ssl

ssl(7)                    Erlang Application Definition                   ssl(7)



NAME
       ssl - The ssl application provides secure communication over
         sockets.

DESCRIPTION
       The ssl application is an implementation of the SSL/TLS/DTLS protocol in
       Erlang.

         * Supported SSL/TLS/DTLS-versions are SSL-3.0, TLS-1.0, TLS-1.1,
           TLS-1.2, DTLS-1.0 (based on TLS-1.1), DTLS-1.2 (based on TLS-1.2)

         * For security reasons SSL-2.0 is not supported. Interoperability with
           SSL-2.0 enabled clients dropped. (OTP 21)

         * For security reasons SSL-3.0 is no longer supported by default, but
           can be configured. (OTP 19)

         * For security reasons RSA key exchange cipher suites are no longer
           supported by default, but can be configured. (OTP 21)

         * For security reasons DES cipher suites are no longer supported by
           default, but can be configured. (OTP 20)

         * For security reasons 3DES cipher suites are no longer supported by
           default, but can be configured. (OTP 21)

         *
            Renegotiation Indication Extension RFC 5746 is supported

         * Ephemeral Diffie-Hellman cipher suites are supported, but not Diffie
           Hellman Certificates cipher suites.

         * Elliptic Curve cipher suites are supported if the Crypto application
           supports it and named curves are used.

         * Export cipher suites are not supported as the U.S. lifted its export
           restrictions in early 2000.

         * IDEA cipher suites are not supported as they have become deprecated
           by the latest TLS specification so it is not motivated to implement
           them.

         * Compression is not supported.

         * CRL validation is supported.

         * Policy certificate extensions are not supported.

         * 'Server Name Indication' extension (RFC 6066) is supported.

         * Application Layer Protocol Negotiation (ALPN) and its successor Next
           Protocol Negotiation (NPN) are supported.

         * It is possible to use Pre-Shared Key (PSK) and Secure Remote Password
           (SRP) cipher suites, but they are not enabled by default.

DEPENDENCIES
       The SSL application uses the public_key, asn1 and Crypto application to
       handle public keys and encryption, hence these applications must be
       loaded for the SSL application to work. In an embedded environment this
       means they must be started with application:start/[1,2] before the SSL
       application is started.

CONFIGURATION
       The application environment configuration parameters in this section are
       defined for the SSL application. For more information about configuration
       parameters, see the application(3erl) manual page in Kernel.

       The environment parameters can be set on the command line, for example:

       erl -ssl protocol_version "['tlsv1.2', 'tlsv1.1']"

         protocol_version = ssl:ssl_tls_protocol()<optional>:
           Protocol supported by started clients and servers. If this option is
           not set, it defaults to all TLS protocols currently supported by the
           SSL application. This option can be overridden by the version option
           to ssl:connect/[2,3] and ssl:listen/2.

         dtls_protocol_version = ssl:dtls_protocol()<optional>:
           Protocol supported by started clients and servers. If this option is
           not set, it defaults to all DTLS protocols currently supported by the
           SSL application. This option can be overridden by the version option
           to ssl:connect/[2,3] and ssl:listen/2.

         session_lifetime = integer() <optional>:
           Maximum lifetime of the session data in seconds. Defaults to 24 hours
           which is the maximum recommended lifetime by RFC 5246. However
           sessions may be invalidated earlier due to the maximum limitation of
           the session cache table.

         session_cb = atom() <optional>:
           Name of the session cache callback module that implements the
           ssl_session_cache_api behavior. Defaults to ssl_session_cache.

         session_cb_init_args = proplist:proplist() <optional>:
           List of extra user-defined arguments to the init function in the
           session cache callback module. Defaults to [].

         session_cache_client_max = integer() <optional>
           : Limits the growth of the clients session cache, that is how many
           sessions towards servers that are cached to be used by new client
           connections. If the maximum number of sessions is reached, the
           current cache entries will be invalidated regardless of their
           remaining lifetime. Defaults to 1000. Recommended ssl-8.2.1 or later
           for this option to work as intended.

         session_cache_server_max = integer() <optional>:
           Limits the growth of the servers session cache, that is how many
           client sessions are cached by the server. If the maximum number of
           sessions is reached, the current cache entries will be invalidated
           regardless of their remaining lifetime. Defaults to 1000. Recommended
           ssl-8.2.1 or later for this option to work as intended.

         ssl_pem_cache_clean = integer() <optional>:
           Number of milliseconds between PEM cache validations. Defaults to 2
           minutes.ssl:clear_pem_cache/0

         bypass_pem_cache = boolean() <optional>:
           Introduced in ssl-8.0.2. Disables the PEM-cache. Can be used as a
           workaround for the PEM-cache bottleneck before ssl-8.1.1. Defaults to
           false.

         alert_timeout = integer() <optional>:
           Number of milliseconds between sending of a fatal alert and closing
           the connection. Waiting a little while improves the peers chances to
           properly receiving the alert so it may shutdown gracefully. Defaults
           to 5000 milliseconds.

         internal_active_n = integer() <optional>:
           For TLS connections this value is used to handle the internal socket.
           As the implementation was changed from an active once to an active N
           behavior (N = 100), for performance reasons, this option exist for
           possible tweaking or restoring of the old behavior (internal_active_n
           = 1) in unforeseen scenarios. The option will not affect erlang
           distribution over TLS that will always run in active N mode. Added in
           ssl-9.1 (OTP-21.2).

ERROR LOGGER AND EVENT HANDLERS
       The SSL application uses the default OTP error logger to log unexpected
       errors and TLS/DTLS alerts. The logging of TLS/DTLS alerts may be turned
       off with the log_alert option.

SEE ALSO
       application(3erl)



Ericsson AB                         ssl 9.1.2                             ssl(7)