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<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
<header>
<copyright>
<year>2003</year><year>2013</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
The contents of this file are subject to the Erlang Public License,
Version 1.1, (the "License"); you may not use this file except in
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
the License for the specific language governing rights and limitations
under the License.
</legalnotice>
<title>Using SSL API</title>
<prepared></prepared>
<responsible></responsible>
<docno></docno>
<approved></approved>
<checked></checked>
<date></date>
<rev></rev>
<file>using_ssl.xml</file>
</header>
<p>To see relevant version information for ssl, call <c>ssl:versions/0</c>.</p>
<p>To see all supported cipher suites, call <c>ssl:cipher_suites/0</c>.
The available cipher suites for a connection depend on your certificate.
Specific cipher suites that you want your connection to use can also be
specified. Default is to use the strongest available.</p>
<section>
<title>Setting up Connections</title>
<p>This section shows a small example of how to set up client/server connections
using the Erlang shell. The returned value of the <c>sslsocket</c> is abbreviated
with <c>[...]</c> as it can be fairly large and is opaque.</p>
<section>
<title>Minimal Example</title>
<note><p> The minimal setup is not the most secure setup of SSL.</p>
</note>
<p>To set up client/server connections:</p>
<p><em>Step 1:</em> Start the server side:</p>
<code type="erl">1 server> ssl:start().
ok</code>
<p><em>Step 2:</em> Create an SSL listen socket:</p>
<code type="erl">2 server> {ok, ListenSocket} =
ssl:listen(9999, [{certfile, "cert.pem"}, {keyfile, "key.pem"},{reuseaddr, true}]).
{ok,{sslsocket, [...]}}</code>
<p><em>Step 3:</em> Do a transport accept on the SSL listen socket:</p>
<code type="erl">3 server> {ok, Socket} = ssl:transport_accept(ListenSocket).
{ok,{sslsocket, [...]}}</code>
<p><em>Step 4:</em> Start the client side:</p>
<code type="erl">1 client> ssl:start().
ok</code>
<code type="erl">2 client> {ok, Socket} = ssl:connect("localhost", 9999, [], infinity).
{ok,{sslsocket, [...]}}</code>
<p><em>Step 5:</em> Do the SSL handshake:</p>
<code type="erl">4 server> ok = ssl:ssl_accept(Socket).
ok</code>
<p><em>Step 6:</em> Send a message over SSL:</p>
<code type="erl">5 server> ssl:send(Socket, "foo").
ok</code>
<p><em>Step 7:</em> Flush the shell message queue to see that the message
was sent on the server side:</p>
<code type="erl">3 client> flush().
Shell got {ssl,{sslsocket,[...]},"foo"}
ok</code>
</section>
<section>
<title>Upgrade Example</title>
<note><p>To upgrade a TCP/IP connection to an SSL connection, the
client and server must agree to do so. The agreement
can be accomplished by using a protocol, for example, the one used by HTTP
specified in RFC 2817.</p></note>
<p>To upgrade to an SSL connection:</p>
<p><em>Step 1:</em> Start the server side:</p>
<code type="erl">1 server> ssl:start().
ok</code>
<p><em>Step 2:</em> Create a normal TCP listen socket:</p>
<code type="erl">2 server> {ok, ListenSocket} = gen_tcp:listen(9999, [{reuseaddr, true}]).
{ok, #Port<0.475>}</code>
<p><em>Step 3:</em> Accept client connection:</p>
<code type="erl">3 server> {ok, Socket} = gen_tcp:accept(ListenSocket).
{ok, #Port<0.476>}</code>
<p><em>Step 4:</em> Start the client side:</p>
<code type="erl">1 client> ssl:start().
ok</code>
<code type="erl">2 client> {ok, Socket} = gen_tcp:connect("localhost", 9999, [], infinity).</code>
<p><em>Step 5:</em> Ensure <c>active</c> is set to <c>false</c> before trying
to upgrade a connection to an SSL connection, otherwise
SSL handshake messages can be delivered to the wrong process:</p>
<code type="erl">4 server> inet:setopts(Socket, [{active, false}]).
ok</code>
<p><em>Step 6:</em> Do the SSL handshake:</p>
<code type="erl">5 server> {ok, SSLSocket} = ssl:ssl_accept(Socket, [{cacertfile, "cacerts.pem"},
{certfile, "cert.pem"}, {keyfile, "key.pem"}]).
{ok,{sslsocket,[...]}}</code>
<p><em>Step 7:</em> Upgrade to an SSL connection. The client and server
must agree upon the upgrade. The server must call
<c>ssl:accept/2</c> before the client calls <c>ssl:connect/3.</c></p>
<code type="erl">3 client>{ok, SSLSocket} = ssl:connect(Socket, [{cacertfile, "cacerts.pem"},
{certfile, "cert.pem"}, {keyfile, "key.pem"}], infinity).
{ok,{sslsocket,[...]}}</code>
<p><em>Step 8:</em> Send a message over SSL:</p>
<code type="erl">4 client> ssl:send(SSLSocket, "foo").
ok</code>
<p><em>Step 9:</em> Set <c>active true</c> on the SSL socket:</p>
<code type="erl">4 server> ssl:setopts(SSLSocket, [{active, true}]).
ok</code>
<p><em>Step 10:</em> Flush the shell message queue to see that the message
was sent on the client side:</p>
<code type="erl">5 server> flush().
Shell got {ssl,{sslsocket,[...]},"foo"}
ok</code>
</section>
</section>
</chapter>
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