```Python hl_lines="2  6"
{!../../../docs_src/advanced_middleware/tutorial001.py!}
```

## `TrustedHostMiddleware`

Enforces that all incoming requests have a correctly set `Host` header, in order to guard against HTTP Host Header attacks.

```Python hl_lines="2  6-8"
{!../../../docs_src/advanced_middleware/tutorial002.py!}
```

The following arguments are supported:

!!! tip "Tipp"

🔬 🔢 🔜 🔁, 👆 💪 🔜 🤙 (& `await`) 🎏 `async` 🔢 ↖️ ⚪️➡️ 📨 📨 👆 FastAPI 🈸 👆 💯, ⚫️❔ 👆 🔜 🤙 👫 🙆 🙆 👆 📟.

!!! tip

    # Return some error
    ...
```

But by using the `secrets.compare_digest()` it will be secure against a type of attacks called "timing attacks".

### Timing Attacks

But what's a "timing attack"?

Let's imagine some attackers are trying to guess the username and password.

And they send a request with a username `johndoe` and a password `love123`.

!!! tip