<!-- review: finished -->

<a id="stream-ssl"></a>

# SSL

Provides the necessary support for a stream proxy server to work with the SSL/TLS protocol.

When [building from the source code](https://en.angie.software//angie/docs/installation/sourcebuild.md#sourcebuild),
this module isn't built by default;
it should be enabled with the
`--with-stream_ssl_module`
[build option](https://en.angie.software//angie/docs/installation/sourcebuild.md#configure).

In packages and images from [our repos](https://en.angie.software//angie/docs/installation/index.md#install-packages),
the module is included in the build.

#### NOTE
This module requires the OpenSSL library.

<a id="configuration-example-71"></a>

## Configuration Example

To reduce the processor load it is recommended to

* set the number of [worker processes](https://en.angie.software//angie/docs/configuration/modules/core.md#worker-processes) equal to the number of processors,
* enable the [shared](#s-ssl-session-cache) session cache,
* disable the [built-in](#s-ssl-session-cache) session cache,
* and possibly increase the session [lifetime](#s-ssl-session-timeout) (by default, 5 minutes):

```nginx
worker_processes auto;

stream {

    #...

    server {
        listen              12345 ssl;

        ssl_protocols       TLSv1.2 TLSv1.3;
        ssl_ciphers         AES128-SHA:AES256-SHA:RC4-SHA:DES-CBC3-SHA:RC4-MD5;
        ssl_certificate     /usr/local/angie/conf/cert.pem;
        ssl_certificate_key /usr/local/angie/conf/cert.key;
        ssl_session_cache   shared:SSL:10m;
        ssl_session_timeout 10m;

    #    ...
    }
```

<a id="directives-80"></a>

## Directives

<a id="index-0"></a>

<a id="s-ssl-alpn"></a>

### ssl_alpn

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_alpn` protocol ...;   |
|------------------------------------------------------------------------------------------|----------------------------|
| Default                                                                                  | —                          |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server             |

Specifies the list of supported [ALPN](https://datatracker.ietf.org/doc/html/rfc7301) protocols. One of the protocols must be [negotiated](#v-s-ssl-alpn-protocol) if the client uses ALPN:

```nginx
map $ssl_alpn_protocol $proxy {
    h2                 127.0.0.1:8001;
    http/1.1           127.0.0.1:8002;
}

server {
    listen      12346;
    proxy_pass  $proxy;
    ssl_alpn    h2 http/1.1;
}
```

<a id="index-1"></a>

<a id="s-ssl-certificate"></a>

### ssl_certificate

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_certificate` file;   |
|------------------------------------------------------------------------------------------|---------------------------|
| Default                                                                                  | —                         |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server            |

Specifies a file with the certificate in the PEM format for the given server. If intermediate certificates should be specified in addition to a primary certificate, they should be specified in the same file in the following order: the primary certificate comes first, then the intermediate certificates. A secret key in the PEM format may be placed in the same file.

This directive can be specified multiple times to load certificates of different types, for example, RSA and ECDSA:

```nginx
server {
    listen              12345 ssl;

    ssl_certificate     example.com.rsa.crt;
    ssl_certificate_key example.com.rsa.key;

    ssl_certificate     example.com.ecdsa.crt;
    ssl_certificate_key example.com.ecdsa.key;

#    ...
}
```

Only OpenSSL 1.0.2 or higher supports separate certificate chains for different certificates. With older versions, only one certificate chain can be used.

#### NOTE
Variables can be used in the file name when using OpenSSL 1.0.2 or higher:

```nginx
ssl_certificate     $ssl_server_name.crt;
ssl_certificate_key $ssl_server_name.key;
```

Note that using variables implies that a certificate will be loaded for each SSL handshake, and this may have a negative impact on performance.

The value `data:`$variable`` can be specified instead of the `file`, which loads a certificate from a variable without using intermediate files.

Note that inappropriate use of this syntax may have its security implications, such as writing secret key data to [error log](https://en.angie.software//angie/docs/configuration/modules/core.md#error-log).

<a id="index-2"></a>

<a id="s-ssl-certificate-compression"></a>

### ssl_certificate_compression

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_certificate_compression` `on` | `off`;   |
|------------------------------------------------------------------------------------------|-----------------------------------------------|
| Default                                                                                  | `ssl_certificate_compression off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                                |

Enables TLS 1.3 [compression](https://datatracker.ietf.org/doc/html/rfc8879) of server certificates.

#### NOTE
The directive is supported when using OpenSSL 3.2 or higher; the list of supported compression algorithms is provided by the library.

#### NOTE
The directive is supported when using [BoringSSL](https://boringssl.googlesource.com/boringssl/); the list of supported compression algorithms includes `zlib`.

If [ssl_stapling](#s-ssl-stapling) is enabled, certificate compression is disabled.

<a id="index-3"></a>

<a id="s-ssl-certificate-key"></a>

### ssl_certificate_key

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_certificate_key` file;   |
|------------------------------------------------------------------------------------------|-------------------------------|
| Default                                                                                  | —                             |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                |

Specifies a file with the secret key in the PEM format for the given server.

#### NOTE
Variables can be used in the file name when using OpenSSL 1.0.2 or higher.

The value `engine:`name`:id` can be specified instead of the `file`, which loads a secret key with a specified id from the OpenSSL engine name.

The value `store:scheme:id` can be specified instead of the `file`, which is used to load a secret key with a specified id and OpenSSL provider registered URI scheme, such as [pkcs11](https://datatracker.ietf.org/doc/html/rfc7512).

The value `data:`$variable`` can be specified instead of the `file`, which loads a secret key from a variable without using intermediate files. Note that inappropriate use of this syntax may have its security implications, such as writing secret key data to [error log](https://en.angie.software//angie/docs/configuration/modules/core.md#error-log).

<a id="index-4"></a>

<a id="s-ssl-ciphers"></a>

### ssl_ciphers

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ciphers` ciphers;          |
|------------------------------------------------------------------------------------------|---------------------------------|
| Default                                                                                  | `ssl_ciphers HIGH:!aNULL:!MD5;` |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                  |

Specifies the enabled ciphers. The ciphers are specified in the format understood by the OpenSSL library, for example:

```nginx
ssl_ciphers ALL:!aNULL:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
```

The list of ciphers depends on the version of OpenSSL installed.
The full list can be viewed using the `openssl ciphers` command.

#### WARNING
The `ssl_ciphers` directive does *not* configure ciphers for TLS
1.3 when using OpenSSL. To configure TLS 1.3 ciphers with OpenSSL, use the
[ssl_conf_command](#s-ssl-conf-command) directive, which was added to support advanced
SSL configuration.

- In LibreSSL, TLS 1.3 ciphers *can* be configured using
  `ssl_ciphers`.
- In BoringSSL, TLS 1.3 ciphers cannot be configured at all.

<a id="index-5"></a>

<a id="s-ssl-client-certificate"></a>

### ssl_client_certificate

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_client_certificate` file;   |
|------------------------------------------------------------------------------------------|----------------------------------|
| Default                                                                                  | —                                |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                   |

Specifies a file with trusted CA certificates in the PEM format used to
[verify](#s-ssl-verify-client) client certificates and OCSP responses if
[ssl_stapling](#s-ssl-stapling) is enabled.

The list of certificates will be sent to clients. If this is not desired, the [ssl_trusted_certificate](#s-ssl-trusted-certificate) directive can be used.

<a id="index-6"></a>

<a id="s-ssl-conf-command"></a>

### ssl_conf_command

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_conf_command` name value;   |
|------------------------------------------------------------------------------------------|----------------------------------|
| Default                                                                                  | —                                |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                   |

Sets arbitrary OpenSSL configuration [commands](https://docs.openssl.org/master/man3/SSL_CONF_cmd/).

#### NOTE
The directive is supported when using OpenSSL 1.0.2 or higher.
To configure TLS 1.3 ciphers with OpenSSL, use the `ciphersuites` command.

Several ssl_conf_command directives can be specified on the same level:

```nginx
ssl_conf_command Options PrioritizeChaCha;
ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256;
```

These directives are inherited from the previous configuration level if and only if there are no ssl_conf_command directives defined on the current level.

#### WARNING
Configuring OpenSSL directly might result in unexpected behavior.

<a id="index-7"></a>

<a id="s-ssl-crl"></a>

### ssl_crl

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_crl` file;   |
|------------------------------------------------------------------------------------------|-------------------|
| Default                                                                                  | —                 |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server    |

Specifies a file with revoked certificates (CRL) in the PEM format used to [verify](#s-ssl-verify-client) client certificates.

<a id="index-8"></a>

<a id="s-ssl-dhparam"></a>

### ssl_dhparam

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_dhparam` file;   |
|------------------------------------------------------------------------------------------|-----------------------|
| Default                                                                                  | —                     |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server        |

Specifies a file with DH parameters for DHE ciphers.

#### WARNING
By default no parameters are set, and therefore DHE ciphers will not be used.

<a id="index-9"></a>

<a id="s-ssl-early-data"></a>

### ssl_early_data

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_early_data` `on` | `off`;   |
|------------------------------------------------------------------------------------------|----------------------------------|
| Default                                                                                  | `ssl_early_data off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                   |

Enables or disables TLS 1.3 [early data](https://datatracker.ietf.org/doc/html/rfc8446#section-2.3).

#### NOTE
The directive is supported when using OpenSSL 1.1.1 or higher or [BoringSSL](https://boringssl.googlesource.com/boringssl/).

<a id="index-10"></a>

<a id="s-ssl-encrypted-hello-key"></a>

### ssl_encrypted_hello_key

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_encrypted_hello_key` file;   |
|------------------------------------------------------------------------------------------|-----------------------------------|
| Default                                                                                  | —                                 |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                    |

Specifies a file with an ECH private key and ECHConfigList in PEM format.
The directive can be specified multiple times.
Requires an OpenSSL or BoringSSL build with Encrypted Client Hello (ECH)
support; otherwise it is not supported.

<a id="index-11"></a>

<a id="s-ssl-ecdh-curve"></a>

### ssl_ecdh_curve

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ecdh_curve` curve;   |
|------------------------------------------------------------------------------------------|---------------------------|
| Default                                                                                  | `ssl_ecdh_curve auto;`    |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server            |

Specifies a curve for ECDHE ciphers.

#### NOTE
When using OpenSSL 1.0.2 or higher, it is possible to specify multiple curves, for example:

```nginx
ssl_ecdh_curve prime256v1:secp384r1;
```

The special value `auto` instructs Angie to use a list built into the OpenSSL library when using OpenSSL 1.0.2 or higher, or prime256v1 with older versions.

#### NOTE
When using OpenSSL 1.0.2 or higher, this directive sets the list of curves supported by the server. Thus, in order for ECDSA certificates to work, it is important to include the curves used in the certificates.

<a id="index-12"></a>

<a id="s-ssl-handshake-timeout"></a>

### ssl_handshake_timeout

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_handshake_timeout` time;   |
|------------------------------------------------------------------------------------------|---------------------------------|
| Default                                                                                  | `ssl_handshake_timeout 60s;`    |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                  |

Specifies a timeout for the SSL handshake to complete.

<a id="index-13"></a>

<a id="s-ssl-ocsp"></a>

### ssl_ocsp

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ocsp` `on` | `off` | `leaf`;   |
|------------------------------------------------------------------------------------------|-------------------------------------|
| Default                                                                                  | `ssl_ocsp off;`                     |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                      |

Enables OCSP validation of the client certificate chain. The `leaf`
parameter enables validation of the client certificate only.

For the OCSP validation to work, the [ssl_verify_client](#s-ssl-verify-client) directive should
be set to `on` or `optional`.

To resolve the OCSP responder hostname, the [resolver](https://en.angie.software//angie/docs/configuration/modules/stream/index.md#s-resolver) directive should
also be specified.

Example:

```nginx
ssl_verify_client on;
ssl_ocsp          on;
resolver          127.0.0.53;
```

<a id="index-14"></a>

<a id="s-ssl-ocsp-cache"></a>

### ssl_ocsp_cache

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ocsp_cache` `off` | [shared:name:size];   |
|------------------------------------------------------------------------------------------|------------------------------------------------|
| Default                                                                                  | `ssl_ocsp_cache off;`                          |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                                 |

Sets name and size of the cache that stores client certificates status for OCSP
validation. The cache is shared between all worker processes. A cache with the
same name can be used in several virtual servers.

The `off` parameter prohibits the use of the cache.

<a id="index-15"></a>

<a id="s-ssl-ocsp-responder"></a>

### ssl_ocsp_responder

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ocsp_responder` uri;   |
|------------------------------------------------------------------------------------------|-----------------------------|
| Default                                                                                  | —                           |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server              |

Overrides the URI of the OCSP responder specified in the ["Authority Information
Access"](https://datatracker.ietf.org/doc/html/rfc5280#section-4.2.2.1)
certificate extension for [validation](#s-ssl-ocsp) of client certificates.

Only `http://` OCSP responders are supported:

```nginx
ssl_ocsp_responder http://ocsp.example.com/;
```

<a id="index-16"></a>

<a id="s-ssl-ntls"></a>

### ssl_ntls

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_ntls` `on` | `off`;   |
|------------------------------------------------------------------------------------------|----------------------------|
| Default                                                                                  | `ssl_ntls off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server             |

Enables server-side support for NTLS using [TongSuo](https://github.com/Tongsuo-Project/Tongsuo) library.

```nginx
listen ... ssl;
ssl_ntls  on;
```

#### NOTE
Angie must be built using the `--with-ntls` build option and linked with NTLS-enabled SSL library

```default
./configure --with-openssl=../Tongsuo-8.3.0 \
            --with-openssl-opt=enable-ntls  \
            --with-ntls
```

<a id="index-17"></a>

<a id="s-ssl-password-file"></a>

### ssl_password_file

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_password_file` file;   |
|------------------------------------------------------------------------------------------|-----------------------------|
| Default                                                                                  | —                           |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server              |

Specifies a file with passphrases for [secret keys](#s-ssl-certificate-key) where each passphrase is specified on a separate line. Passphrases are tried in turn when loading the key.

Example:

```nginx
stream {
    ssl_password_file /etc/keys/global.pass;
    ...

    server {
        listen 127.0.0.1:12345;
        ssl_certificate_key /etc/keys/first.key;
    }

    server {
        listen 127.0.0.1:12346;

        # named pipe can also be used instead of a file
        ssl_password_file /etc/keys/fifo;
        ssl_certificate_key /etc/keys/second.key;
    }
}
```

<a id="index-18"></a>

<a id="s-ssl-prefer-server-ciphers"></a>

### ssl_prefer_server_ciphers

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_prefer_server_ciphers` `on` | `off`;   |
|------------------------------------------------------------------------------------------|---------------------------------------------|
| Default                                                                                  | `ssl_prefer_server_ciphers off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                              |

Specifies that server ciphers should be preferred over client ciphers when the SSLv3 and TLS protocols are used.

<a id="index-19"></a>

<a id="s-ssl-protocols"></a>

### ssl_protocols

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_protocols` [`SSLv2`] [`SSLv3`] [`TLSv1`] [`TLSv1.1`] [`TLSv1.2`] [`TLSv1.3`];   |
|------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------|
| Default                                                                                  | `ssl_protocols TLSv1.2 TLSv1.3;`                                                     |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                                                                       |

#### Versionchanged
Changed in version 1.2.0: `TLSv1.3` parameter added to default set.

Enables the specified protocols.

#### NOTE
The TLSv1.1 and TLSv1.2 parameters work only when OpenSSL 1.0.1 or higher is used.

The TLSv1.3 parameter works only when OpenSSL 1.1.1 or higher is used.

<a id="index-20"></a>

<a id="s-ssl-session-cache"></a>

### ssl_session_cache

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_session_cache` `off` | `none` | [builtin[:size]] [shared:name:size];   |
|------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------|
| Default                                                                                  | `ssl_session_cache none;`                                                   |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                                                              |

Sets the types and sizes of caches that store session parameters. A cache can be of any of the following types:

| `off`     | the use of a session cache is strictly prohibited: Angie explicitly tells a client that sessions may not be reused.                                                                                                                                                                                                                                                                                                                                |
|-----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `none`    | the use of a session cache is gently disallowed: Angie tells a client that sessions may be reused, but does not actually store session parameters in the cache.                                                                                                                                                                                                                                                                                    |
| `builtin` | a cache built in OpenSSL; used by one worker process only. The cache size is specified in sessions. If size is not given, it is equal to 20480 sessions. Use of the built-in cache can cause memory fragmentation.                                                                                                                                                                                                                                 |
| `shared`  | a cache shared between all worker processes. The cache size is specified in bytes; one megabyte can store about 4000 sessions. Each shared cache should have an arbitrary name. A cache with the same name can be used in several servers. It is also used to automatically generate, store, and periodically rotate TLS session ticket keys unless configured explicitly using the [ssl_session_ticket_key](#s-ssl-session-ticket-key) directive. |

Both cache types can be used simultaneously, for example:

```nginx
ssl_session_cache builtin:1000 shared:SSL:10m;
```

but using only shared cache without the built-in cache should be more efficient.

<a id="index-21"></a>

<a id="s-ssl-session-ticket-key"></a>

### ssl_session_ticket_key

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_session_ticket_key` file;   |
|------------------------------------------------------------------------------------------|----------------------------------|
| Default                                                                                  | —                                |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                   |

Sets a file with the secret key used to encrypt and decrypt TLS session tickets. The directive is necessary if the same key has to be shared between multiple servers. By default, a randomly generated key is used.

If several keys are specified, only the first key is used to encrypt TLS session tickets. This allows configuring key rotation, for example:

```nginx
ssl_session_ticket_key current.key;
ssl_session_ticket_key previous.key;
```

The file must contain 80 or 48 bytes of random data and can be created using the following command:

```console
openssl rand 80 > ticket.key
```

Depending on the file size, either AES256 (for 80-byte keys) or AES128 (for 48-byte keys) will be used for encryption.

<a id="index-22"></a>

<a id="s-ssl-session-tickets"></a>

### ssl_session_tickets

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_session_tickets` `on` | `off`;   |
|------------------------------------------------------------------------------------------|---------------------------------------|
| Default                                                                                  | `ssl_session_tickets on;`             |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                        |

Enables or disables session resumption through [TLS session tickets](https://datatracker.ietf.org/doc/html/rfc5077).

<a id="index-23"></a>

<a id="s-ssl-session-timeout"></a>

### ssl_session_timeout

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_session_timeout` time;   |
|------------------------------------------------------------------------------------------|-------------------------------|
| Default                                                                                  | `ssl_session_timeout 5m;`     |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                |

Specifies a time during which a client may reuse the session parameters.

<a id="index-24"></a>

<a id="s-ssl-stapling"></a>

### ssl_stapling

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_stapling` `on` | `off`;   |
|------------------------------------------------------------------------------------------|--------------------------------|
| Default                                                                                  | `ssl_stapling off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | http, server                   |

Enables or disables [stapling of OCSP responses](https://datatracker.ietf.org/doc/html/rfc6066#section-8) by the server.
Example:

```nginx
ssl_stapling on;
resolver 127.0.0.53;
```

For the OCSP stapling to work, the certificate of the server certificate issuer
should be known. If the [ssl_certificate](#s-ssl-certificate) file does not contain
intermediate certificates, the certificate of the server certificate issuer
should be present in the [ssl_trusted_certificate](#s-ssl-trusted-certificate) file.

#### WARNING
For the resolution of the OCSP responder hostname, the [resolver](https://en.angie.software//angie/docs/configuration/modules/stream/index.md#s-resolver)
directive should also be specified.

<a id="index-25"></a>

<a id="s-ssl-stapling-file"></a>

### ssl_stapling_file

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_stapling_file` file;   |
|------------------------------------------------------------------------------------------|-----------------------------|
| Default                                                                                  | —                           |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | http, server                |

When set, the stapled OCSP response will be taken from the specified file
instead of querying the OCSP responder specified in the server certificate.

The file should be in the DER format as produced by the `openssl ocsp`
command.

<a id="index-26"></a>

<a id="s-ssl-stapling-responder"></a>

### ssl_stapling_responder

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_stapling_responder` uri;   |
|------------------------------------------------------------------------------------------|---------------------------------|
| Default                                                                                  | —                               |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | http, server                    |

Overrides the URI of the OCSP responder specified in the ["Authority Information
Access"](https://datatracker.ietf.org/doc/html/rfc5280#section-4.2.2.1)
certificate extension.

Only `http://` OCSP responders are supported:

```nginx
ssl_stapling_responder http://ocsp.example.com/;
```

<a id="index-27"></a>

<a id="s-ssl-stapling-verify"></a>

### ssl_stapling_verify

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_stapling_verify` `on` | `off`;   |
|------------------------------------------------------------------------------------------|---------------------------------------|
| Default                                                                                  | `ssl_stapling_verify off;`            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | http, server                          |

Enables or disables verification of OCSP responses by the server.

For verification to work, the certificate of the server certificate issuer, the root certificate, and all intermediate certificates should be configured as trusted using the [ssl_trusted_certificate](#s-ssl-trusted-certificate) directive.

<a id="index-28"></a>

<a id="s-ssl-trusted-certificate"></a>

### ssl_trusted_certificate

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_trusted_certificate` file;   |
|------------------------------------------------------------------------------------------|-----------------------------------|
| Default                                                                                  | —                                 |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                    |

Specifies a file with trusted CA certificates in the PEM format used to [verify](#s-ssl-verify-client) client certificates.

In contrast to the certificate set by [ssl_client_certificate](#s-ssl-client-certificate), the list of these certificates will not be sent to clients.

<a id="index-29"></a>

<a id="s-ssl-verify-client"></a>

### ssl_verify_client

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_verify_client` `on` | `off` | `optional` | `optional_no_ca`;   |
|------------------------------------------------------------------------------------------|---------------------------------------------------------------------|
| Default                                                                                  | `ssl_verify_client off;`                                            |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server                                                      |

Enables verification of client certificates. The verification result is stored in the [$ssl_client_verify](#v-s-ssl-client-verify) variable. If an error has occurred during the client certificate verification or a client has not presented the required certificate, the connection is closed.

| `optional`       | requests the client certificate and verifies it if the certificate is present.                                                                                                                                             |
|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `optional_no_ca` | requests the client certificate but does not require it to be signed by a trusted CA certificate. This is intended for use in cases when a service that is external to Angie performs the actual certificate verification. |

<a id="index-30"></a>

<a id="s-ssl-verify-depth"></a>

### ssl_verify_depth

| [Syntax](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)   | `ssl_verify_depth` number;   |
|------------------------------------------------------------------------------------------|------------------------------|
| Default                                                                                  | `ssl_verify_depth 1;`        |
| [Context](https://en.angie.software//angie/docs/configuration/configfile.md#configfile)  | stream, server               |

Sets the verification depth in the client certificates chain.

<a id="built-in-variables-23"></a>

## Built-in Variables

The `stream_ssl` module supports the following variables:

<a id="v-s-ssl-alpn-protocol"></a>

### `$ssl_alpn_protocol`

returns the protocol selected by ALPN during the SSL handshake, or an empty string otherwise.

<a id="v-s-ssl-cipher"></a>

### `$ssl_cipher`

returns the name of the cipher used for an established SSL connection.

<a id="v-s-ssl-ciphers"></a>

### `$ssl_ciphers`

returns the list of ciphers supported by the client. Known ciphers are listed by names, unknown are shown in hexadecimal, for example:

> AES128-SHA:AES256-SHA:0x00ff

#### NOTE
The variable is fully supported only when using OpenSSL version 1.0.2 or higher. With older versions, the variable is available only for new sessions and lists only known ciphers.

<a id="v-s-ssl-client-cert"></a>

### `$ssl_client_cert`

returns the client certificate in the PEM format for an established SSL connection, with each line except the first prepended with the tab character.

<a id="v-s-ssl-client-fingerprint"></a>

### `$ssl_client_fingerprint`

returns the SHA1 fingerprint of the client certificate for an established SSL connection.

<a id="v-s-ssl-client-i-dn"></a>

### `$ssl_client_i_dn`

returns the "issuer DN" string of the client certificate for an established SSL connection according to [RFC 2253](https://datatracker.ietf.org/doc/html/rfc2253).

<a id="v-s-ssl-client-raw-cert"></a>

### `$ssl_client_raw_cert`

returns the client certificate in the PEM format for an established SSL connection.

<a id="v-s-ssl-client-s-dn"></a>

### `$ssl_client_s_dn`

returns the "subject DN" string of the client certificate for an established SSL connection according to [RFC 2253](https://datatracker.ietf.org/doc/html/rfc2253).

<a id="v-s-ssl-client-serial"></a>

### `$ssl_client_serial`

returns the serial number of the client certificate for an established SSL connection.

<a id="v-s-ssl-client-sigalg"></a>

### `$ssl_client_sigalg`

returns the [signature algorithm](https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-16) for the client certificate for an established SSL connection.

#### NOTE
The variable is supported only when using OpenSSL version 3.5 or higher. With older versions, the variable value will be an empty string.

#### NOTE
The variable is available only for new sessions.

<a id="v-s-ssl-client-v-end"></a>

### `$ssl_client_v_end`

returns the end date of the client certificate.

<a id="v-s-ssl-client-v-remain"></a>

### `$ssl_client_v_remain`

returns the number of days until the client certificate expires.

<a id="v-s-ssl-client-v-start"></a>

### `$ssl_client_v_start`

returns the start date of the client certificate.

<a id="v-s-ssl-client-verify"></a>

### `$ssl_client_verify`

returns the result of client certificate verification: `SUCCESS`, `FAILED:reason`, and `NONE` if a certificate was not present.

<a id="v-s-ssl-curve"></a>

### `$ssl_curve`

returns the negotiated curve used for SSL handshake key exchange process. Known curves are listed by names, unknown are shown in hexadecimal, for example:

> prime256v1

#### NOTE
The variable is supported only when using OpenSSL version 3.0 or higher. With older versions, the variable value will be an empty string.

<a id="v-s-ssl-curves"></a>

### `$ssl_curves`

returns the list of curves supported by the client. Known curves are listed by names, unknown are shown in hexadecimal, for example:

> 0x001d:prime256v1:secp521r1:secp384r1

#### NOTE
The variable is supported only when using OpenSSL version 1.0.2 or higher. With older versions, the variable value will be an empty string.

The variable is available only for new sessions.

<a id="v-s-ssl-early-data"></a>

### `$ssl_early_data`

returns "1" if TLS 1.3 [early data](https://en.angie.software//angie/docs/configuration/modules/http/http_ssl.md#ssl-early-data) is used and the handshake is not complete, otherwise "".

<a id="v-s-ssl-encrypted-hello"></a>

### `$ssl_encrypted_hello`

returns "1" if Encrypted Client Hello (ECH) is used, otherwise "".

<a id="v-s-ssl-protocol"></a>

### `$ssl_protocol`

returns the protocol of an established SSL connection.

<a id="v-s-ssl-server-cert-type"></a>

### `$ssl_server_cert_type`

takes the values `RSA`, `DSA`, `ECDSA`, `ED448`,
`ED25519`, `SM2`, `RSA-PSS`, or `unknown` depending
on the type of server certificate and key.

<a id="v-s-ssl-server-name"></a>

### `$ssl_server_name`

returns the server name requested through [SNI](http://en.wikipedia.org/wiki/Server_Name_Indication).

<a id="v-s-ssl-session-id"></a>

### `$ssl_session_id`

returns the session identifier of an established SSL connection.

<a id="v-s-ssl-session-reused"></a>

### `$ssl_session_reused`

returns "r" if an SSL session was reused, or "." otherwise.

<a id="v-s-ssl-sigalg"></a>

### `$ssl_sigalg`

returns the [signature algorithm](https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-16) for the server certificate for an established SSL connection.

#### NOTE
The variable is supported only when using OpenSSL version 3.5 or higher. With older versions, the variable value will be an empty string.

#### NOTE
The variable is available only for new sessions.