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:tls_version() | [ssl:tls_version()] <op‐
32 tional>:
33 Protocol supported by started clients and servers. If this option
34 is not set, it defaults to all TLS protocols currently supported,
35 more might be configurable, by the SSL application. This option can
36 be overridden by the version option to ssl:connect/[2,3] and
37 ssl:listen/2.
38 dtls_protocol_version = ssl:dtls_version() | [ssl:dtls_version()]
40 <optional>:
41 Protocol supported by started clients and servers. If this option
42 is not set, it defaults to all DTLS protocols currently supported,
43 more might be configurable, by the SSL application. This option can
44 be overridden by the version option to ssl:connect/[2,3] and
45 ssl:listen/2.
46 session_lifetime = integer() <optional>:
48 Maximum lifetime of the session data in seconds. Defaults to 24
49 hours which is the maximum recommended lifetime by RFC 5246. How‐
50 ever sessions may be invalidated earlier due to the maximum limita‐
51 tion of the session cache table.
52 session_cb = atom() <optional>:
54 Deprecated Since OTP-23.3 replaced by client_session_cb and
55 server_session_cb
56 client_session_cb = atom() <optional>:
58 Since OTP-23.3 Name client of the session cache callback module
59 that implements the ssl_session_cache_api behavior. Defaults to
60 ssl_client_session_cache_db.
61 server_session_cb = atom() <optional>:
63 Since OTP-23.3 Name of the server session cache callback module
64 that implements the ssl_session_cache_api behavior. Defaults to
65 ssl_server_session_cache_db.
66 session_cb_init_args = proplist:proplist() <optional>:
68 Deprecated Since OTP-23.3 replaced by client_session_cb_init_args
69 and server_session_cb_init_args
70 client_session_cb_init_args = proplist:proplist() <optional>:
72 List of extra user-defined arguments to the init function in the
73 session cache callback module. Defaults to [].
74 server_session_cb_init_args = proplist:proplist() <optional>:
76 List of extra user-defined arguments to the init function in the
77 session cache callback module. Defaults to [].
78 session_cache_client_max = integer() <optional>
80 : Limits the growth of the clients session cache, that is how many
81 sessions towards servers that are cached to be used by new client
82 connections. If the maximum number of sessions is reached, the cur‐
83 rent cache entries will be invalidated regardless of their remain‐
84 ing lifetime. Defaults to 1000. Recommended ssl-8.2.1 or later for
85 this option to work as intended.
86 session_cache_server_max = integer() <optional>:
88 Limits the growth of the servers session cache, that is how many
89 client sessions are cached by the server. If the maximum number of
90 sessions is reached, the current cache entries will be invalidated
91 regardless of their remaining lifetime. Defaults to 1000. Recom‐
92 mended ssl-8.2.1 or later for this option to work as intended.
93 ssl_pem_cache_clean = integer() <optional>:
95 Number of milliseconds between PEM cache validations. Defaults to 2
96 minutes.ssl:clear_pem_cache/0
97 bypass_pem_cache = boolean() <optional>:
99 Introduced in ssl-8.0.2. Disables the PEM-cache. Can be used as a
100 workaround for the PEM-cache bottleneck before ssl-8.1.1. Defaults
101 to false.
102 alert_timeout = integer() <optional>:
104 Number of milliseconds between sending of a fatal alert and closing
105 the connection. Waiting a little while improves the peers chances
106 to properly receiving the alert so it may shutdown gracefully. De‐
107 faults to 5000 milliseconds.
108 internal_active_n = integer() <optional>:
110 For TLS connections this value is used to handle the internal
111 socket. As the implementation was changed from an active once to an
112 active N behavior (N = 100), for performance reasons, this option
113 exist for possible tweaking or restoring of the old behavior (in‐
114 ternal_active_n = 1) in unforeseen scenarios. The option will not
115 affect erlang distribution over TLS that will always run in active
116 N mode. Added in ssl-9.1 (OTP-21.2).
117 server_session_tickets_amount = integer() <optional>:
119 Number of session tickets sent by the server. It must be greater
120 than 0. Defaults to 3.
121 server_session_ticket_lifetime = integer() <optional>:
123 Lifetime of session tickets sent by the server. Servers must not
124 use any value greater than 604800 seconds (7 days). Expired tickets
125 are automatically removed. Defaults to 7200 seconds (2 hours).
126 server_session_ticket_store_size = integer() <optional>:
128 Sets the maximum size of the server session ticket store (stateful
129 tickets). Defaults to 1000. Size limit is enforced by dropping old
130 tickets.
131 server_session_ticket_max_early_data = integer() <optional>:
133 Sets the maximum size of the early data that the server accepts and
134 also configures its NewSessionTicket messages to include this same
135 size limit in their early_data_indication extension. Defaults to
136 16384. Size limit is enforced by both client and server.
137 client_session_ticket_lifetime = integer() <optional>:
139 Lifetime of session tickets in the client ticket store. Expired
140 tickets are automatically removed. Defaults to 7200 seconds (2
141 hours).
142 client_session_ticket_store_size = integer() <optional>:
144 Sets the maximum size of the client session ticket store. Defaults
145 to 1000. Size limit is enforced by dropping old tickets.
146
148 The SSL application uses OTP logger. TLS/DTLS alerts are logged on no‐
149 tice level. Unexpected errors are logged on error level. These log en‐
150 tries will by default end up in the default Erlang log. The option
151 log_level may be used to in run-time to set the log level of a specific
152 TLS connection, which is handy when you want to use level debug to in‐
153 spect the TLS handshake setup.
154
156 application(3)
157Ericsson AB ssl 10.7.3.1 ssl(7)