update_ddns.sh

#!/bin/bash

# Set up your username stuff here:
DDNS_USER=YOUR_USERNAME
DDNS_PASS=YOUR_PASS
DDNS_PREFIX=YOUR_DDNS_PREFIX

IP_TMP=/tmp/current_ip
CURL_PATH=/usr/bin/curl
current_ip=$(${CURL_PATH} -s whatismyip.akamai.com)

update_ip() {
    echo $current_ip > $IP_TMP
	${CURL_PATH} http://${DDNS_USER}:${DDNS_PASS}@members.3322.net/dyndns/update?hostname=${DDNS_PREFIX}.f3322.net > /dev/null 2>&1
}

if [ -f $IP_TMP ];then
  saved_ip=$(cat ${IP_TMP})
  if [ $saved_ip != $current_ip ];then
  	update_ip
  fi
  unset saved_ip
else
  update_ip
fi

unset YOUR_USERNAME YOUR_PASS YOUR_DDNS_PREFIX
unset IP_TMP CURL_PATH current_ip