Dynamic DNS script for Amazon Route53

dynamic_dns.sh

#!/bin/bash
# Update Dynamic DNS

CURRENTIP=""
IPADDR=""

# Various get IP websites
# WWW_IP=http://www.focb.co.nz/myip.php
WWW_IP=http://icanhazip.com/

# Route53 settings, AWS keys are in boto config
ROUTE53_HOST_LIST="nutmeg.maungawhau.net.nz. maungawhau.net.nz." # notice trailing dot
ROUTE53_ZONEID="xxxxxx" # Zone ID here
ROUTE53=/usr/local/bin/route53

IPFILE=/var/tmp/dynamic-dns.ip
[ -f $IPFILE ] && CURRENTIP=$(cat $IPFILE)

IPADDR=$(curl -s $WWW_IP)
[ -z "$IPADDR" ] && IPADDR=$PPP_LOCAL

# abort if the IP is localhost - probably right after a reboot?
[ "$IPADDR" = "127.0.0.1" ] && exit

if [ ! "$IPADDR" = "$CURRENTIP" ]; then
        logger -t "Dynamic DNS" "Updating DNS to new IP ($IPADDR)"
    
    # Update AWS Route53
    for ROUTE53_HOST in $ROUTE53_HOST_LIST;
    do
        ROUTE53_IP=$($ROUTE53 get $ROUTE53_ZONEID | awk '/^'${ROUTE53_HOST}'/{print $4}' | tr -d '\n')
        if [ -z "$ROUTE53_IP" ]; then
            # no record for this hostname - better make one
            logger -t "Dynamic DNS" "Creating new Route53 record $ROUTE53_HOST $IPADDR"
            $ROUTE53 add_record $ROUTE53_ZONEID $ROUTE53_HOST A $IPADDR
        elif [ "$ROUTE53_IP" != "$IPADDR" ]; then
            # update the record
            logger -t "Dynamic DNS" "Updating Route53 record for $ROUTE53_HOST from $ROUTE53_IP to $IPADDR"
            $ROUTE53 change_record $ROUTE53_ZONEID $ROUTE53_HOST A $IPADDR
        else
            logger -t "Dynamic DNS" "Route53 IP unchanged ($IPADDR)"
        fi
        
            echo >$IPFILE $IPADDR
    done
else
        logger -t "Dynamic DNS" "External IP unchanged ($IPADDR)"
fi