 
NOW=$(date)
 
echo "${NOW} - Current IP: ${Current_IP}" >> ${LOGFILE}
 
if [ ! -f ${IPFILE} ]; then
        /usr/sbin/ufw allow from ${Current_IP} to any port 22 proto tcp
        echo ${Current_IP} >> ${IPFILE}
else
 
Old_IP=$(cat ${IPFILE})
  echo "${NOW} - Old IP: ${Old_IP}"
  if [ "${Current_IP}" = "${Old_IP}" ] ; then
        echo ${NOW} - IP address has not changed >> ${LOGFILE}
  else
        /usr/sbin/ufw delete allow from ${Old_IP} proto tcp to any port 22
        /usr/sbin/ufw allow from ${Current_IP} proto tcp to any port 22
 
        /usr/sbin/ufw delete allow from ${Old_IP} proto tcp to any port 81
        /usr/sbin/ufw allow from ${Current_IP} proto tcp to any port 81
 
        #/usr/sbin/ufw delete allow from ${Old_IP} proto tcp to any port 9000
        #/usr/sbin/ufw allow from ${Current_IP} proto tcp to any port 9000
 
        #/usr/sbin/ufw delete allow from $Old_IP proto tcp to any port 80
        #/usr/sbin/ufw allow from $Current_IP proto tcp to any port 80
 
        echo ${Current_IP} > ${IPFILE}
        /usr/sbin/ufw status numbered >> ${LOGFILE}
        echo ${NOW} - iptables have been updated >> ${LOGFILE}
  fi
fi