diff --git a/source/ubl-settings-usergroups-settings.c b/source/ubl-settings-usergroups-settings.c
index 5a0aada..1479b82 100644
--- a/source/ubl-settings-usergroups-settings.c
+++ b/source/ubl-settings-usergroups-settings.c
@@ -390,6 +390,8 @@ ubl_settings_usergroups_additional_settings_window *yon_ubl_settings_usergroups_
 	window->GroupMinCell=GTK_CELL_RENDERER(gtk_builder_get_object(builder,"GroupMinCell"));
 	window->GroupMaxCell=GTK_CELL_RENDERER(gtk_builder_get_object(builder,"GroupMaxCell"));
 
+	yon_gtk_login_block_symbols(GTK_ENTRY(window->DefaultUserNameEntry));
+
 	yon_gtk_revealer_set_from_expander(GTK_REVEALER(window->UserShutdownRevealer),GTK_EXPANDER(window->UsersShutdownExpander));
 	yon_gtk_revealer_set_from_expander(GTK_REVEALER(window->GroupShutdownRevealer),GTK_EXPANDER(window->GroupsShutdownExpander));
 
diff --git a/source/ubl-settings-usergroups-user.c b/source/ubl-settings-usergroups-user.c
index 1b51851..3378695 100644
--- a/source/ubl-settings-usergroups-user.c
+++ b/source/ubl-settings-usergroups-user.c
@@ -1,5 +1,33 @@
 #include "ubl-settings-usergroups.h"
 
+void on_login_insert_custom_restricted_check(GtkEditable *editable, const gchar *text, gint length, gint *position){
+        gchar *new_text = g_new(gchar, length + 1);
+        memset(new_text,0,length+1);
+    gint i, j = 0;
+
+	
+    for (i = 0; i < length; i++) {
+        if ((text[i]>='a'&&text[i]<='z')||(text[i]>='0'&&text[i]<='9')||strchr("_-",text[i])) {
+            new_text[j] = text[i];
+            j++;
+        }
+    }
+
+    if (j < length) {
+        g_signal_handlers_block_by_func(editable, G_CALLBACK(on_login_insert_custom_restricted_check), NULL);
+        gtk_editable_insert_text(editable, new_text, j, position);
+        g_signal_handlers_unblock_by_func(editable, G_CALLBACK(on_login_insert_custom_restricted_check), NULL);
+        g_signal_stop_emission_by_name(editable, "insert-text");
+    }
+
+    g_free(new_text);
+}
+
+void yon_gtk_login_block_symbols(GtkEntry *target){
+    g_return_if_fail(GTK_IS_ENTRY(target));
+    g_signal_connect(G_OBJECT(target),"insert-text",G_CALLBACK(on_login_insert_custom_restricted_check),NULL);
+}
+
 void on_parameter_changed(GtkWidget *,ubl_settings_usergroups_user_window *window){
 	char *user_shell=NULL;
 	char *user_home=NULL;
@@ -130,6 +158,7 @@ ubl_settings_usergroups_user_window *yon_ubl_settings_usergroups_user_new(){
 	window->MainNotebook=yon_gtk_builder_get_widget(builder,"MainNotebook");
 	window->expiration_unix=NULL;
 	window->last_uid=NULL;
+	yon_gtk_entry_block_symbols(GTK_ENTRY(window->userUserNameEntry),":");
 
 	time_t t = time(NULL);
 	struct tm tm = *localtime(&t);
diff --git a/source/ubl-settings-usergroups.h b/source/ubl-settings-usergroups.h
index 37af024..c2bc9f2 100644
--- a/source/ubl-settings-usergroups.h
+++ b/source/ubl-settings-usergroups.h
@@ -562,4 +562,6 @@ void on_additional_settings_cell_toggled(GtkCellRenderer *self, char *path, ubl_
 void on_additional_settings_cell_edited(GtkCellRenderer *self, char *path, char *new_text, ubl_settings_usergroups_additional_settings_window *window);
 void on_adiitional_settings_tree_selection_changed(GtkWidget *self, ubl_settings_usergroups_additional_settings_window *window);
 void on_useradd_sync_changed(ubl_settings_usergroups_additional_settings_window *window);
+void yon_gtk_login_block_symbols(GtkEntry *target);
+void on_login_insert_custom_restricted_check(GtkEditable *editable, const gchar *text, gint length, gint *position);
 #endif
\ No newline at end of file
diff --git a/ubl-settings-usergroups-additional-settings.glade b/ubl-settings-usergroups-additional-settings.glade
index 6772a79..e2a11e8 100644
--- a/ubl-settings-usergroups-additional-settings.glade
+++ b/ubl-settings-usergroups-additional-settings.glade
@@ -76,8 +76,8 @@
       <row>
         <col id="0">False</col>
         <col id="1" translatable="yes">Group GID range</col>
-        <col id="2" translatable="yes"></col>
-        <col id="3" translatable="yes"></col>
+        <col id="2" translatable="yes"/>
+        <col id="3" translatable="yes"/>
         <col id="4">True</col>
         <col id="5">True</col>
         <col id="6">False</col>
@@ -90,8 +90,8 @@
       <row>
         <col id="0">False</col>
         <col id="1" translatable="yes">Group GID in system</col>
-        <col id="2" translatable="yes"></col>
-        <col id="3" translatable="yes"></col>
+        <col id="2" translatable="yes"/>
+        <col id="3" translatable="yes"/>
         <col id="4">True</col>
         <col id="5">True</col>
         <col id="6">False</col>
@@ -176,8 +176,8 @@
       <row>
         <col id="0">False</col>
         <col id="1" translatable="yes">Users UID range</col>
-        <col id="2" translatable="yes"></col>
-        <col id="3" translatable="yes"></col>
+        <col id="2" translatable="yes"/>
+        <col id="3" translatable="yes"/>
         <col id="4">True</col>
         <col id="5">True</col>
         <col id="6">False</col>
@@ -190,8 +190,8 @@
       <row>
         <col id="0">False</col>
         <col id="1" translatable="yes">User UID in system</col>
-        <col id="2" translatable="yes"></col>
-        <col id="3" translatable="yes"></col>
+        <col id="2" translatable="yes"/>
+        <col id="3" translatable="yes"/>
         <col id="4">True</col>
         <col id="5">True</col>
         <col id="6">False</col>
@@ -321,6 +321,7 @@
                           <object class="GtkEntry" id="DefaultUserNameEntry">
                             <property name="visible">True</property>
                             <property name="can-focus">True</property>
+                            <property name="max-length">32</property>
                             <property name="placeholder-text" translatable="yes">superadmin</property>
                           </object>
                           <packing>