.. _dh-apache: Diffie-Hellman Security ----------------------- To secure your web server, the `Guide to Deploying Diffie-Hellman for TLS`_ contains important information worth reading. This link contains some good `secure Apache configuration`_ examples. To secure your deployment of Diffie-Hellman, configure the following: 1. Generate a strong Diffie-hellman group, 2048-bit or stronger. .. code-block:: bash # to generate your dhparam.pem file, run in the terminal openssl dhparam -out /etc/apache/ssl/dhparam.pem 2048 2. Configure your server to only use modern, secure cipher suites in the virtual hosts configuration file. .. code-block:: apache # Set the protocol to only use modern, secure cipher suites. SSLProtocol all -SSLv2 -SSLv3 SSLHonorCipherOrder on SSLCipherSuite ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA # Specify your DH params file as follows SSLOpenSSLConfCmd DHParameters "{path to dhparams.pem}" .. _Guide to Deploying Diffie-Hellman for TLS: https://weakdh.org/sysadmin.html .. _secure Apache configuration: http://www.apache-ssl.org/httpd.conf.example