---
title: "Traefik TLS Options Documentation"
description: "Learn how to configure the transport layer security (TLS) connection in Traefik Proxy. Read the technical documentation."
---

The TLS options allow one to configure some parameters of the TLS connection.

!!! important "'default' TLS Option"

    The `default` option is special.
    When no tls options are specified in a tls router, the `default` option is used.  
    When specifying the `default` option explicitly, make sure not to specify provider namespace as the `default` option does not have one.  
    Conversely, for cross-provider references, for example, when referencing the file provider from a docker label,
    you must specify the provider namespace, for example:  
    `traefik.http.routers.myrouter.tls.options=myoptions@file`

!!! important "Providers"

    TLS options are not supported by label or tag-based providers. However, you can define them when using a [KV provider](../../other-providers/kv.md).

### Minimum TLS Version

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      minVersion: VersionTLS12

    mintls13:
      minVersion: VersionTLS13
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]

  [tls.options.default]
    minVersion = "VersionTLS12"

  [tls.options.mintls13]
    minVersion = "VersionTLS13"
```

### Maximum TLS Version

We discourage the use of this setting to disable TLS1.3.

The recommended approach is to update the clients to support TLS1.3.

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      maxVersion: VersionTLS13

    maxtls12:
      maxVersion: VersionTLS12
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]

  [tls.options.default]
    maxVersion = "VersionTLS13"

  [tls.options.maxtls12]
    maxVersion = "VersionTLS12"
```

### Cipher Suites

See [cipherSuites](https://godoc.org/crypto/tls#pkg-constants) for more information.

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      cipherSuites:
        - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    cipherSuites = [
      "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"
    ]
```

!!! important "TLS 1.3"

    Cipher suites defined for TLS 1.2 and below cannot be used in TLS 1.3, and vice versa. (<https://tools.ietf.org/html/rfc8446>)  
    With TLS 1.3, the cipher suites are not configurable (all supported cipher suites are safe in this case).
    <https://golang.org/doc/go1.12#tls_1_3>

### Curve Preferences

This option allows to set the preferred elliptic curves.

The names of the curves defined by [`crypto`](https://godoc.org/crypto/tls#CurveID) (e.g. `CurveP521`) and the [RFC defined names](https://tools.ietf.org/html/rfc8446#section-4.2.7) (e. g. `secp521r1`) can be used.

See [CurveID](https://godoc.org/crypto/tls#CurveID) for more information.

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      curvePreferences:
        - CurveP521
        - CurveP384
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    curvePreferences = ["CurveP521", "CurveP384"]
```

### Strict SNI Checking

With strict SNI checking enabled, Traefik won't allow connections from clients that do not specify a server_name extension
or don't match any of the configured certificates.
The default certificate is irrelevant on that matter.

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      sniStrict: true
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    sniStrict = true
```

### ALPN Protocols

_Optional, Default="h2, http/1.1, acme-tls/1"_

This option allows to specify the list of supported application level protocols for the TLS handshake,
in order of preference.
If the client supports ALPN, the selected protocol will be one from this list, 
and the connection will fail if there is no mutually supported protocol.

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      alpnProtocols:
        - http/1.1
        - h2
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    alpnProtocols = ["http/1.1", "h2"]
```

### Client Authentication (mTLS)

Traefik supports mutual authentication, through the `clientAuth` section.

For authentication policies that require verification of the client certificate, the certificate authority for the certificates should be set in `clientAuth.caFiles`.

In Kubernetes environment, CA certificate can be set in `clientAuth.secretNames`. See [TLSOption resource](../../kubernetes/crd/tls/tlsoption.md) for more details.

The `clientAuth.clientAuthType` option governs the behaviour as follows:

| Option    |  Operation | 
| --------- | ----------- |
| <a id="opt-NoClientCert" href="#opt-NoClientCert" title="#opt-NoClientCert">`NoClientCert`</a> | Disregards any client certificate.| 
| <a id="opt-RequestClientCert" href="#opt-RequestClientCert" title="#opt-RequestClientCert">`RequestClientCert`</a> | Asks for a certificate but proceeds anyway if none is provided. |
| <a id="opt-RequireAnyClientCert" href="#opt-RequireAnyClientCert" title="#opt-RequireAnyClientCert">`RequireAnyClientCert`</a> | Requires a certificate but does not verify if it is signed by a CA listed in `clientAuth.caFiles` or in `clientAuth.secretNames`. |
| <a id="opt-VerifyClientCertIfGiven" href="#opt-VerifyClientCertIfGiven" title="#opt-VerifyClientCertIfGiven">`VerifyClientCertIfGiven`</a> | If a certificate is provided, verifies if it is signed by a CA listed in `clientAuth.caFiles` or in `clientAuth.secretNames`. Otherwise proceeds without any certificate. |
| <a id="opt-RequireAndVerifyClientCert" href="#opt-RequireAndVerifyClientCert" title="#opt-RequireAndVerifyClientCert">`RequireAndVerifyClientCert`</a> |  requires a certificate, which must be signed by a CA listed in `clientAuth.caFiles` or in `clientAuth.secretNames`. |

```yaml tab="Structured (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      clientAuth:
        # in PEM format. each file can contain multiple CAs.
        caFiles:
          - tests/clientca1.crt
          - tests/clientca2.crt
        clientAuthType: RequireAndVerifyClientCert
```

```toml tab="Structured (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    [tls.options.default.clientAuth]
      # in PEM format. each file can contain multiple CAs.
      caFiles = ["tests/clientca1.crt", "tests/clientca2.crt"]
      clientAuthType = "RequireAndVerifyClientCert"
```

### Disable Session Tickets

_Optional, Default="false"_

When set to true, Traefik disables the use of session tickets, forcing every client to perform a full TLS handshake instead of resuming sessions.

```yaml tab="File (YAML)"
# Dynamic configuration

tls:
  options:
    default:
      disableSessionTickets: true
```

```toml tab="File (TOML)"
# Dynamic configuration

[tls.options]
  [tls.options.default]
    disableSessionTickets = true
```

```yaml tab="Kubernetes"
apiVersion: traefik.io/v1alpha1
kind: TLSOption
metadata:
  name: default
  namespace: default

spec:
  disableSessionTickets: true
```

{!traefik-for-business-applications.md!}
