diff --git a/coretk/coretk/coreclient.py b/coretk/coretk/coreclient.py
index c02a3295..827f4d01 100644
--- a/coretk/coretk/coreclient.py
+++ b/coretk/coretk/coreclient.py
@@ -261,12 +261,6 @@ class CoreClient:
                                 self.file_configs[node.id][service] = {}
                             self.file_configs[node.id][service][file] = response.data
 
-            # store links as created links
-            for link in session.links:
-                self.created_links.add(
-                    tuple(sorted([link.node_one_id, link.node_two_id]))
-                )
-
             # draw session
             self.app.canvas.reset_and_redraw(session)
 
diff --git a/coretk/coretk/dialogs/cel.py b/coretk/coretk/dialogs/cel.py
new file mode 100644
index 00000000..847d245b
--- /dev/null
+++ b/coretk/coretk/dialogs/cel.py
@@ -0,0 +1,29 @@
+"""
+check engine light
+"""
+from tkinter import ttk
+
+from coretk.dialogs.dialog import Dialog
+
+
+class CheckLight(Dialog):
+    def __init__(self, master, app):
+        super().__init__(master, app, "CEL", modal=True)
+        self.app = app
+
+        self.columnconfigure(0, weight=1)
+        self.draw()
+
+    def draw(self):
+        row = 0
+        frame = ttk.Frame(self)
+        button = ttk.Button(frame, text="Reset CEL")
+        button.grid(row=0, column=0)
+        button = ttk.Button(frame, text="View core-daemon log")
+        button.grid(row=0, column=1)
+        button = ttk.Button(frame, text="View node log")
+        button.grid(row=0, column=2)
+        button = ttk.Button(frame, text="Close", command=self.destroy)
+        button.grid(row=0, column=3)
+        frame.grid(row=row, column=0, sticky="nsew")
+        ++row
diff --git a/coretk/coretk/dialogs/serviceconfiguration.py b/coretk/coretk/dialogs/serviceconfiguration.py
index 01610eb1..812d1a6a 100644
--- a/coretk/coretk/dialogs/serviceconfiguration.py
+++ b/coretk/coretk/dialogs/serviceconfiguration.py
@@ -43,6 +43,7 @@ class ServiceConfiguration(Dialog):
         self.validation_time_entry = None
         self.validation_mode_entry = None
         self.service_file_data = None
+        self.validation_period_entry = None
         self.original_service_files = {}
         self.temp_service_files = {}
         self.modified_files = set()
@@ -100,8 +101,6 @@ class ServiceConfiguration(Dialog):
         label.grid(row=0, column=0, sticky="ew")
         frame1.grid(row=0, column=0)
         frame2 = ttk.Frame(frame)
-        # frame2.columnconfigure(0, weight=1)
-        # frame2.columnconfigure(1, weight=4)
         label = ttk.Label(frame2, text="Meta-data")
         label.grid(row=0, column=0)
 
diff --git a/coretk/coretk/statusbar.py b/coretk/coretk/statusbar.py
index 8910c742..f45dce9f 100644
--- a/coretk/coretk/statusbar.py
+++ b/coretk/coretk/statusbar.py
@@ -2,6 +2,8 @@
 import tkinter as tk
 from tkinter import ttk
 
+from coretk.dialogs.cel import CheckLight
+
 
 class StatusBar(ttk.Frame):
     def __init__(self, master, app, **kwargs):
@@ -55,8 +57,13 @@ class StatusBar(ttk.Frame):
         self.emulation_light = ttk.Label(
             self, text="CEL TBD", anchor=tk.CENTER, borderwidth=1, relief=tk.RIDGE
         )
+        self.emulation_light.bind("<Button-1>", self.cel_callback)
         self.emulation_light.grid(row=0, column=4, sticky="ew")
 
+    def cel_callback(self, event):
+        dialog = CheckLight(self.app, self.app)
+        dialog.show()
+
     def start_session_callback(self, process_time):
         self.progress_bar.stop()
         self.statusvar.set(f"Session started in {process_time:.3f} seconds")
diff --git a/coretk/coretk/validation.py b/coretk/coretk/validation.py
index 68fc79c3..c7923229 100644
--- a/coretk/coretk/validation.py
+++ b/coretk/coretk/validation.py
@@ -99,7 +99,11 @@ class InputValidation:
             if len(_32bits) > 4:
                 return False
             for _8bits in _32bits:
-                if (_8bits and int(_8bits) > 255) or len(_8bits) > 3:
+                if (
+                    (_8bits and int(_8bits) > 225)
+                    or len(_8bits) > 3
+                    or (_8bits.startswith("0") and len(_8bits) > 1)
+                ):
                     return False
             return True
         else: