Dynamic IPv6 Firewall Update Script for OpenWRT

dynamic_ipv6_update.sh

#!/bin/sh

# CONFIGURABLE PARAMETER: PREFIX
# Set the prefix to the name of the rules that need to be updated. (Can update multiple rules with same name)
PREFIX=Web-ServerIPv6
PREFIX_LEN=${#PREFIX}

# CONFIGURABLE PARAMETER: getIP
# Set your method of getting IPv6 address in here
# Current method is through ip neighbor with MAC address (Lowercase, :)(getIP=$(ip neighbor | grep "Your MAC Here" | grep -v "STALE" | cut -d" " -f1))
# One example is wget which accesses a page on the web-server showing current IP address (getIP=$(wget --read-timeout=10 http://checkipv6.dyndns.com -q -O -))
# Another option could be nslookup your domain to get the IPv6 address. getIP=$(nslookup -query=AAAA $hostname)
printf "Getting your IPv6 address... \n"
getIP=$(ip -6 neigh | grep "YOUR MAC ADDRESS" | grep -v "STALE" | grep -v "fe80" | cut -d" " -f1)

if [ "$getIP" = "" ]
then
    printf "Failed to get IP."
    exit 0
fi

# Set m flag accordingly, only first match is accepted.
prefix6=$(echo "$getIP" | grep -m 1 -E -o "([0-9a-fA-F]{1,4}(:?)){8}")

if [ "$prefix6" = "" ]
then
    printf "Request successful, but no IPv6 detected. \n"
    exit 0
fi

printf "Your current IPv6: {$prefix6}\n\n"

changed=0
index=0
name=$(uci get firewall.@rule[$index].name 2> /dev/null)

while [ "$name" != "" ]
do
    subname=${name:0:$PREFIX_LEN}

    if [ "$subname" == "$PREFIX" ]
    then
        dest_ip=$(uci get firewall.@rule[$index].dest_ip 2> /dev/null)
        printf "Current stored IP address: {$dest_ip} \n"

        if [ "$dest_ip" != "$prefix6" ]
        then
            printf "The IP has changed! \n"
            printf "Updating\n\n"
            changed=1
            uci set firewall.@rule[$index].dest_ip=$prefix6
            uci commit firewall
        else
            printf "IP is the same, no changes made.\n"
        fi

        break 2
    fi

    index=$(expr $index + 1)
    name=$(uci get firewall.@rule[$index].name 2> /dev/null)
done

if [ $changed -eq 1 ] 
then
    printf "Restarting firewall... \n"
    /etc/init.d/firewall reload 2> /dev/null
    printf "All up to date. \n"
fi

exit 0