1ssl(7) Erlang Application Definition ssl(7)
2
6 ssl - The ssl application provides secure communication over
7 sockets.
8
10 The ssl application is an implementation of the SSL, TLS and DTLS pro‐
11 tocols in Erlang.
12 For current statement of standards compliance see the User's Guide.
14
16 The SSL application uses the public_key, asn1 and Crypto application to
17 handle public keys and encryption, hence these applications must be
18 loaded for the SSL application to work. In an embedded environment this
19 means they must be started with application:start/[1,2] before the SSL
20 application is started.
21
23 The application environment configuration parameters in this section
24 are defined for the SSL application. For more information about config‐
25 uration parameters, see the application(3) manual page in Kernel.
26 The environment parameters can be set on the command line, for example:
28 erl -ssl protocol_version "['tlsv1.2', 'tlsv1.1']"
30 protocol_version = ssl:ssl_tls_protocol()<optional>:
32 Protocol supported by started clients and servers. If this option
33 is not set, it defaults to all TLS protocols currently supported,
34 more might be configurable, by the SSL application. This option can
35 be overridden by the version option to ssl:connect/[2,3] and
36 ssl:listen/2.
37 dtls_protocol_version = ssl:dtls_protocol()<optional>:
39 Protocol supported by started clients and servers. If this option
40 is not set, it defaults to all DTLS protocols currently supported,
41 more might be configurable, by the SSL application. This option can
42 be overridden by the version option to ssl:connect/[2,3] and
43 ssl:listen/2.
44 session_lifetime = integer() <optional>:
46 Maximum lifetime of the session data in seconds. Defaults to 24
47 hours which is the maximum recommended lifetime by RFC 5246. How‐
48 ever sessions may be invalidated earlier due to the maximum limita‐
49 tion of the session cache table.
50 session_cb = atom() <optional>:
52 Name of the session cache callback module that implements the
53 ssl_session_cache_api behavior. Defaults to ssl_session_cache.
54 session_cb_init_args = proplist:proplist() <optional>:
56 List of extra user-defined arguments to the init function in the
57 session cache callback module. Defaults to [].
58 session_cache_client_max = integer() <optional>
60 : Limits the growth of the clients session cache, that is how many
61 sessions towards servers that are cached to be used by new client
62 connections. If the maximum number of sessions is reached, the cur‐
63 rent cache entries will be invalidated regardless of their remain‐
64 ing lifetime. Defaults to 1000. Recommended ssl-8.2.1 or later for
65 this option to work as intended.
66 session_cache_server_max = integer() <optional>:
68 Limits the growth of the servers session cache, that is how many
69 client sessions are cached by the server. If the maximum number of
70 sessions is reached, the current cache entries will be invalidated
71 regardless of their remaining lifetime. Defaults to 1000. Recom‐
72 mended ssl-8.2.1 or later for this option to work as intended.
73 ssl_pem_cache_clean = integer() <optional>:
75 Number of milliseconds between PEM cache validations. Defaults to 2
76 minutes.ssl:clear_pem_cache/0
77 bypass_pem_cache = boolean() <optional>:
79 Introduced in ssl-8.0.2. Disables the PEM-cache. Can be used as a
80 workaround for the PEM-cache bottleneck before ssl-8.1.1. Defaults
81 to false.
82 alert_timeout = integer() <optional>:
84 Number of milliseconds between sending of a fatal alert and closing
85 the connection. Waiting a little while improves the peers chances
86 to properly receiving the alert so it may shutdown gracefully.
87 Defaults to 5000 milliseconds.
88 internal_active_n = integer() <optional>:
90 For TLS connections this value is used to handle the internal
91 socket. As the implementation was changed from an active once to an
92 active N behavior (N = 100), for performance reasons, this option
93 exist for possible tweaking or restoring of the old behavior
94 (internal_active_n = 1) in unforeseen scenarios. The option will
95 not affect erlang distribution over TLS that will always run in
96 active N mode. Added in ssl-9.1 (OTP-21.2).
97 server_session_tickets_amount = integer() <optional>:
99 Number of session tickets sent by the server. It must be greater
100 than 0. Defaults to 3.
101 server_session_ticket_lifetime = integer() <optional>:
103 Lifetime of session tickets sent by the server. Servers must not
104 use any value greater than 604800 seconds (7 days). Expired tickets
105 are automatically removed. Defaults to 7200 seconds (2 hours).
106 server_session_ticket_store_size = integer() <optional>:
108 Sets the maximum size of the server session ticket store (stateful
109 tickets). Defaults to 1000. Size limit is enforced by dropping old
110 tickets.
111 client_session_ticket_lifetime = integer() <optional>:
113 Lifetime of session tickets in the client ticket store. Expired
114 tickets are automatically removed. Defaults to 7200 seconds (2
115 hours).
116 client_session_ticket_store_size = integer() <optional>:
118 Sets the maximum size of the client session ticket store. Defaults
119 to 1000. Size limit is enforced by dropping old tickets.
120
122 The SSL application uses OTP logger. TLS/DTLS alerts are logged on
123 notice level. Unexpected errors are logged on error level. These log
124 entries will by default end up in the default Erlang log. The option
125 log_level may be used to in run-time to set the log level of a specific
126 TLS connection, which is handy when you want to use level debug to
127 inspect the TLS handshake setup.
128
130 application(3)
131Ericsson AB ssl 9.6.1 ssl(7)