diff --git a/Containers/mastercontainer/Caddyfile b/Containers/mastercontainer/Caddyfile
index 64b1e8f4..d0806adb 100644
--- a/Containers/mastercontainer/Caddyfile
+++ b/Containers/mastercontainer/Caddyfile
@@ -14,18 +14,17 @@
     servers {
         protocols h1 h2 h2c
     }
+
+    on_demand_tls {
+        ask http://localhost:9876/
+    }
 }
 
 http://:80 {
   redir https://{host}{uri}
 }
 
-# Match only host names and not ip-addresses:
-https://*.*:8443,
-https://*.*.*:8443,
-https://*.*.*.*:8443,
-https://*.*.*.*.*:8443,
-https://*.*.*.*.*.*:8443 {
+https::8443 {
 
     reverse_proxy localhost:8000
 
diff --git a/Containers/mastercontainer/supervisord.conf b/Containers/mastercontainer/supervisord.conf
index 6dc04065..0b60a0d7 100644
--- a/Containers/mastercontainer/supervisord.conf
+++ b/Containers/mastercontainer/supervisord.conf
@@ -55,3 +55,11 @@ stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 command=/session-deduplicator.sh
 user=root
+
+[program:domain-validator]
+stdout_logfile=/dev/stdout
+stdout_logfile_maxbytes=0
+stderr_logfile=/dev/stderr
+stderr_logfile_maxbytes=0
+command=php -S 127.0.0.1:9876 /var/www/docker-aio/php/domain-validator.php
+user=www-data
diff --git a/php/domain-validator.php b/php/domain-validator.php
new file mode 100644
index 00000000..59d94f16
--- /dev/null
+++ b/php/domain-validator.php
@@ -0,0 +1,17 @@
+<?php
+
+$domain = $_GET['domain'] ?? '';
+
+if (strpos($domain, '.') === false) { 
+    http_response_code(400); 
+} elseif (strpos($domain, '/') !== false) { 
+    http_response_code(400);  
+} elseif (strpos($domain, ':') !== false) { 
+    http_response_code(400);  
+} elseif (!filter_var($domain, FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME)) { 
+    http_response_code(400); 
+} elseif (filter_var($domain, FILTER_VALIDATE_IP)) { 
+    http_response_code(400); 
+} else {
+    http_response_code(200);
+}