<?xml version="1.0"?>

<!--
  Copyright (C) 2006, 2007 Anton Yuzhaninov
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_mail_ssl_module"
        link="/en/docs/mail/ngx_mail_ssl_module.html"
        lang="en"
        rev="1">

<section id="summary">

<para>
The <literal>ngx_mail_ssl_module</literal> provides the necessary
support for mail proxy server for the SSL/TLS protocol.
</para>

<para>
This module is not built by default, it should be enabled with
the <literal>--with-mail_ssl_module</literal>
configuration parameter.
<note>
This module requires the <link url="http://www.openssl.org">OpenSSL</link>
library.
</note>
</para>

</section>


<section id="directives" name="Directives">

<directive name="ssl">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>

<para>
Enables the HTTPS protocol for the given virtual server.
</para>

</directive>


<directive name="ssl_certificate">
<syntax><value>file</value></syntax>
<default/>
<context>mail</context>
<context>server</context>

<para>
Specifies a file with a certificate in the PEM format for the given
virtual server.
If intermediate certificates should be specified in addition to a primary
certificate, they should be specified in the same file in the following
order: the primary certificate comes first, then the intermediate certificates.
A secret key in the PEM format may be placed in the same file.
</para>

</directive>


<directive name="ssl_certificate_key">
<syntax><value>file</value></syntax>
<default/>
<context>mail</context>
<context>server</context>

<para>
Specifies a file with a secret key in the PEM format for the given virtual
server.
</para>

</directive>


<directive name="ssl_prefer_server_ciphers">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>

<para>
Specifies that server ciphers should be preferred over client ciphers
when using the SSLv3 and TLS protocols.
</para>

</directive>


<directive name="ssl_protocols">
<syntax>
    [<literal>SSLv2</literal>]
    [<literal>SSLv3</literal>]
    [<literal>TLSv1</literal>]
    [<literal>TLSv1.1</literal>]
    [<literal>TLSv1.2</literal>]</syntax>
<default>SSLv3 TLSv1 TLSv1.1 TLSv1.2</default>
<context>mail</context>
<context>server</context>

<para>
Enables the specified protocols.
The parameters <literal>TLSv1.1</literal> and <literal>TLSv1.2</literal> work
only when using the OpenSSL library version 1.0.1 and higher.
<note>
The parameters <literal>TLSv1.1</literal> and <literal>TLSv1.2</literal> are
supported starting from versions 1.1.13 and 1.0.12
so when using OpenSSL version 1.0.1
and higher on older nginx versions these protocols will work but could not
be disabled.
</note>
</para>

</directive>


<directive name="ssl_session_cache">
<syntax>
    <literal>off</literal> |
    <literal>none</literal> |
    [<literal>builtin</literal>[:<value>size</value>]]
    [<literal>shared</literal>:<value>name</value>:<value>size</value>]</syntax>
<default>none</default>
<context>mail</context>
<context>server</context>

<para>
Sets types and sizes of caches that store session parameters.
A cache can be any of the following types:
<list type="tag">

<tag-name><literal>off</literal></tag-name>
<tag-desc>
the use of session cache is strictly prohibited:
nginx explicitly tells a client that sessions may not be reused.
</tag-desc>

<tag-name><literal>none</literal></tag-name>
<tag-desc>
the use of session cache is gently disallowed:
nginx tells a client that sessions may be reused, but does not
actually do that.
</tag-desc>

<tag-name><literal>builtin</literal></tag-name>
<tag-desc>
a cache built in OpenSSL; used by one worker process only.
The cache size is specified in sessions.
If size is not given, it is equal to 20480 sessions.
Use of the built-in cache can cause memory fragmentation.
</tag-desc>

<tag-name><literal>shared</literal></tag-name>
<tag-desc>
shared between all worker processes.
The cache size is specified in bytes; one megabyte can store
about 4000 sessions.
Each shared cache should have an arbitrary name.
A cache with the same name can be used in several
virtual servers.
</tag-desc>

</list>
</para>

<para>
Both cache types can be used simultaneously, for example:
<example>
ssl_session_cache builtin:1000 shared:SSL:10m;
</example>
but using only shared cache without the built-in cache should
be more efficient.
</para>

</directive>


<directive name="ssl_session_timeout">
<syntax><value>time</value></syntax>
<default>5m</default>
<context>mail</context>
<context>server</context>

<para>
Specifies a time during which a client may reuse the
session parameters stored in a cache.
</para>

</directive>


<directive name="starttls">
<syntax>
  <literal>on</literal> |
  <literal>off</literal> |
  <literal>only</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>

<para>
<list type="tag">

<tag-name><literal>on</literal></tag-name>
<tag-desc>
Allow usage of <literal>STLS</literal> command for the POP3
and <literal>STARTTLS</literal> command for the IMAP;
</tag-desc>

<tag-name><literal>off</literal></tag-name>
<tag-desc>
Deny usage of <literal>STLS</literal>
and <literal>STARTTLS</literal> commands;
</tag-desc>

<tag-name><literal>only</literal></tag-name>
<tag-desc>
require preliminary TLS transition.
</tag-desc>

</list>
</para>

</directive>

</section>

</module>