diff --git a/README.md b/README.md
index 62f487f..0f11188 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,10 @@ to true.
 A machine's host name is defined by `config.vm.hostname`. If this is not
 set, it falls back to the symbol defining the machine in the Vagrantfile.
 
+When using include_offline set to true, only boxes that are up or have a
+private ip configured will be added to the hosts file. You will receive a
+warning on skipped boxes.
+
 In addition, the `hostmanager.aliases` configuration attribute can be used
 to provide aliases for your host names.
 
@@ -49,6 +53,7 @@ Example configuration:
 Vagrant.configure("2") do |config|
   config.hostmanager.enabled = true
   config.hostmanager.ignore_private_ip = false
+  config.hostmanager.include_offline = true
   config.vm.define "example-box" do |node|
     node.vm.hostname = "example-box-hostname"
     node.vm.network :private_network, ip: "192.168.42.42"
@@ -57,6 +62,17 @@ Vagrant.configure("2") do |config|
 end
 ```
 
+As a last option, you can also choose hostmanager as a provisioner.
+This allows you to use the provisioning order to ensure that hostmanager
+runs before or after provisioning. The provisioner will collect hosts from
+boxes with the same provider as the running box.
+
+Use:
+
+```ruby
+config.vm.provision :hostmanager
+```
+
 Contribute
 ----------
 Contributions are welcome.
diff --git a/lib/vagrant-hostmanager/command.rb b/lib/vagrant-hostmanager/command.rb
index 7b886fb..52a0078 100644
--- a/lib/vagrant-hostmanager/command.rb
+++ b/lib/vagrant-hostmanager/command.rb
@@ -8,6 +8,8 @@ module VagrantPlugins
         opts = OptionParser.new do |o|
           o.banner = 'Usage: vagrant hostmanager [vm-name]'
           o.separator ''
+          o.version = VagrantPlugins::HostManager::VERSION
+          o.program_name = 'vagrant hostmanager'
 
           o.on('--provider provider', String,
             'Update machines with the specific provider.') do |provider|
@@ -16,6 +18,8 @@ module VagrantPlugins
         end
 
         argv = parse_options(opts)
+        return if !argv
+
         options[:provider] ||= @env.default_provider
 
         with_target_vms(argv, options) do |machine|
diff --git a/lib/vagrant-hostmanager/config.rb b/lib/vagrant-hostmanager/config.rb
index cb5aace..e537d06 100644
--- a/lib/vagrant-hostmanager/config.rb
+++ b/lib/vagrant-hostmanager/config.rb
@@ -5,46 +5,68 @@ module VagrantPlugins
       attr_accessor :manage_local
       attr_accessor :ignore_private_ip
       attr_accessor :aliases
+      attr_accessor :include_offline
 
       alias_method :enabled?, :enabled
+      alias_method :include_offline?, :include_offline
 
       def initialize
         @enabled = false
         @manage_local = true
         @ignore_private_ip = UNSET_VALUE
         @aliases = Array.new
+        @include_offline = false
       end
 
       def finalize!
         @ignore_private_ip = false if @ignore_private_ip == UNSET_VALUE
+        @aliases = [ @aliases ].flatten
       end
 
       def validate(machine)
         errors = Array.new
 
         # check if enabled option is either true or false
-        if ![TrueClass, FalseClass].include?(enabled.class)
-          errors << "A value for hostmanager.enabled can be true or false."
-        end
+        errors << validate_bool('hostmanager.enabled', enabled)
+
+        # check if include_offline is either true or false
+        errors << validate_bool('hostmanager.include_offline', include_offline)
 
         # check if manage_local option is either true or false
         if ![TrueClass, FalseClass].include?(manage_local.class)
           errors << "A value for hostmanager.manage_local can be true or false."
         end
 
-        # check if ignore_private_ip option is either true or false
-        if ![TrueClass, FalseClass].include?(ignore_private_ip.class) &&
-          @ignore_private_ip != UNSET_VALUE
-          errors << "A value for hostmanager.ignore_private_ip can be true or false."
+        # check if ignore_private_ip option is either true or false (or UNSET_VALUE)
+        if @ignore_private_ip != UNSET_VALUE
+          errors << validate_bool('hostmanager.ignore_private_ip', ignore_private_ip)
         end
 
         # check if aliases option is an Array
-        if !machine.config.hostmanager.aliases.kind_of?(Array)
-          errors << "A value for hostmanager.aliases must be an Array."
+        if  !machine.config.hostmanager.aliases.kind_of?(Array) and
+            !machine.config.hostmanager.aliases.kind_of?(String)
+          errors << I18n.t('vagrant_hostmanager.config.not_an_array_or_string', {
+            :config_key => 'hostmanager.aliases',
+            :is_class   => aliases.class.to_s,
+          })
         end
 
+        errors.compact!
         { "HostManager configuration" => errors }
       end
+
+      private
+      def validate_bool(key, value)
+        if ![TrueClass, FalseClass].include?(value.class)
+          I18n.t('vagrant_hostmanager.config.not_a_bool', {
+            :config_key => key,
+            :value      => value.class.to_s,
+          })
+        else
+          nil
+        end
+      end
+
     end
   end
 end
diff --git a/lib/vagrant-hostmanager/hosts_file.rb b/lib/vagrant-hostmanager/hosts_file.rb
index 6330de8..508ff82 100644
--- a/lib/vagrant-hostmanager/hosts_file.rb
+++ b/lib/vagrant-hostmanager/hosts_file.rb
@@ -69,7 +69,7 @@ module VagrantPlugins
               next if ip
             end
           end
-          ip || machine.ssh_info[:host]
+          ip || (machine.ssh_info ? machine.ssh_info[:host] : nil)
         end
 
       def update_entry(machine,file_name,sudo=false)
@@ -147,6 +147,30 @@ module VagrantPlugins
           machine.communicate.sudo("mv /tmp/hosts /etc/hosts")
         end
       end
+
+      private
+      # Either use the active machines, or loop over all available machines and
+      # get those with the same provider (aka, ignore boxes that throw MachineNotFound errors).
+      #
+      # Returns an array with the same structure as env.active_machines:
+      # [ [:machine, :virtualbox], [:foo, :virtualbox] ]
+      def get_machines(env, provider)
+        if env.config_global.hostmanager.include_offline?
+          machines = []
+          env.machine_names.each do |name|
+            begin
+              m = env.machine(name, provider)
+              machines << [name, provider]
+            rescue Vagrant::Errors::MachineNotFound => ex
+              # ignore this box.
+            end
+          end
+          machines
+        else
+          env.active_machines
+        end
+      end
+
     end
   end
 end
diff --git a/lib/vagrant-hostmanager/plugin.rb b/lib/vagrant-hostmanager/plugin.rb
index f0af8d7..7323544 100644
--- a/lib/vagrant-hostmanager/plugin.rb
+++ b/lib/vagrant-hostmanager/plugin.rb
@@ -10,6 +10,8 @@ module VagrantPlugins
       description <<-DESC
         This plugin manages the /etc/hosts file for guest machines. An entry is
         created for each active machine using the hostname attribute.
+
+        You can also use the hostmanager provisioner to update the hosts file.
       DESC
 
       config(:hostmanager) do
@@ -31,6 +33,11 @@ module VagrantPlugins
         hook.append(Action::DeleteGuests)
       end
 
+      provisioner(:hostmanager) do
+        require_relative 'provisioner'
+        Provisioner
+      end
+
       command(:hostmanager) do
         require_relative 'command'
         Command
diff --git a/lib/vagrant-hostmanager/provisioner.rb b/lib/vagrant-hostmanager/provisioner.rb
new file mode 100644
index 0000000..65d43db
--- /dev/null
+++ b/lib/vagrant-hostmanager/provisioner.rb
@@ -0,0 +1,12 @@
+module VagrantPlugins
+  module HostManager
+    class Provisioner < Vagrant.plugin('2', :provisioner)
+      include HostsFile
+
+      def provision
+        generate(@machine.env, @machine.box.provider.to_sym)
+        update(@machine)
+      end
+    end
+  end
+end
diff --git a/lib/vagrant-hostmanager/version.rb b/lib/vagrant-hostmanager/version.rb
index dc96dc4..bf8a05a 100644
--- a/lib/vagrant-hostmanager/version.rb
+++ b/lib/vagrant-hostmanager/version.rb
@@ -1,5 +1,5 @@
 module VagrantPlugins
   module HostManager
-    VERSION = '0.2.0'
+    VERSION = '0.4.0'
   end
 end
diff --git a/locales/en.yml b/locales/en.yml
index 7bcb324..e27083b 100644
--- a/locales/en.yml
+++ b/locales/en.yml
@@ -4,3 +4,9 @@ en:
       update_guest: "[%{name}] Updating /etc/hosts file"
       update_host: "Updating local /etc/hosts file"
       run_sudo: "Running sudo to modify host machine's /etc/hosts file"
+      add_host: "Adding /etc/hosts entry: %{ip} %{host} %{aliases}"
+      host_no_ip: "Could not determine ip for machine '%{name}': no private ip configured or machine not up."
+      update: "[%{name}] Updating /etc/hosts file"
+    config:
+      not_a_bool: "A value for %{config_key} can only be true or false, not type '%{value}'"
+      not_an_array_or_string: "A value for %{config_key} must be an Array or String, not type '%{is_class}'"