Figured out mac saving issue

app/models/mac.rb

@@ -1,4 +1,4 @@
 class Mac < ActiveRecord::Base
   belongs_to :user
-  attr_accessible :active, :ip, :mac, :refreshed, :since
+  attr_accessible :active, :ip, :mac, :refreshed, :since, :user_id
 end

app/views/macs/index.html.erb

@@ -1,7 +1,7 @@
 <h2>What machines are on our network?</h2>
 <% @macs.each do |mac| %>
   <%= mac.user.name unless mac.user.blank? %>  
-  <%= mac.mac %> <!-- 
+  <%= mac.mac if mac.user.blank? %> <!-- 
   <%= mac.since %>, 
   <%= mac.refreshed %>,
   <%= mac.active %>--> |