---
title: "Select TLS protocol versions"
sidebar_label: "Select TLS protocol versions"
description: "How to select TLS versions and enable SSL encryption for a CDN resource"
sidebar_position: 9
---

import Formbricks from '@theme/MDXComponents/Formbricks'

# Select TLS protocol versions

TLS (Transport Layer Security) is a cryptographic protocol that provides secure data transmission between a CDN server and a user's browser.

By default, a CDN resource supports all TLS protocol versions, as well as SSLv3 for browser compatibility. Not all supported protocols meet security standards: TLSv1, TLSv1.1, and SSLv3 are considered obsolete. The use of modern protocols can be important, for example, if a service processes payments—it must comply with the PCI DSS standard, which requires the use of only modern TLS versions 1.2 and 1.3.

To improve the security of a TLS connection, you can use modern versions of the TLS protocol or select specific versions that the CDN resource will support. When using modern TLS versions, you can also enable SSL encryption for additional protection.

To select TLS protocol versions:

1. In the [control panel](https://my.selectel.ru/cdn-v3), in the top menu, click **Products** and select **CDN**.

2. In the **CDN Resources** section, open the resource page → **General** tab.

3. Select which TLS protocol versions the CDN resource will support:

   * modern TLS versions — select the **Use only modern TLS versions** checkbox. The connection will be established using TLSv1.2 and TLSv1.3, and other protocol versions will be disabled;

   * specific TLS versions — in the **TLS Protocols** field, select the required versions.

4. Optional: if you selected the **Use only modern TLS versions** checkbox in step 3, select the **Use strong SSL ciphers** checkbox. SSL encryption further enhances TLS connection security.

5. Click **Apply**. While settings are being applied, the CDN resource will be in the `PROCESSING` status. During this time, other settings cannot be applied. Settings will be applied when the CDN resource transitions to the `ACTIVE`.

<Formbricks />