> ## Documentation Index
> Fetch the complete documentation index at: https://docs.httpmon.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# CA certificate setup

> Trust the httpmon CA for HTTPS interception

httpmon generates a CA certificate the first time it runs. To intercept HTTPS traffic, your system must trust this certificate. The certificate is stored at `~/.httpmon/mitmproxy-ca-cert.pem`.

## Automatic installation

The simplest approach. Run httpmon with `--install-ca` and it handles everything.

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
sudo httpmon --install-ca
```

This works on both macOS and Linux. It generates the CA certificate if it does not exist yet and adds it to your system trust store.

## Manual installation

If you prefer to install the certificate yourself, use the platform-specific instructions below.

<Tabs>
  <Tab title="macOS">
    Add the certificate to the system keychain.

    ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
    sudo security add-trusted-cert -d -r trustRoot \
      -k /Library/Keychains/System.keychain \
      ~/.httpmon/mitmproxy-ca-cert.pem
    ```
  </Tab>

  <Tab title="Linux">
    Copy the certificate to the system CA directory and update the trust store.

    ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
    sudo cp ~/.httpmon/mitmproxy-ca-cert.pem \
      /usr/local/share/ca-certificates/httpmon.crt
    sudo update-ca-certificates
    ```
  </Tab>
</Tabs>

## Firefox

Firefox uses its own certificate trust store and does not use the system store. You need to import the certificate manually.

1. Open Firefox and go to **Settings**.
2. Search for **Certificates** and click **View Certificates**.
3. Select the **Authorities** tab and click **Import**.
4. Select `~/.httpmon/mitmproxy-ca-cert.pem`.
5. Check **Trust this CA to identify websites** and click **OK**.

## Certificate location

The CA certificate and key are stored in `~/.httpmon/`.

| File                               | Purpose                                        |
| ---------------------------------- | ---------------------------------------------- |
| `~/.httpmon/mitmproxy-ca-cert.pem` | CA certificate (share this to trust the proxy) |
| `~/.httpmon/mitmproxy-ca.pem`      | CA private key (keep this secret)              |