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 # he-dyndns
-Shell-based dynamic DNS client for Hurricane Electric's dns.he.net service
+This code is a shell-based dynamic DNS client for Hurricane Electric's
+dns.he.net service. This code is designed to be maximally portable
+using common Linux/BSD commands and avoid Perl, Python, etc. In its
+default mode, it updates one or more FQDNs with the IP address that
+dns.he.net detects as the source request.
+
+# Installation
+There is really nothing to install. Copy he-dyndns somewhere useful
+such as /usr/local/bin.
+
+# Configuration
+The only configuration file/item is if you want to use the file
+/etc/he-dns-secret to contain the key for authenticating to
+dns.he.net. Otherwise, you can provide it on the command line with the
+**-s** option.
+
+# Runtime Options
+**he-dyndns** takes the following options:
+
+## Requied Options
+- **-4**: Update the IPv4 "A" record for the FQDN(s)
+- **-6**: Update the IPv6 "AAAA" record for the FQDN(s).
+- **-d**: One or more fully-qualified host entries for the domain separated by commas
+
+Note that one or both of -4 and -6 must be specified for the script to
+actually do anything. 
+
+## Optional Options
+- **-s**: The secret key for updating the entries
+
+Any other unsupported option or no options will print a usage message
+
+# Return Values
+Returns 0 on success or 1 on failure. Failure message returns the exact error
+from dyn.dns.he.net, no more and no less.
+
+# Usage
+This script is designed to be called from a Cron entry or another script. An
+example usage:
+
+```
+# /usr/local/bin/he-dyndns -46 -s SECRETKEY -d foo.example.com,bar.example.com
+```