Dynamic DNS with Zerigo and a cron job

update-ip

#!/bin/bash

# Run `crontab -e` and add this line:
#  */1 *   *  *  *     /Users/youraccount/bin/update-ip

# Enable API access under Zerigo's DNS / Preferences / API Access and Dynamic Updates
# Then get your API key from that same page after you save the form.

ZERIGO_HOSTNAME=host.example.com
ZERIGO_USERNAME=email%40gmail.com
ZERIGO_API_KEY=BiGrAnDoMkEyGoEsHeRe 

IP_CACHE_FILE="$(dirname $0)/update-ip.cache"

if [[ -r "$IP_CACHE_FILE" ]]; then
    LAST_KNOWN_IP=$(< "$IP_CACHE_FILE")
fi

CURRENT_IP=$(curl -s http://checkip4.zerigo.com/ | perl -pe 's{<ipv4>(.*?)</ipv4>}{$1}')

if [[ "$CURRENT_IP" != "$LAST_KNOWN_IP" ]]; then
    echo "Updating IP Address -- ${LAST_KNOWN_IP} -> ${CURRENT_IP}"
    curl -s "http://update.zerigo.com/dynamic?host=${ZERIGO_HOSTNAME}&user=${ZERIGO_USERNAME}&password=${ZERIGO_API_KEY}"
    echo "$CURRENT_IP" > "$IP_CACHE_FILE"
fi