everydns dynamic ip updater

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I setup a free EveryDNS account today. I wanted to do a dynamic ip address, for a subdomain off my main domain.

I setup an ns record in my main domain, to give authority over the subdomain to the everydns nameservers.

I didn't like the perl script that everydns provides to update the mapping. I wanted a simple shell script that I could cron.

So, I wrote this.

#!/bin/bash
DOMAIN="your.domain.net"
USER="username"
PASS="password"
VER="0.1"

IP=$(wget -q http://whatismyip.com -O - | grep -m1 -oE "([0-9]{1,3}\.?){4}")

if [ -r "/tmp/oldip.txt" ]; then
  OLDIP=`cat /tmp/oldip.txt`
  if [ "$OLDIP" = "$IP" ]; then exit 0; fi
fi

echo $IP > /tmp/oldip.txt

wget -q --http-user="${USER}" --http-password="${PASS}" "http://dyn.everydns.net/index.php?ver=${VER}&ip=${IP}&domain=${DOMAIN}" -O -

I set that cron to run once an hour.

0 * * * * /path/to/dydns.sh >>/dev/null 2>&1

Works great!