diff --git a/docs/Commands.txt b/docs/Commands.txt
index d03259fd..96c2b089 100644
--- a/docs/Commands.txt
+++ b/docs/Commands.txt
@@ -178,6 +178,8 @@ ESP_AUTO_NOTIFICATION   1022    //1 byte = flag
 ESP_VERBOSE_BOOT	1023	//1 byte = flag
 ESP_WEBDAV_ON           1024    //1 byte = flag
 ESP_WEBDAV_PORT  	1025	//4  bytes = int
+ESP_STA_DNS_VALUE       1029    //4  bytes= int
+ESP_SECURE_SERIAL       1033    //1 byte = flag
 
 * Get/Set Check update at boot state which can be ON, OFF
 [ESP402]<state>pwd=<admin password>
diff --git a/esp3d/src/core/commands.cpp b/esp3d/src/core/commands.cpp
index 3a9de560..cb43a551 100644
--- a/esp3d/src/core/commands.cpp
+++ b/esp3d/src/core/commands.cpp
@@ -253,7 +253,7 @@ bool Commands::execute_internal_command (int cmd, const char* cmd_params, level_
     //do not overwrite previous authetic <time=YYYY-MM-DD#H24:MM:SS>ation level
     if (auth_type == LEVEL_GUEST) {
         String pwd=get_param (cmd_params, "pwd=");
-        auth_type = AuthenticationService::authenticated_level(pwd.c_str());
+        auth_type = AuthenticationService::authenticated_level(pwd.c_str(), output);
     }
 #endif //AUTHENTICATION_FEATURE
     //log_esp3d("Authentication = %d", auth_type);
diff --git a/esp3d/src/core/espcmd/ESP103.cpp b/esp3d/src/core/espcmd/ESP103.cpp
index ff3e117b..c631934a 100644
--- a/esp3d/src/core/espcmd/ESP103.cpp
+++ b/esp3d/src/core/espcmd/ESP103.cpp
@@ -53,7 +53,7 @@ bool Commands::ESP103(const char* cmd_params, level_authenticate_type auth_type,
         res += Settings_ESP3D::read_IP_String(ESP_STA_GATEWAY_VALUE);
         res += ", MSK:";
         res += Settings_ESP3D::read_IP_String(ESP_STA_MASK_VALUE);
-         res += ", DNS:";
+        res += ", DNS:";
         res += Settings_ESP3D::read_IP_String(ESP_STA_DNS_VALUE);
         output->printMSG (res.c_str());
     } else { //set
diff --git a/esp3d/src/core/espcmd/ESP400.cpp b/esp3d/src/core/espcmd/ESP400.cpp
index 0ca39fa0..82a9afae 100644
--- a/esp3d/src/core/espcmd/ESP400.cpp
+++ b/esp3d/src/core/espcmd/ESP400.cpp
@@ -209,6 +209,13 @@ bool Commands::ESP400(const char* cmd_params, level_authenticate_type auth_type,
     output->print ("\",\"H\":\"session timeout\",\"M\":\"");
     output->print (Settings_ESP3D::get_min_byte(ESP_SESSION_TIMEOUT));
     output->print ("\"}");
+
+    //Secure Serial
+    output->print (",{\"F\":\"security/security\",\"P\":\"");
+    output->print (ESP_SECURE_SERIAL);
+    output->print ("\",\"T\":\"B\",\"V\":\"");
+    output->print (Settings_ESP3D::read_byte(ESP_SECURE_SERIAL));
+    output->print ("\",\"H\":\"serial\",\"O\":[{\"no\":\"0\"},{\"yes\":\"1\"}]}");
 #endif //AUTHENTICATION_FEATURE
 
 #ifdef HTTP_FEATURE
diff --git a/esp3d/src/core/espcmd/ESP401.cpp b/esp3d/src/core/espcmd/ESP401.cpp
index a075752f..9bd0104f 100644
--- a/esp3d/src/core/espcmd/ESP401.cpp
+++ b/esp3d/src/core/espcmd/ESP401.cpp
@@ -85,6 +85,9 @@ bool Commands::ESP401(const char* cmd_params, level_authenticate_type auth_type,
                 case ESP_TARGET_FW:
                     Settings_ESP3D::GetFirmwareTarget(true);
                     break;
+                case ESP_SECURE_SERIAL:
+                    serial_service.setParameters();
+                    break;
 #ifdef AUTHENTICATION_FEATURE
                 case ESP_SESSION_TIMEOUT:
                     AuthenticationService::setSessionTimeout(1000*60*sval.toInt());
diff --git a/esp3d/src/core/settings_esp3d.cpp b/esp3d/src/core/settings_esp3d.cpp
index 714c8374..cb4cd013 100644
--- a/esp3d/src/core/settings_esp3d.cpp
+++ b/esp3d/src/core/settings_esp3d.cpp
@@ -118,6 +118,7 @@
 #define DEFAULT_NOTIFICATION_TOKEN2 ""
 #define DEFAULT_NOTIFICATION_SETTINGS ""
 #define DEFAULT_AUTO_NOTIFICATION_STATE 1
+#define DEFAULT_SECURE_SERIAL 1
 
 
 //default int values
@@ -239,6 +240,9 @@ uint8_t Settings_ESP3D::get_default_byte_value(int pos)
 {
     uint8_t res;
     switch(pos) {
+    case ESP_SECURE_SERIAL:
+        res = DEFAULT_SECURE_SERIAL;
+        break;
     case ESP_RADIO_MODE:
         res = DEFAULT_ESP_RADIO_MODE;
         break;
@@ -1068,7 +1072,7 @@ bool Settings_ESP3D::reset(bool networkonly)
     Settings_ESP3D::write_IP(ESP_STA_GATEWAY_VALUE, Settings_ESP3D::get_default_IP_value(ESP_STA_GATEWAY_VALUE));
     //STA static Mask
     Settings_ESP3D::write_IP(ESP_STA_MASK_VALUE, Settings_ESP3D::get_default_IP_value(ESP_STA_MASK_VALUE));
-     //STA static DNS
+    //STA static DNS
     Settings_ESP3D::write_IP(ESP_STA_DNS_VALUE, Settings_ESP3D::get_default_IP_value(ESP_STA_DNS_VALUE));
 #endif //WIFI_FEATURE || ETH_FEATURE
     if (networkonly) {
@@ -1095,7 +1099,8 @@ bool Settings_ESP3D::reset(bool networkonly)
     Settings_ESP3D::write_byte(ESP_SETUP,Settings_ESP3D::get_default_byte_value(ESP_SETUP));
     //Verbose boot
     Settings_ESP3D::write_byte(ESP_VERBOSE_BOOT,Settings_ESP3D::get_default_byte_value(ESP_VERBOSE_BOOT));
-
+    //Secure Serial
+    Settings_ESP3D::write_byte(ESP_SECURE_SERIAL,Settings_ESP3D::get_default_byte_value(ESP_SECURE_SERIAL));
 #if defined(DISPLAY_DEVICE) && defined(DISPLAY_TOUCH_DRIVER)
     //Calibration done (internal only)
     Settings_ESP3D::write_byte(ESP_CALIBRATION,Settings_ESP3D::get_default_byte_value(ESP_CALIBRATION));
diff --git a/esp3d/src/core/settings_esp3d.h b/esp3d/src/core/settings_esp3d.h
index 04147c35..475bab24 100644
--- a/esp3d/src/core/settings_esp3d.h
+++ b/esp3d/src/core/settings_esp3d.h
@@ -105,6 +105,7 @@
 #define ESP_WEBDAV_ON           1024    //1 byte = flag
 #define ESP_WEBDAV_PORT         1025    //4  bytes= int
 #define ESP_STA_DNS_VALUE       1029    //4  bytes= int
+#define ESP_SECURE_SERIAL       1033    //1 byte = flag
 
 
 //Hidden password
diff --git a/esp3d/src/include/version.h b/esp3d/src/include/version.h
index d29c7582..7981d0cf 100644
--- a/esp3d/src/include/version.h
+++ b/esp3d/src/include/version.h
@@ -22,7 +22,7 @@
 #define _VERSION_ESP3D_H
 
 //version and sources location
-#define FW_VERSION "3.0.0.a90"
+#define FW_VERSION "3.0.0.a91"
 #define REPOSITORY "https://github.com/luc-github/ESP3D/tree/3.0"
 
 #endif //_VERSION_ESP3D_H
diff --git a/esp3d/src/modules/authentication/authentication_service.cpp b/esp3d/src/modules/authentication/authentication_service.cpp
index 81b04db9..b6d416b5 100644
--- a/esp3d/src/modules/authentication/authentication_service.cpp
+++ b/esp3d/src/modules/authentication/authentication_service.cpp
@@ -48,7 +48,7 @@ uint8_t AuthenticationService::_current_nb_ip = 0;
 //#define ALLOW_MULTIPLE_SESSIONS
 
 //check authentification
-level_authenticate_type AuthenticationService::authenticated_level(const  char * pwd)
+level_authenticate_type AuthenticationService::authenticated_level(const  char * pwd, ESP3DOutput * output)
 {
 #ifdef AUTHENTICATION_FEATURE
     level_authenticate_type auth_type = LEVEL_GUEST;
@@ -60,7 +60,13 @@ level_authenticate_type AuthenticationService::authenticated_level(const  char *
         if (isuser (pwd) && (auth_type != LEVEL_ADMIN)) {
             auth_type = LEVEL_USER;
         }
+        return auth_type;
     } else {
+        if(output) {
+            if (output->client() !=ESP_HTTP_CLIENT) {
+                return auth_type;
+            }
+        }
 #if defined (HTTP_FEATURE)
         if (_webserver) {
             if (_webserver->hasHeader ("Authorization") ) {
@@ -92,6 +98,7 @@ level_authenticate_type AuthenticationService::authenticated_level(const  char *
     return auth_type;
 #else
     (void)pwd;
+    (void)output;
     return LEVEL_ADMIN;
 #endif //AUTHENTICATION_FEATURE
 }
diff --git a/esp3d/src/modules/authentication/authentication_service.h b/esp3d/src/modules/authentication/authentication_service.h
index 07479af1..9be9d676 100644
--- a/esp3d/src/modules/authentication/authentication_service.h
+++ b/esp3d/src/modules/authentication/authentication_service.h
@@ -32,6 +32,7 @@ const char DEFAULT_ADMIN_LOGIN [] =      "admin";
 const char DEFAULT_USER_LOGIN [] =       "user";
 
 #include "../../include/esp3d_config.h"
+#include "../../core/esp3doutput.h"
 #if defined (AUTHENTICATION_FEATURE)
 #if defined (HTTP_FEATURE)
 #include <IPAddress.h>
@@ -58,7 +59,7 @@ typedef void Authwebserver;
 class AuthenticationService
 {
 public:
-    static level_authenticate_type  authenticated_level(const  char * pwd = nullptr);
+    static level_authenticate_type  authenticated_level(const  char * pwd = nullptr, ESP3DOutput * output= nullptr);
 #ifdef AUTHENTICATION_FEATURE
     static bool begin(Authwebserver * webserver);
     static void end();
diff --git a/esp3d/src/modules/serial/serial_service.cpp b/esp3d/src/modules/serial/serial_service.cpp
index 9775b9fa..47023ed1 100644
--- a/esp3d/src/modules/serial/serial_service.cpp
+++ b/esp3d/src/modules/serial/serial_service.cpp
@@ -26,6 +26,7 @@
 #if COMMUNICATION_PROTOCOL == MKS_SERIAL
 #include "../mks/mks_service.h"
 #endif //COMMUNICATION_PROTOCOL == MKS_SERIAL
+#include "../authentication/authentication_service.h"
 
 //Serial Parameters
 #define ESP_SERIAL_PARAM SERIAL_8N1
@@ -59,6 +60,7 @@ SerialService::SerialService()
 {
     _buffer_size = 0;
     _started = false;
+    _needauthentication = true;
 }
 
 //Destructor
@@ -79,12 +81,23 @@ void ESP3DSerialTaskfn( void * parameter )
 }
 #endif //ARDUINO_ARCH_ESP32 
 
+//extra parameters that do not need a begin
+void SerialService::setParameters()
+{
+#if defined (AUTHENTICATION_FEATURE)
+    _needauthentication = (Settings_ESP3D::read_byte (ESP_SECURE_SERIAL)==0)?false:true;
+#else
+    _needauthentication = false;
+#endif //AUTHENTICATION_FEATURE
+}
+
 //Setup Serial
 bool SerialService::begin()
 {
     _lastflush = millis();
     //read from settings
     long br = Settings_ESP3D::read_uint32(ESP_BAUD_RATE);
+    setParameters();
     _buffer_size = 0;
     //change only if different from current
     if (br != baudRate() || (ESP_RX_PIN != -1) || (ESP_TX_PIN != -1)) {
@@ -197,7 +210,7 @@ void SerialService::flushbuffer()
     ESP3DOutput output(ESP_SERIAL_CLIENT);
     _buffer[_buffer_size] = 0x0;
     //dispatch command
-    esp3d_commands.process(_buffer, _buffer_size, &output);
+    esp3d_commands.process(_buffer, _buffer_size, &output,_needauthentication?LEVEL_GUEST:LEVEL_ADMIN);
     _lastflush = millis();
     _buffer_size = 0;
 }
diff --git a/esp3d/src/modules/serial/serial_service.h b/esp3d/src/modules/serial/serial_service.h
index cd4460e0..943318b4 100644
--- a/esp3d/src/modules/serial/serial_service.h
+++ b/esp3d/src/modules/serial/serial_service.h
@@ -30,6 +30,7 @@ class SerialService : public Print
 public:
     SerialService();
     ~SerialService();
+    void setParameters();
     bool begin();
     bool end();
     void updateBaudRate(long br);
@@ -73,6 +74,7 @@ public:
     }
 private:
     bool _started;
+    bool _needauthentication;
     uint32_t _lastflush;
     uint8_t _buffer[ESP3D_SERIAL_BUFFER_SIZE + 1]; //keep space of 0x0 terminal
     size_t _buffer_size;
diff --git a/esp3d/src/modules/update/update_service.cpp b/esp3d/src/modules/update/update_service.cpp
index 3ae6de27..49f264bd 100644
--- a/esp3d/src/modules/update/update_service.cpp
+++ b/esp3d/src/modules/update/update_service.cpp
@@ -148,7 +148,8 @@ const char * SysboolKeysVal[] = {"Active_Printer_LCD",
                                  "Active_WebSocket",
                                  "Active_Telnet",
                                  "Active_BT",
-                                 "Boot_verbose"
+                                 "Boot_verbose",
+                                 "Secure_serial"
                                 } ;
 
 const uint16_t SysboolKeysPos[] = {ESP_PRINTER_LCD_FLAG,
@@ -157,7 +158,8 @@ const uint16_t SysboolKeysPos[] = {ESP_PRINTER_LCD_FLAG,
                                    ESP_WEBSOCKET_FLAG,
                                    ESP_TELNET_FLAG,
                                    ESP_BT_FLAG,
-                                   ESP_VERBOSE_BOOT
+                                   ESP_VERBOSE_BOOT,
+                                   ESP_SECURE_SERIAL
                                   } ;
 
 const char * NetbyteKeysVal[] = {