diff --git a/app/controllers/heartbeat_controller.rb b/app/controllers/heartbeat_controller.rb
--- a/app/controllers/heartbeat_controller.rb
+++ b/app/controllers/heartbeat_controller.rb
@@ -1,14 +1,29 @@
 class HeartbeatController < ApplicationController
+  before_filter :admin_authorization, :only => ['index']
+
   def edit
-    render layout: 'empty'
     @user = User.find_by_login(params[:id])
-    return unless @user
-    
+    unless @user
+      render text: "LOGIN_NOT_FOUND"
+      return
+    end
+
     hb = HeartBeat.where(user_id: @user.id, ip_address: request.remote_ip).first
+    puts "status = #{params[:status]}"
     if hb
+      if params[:status]
+        hb.status = params[:status]
+        hb.save
+      end
       hb.touch
     else
-      HeartBeat.create(user_id: @user.id, ip_address: request.remote_ip)
+      HeartBeat.creae(user_id: @user.id, ip_address: request.remote_ip)
     end
+    render text: "OK"
+  end
+
+  def index
+    @hb = HeartBeat.includes(:user).order(:user_id).all
+    @num = HeartBeat.where("updated_at >= ?",Time.zone.now-5.minutes).count
   end
 end
diff --git a/app/controllers/user_admin_controller.rb b/app/controllers/user_admin_controller.rb
--- a/app/controllers/user_admin_controller.rb
+++ b/app/controllers/user_admin_controller.rb
@@ -62,6 +62,13 @@
     end    
   end
 
+  def clear_last_ip
+    @user = User.find(params[:id])
+    @user.last_ip = nil
+    @user.save
+    redirect_to action: 'list', page: params[:page]
+  end
+
   def create_from_list
     lines = params[:user_list]
 
@@ -213,7 +220,7 @@
       @changed = true
     end
   end
-  
+
   # contest management
 
   def contests
diff --git a/app/views/heartbeat/edit.html.haml b/app/views/heartbeat/edit.html.haml
deleted file mode 100644
--- a/app/views/heartbeat/edit.html.haml
+++ /dev/null
@@ -1,1 +0,0 @@
-OK
diff --git a/app/views/heartbeat/index.html.haml b/app/views/heartbeat/index.html.haml
new file mode 100644
--- /dev/null
+++ b/app/views/heartbeat/index.html.haml
@@ -0,0 +1,30 @@
+- content_for :header do
+  = javascript_include_tag 'local_jquery'
+  = stylesheet_link_tag 'tablesorter-theme.cafe'
+
+%script{:type=>"text/javascript"}
+  $(function () {
+  $('#since_datetime').datetimepicker({ showButtonPanel: true, dateFormat: "yy-mm-dd", controlType: "slider"} );
+  $('#until_datetime').datetimepicker({ showButtonPanel: true, dateFormat: "yy-mm-dd", controlType: "slider"} );
+  $('#my_table').tablesorter({widgets: ['zebra']});
+  });
+
+%h1 Heart Beat Count
+= "Last 5 minutes distinct user count = #{@num}"
+
+%h1 Heart Beat List
+
+%table.tablesorter-cafe#my_table
+  %thead
+    %tr
+      %th Login
+      %th Full name
+      %th IP
+      %th Last Update
+  %tbody
+    - @hb.each do |hb|
+      %tr{class: cycle('info-even','info-odd')}
+        %td= link_to hb.user.login, controller: :users, :action => 'profile', :id => hb.user.id
+        %td= hb.user.full_name
+        %td= hb.ip_address
+        %td= "#{time_ago_in_words(hb.updated_at)} ago"
diff --git a/app/views/user_admin/list.html.erb b/app/views/user_admin/list.html.erb
--- a/app/views/user_admin/list.html.erb
+++ b/app/views/user_admin/list.html.erb
@@ -64,6 +64,7 @@
     <th></th>
     <th></th>
     <th></th>
+    <th></th>
   </tr>
   
 <% for user in @users %>
@@ -74,6 +75,7 @@
         <td><%=h user.send(column.name) %></td>
       <% end %>
     <% end %>
+    <td><%= link_to 'Clear IP', {:action => 'clear_last_ip', :id => user, :page=>params[:page]}, :confirm => 'This will reset last logging in ip of the user, are you sure?' %></td>
     <td><%= link_to 'Show', :action => 'show', :id => user %></td>
     <td><%= link_to 'Edit', :action => 'edit', :id => user %></td>
     <td><%= link_to 'Destroy', { :action => 'destroy', :id => user }, :confirm => 'Are you sure?', :method => :post %></td>
diff --git a/db/migrate/20150914155101_add_status_to_heart_beat.rb b/db/migrate/20150914155101_add_status_to_heart_beat.rb
new file mode 100644
--- /dev/null
+++ b/db/migrate/20150914155101_add_status_to_heart_beat.rb
@@ -0,0 +1,5 @@
+class AddStatusToHeartBeat < ActiveRecord::Migration
+  def change
+    add_column :heart_beats, :status, :string
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,16 +11,16 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20150914090545) do
+ActiveRecord::Schema.define(:version => 20150914155101) do
 
   create_table "announcements", :force => true do |t|
     t.string   "author"
-    t.text     "body"
+    t.text     "body",         :limit => 16777215
     t.boolean  "published"
-    t.datetime "created_at",                      :null => false
-    t.datetime "updated_at",                      :null => false
-    t.boolean  "frontpage",    :default => false
-    t.boolean  "contest_only", :default => false
+    t.datetime "created_at",                                          :null => false
+    t.datetime "updated_at",                                          :null => false
+    t.boolean  "frontpage",                        :default => false
+    t.boolean  "contest_only",                     :default => false
     t.string   "title"
     t.string   "notes"
   end
@@ -50,19 +50,19 @@
   end
 
   create_table "descriptions", :force => true do |t|
-    t.text     "body"
+    t.text     "body",       :limit => 16777215
     t.boolean  "markdowned"
-    t.datetime "created_at", :null => false
-    t.datetime "updated_at", :null => false
+    t.datetime "created_at",                     :null => false
+    t.datetime "updated_at",                     :null => false
   end
 
   create_table "grader_configurations", :force => true do |t|
     t.string   "key"
     t.string   "value_type"
     t.string   "value"
-    t.datetime "created_at",  :null => false
-    t.datetime "updated_at",  :null => false
-    t.text     "description"
+    t.datetime "created_at",                      :null => false
+    t.datetime "updated_at",                      :null => false
+    t.text     "description", :limit => 16777215
   end
 
   create_table "grader_processes", :force => true do |t|
@@ -84,6 +84,7 @@
     t.string   "ip_address"
     t.datetime "created_at", :null => false
     t.datetime "updated_at", :null => false
+    t.string   "status"
   end
 
   create_table "languages", :force => true do |t|
@@ -104,10 +105,10 @@
     t.integer  "sender_id"
     t.integer  "receiver_id"
     t.integer  "replying_message_id"
-    t.text     "body"
+    t.text     "body",                :limit => 16777215
     t.boolean  "replied"
-    t.datetime "created_at",          :null => false
-    t.datetime "updated_at",          :null => false
+    t.datetime "created_at",                              :null => false
+    t.datetime "updated_at",                              :null => false
   end
 
   create_table "problems", :force => true do |t|
@@ -149,7 +150,7 @@
 
   create_table "sessions", :force => true do |t|
     t.string   "session_id"
-    t.text     "data"
+    t.text     "data",       :limit => 16777215
     t.datetime "updated_at"
   end
 
@@ -177,14 +178,14 @@
     t.integer  "user_id"
     t.integer  "problem_id"
     t.integer  "language_id"
-    t.text     "source"
+    t.text     "source",                :limit => 16777215
     t.binary   "binary"
     t.datetime "submitted_at"
     t.datetime "compiled_at"
-    t.text     "compiler_message"
+    t.text     "compiler_message",      :limit => 16777215
     t.datetime "graded_at"
     t.integer  "points"
-    t.text     "grader_comment"
+    t.text     "grader_comment",        :limit => 16777215
     t.integer  "number"
     t.string   "source_filename"
     t.float    "max_runtime"
@@ -205,10 +206,10 @@
 
   create_table "test_pairs", :force => true do |t|
     t.integer  "problem_id"
-    t.text     "input",      :limit => 16777215
-    t.text     "solution",   :limit => 16777215
-    t.datetime "created_at",                     :null => false
-    t.datetime "updated_at",                     :null => false
+    t.text     "input",      :limit => 2147483647
+    t.text     "solution",   :limit => 2147483647
+    t.datetime "created_at",                       :null => false
+    t.datetime "updated_at",                       :null => false
   end
 
   create_table "test_requests", :force => true do |t|
@@ -219,13 +220,13 @@
     t.string   "output_file_name"
     t.string   "running_stat"
     t.integer  "status"
-    t.datetime "updated_at",       :null => false
+    t.datetime "updated_at",                           :null => false
     t.datetime "submitted_at"
     t.datetime "compiled_at"
-    t.text     "compiler_message"
+    t.text     "compiler_message", :limit => 16777215
     t.datetime "graded_at"
     t.string   "grader_comment"
-    t.datetime "created_at",       :null => false
+    t.datetime "created_at",                           :null => false
     t.float    "running_time"
     t.string   "exit_status"
     t.integer  "memory_usage"
@@ -253,10 +254,10 @@
     t.boolean  "activated",                     :default => false
     t.datetime "created_at"
     t.datetime "updated_at"
+    t.string   "section"
     t.boolean  "enabled",                       :default => true
     t.string   "remark"
     t.string   "last_ip"
-    t.string   "section"
   end
 
   add_index "users", ["login"], :name => "index_users_on_login", :unique => true