Skip if it's an IPv6 address; at some point, maybe we'll support that too.

update_ip.sh

@@ -17,6 +17,11 @@ if [ -f "${HOME}/${cache}" ]; then
 	old_ip=$(cat "${HOME}/${cache}")
 fi
 
+# Exit if we're at an IPv6 address
+if [ -z "${ip##*:*}" ]; then
+    exit;
+fi
+
 if [ "${set_ip}" = "${ip}" ] && [ "${ip}" = "${old_ip}" ]; then
 	exit;
 else