Add screening by IP address. When deleting a user as a spammer, block all signups from the same IP address.

db/fixtures/screened_ip_addresses.rb

@@ -0,0 +1,30 @@
+ScreenedIpAddress.seed do |s|
+  s.id = 1
+  s.ip_address = "10.0.0.0/8"
+  s.action_type = ScreenedIpAddress.actions[:do_nothing]
+end
+
+ScreenedIpAddress.seed do |s|
+  s.id = 2
+  s.ip_address = "192.168.0.0/16"
+  s.action_type = ScreenedIpAddress.actions[:do_nothing]
+end
+
+ScreenedIpAddress.seed do |s|
+  s.id = 3
+  s.ip_address = "127.0.0.0/8"
+  s.action_type = ScreenedIpAddress.actions[:do_nothing]
+end
+
+ScreenedIpAddress.seed do |s|
+  s.id = 4
+  s.ip_address = "172.16.0.0/12"
+  s.action_type = ScreenedIpAddress.actions[:do_nothing]
+end
+
+# IPv6
+ScreenedIpAddress.seed do |s|
+  s.id = 5
+  s.ip_address = "fc00::/7"
+  s.action_type = ScreenedIpAddress.actions[:do_nothing]
+end

db/migrate/20131017205954_create_screened_ip_addresses.rb

@@ -0,0 +1,13 @@
+class CreateScreenedIpAddresses < ActiveRecord::Migration
+  def change
+    create_table :screened_ip_addresses do |t|
+      t.column :ip_address, :inet, null: false
+      t.integer :action_type, null: false
+      t.integer :match_count, null: false, default: 0
+      t.datetime :last_match_at
+      t.timestamps
+    end
+    add_index :screened_ip_addresses, :ip_address, unique: true
+    add_index :screened_ip_addresses, :last_match_at
+  end
+end