Dyn SLA Update – or, How To Lose Friends and Alienate Customers

I today received an email from Dyn (previously DynDNS), stating:

Starting now, if you would like to maintain your free Dyn account, you must log into your account once a month. Failure to do so will result in expiration and loss of your hostname. Note that using an update client will no longer suffice for this monthly login.

(emphasis theirs)

Now, if this were a service which requires interaction then this would be an unfriendly but potentially fair way to weed-out inactive accounts. This isn’t one of those cases, though – I can happily go for months or even years where my only interaction with Dyn(DNS) is via auto-update clients. And this is the heart of the problem – many routers and embedded devices have built-in DynDNS clients, frequently with no option to switch to an alternative service. Possibly this is worth $25/year, possibly it isn’t. Personally, I’m not paying a penny to a company trying to hold its users to ransom like this. For my usage, there are a handful for hostnames in a Dyn(DNS) domain – and therefore these cannot to transferred to a different provider. I keep them going purely so that historic links will still work.

And, to resolve the immediate problem, I wrote this script which can be scheduled to run every 15 days in order to keep my account active – enjoy!



#UA="Mozilla/5.0 (Macintosh; Intel Mac OS X) AppleWebKit/0.0.0 (KHTML, like Gecko) Version/0.0.0 Safari/0.0.0"


(( DEBUG )) && DST="-" || DST="/dev/null"

[[ -w "$( dirname "$COOKIES" )" ]] || { echo >&2 "FATAL: Cannot write to directory '$( dirname "$COOKIES" )'" ; exit 1; }

# Ensure no broken session caching...
if [[ -s "$COOKIES" ]]; then
	[[ -w "$COOKIES" ]] || { echo >&2 "FATAL: Cannot write to file '$COOKIES'" ; exit 1 ; }
	rm -f "$COOKIES" >/dev/null 2>&1

(( DEBUG )) && echo >&2 "DEBUG: Fetching initial headers to pre-load cookies..."
curl -b $COOKIES -c $COOKIES -Ikso "$DST" -A "$UA" --url "$LOGINURL"

(( DEBUG )) && echo >&2 "DEBUG: Fetching UID..."
	   curl -b $COOKIES -c $COOKIES -kso - -A "$UA" --url "$LOGINURL" | \
	   grep -m 1 "multiform" | \
	   cut -d"'" -f 6

(( DEBUG )) && echo >&2 "DEBUG: Read UID as '$VALUE' - posting data..."
curl -b $COOKIES -c $COOKIES -d "username=$LOGIN" -d "password=$PASSWORD" -d "iov_id" -d "multiform=$VALUE" -e "$LOGINURL" -kso "$DST" -A "$UA" --url "$POSTURL"

(( DEBUG )) && echo >&2 "DEBUG: Response received - verifying result..."
curl -b $COOKIES -c $COOKIES -e "$POSTURL" -kso - -A "$UA" -H "Accept-Language: $AL" --url "$CHKURL" | \
	   grep -qE "<span>(Welcome|Hi)&nbsp;<b>$LOGIN</b></span>" \
	&& echo "Login successful" \
	|| { echo >&2 "Login failed" ; exit 1 ; }

exit 0

Download this script from http://files.stuart.shelton.me/unix/dyndns-login.sh.