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

SSH into your router and create a file, call it whatever you like, mine is called “dynamic_ipv6_update” with ‘chmod +x’ for execution.
Paste the code into the file, editing the PREFIX to whatever you called your Traffic Rule, and set the MAC address to your server’s MAC address (use lowercase and colons).
Test run the script, it will talk you through what is happening.
Create a cronjob to run the file (can be done through Luci in System->Scheduled Tasks). Mine is “*/20 * * * * /usr/bin/dynamic_ipv6_update > /dev/null 2>&1”