diff --git a/scripts/dhcp b/scripts/dhcp
index 4fcd8ef..922efb9 100755
--- a/scripts/dhcp
+++ b/scripts/dhcp
@@ -36,53 +36,64 @@ GLOBAL_OPTIONS = OptionParser.new do |opts|
   opts.separator <<HELP
 Available subcommands:
 add [options] NAME MACADDRESS: add dhcp lease
-remove [options] NAME: remove dhcp static lease
+remove [options] NAME:         remove dhcp static lease
+regenerate:                    regenerate dhcp configuration
 
 See 'dhcp COMMAND --help' for more information on a specific command.
 HELP
 end
 
-def add_command(registry, args)
-  ipv4, ipv6 = nil, nil
-  parser = OptionParser.new do |opts|
-    opts.banner = "Usage: dhcp add [options] NAME MACADDRESS"
-    opts.on("-4", "--ipv4 ADDRESS", "set fixed ipv4 address") do |address|
-      ipv4 = address
+class Application
+  def run(args)
+    GLOBAL_OPTIONS.order!(args)
+    @registry = DhcpRegistry.new
+    case command = args.shift
+    when "add"
+      add_command
+    when "remove"
+      remove_command
+    when nil
+      puts(GLOBAL_OPTIONS.help())
+      exit(0)
+    when "regenerate" # fall through
+    else
+      die "unknown subcommand #{command}"
     end
-    opts.on("-6", "--ipv6 ADDRESS", "set fixed ipv6 address") do |address|
-      ipv6 = address
+
+    registry.save
+    registry.update_leases
+  end
+
+  private
+    def add_command(args)
+      ipv4, ipv6 = nil, nil
+      parser = OptionParser.new do |opts|
+        opts.banner = "Usage: dhcp add [options] NAME MACADDRESS"
+        opts.on("-4", "--ipv4 ADDRESS", "set fixed ipv4 address") do |address|
+          ipv4 = address
+        end
+        opts.on("-6", "--ipv6 ADDRESS", "set fixed ipv6 address") do |address|
+          ipv6 = address
+        end
+      end.order!(args)
+      if ARGV.size < 2
+        $stderr.puts "no enough arguments"
+        die(parser.help)
+      end
+      name, macaddress = args
+      @registry.add_lease(name, macaddress, ipv4, ipv6)
+    end
+
+    def remove_command(args)
+      parser = OptionParser.new do |opts|
+        opts.banner = "Usage: dhcp remove NAME"
+      end.order!(args)
+      if args.empty?
+        $stderr.puts "no enough arguments"
+        die(parser.help)
+      end
+      @registry.remove_lease(args.first)
     end
-  end.order!
-  if ARGV.size < 2
-    $stderr.puts "no enough arguments"
-    die(parser.help)
-  end
-  name, macaddress = args
-  registry.add_lease(name, macaddress, ipv4, ipv6)
 end
 
-def remove_command(registry, args)
-  parser = OptionParser.new do |opts|
-    opts.banner = "Usage: dhcp remove NAME"
-  end.order!
-  if args.empty?
-    $stderr.puts "no enough arguments"
-    die(parser.help)
-  end
-  registry.remove_lease(args.first)
-end
-
-GLOBAL_OPTIONS.order!
-registry = DhcpRegistry.new
-case command = ARGV.shift
-when "add"
-  add_command(registry, ARGV)
-when "remove"
-  remove_command(registry, ARGV)
-when nil # just update
-else
-  die "unknown subcommand #{command}"
-end
-
-registry.save
-registry.update_leases
+Application.new.run(ARGV)