diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 9a29ee14..b0e42fb6 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -43,7 +43,7 @@ jobs:
         pip install ./plugins/kernels
         pip install ./plugins/lab
         pip install ./plugins/jupyterlab
-        pip install flake8 black mypy pytest requests
+        pip install flake8 black mypy pytest pytest-asyncio requests ipykernel
 
     - name: Check style
       run: |
diff --git a/plugins/kernels/fps_kernels/kernel_server/server.py b/plugins/kernels/fps_kernels/kernel_server/server.py
index 949f957d..ee1d6fae 100644
--- a/plugins/kernels/fps_kernels/kernel_server/server.py
+++ b/plugins/kernels/fps_kernels/kernel_server/server.py
@@ -2,7 +2,7 @@
 import asyncio
 import signal
 from datetime import datetime
-from typing import Optional, List, Dict, cast
+from typing import Iterable, Optional, List, Dict, cast
 
 from fastapi import WebSocket, WebSocketDisconnect  # type: ignore
 
@@ -43,6 +43,29 @@ def __init__(
         self.key = cast(str, self.connection_cfg["key"])
         self.channel_tasks: List[asyncio.Task] = []
         self.sessions: Dict[str, WebSocket] = {}
+        # blocked messages and allowed messages are mutually exclusive
+        self.blocked_messages: List[str] = []
+        self.allowed_messages: Optional[
+            List[str]
+        ] = None  # when None, all messages are allowed
+        # when [], no message is allowed
+
+    def block_messages(self, message_types: Iterable[str] = []):
+        # if using blocked messages, discard allowed messages
+        self.allowed_messages = None
+        if isinstance(message_types, str):
+            message_types = [message_types]
+        self.blocked_messages = list(message_types)
+
+    def allow_messages(self, message_types: Optional[Iterable[str]] = None):
+        # if using allowed messages, discard blocked messages
+        self.blocked_messages = []
+        if message_types is None:
+            self.allowed_messages = None
+            return
+        if isinstance(message_types, str):
+            message_types = [message_types]
+        self.allowed_messages = list(message_types)
 
     @property
     def connections(self) -> int:
@@ -71,10 +94,17 @@ async def start(self) -> None:
         ]
 
     async def stop(self) -> None:
-        self.kernel_process.send_signal(signal.SIGINT)
-        self.kernel_process.kill()
-        await self.kernel_process.wait()
-        os.remove(self.connection_file_path)
+        # FIXME: stop kernel in a better way
+        try:
+            self.kernel_process.send_signal(signal.SIGINT)
+            self.kernel_process.kill()
+            await self.kernel_process.wait()
+        except Exception:
+            pass
+        try:
+            os.remove(self.connection_file_path)
+        except Exception:
+            pass
         for task in self.channel_tasks:
             task.cancel()
         self.channel_tasks = []
@@ -110,6 +140,12 @@ async def listen_web(self, websocket: WebSocket):
         try:
             while True:
                 msg = await websocket.receive_json()
+                msg_type = msg["header"]["msg_type"]
+                if (msg_type in self.blocked_messages) or (
+                    self.allowed_messages is not None
+                    and msg_type not in self.allowed_messages
+                ):
+                    continue
                 channel = msg["channel"]
                 msg = {
                     "header": msg["header"],
diff --git a/setup.cfg b/setup.cfg
index dbd9ca39..08d549ab 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -40,7 +40,9 @@ test =
   black
   mypy
   pytest
+  pytest-asyncio
   requests
+  ipykernel
 
 [options.entry_points]
 console_scripts =
diff --git a/tests/conftest.py b/tests/conftest.py
index 373fcd1c..1c6f9162 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -2,12 +2,21 @@
 import socket
 import subprocess
 import time
+import asyncio
 
 import pytest
 
 pytest_plugins = ("fps.testing.fixtures",)
 
 
+@pytest.fixture(scope="session")
+def event_loop():
+    """Change event_loop fixture to module level."""
+    loop = asyncio.get_event_loop_policy().new_event_loop()
+    yield loop
+    loop.close()
+
+
 @pytest.fixture()
 def authenticated_user(client):
     username = uuid4().hex
diff --git a/tests/test_auth.py b/tests/test_auth.py
index ac70cf64..63c911cc 100644
--- a/tests/test_auth.py
+++ b/tests/test_auth.py
@@ -8,7 +8,15 @@
 )
 
 
-def test_kernel_channels(client, authenticated_user):
+def test_kernel_channels_unauthenticated(client):
+    with pytest.raises(KeyError):
+        with client.websocket_connect(
+            "/api/kernels/kernel_id_0/channels?session_id=session_id_0",
+        ):
+            pass
+
+
+def test_kernel_channels_authenticated(client, authenticated_user):
     with client.websocket_connect(
         "/api/kernels/kernel_id_0/channels?session_id=session_id_0",
         cookies=client.cookies,
diff --git a/tests/test_kernels.py b/tests/test_kernels.py
new file mode 100644
index 00000000..ab6f998e
--- /dev/null
+++ b/tests/test_kernels.py
@@ -0,0 +1,75 @@
+import os
+from time import sleep
+
+import pytest
+from fps_kernels.kernel_server.server import kernels, KernelServer
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("auth_mode", ("noauth",))
+async def test_kernel_messages(auth_mode, client, capfd):
+    kernel_id = "kernel_id_0"
+    kernel_name = "python3"
+    kernelspec_path = (
+        os.environ["CONDA_PREFIX"] + f"/share/jupyter/kernels/{kernel_name}/kernel.json"
+    )
+    kernel_server = KernelServer(
+        kernelspec_path=kernelspec_path, capture_kernel_output=False
+    )
+    await kernel_server.start()
+    kernels[kernel_id] = {"server": kernel_server}
+    msg_id = "0"
+    msg = {
+        "channel": "shell",
+        "parent_header": None,
+        "content": None,
+        "metadata": None,
+        "header": {
+            "msg_type": "msg_type_0",
+            "msg_id": msg_id,
+        },
+    }
+
+    # block msg_type_0
+    msg["header"]["msg_id"] = str(int(msg["header"]["msg_id"]) + 1)
+    kernel_server.block_messages("msg_type_0")
+    with client.websocket_connect(
+        f"/api/kernels/{kernel_id}/channels?session_id=session_id_0",
+    ) as websocket:
+        websocket.send_json(msg)
+    sleep(0.1)
+    out, err = capfd.readouterr()
+    assert not err
+
+    # allow only msg_type_0
+    msg["header"]["msg_id"] = str(int(msg["header"]["msg_id"]) + 1)
+    kernel_server.allow_messages("msg_type_0")
+    with client.websocket_connect(
+        f"/api/kernels/{kernel_id}/channels?session_id=session_id_0",
+    ) as websocket:
+        websocket.send_json(msg)
+    sleep(0.1)
+    out, err = capfd.readouterr()
+    assert err.count("[IPKernelApp] WARNING | Unknown message type: 'msg_type_0'") == 1
+
+    # block all messages
+    msg["header"]["msg_id"] = str(int(msg["header"]["msg_id"]) + 1)
+    kernel_server.allow_messages([])
+    with client.websocket_connect(
+        f"/api/kernels/{kernel_id}/channels?session_id=session_id_0",
+    ) as websocket:
+        websocket.send_json(msg)
+    sleep(0.1)
+    out, err = capfd.readouterr()
+    assert not err
+
+    # allow all messages
+    msg["header"]["msg_id"] = str(int(msg["header"]["msg_id"]) + 1)
+    kernel_server.allow_messages()
+    with client.websocket_connect(
+        f"/api/kernels/{kernel_id}/channels?session_id=session_id_0",
+    ) as websocket:
+        websocket.send_json(msg)
+    sleep(0.1)
+    out, err = capfd.readouterr()
+    assert err.count("[IPKernelApp] WARNING | Unknown message type: 'msg_type_0'") == 1