UFW Updater (MySQL)

ufw-updater.sh

#!/bin/bash

target_hosts="dynhost.does-not-exist.com another-host.does-not-exist.com"

if [ -f "/root/mysql-allow-hosts-current" ]; then
    mv /root/mysql-allow-hosts-current /root/mysql-allow-hosts-prev
fi

touch /root/mysql-allow-hosts-current

if [ -f "/root/mysql-allow-hosts-prev" ]; then
    # Remove previously set firewall allows
    for prev_ip in `cat /root/mysql-allow-hosts-prev`; do
        ufw delete allow from $prev_ip to any port 3306 > /dev/null
    done
fi

for target_host in $target_hosts; do
    # Look up IP per host
    # echo "Looking up IP for host:" $target_host
    target_ip=`host $target_host | cut -d ' ' -f 4`
    if [ $? -eq 0 ]; then
        echo $target_ip >> /root/mysql-allow-hosts-current
        ufw allow from $target_ip to any port 3306 > /dev/null
    fi
done

Adapted from awesome script here: http://superuser.com/questions/79855/how-to-use-fqdn-in-firewall-rules-for-gnu-linux/84988#84988