---
title: Block on TLS
description: Inspects the incoming request's TLS version and blocks if under TLSv1.2.
image: https://edgetunnel-b2h.pages.dev/dev-products-preview.png
---

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# Block on TLS

Inspects the incoming request's TLS version and blocks if under TLSv1.2.

* [  JavaScript ](#tab-panel-12459)
* [  TypeScript ](#tab-panel-12460)
* [  Hono ](#tab-panel-12461)
* [  Python ](#tab-panel-12462)

**JavaScript**

```js
export default {
  async fetch(request) {
    try {
      const tlsVersion = request.cf.tlsVersion;
      // Allow only TLS versions 1.2 and 1.3
      if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
        return new Response("Please use TLS version 1.2 or higher.", {
          status: 403,
        });
      }
      return fetch(request);
    } catch (err) {
      console.error(
        "request.cf does not exist in the previewer, only in production",
      );
      return new Response(`Error in workers script ${err.message}`, {
        status: 500,
      });
    }
  },
};
```

**TypeScript**

```ts
export default {
  async fetch(request): Promise<Response> {
    try {
      const tlsVersion = request.cf.tlsVersion;
      // Allow only TLS versions 1.2 and 1.3
      if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
        return new Response("Please use TLS version 1.2 or higher.", {
          status: 403,
        });
      }
      return fetch(request);
    } catch (err) {
      console.error(
        "request.cf does not exist in the previewer, only in production",
      );
      return new Response(`Error in workers script ${err.message}`, {
        status: 500,
      });
    }
  },
} satisfies ExportedHandler;
```

**TypeScript**

```ts
import { Hono } from "hono";


const app = new Hono();


// Middleware to check TLS version
app.use("*", async (c, next) => {
  // Access the raw request to get the cf object with TLS info
  const request = c.req.raw;
  const tlsVersion = request.cf?.tlsVersion;


  // Allow only TLS versions 1.2 and 1.3
  if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
    return c.text("Please use TLS version 1.2 or higher.", 403);
  }


  await next();


});


app.onError((err, c) => {
    console.error(
      "request.cf does not exist in the previewer, only in production",
    );
    return c.text(`Error in workers script: ${err.message}`, 500);
});


app.get("/", async (c) => {
  return c.text(`TLS Version: ${c.req.raw.cf.tlsVersion}`);
});


export default app;
```

**Python**

```py
from workers import WorkerEntrypoint, Response, fetch


class Default(WorkerEntrypoint):
    async def fetch(self, request):
        tls_version = request.cf.tlsVersion
        if tls_version not in ("TLSv1.2", "TLSv1.3"):
            return Response("Please use TLS version 1.2 or higher.", status=403)
        return fetch(request)
```

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```