diff --git a/src/judas_protocol/types.py b/src/judas_protocol/types.py
new file mode 100644
index 0000000..0d0b412
--- /dev/null
+++ b/src/judas_protocol/types.py
@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+"""Types used in the judas protocol."""
+
+from __future__ import annotations
+
+from enum import Enum
+
+
+class Category(str, Enum):
+    CONTROL = "control"
+
+
+class ControlAction(str, Enum):
+    HELLO = "hello"
+    ACK = "ack"