# Configure how Liberator handles HTTPS connections Here’s how to configure Liberator’s HTTPS connections. **❗ IMPORTANT**\ In production environments, always use HTTPS connections to Liberator, to ensure high security. Don’t use HTTP in production environments. HTTPS is the secure version of HTTP that uses the Secure Sockets Layer of TCP/IP (SSL) and offers a much greater level of protection than standard HTTP transmission. Liberator can run as an HTTPS web server like most common web servers. Web pages and other standard HTTP traffic can be sent over HTTPS, and if HTTPS is enabled all [RTTP](liberator-rttp.md) data is sent over an HTTPS connection too. Liberator supports standard TLS server-side certificates to authenticate the server to the client. They must be generated and signed by a certificate authority. **💡 TIP**\ Some of the instructions on this page require you to use the `dfw` command of the Deployment Framework. Before entering any `dfw` command as `./dfw `, make sure your current (working) directory is set to the Deployment Framework’s topmost directory. For a list of `dfw` commands, [click here](../deployment-framework/cdf-the-deployment-framework-command-utility-dfw.md). ## Liberator’s TLS implementation Liberator uses [OpenSSL](https://www.openssl.org/) to provide its implementation of TLS. The OpenSSL library is built-in to Liberator and is independent of the host system’s installation of OpenSSL. To determine the version of OpenSSL bundled with a specific release of Liberator, see Liberator’s release notes or run the `strings` command on the Liberator binary and grep the output: ``` $ strings rttpd | grep -i '^openssl [0-9]' ``` ## Enabling Liberator’s HTTPS interface Liberator’s default HTTP and HTTPS configuration is provided in two feature blades ( [config blades](../deployment-framework/cdf-blade-types.md)): `HTTP` and `HTTPS`. The HTTP feature blade is activated by default. To deactivate HTTP and activate HTTPS, follow the steps below: 1. Run the commands below to deactivate the HTTP blade and activate the HTTPS blade: ``` ./dfw deactivate HTTP ./dfw activate HTTPS ``` 2. Configure the HTTPS port number (default 18081). See [Configuring the HTTPS port number](#configuring-the-https-port-number). 3. Configure the HTTPS network interface (default all interfaces). See [Configuring the HTTPS network interface](#configuring-the-https-network-interface). 4. Install a TLS key, password file, and certificate. See [Installing a TLS key and certificate](#installing-a-tls-key-and-certificate). 5. Configure TLS protocol support (you should also repeat this task periodically as part of a regular security review). See [Configuring supported TLS protocol versions](#configuring-supported-tls-protocol-versions). 6. Configure TLS cipher support (you should also repeat this task periodically as part of a regular security review). See [Configuring supported TLS ciphers](#configuring-supported-tls-ciphers). 7. Generate a Diffie-Hellman (DH) parameters file to allow Liberator to use ephemeral Diffie-Hellman (DHE) ciphers. See [Generating a Diffie-Hellman parameters file for DHE ciphers](#generating-a-diffie-hellman-parameters-file-for-dhe-ciphers). 8. If this is a production server, disable Liberator’s built-in administrator website: ``` ./dfw deactivate LiberatorWebsite ./dfw activate MinimalLiberatorWebsite ``` 9. If this is a production server, enable TLS for Liberator’s direct RTTP interface too, or disable the direct RTTP interface entirely. See [Configure how Liberator handles direct client connections](liberator-configure-how-liberator-handles-direct-client-connections.md) for more information. ## Configuring the HTTPS port number By default, Liberator’s HTTPS port is 18081. If you plan to route Internet traffic to Liberator’s HTTPS interface, then for the broadest compatibility with your customers' firewall policies, we recommend that you expose Liberator’s HTTPS interface on port 443. The easiest way to expose Liberator’s HTTPS interface on port 443 is to use port-forwarding on your gateway firewall to route incoming traffic on 443 to port 18081 on your Liberator server. Alternatively, follow the instructions below to bind Liberator’s HTTPS interface to port 443 on the Liberator host: 1. In the Deployment Framework’s `global_config/environment.conf` file, set the `LIBERATOR${THIS_LEG}_HTTPSPORT` configuration variable to `443`: ``` define LIBERATOR${THIS_LEG}_HTTPSPORT 443 ``` **❗ IMPORTANT**\ Do not set the value of the [https-port](liberator-https-configuration.md#https-port) configuration item directly. Redefine the `LIBERATOR${THIS_LEG}_HTTPSPORT` configuration variable instead. 2. Run the system command below to permit the Liberator binary to bind to port 443: ``` $ sudo setcap 'cap_net_bind_service=+ep' __dfw_root__/kits/Liberator/Latest/bin/rttpd ``` where __dfw_root__ is the path to your Deployment Framework. ## Configuring the HTTPS network interface By default, Liberator’s HTTP and HTTPS server sockets are bound to all network interfaces on Liberator’s host. To bind Liberator’s HTTP and HTTPS server sockets to specific network interfaces, redefine the `LIBERATOR${THIS_LEG}_HTTPINTERFACE` configuration variable in the `/global_config/environment.conf` file: **Binding Liberator’s HTTP and HTTPS sockets to two network addresses** ``` define LIBERATOR${THIS_LEG}_HTTPINTERFACE 203.0.113.1 198.51.100.11 ``` The configuration variable supports IPv6 addresses from version 7 of Liberator. To listen for connections on both the IPv4 and IPv6 address of a dual-stack network interface, assign _both_ the IPv4 and IPv6 addresses to the configuration variable. Despite the name of the `LIBERATOR${THIS_LEG}_HTTPINTERFACE` variable implying that it applies only to HTTP server sockets, the variable applies to both HTTP and HTTPS server sockets. **❗ IMPORTANT**\ Do not set the value of the [https-interface](liberator-https-configuration.md#https-interface) configuration item directly. Redefine the `LIBERATOR${THIS_LEG}_HTTPINTERFACE` configuration variable instead. ## Installing a TLS key and certificate This section describes how to install a key, key password file, and certificate. ### Default key and certificate paths By default, the Deployment Framework (DFW) expects keys and certificates to be stored in the `global_config/ssl` directory. For convenience in writing configuration, the Deployment Framework sets a [configuration variable](../datasource/datasource-configuration-syntax.md#configuration-variables) `SSLCERT_PATH` to this directory. **💡 TIP**\ For a full list of Deployment Framework configuration variables, see [Configuration macros and items](../deployment-framework/cdf-configuration-macros-and-items.md). Liberator’s HTTPS feature blade configures default key and certificate locations as follows: **Default key, passphrase, and certificate paths** | File | Configuration item | Default value | | --- | --- | --- | | Certificate | [https-certificate](liberator-https-configuration.md#https-certificate) | global_config/ssl/rttpd_https.pem | | Private key | [https-privatekey](liberator-https-configuration.md#https-privatekey) | global_config/ssl/rttpd_https.key | | Private-key passphrase | [https-passwordfile](liberator-https-configuration.md#https-passwordfile) | global_config/ssl/rttpd_https.pwd | To override the default paths, assign new values to the [https-certificate](liberator-https-configuration.md#https-certificate), [https-privatekey](liberator-https-configuration.md#https-privatekey), and [https-passwordfile](liberator-https-configuration.md#https-passwordfile) configuration items in the Deployment Framework file `global_config/overrides/servers/Liberator/etc/rttpd.conf`. **❗ IMPORTANT**\ If you want to use an environment variable as your passphrase you can use the [https-password](liberator-https-configuration.md#https-password) configuration item instead of `https-passwordfile`. ### Deprecation of certificates with MD5- and SHA1-based digital signatures Certificates signed with an MD5 hash with RSA encryption have long been deprecated and some platforms and libraries no longer support them. The digital security industry now recommends using the SHA-2 family of hashing algorithms in digital signatures. Liberator’s demonstration self-signed SSL certificate was re-issued with a SHA256-based digital signature in versions 6.2.23, 7.0.5, and 7.1.1 of Liberator. Liberator 7.1 continues to support certificates signed with an MD5 hashing algorithm, but support may be dropped in future. StreamLink.NET 7.1 is compiled with .NET 4.6, which does _not_ support certificates signed with the MD5 hashing algorithm. To determine the digital signature algorithm used in a certificate, use OpenSSL’s x509 command to read the certificate and then grep the output: **Determining the digital signature algorithm in certificate 'rttpd_https.pem'** ```console $ openssl x509 -in rttpd_https.pem -text -noout | grep -m1 'Signature Algorithm' Signature Algorithm: sha256WithRSAEncryption ``` **Digital signature algorithms used in certificates** | Algorithm | Status | Notes | | --- | --- | --- | | md5WithRSAEncryption | Deprecated | Not supported by Caplin’s StreamLink.NET 7.1. | | sha1WithRSAEncryption | Deprecated | See [SHA1 Deprecation: What you need to know](https://blog.qualys.com/product-tech/2014/09/09/sha1-deprecation-what-you-need-to-know) on the Qualys blog. | | sha256WithRSAEncryption | Recommended | | ### Installing certificates for development and testing For the convenience of developers and software testers, Caplin ships a self-signed demonstration certificate with Liberator. **❗ IMPORTANT**\ Do not use Caplin’s self-signed certificate in production. In versions of the Deployment Framework prior to 7.0.2, the Deployment Framework automatically deploys Caplin’s self-signed certificate with Liberator if no keys and certificate exist for Liberator in the `global_config/ssl` directory. From version 7.0.2 of the Deployment Framework, the Deployment Framework does not automatically deploy Caplin’s self-signed certificate with Liberator. To manually deploy the self-signed certificate, run the [copy-ssl-demo-files](../deployment-framework/cdf-the-deployment-framework-command-utility-dfw.md#copy-ssl-demo-files) Deployment Framework command: ``` ./dfw copy-ssl-demo-files ``` When you first connect a web browser to a Liberator that presents Caplin’s self-signed certificate, your web browser will prompt you to trust the certificate. ### Installing certificates for production use Follow the instructions below to install a production certificate: 1. Follow the instructions provided by your chosen certificate authority (CA) to generate a certificate signing request (CSR) for your Liberator host. When generating the CSR, we recommend that you specify a SHA-2 hashing algorithm or stronger. See [Deprecation of certificates with MD5- and SHA1-based digital signatures](#deprecation-of-certificates-with-md5--and-sha1-based-digital-signatures) above. 2. When your CA delivers a signed certificate, rename the certificate, key, and passphrase files to Liberator’s default file names: `rttpd_https.pem`, `rttpd_https.key`, and `rttpd_https.pwd`. If you don’t want to use Liberator’s default file names, assign your own file names to the configuration items [https-certificate](liberator-https-configuration.md#https-certificate), [https-privatekey](liberator-https-configuration.md#https-privatekey), and [https-passwordfile](liberator-https-configuration.md#https-passwordfile) in the file `global_config/overrides/servers/Liberator/etc/rttpd.conf`. 3. Copy the private key, certificate, and password files to the _<Framework-root>/global_config/ssl/_ directory. If the private key is unencrypted, the password file must be empty. **From Liberator 7.1.9**: If the private key is unencrypted and you don’t want to deploy an empty password file, then set the configuration variable [`HTTPS_PASSWORD_FILE_REQUIRED`](../deployment-framework/cdf-configuration-macros-and-items.md#https-password-file-required) to `NO` in the Deployment Framework file `global_config/environment.conf`. ## Configuring supported TLS protocol versions To specify which TLS protocol versions are supported by Liberator, use the [`https-ssl-options`](liberator-https-configuration.md#https-ssl-options) configuration item to _disable_ protocol versions. For guidance on choosing which TLS protocol versions to support, see [Further reading on TLS](#further-reading-on-tls) below. ### Default TLS protocol versions The default TLS configuration is not updated regularly and is for your initial convenience only; it is not a security recommendation. All protocols supported by the version of OpenSSL included with Liberator are enabled unless explicitly disabled by [`https-ssl-options`](liberator-https-configuration.md#https-ssl-options). **Default TLS protocols** | Liberator | SSL 2 ^{asterisk}^ | SSL 3 ^†^ | TLS 1.0 ^‡^ | TLS 1.1 ^‡^ | TLS 1.2 | TLS 1.3 | | --- | :-: | :-: | :-: | :-: | :-: | :-: | | **7.1.25** | - | icon:square-o[] | icon:square-o[] | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | | **7.1.5** | - | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | icon:check-square-o[] | icon:check-square-o[] | | **7.1.2** | - | icon:square-o[] | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | - | | **7.0.1** | icon:square-o[] | icon:square-o[] | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | - | | **6.2.2** | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | icon:check-square-o[] | icon:check-square-o[] | - | | **6.2.0** | icon:square-o[] | icon:check-square-o[] | icon:check-square-o[] | - | - | - | [small]#-   Protocol not available\ icon:square-o[] Protocol disabled (see [https-ssl-options](liberator-https-configuration.md#https-ssl-options))\ icon:check-square-o[] Protocol enabled\ {asterisk} The IETF prohibited SSL 2 in March 2011: [RFC 6176](https://datatracker.ietf.org/doc/html/rfc6176)\ † The IETF deprecated SSL 3 in June 2015: [RFC 7568](https://datatracker.ietf.org/doc/html/rfc7568)\ ‡ The IETF deprecated TLS 1.0 and TLS 1.1 in March 2021: [RFC 8996](https://datatracker.ietf.org/doc/rfc8996/)# ### Worked example **❗ IMPORTANT**\ The configuration in this example is provided for illustrative purposes only, is not updated regularly, and does not constitute security advice. Review all TLS configuration before deploying to production, and schedule regular reviews thereafter. Liberator 7.1.24’s TLS implementation supports SSL 3, TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3. By default, TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3 are enabled on the HTTPS interface (see [Default TLS protocol versions](#default-tls-protocol-versions), below). To configure Liberator 7.1.24 so that only TLS 1.2 and TLS 1.3 are enabled on the HTTPS interface, set [`https-ssl-options`](liberator-https-configuration.md#https-ssl-options) to disable SSL 3, TLS 1.0, and TLS 1.1: ``` https-ssl-options SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1|SSL_OP_NO_TLSv1_1 ``` For a complete HTTPS configuration example, see [Example HTTPS configuration](#example-https-configuration) below. ## Configuring supported TLS ciphers To specify which TLS 1.0, 1.1 and 1.2 ciphers are supported by Liberator, set [`https-cipher-list`](liberator-https-configuration.md#https-cipher-list) to an [OpenSSL cipher list](https://docs.openssl.org/1.1.1/man1/ciphers/#CIPHER-LIST-FORMAT). To specify which TLS 1.3 ciphers are supported by Liberator, set [`https-ciphersuites`](liberator-https-configuration.md#https-ciphersuites) to an [OpenSSL cipher list](https://docs.openssl.org/1.1.1/man1/ciphers/#CIPHER-LIST-FORMAT). This is an advanced configuration option and is not required to enable support for TLS 1.3. For guidance on deciding which TLS ciphers to support, see [Further reading on TLS](#further-reading-on-tls) below. In accordance with the TLS specification, when choosing a cipher for a TLS connection, Liberator chooses the client’s most preferred cipher from among the ciphers they have in common. To reverse this default behaviour, set the `SSL_OP_CIPHER_SERVER_PREFERENCE` flag in [https-ssl-options](liberator-https-configuration.md#https-ssl-options). To define Liberator’s cipher preference, order ciphers in [`https-cipher-list`](liberator-https-configuration.md#https-cipher-list) in descending order of preference, most preferred cipher first. If your cipher list includes ephemeral Diffie-Hellman (DHE) ciphers, then configure the [`https-dhparams`](liberator-https-configuration.md#https-dhparams) configuration item with the location of a valid Diffie-Hellman (DH) parameters file. If you fail to do so, Liberator silently drops DHE ciphers from its list of supported ciphers. See [Generating a Diffie-Hellman parameters file for DHE ciphers](#generating-a-diffie-hellman-parameters-file-for-dhe-ciphers). ### Default cipher list The default TLS configuration is not updated regularly and is for your initial convenience only; it is not a security recommendation. **Default cipher string** | Liberator | Cipher string | | --- | --- | | **7.1.25** | TLSv1.2+ECDHE+AESGCM:TLSv1.2+ECDHE+AESCCM:TLSv1.2+ECDHE+CHACHA20:TLSv1.2+DHE+AESGCM:TLSv1.2+DHE+AESCCM:TLSv1.2+DHE+CHACHA20 | | **7.1.5** | ECDHE:DHE:!SSLv3:!SSLv2:@STRENGTH | | **7.0.1** | DEFAULT:!RC4-SHA:!RC4-MD5:!DES-CBC3-SHA | | **6.0.0** | DEFAULT | From Liberator 7.1.5, only cipher suites that support [forward secrecy](https://en.wikipedia.org/wiki/Forward_secrecy) (ECDHE and DHE) are enabled by default. DHE ciphers require a Diffie-Hellman parameters file, which is not distributed with Liberator (see [Generating a Diffie-Hellman parameters file for DHE ciphers](#generating-a-diffie-hellman-parameters-file-for-dhe-ciphers)). ### Preparing a cipher list You can preview how Liberator’s OpenSSL will interpret a cipher list by using the `**openssl ciphers**` command. For accuracy, use a version of OpenSSL that matches the version of OpenSSL used by your version of Liberator (see [Liberator’s TLS implementation](#liberators-tls-implementation)). For example, to expand the cipher list `ECDHE+TLSv1.2 DHE+TLSv1.2` to individual cipher names, use the command below: ``` $ openssl ciphers -v 'ECDHE+TLSv1.2 DHE+TLSv1.2' | column -t ``` The `**openssl cipher**` command’s output uses OpenSSL cipher names, but security literature and vulnerability scanners often use IANA cipher names. To translate between the two naming schemes, refer to the table on [Security: Cipher Suites](https://wiki.mozilla.org/Security/Cipher_Suites) on the Mozilla wiki. ### Worked example **❗ IMPORTANT**\ The configuration in this example is provided for illustrative purposes only, is not updated regularly, and does not constitute security advice. Review all TLS configuration before deploying to production, and schedule regular reviews thereafter. A Liberator has been configured to support only TLS versions 1.2 and 1.3: ``` https-ssl-options SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1|SSL_OP_NO_TLSv1_1 ``` In this example, we’ll construct an OpenSSL cipher list of TLS 1.2 ciphers. TLS 1.3 ciphers are automatically included by OpenSSL and do not need to be configured. The [Qualys SSL Labs recommendations](https://github.com/ssllabs/research/wiki/SSL-and-TLS-Deployment-Best-Practices) at the time of writing (June 2022) state that the following cipher suites must be preferred: * AEAD (Authenticated Encryption with Associated Data) cipher suites: CHACHA20_POLY1305, AES with GCM, and AES with CCM * PFS (Perfect Forward Secrecy) ciphers: ECDHE_RSA, ECDHE_ECDSA, DHE_RSA, DHE_DSS, CECPQ1 and all TLS 1.3 ciphers We’ll use the following OpenSSL [cipher strings](https://docs.openssl.org/1.1.1/man1/ciphers/#CIPHER-STRINGS) to construct our cipher list: | Cipher string | Description | | --- | --- | | TLSv1.2 | All TLS 1.2 ciphers | | ECHDE | All ciphers using authenticated ephemeral ECDH key agreement. | | DHE | All ciphers using authenticated ephemeral DH key agreement. | | AESGCM | All ciphers that use AES-GCM encryption | | AESCCM | All ciphers that use AES-CCM encryption | | CHACHA20 | All ciphers that use ChaCha20 encryption | We use the OpenSSL cipher-string logical AND (`+`) operator to combine the cipher strings into six subsets: * `TLSv1.2+ECDHE+AESGCM` * `TLSv1.2+ECDHE+AESCCM` * `TLSv1.2+ECDHE+CHACHA20` * `TLSv1.2+DHE+AESGCM` * `TSLv1.2+DHE+AESCCM` * `TSLv1.2+DHE+CHACHA20` We then assign this list to `https-ssl-ciphers`: ``` https-ssl-ciphers "TLSv1.2+ECDHE+AESGCM TLSv1.2+ECDHE+AESCCM TLSv1.2+ECDHE+CHACHA20 TLSv1.2+DHE+AESGCM TLSv1.2+DHE+AESCCM TLSv1.2+DHE+CHACHA20" ``` In an OpenSSL cipher list, cipher strings can be separated by spaces or colons (`:`). We have used spaces for clarity. When separated by spaces, the cipher list must be enclosed in quotes. For a complete HTTPS configuration example, see [Example HTTPS configuration](#example-https-configuration) below. ## Example HTTPS configuration **❗ IMPORTANT**\ The configuration in this section is provided for illustrative purposes only, is not updated regularly, and does not constitute security advice. Review all TLS configuration before deploying to production, and schedule regular reviews thereafter. This example supports modern web clients (defined as all clients that support TLS 1.2 and above). Features: * **TLS protocols**: TLS 1.2, TLS 1.3 (Liberator supports TLS 1.3 from Liberator 7.1.5) * **TLS 1.3 ciphers**: All mandatory ciphers * **TLS 1.2 ciphers**: Forward-secrecy ciphers (ECDHE, DHE) that implement AES-GCM, AES-CCM, or CHACHA20 encryption. * **Diffie-Hellman parameters**: 2048-bit When tested with Liberator 7.1.24 using the [SSL Labs Server Test](https://www.ssllabs.com/ssltest/index.html) on 5 June 2022, the configuration below scored A+. View the [SSL Labs report](https://docs.caplin.com/developer/docs/liberator-7.1.24-ssllabs-20220605.pdf). **❗ IMPORTANT**\ While the configuration below achieved an SSL Labs score of A+ on 5 June 2022, ciphers may weaken over time and the configuration may not achieve that score today. Retest and review this configuration before considering deploying it to production. ``` # OpenSSL options define SSL_OPTIONS "SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1|SSL_OP_NO_TLSv1_1" # OpenSSL ciphers to include define CIPHER_INCLUDES "ECDHE+TLSv1.2+AESGCM ECDHE+TLSv1.2+AESCCM ECDHE+TLSv1.2+CHACHA20 DHE+TLSv1.2+AESGCM DHE+TLSv1.2+AESCCM DHE+TLSv1.2+CHACHA20" # OpenSSL ciphers to exclude define CIPHER_EXCLUDES "" https-ssl-options "${SSL_OPTIONS}" https-cipher-list "${CIPHER_INCLUDES} ${CIPHER_EXCLUDES}" https-dhparams "${SSLCERT_PATH}/rttpd-dhparam-2048.pem" ``` ## Generating a Diffie-Hellman parameters file for DHE ciphers Ephemeral Diffie-Hellman ciphers (DHE) ciphers are supported by Liberator from version 6.2.14 and 7.0.1. DHE ciphers require a Diffie-Hellman (DH) parameter file. If you do not configure the `https-dhparams` configuration item with the location of a valid DH parameters file, Liberator silently removes DHE ciphers from its list of supported ciphers. No DH parameters file is provided with Liberator; you must generate your own. To generate a Diffie-Hellman (DH) parameters file, follow the steps below: 1. In the Deployment Framework’s `global_config/ssl/` directory, run the command below: ``` $ openssl dhparam -out rttpd-dhparam-2048.pem 2048 ``` This command can take a long time to complete. 2. Assign the location of the DH parameters file to the [https-dhparams](liberator-https-configuration.md#https-dhparams) configuration item in the Deployment Framework’s `global_config/overrides/servers/Liberator/etc/rttpd.conf` file: ``` https-dhparams ${SSLCERT_PATH}/rttpd-dhparam-2048.pem ``` To test that a Liberator supports DHE ciphers, follow the steps below: 1. In the file `global_config/overrides/servers/Liberator/rttpd.conf`, assign a cipher string containing DHE ciphers to the `https-cipher-list` configuration item. For example: ``` https-cipher-list "ECDHE+TLSv1.2:##DHE+TLSv1.2##" ``` 2. Restart Liberator 3. Run the command below to test connecting to Liberator using a DHE cipher. The example below tests connecting with the DHE-RSA-AES256-GCM-SHA384 cipher, one of the DHE ciphers included in OpenSSL’s [TLS 1.2 cipher suite](https://docs.openssl.org/1.1.1/man1/ciphers/#TLS-v1.2-cipher-suites): ``` $ openssl s_client -cipher DHE-RSA-AES256-GCM-SHA384 -connect __host__:__port__ ``` ## Seeding the OpenSSL random number generator See How can I... [Seed the OpenSSL random number generator](../datasource/datasource-seed-the-openssl-random-number-generator.md). ## Configuring OpenSSL Liberator uses the [OpenSSL](https://www.openssl.org) software to implement the security policies for secure (HTTPS) connections with clients. You can configure OpenSSL using the following DataSource configuration items, which are defined on the page [DataSource Secure Sockets Layer (SSL) configuration](../datasource/datasource-datasource-secure-sockets-layer-ssl-configuration.md): * [`ssl-config-name`](../datasource/datasource-datasource-secure-sockets-layer-ssl-configuration.md#ssl-config-name) * [`ssl-engine-flags`](../datasource/datasource-datasource-secure-sockets-layer-ssl-configuration.md#ssl-engine-flags) * [`ssl-engine-id`](../datasource/datasource-datasource-secure-sockets-layer-ssl-configuration.md#ssl-engine-id) **📌 NOTE**\ When you change the configuration of OpenSSL, the new settings apply to all of Liberator’s secure (SSL) connections: HTTPS connections, [Direct secure connections](liberator-configure-how-liberator-handles-direct-client-connections.md) to clients, and [secure connections between Liberator and other DataSource applications](../datasource/datasource-set-up-secure-connections-between-datasource-applications.md). ## Further reading on TLS Choosing which TLS protocols and ciphers to support is a balance between minimising security risk and supporting the broadest range of clients. For introductory guidance on choosing protocols and ciphers, read the third-party resources below: * [Security: Server Side TLS](https://wiki.mozilla.org/Security/Server_Side_TLS) on the Mozilla wiki * [Security: Cipher Suites](https://wiki.mozilla.org/Security/Cipher_Suites) on the Mozilla wiki * [OWASP Transport Layer Security Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Transport_Layer_Protection_Cheat_Sheet.html) * [SSL Labs SSL and TLS Deployment Best Practices](https://www.ssllabs.com/projects/best-practices/index.html) * [SSL Labs server rating guide](https://www.ssllabs.com/projects/rating-guide/index.html) --- **See also:** * How can I... [Configure how Liberator handles HTTP connections](liberator-configure-how-liberator-handles-http-connections.md) * How can I... [Configure how Liberator handles direct client connections](liberator-configure-how-liberator-handles-direct-client-connections.md) * How can I... [Set up secure connections between DataSource applications](../datasource/datasource-set-up-secure-connections-between-datasource-applications.md) * Reference: [HTTPS configuration](liberator-https-configuration.md) * Reference: [HTTP configuration](liberator-http-configuration-part-1.md)