ddns-scripts: send_update() detection private IPv4

correction of excluding private IPv4 in send_update() function.
Signed-off-by: Christian Schoenebeck <christian.schoenebeck@gmail.com>

net/ddns-scripts/files/usr/lib/ddns/dynamic_dns_functions.sh

@@ -552,9 +552,9 @@ send_update() {
 	# $1	# IP to set at DDNS service provider
 	local __IP __URL __ANSWER __ERR
 
-	# verify given IP
-	[ $use_ipv6 -eq 0 ] && __IP=$(echo $1 | grep -v -E "(^0|^10\.|^127|^172|^192)")	# no private IPv4's
-	[ $use_ipv6 -eq 1 ] && __IP=$(echo $1 | grep "^[0-9a-eA-E]")	# no IPv6 addr starting with fxxx of with ":"
+	# verify given IP / no private IPv4's / no IPv6 addr starting with fxxx of with ":"
+	[ $use_ipv6 -eq 0 ] && __IP=$(echo $1 | grep -v -E "(^0|^10\.|^127|^172\.1[6-9]\.|^172\.2[0-9]\.|^172\.3[0-1]\.|^192\.168)")
+	[ $use_ipv6 -eq 1 ] && __IP=$(echo $1 | grep "^[0-9a-eA-E]")
 	[ -z "$__IP" ] && critical_error "Invalid or no IP '$1' given"
 
 	# do replaces in URL