All this work was done by Eric Calder - I've just tweaked a few lines since
Eric's trick to retrieve external IPs wasn't working. I've replaced it with
whatismyip.org, which seems to work nicely. Ideally, I would query my 
router/gateway but this is very device specific.

Next improvement will be for the script to accept more than one hostname: I
have several names to update, but certainly don't want them all pointing
to the same IP, which is Eric's default behaviour if no hostname is specified.

Also, keep in mind that I only care about Linux functionality and may have 
broken OSX & Windows compatibility. In particular, the install script is now
Linux (CentOS) only. See the original at perl.arix.com.

Peter Krnjevic  2012/2/10

======================================================

SYNOPSIS

    This utility implements a client for the afraid.org dynamic DNS service.
    A cron job is set up to check whether the external IP address has
    changed, and when it does, connects to afraid.org and updates the
    DNS entries of all the domains of the given account.

SUPPORTED OPERATING SYSTEMS

   * Fedora
   * CentOS
   * RHEL
   * OSX

INSTALL

    1. log in as root (needed to access config, cron and cache directories):
        # su -
    2. Download the tarball:
	    # cd /tmp
	    # wget ftp://arix.com/afraid-dyndns-x.x.tar.gz

	    on OSX, you can use:
        # curl -O ftp://[email protected]/afraid-dyndns-x.x.tar.gz
    3. Untar:
	    # tar xzvf afraid-dyndns-x.x.tgz
    4. Install:
	    # cd afraid-dyndns-x.x
	    # ./install

CONFIGURATION

   To configure, edit the /etc/afraid-dyndns.conf file.  The AccountHash
   field refers to the SHA value assigned to your afraid.org account.
   To get it, log into afraid.org and visit:

	   http://freedns.afraid.org/api/

   then click on either of your "ChoOsE YoUr WeApOn" links and take
   the value of the "sha" parameter (it's a long string). The Notify
   address (if present) will be sent e-mail whenever the DNS is
   refreshed.  CacheFile is the file name where the external IP address
   will be cached.

   Additionally, the cron job checks the external IP address every 15
   minutes.  To modify this, edit /etc/cron.d/afraid-dyndns - on OSX you'll
   need to edit the file /Library/LaunchDaemons/org.afraid.dyndns.plist (and
   reboot)

   Unlink on Linux systems where all names on the account are refreshed with
   the IP of the host, on OSX the default configuration only names matching
   the host's name will be refreshed.  The assumption here is that Linux
   hosts are likely to be used as servers (which may require multiple names
   as in the case of a webserver hosting multiple domains), whereas OSX
   hosts are likely to be used as clients e.g. laptops which we want
   accessible via a domain name but which roam.

	To change this behaviour on OSX, edit the plist, take out the
    hostname parameter (after the --quiet) and reboot.

SYNTAX

   Call the script with --help

LIMITATIONS

   At present, only one account is supported.

AUTHOR/SUPPORT

   Erick Calder <[email protected]> - For bugs, suggestions, etc. please
   feel free to contact me.