+ # If no local IP address could be determined, we will fall back to the guess
+ # it with help of an external server...
+ if not local_ip_address:
+ local_ip_address = self.guess_external_ip_address(proto)
+
+ return local_ip_address
+
+ def _is_usable_ip_address(self, proto, address):
+ """
+ Returns True is the local IP address is usable
+ for dynamic DNS (i.e. is not a RFC1918 address or similar).
+ """
+ if proto == "ipv4":
+ # This is not the most perfect solution to match
+ # these addresses, but instead of pulling in an entire
+ # library to handle the IP addresses better, we match
+ # with regular expressions instead.
+ matches = (
+ # RFC1918 address space
+ r"^10\.\d+\.\d+\.\d+$",
+ r"^192\.168\.\d+\.\d+$",
+ r"^172\.(1[6-9]|2[0-9]|31)\.\d+\.\d+$",
+
+ # Dual Stack Lite address space
+ r"^100\.(6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])\.\d+\.\d+$",
+ )
+
+ for match in matches:
+ m = re.match(match, address)
+ if m is None:
+ continue
+
+ # Found a match. IP address is not usable.
+ return False
+
+ # In all other cases, return OK.
+ return True