diff --git a/control_legacy.c b/control_legacy.c
index 08ac6f3..8ef9ea9 100644
--- a/control_legacy.c
+++ b/control_legacy.c
@@ -8,6 +8,31 @@
 #include "control_dbus.h"
 #include "mbox.h"
 
+/* Command IDs (Legacy interface) */
+#define DBUS_C_PING            0x00
+#define DBUS_C_DAEMON_STATE    0x01
+#define DBUS_C_RESET           0x02
+#define DBUS_C_SUSPEND         0x03
+#define DBUS_C_RESUME          0x04
+#define DBUS_C_MODIFIED        0x05
+#define DBUS_C_KILL            0x06
+#define DBUS_C_LPC_STATE       0x07
+#define NUM_DBUS_CMDS          (DBUS_C_LPC_STATE + 1)
+
+/* Return Values (Legacy interface) */
+#define DBUS_SUCCESS           0x00 /* Command Succeded */
+#define E_DBUS_INTERNAL        0x01 /* Internal DBUS Error */
+#define E_DBUS_INVAL           0x02 /* Invalid Command */
+#define E_DBUS_REJECTED        0x03 /* Daemon Rejected Request */
+#define E_DBUS_HARDWARE        0x04 /* BMC Hardware Error */
+#define E_DBUS_NO_MEM          0x05 /* Failed Memory Allocation */
+
+struct mbox_dbus_msg {
+       uint8_t cmd;
+       size_t num_args;
+       uint8_t *args;
+};
+
 /*
  * Command: DBUS Ping
  * Ping the daemon