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<a href="https://github.com/docker-mailserver/docker-mailserver/edit/master/docs/content/config/security/ssl.md" title="Edit this page" class="md-content__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20.71 7.04c.39-.39.39-1.04 0-1.41l-2.34-2.34c-.37-.39-1.02-.39-1.41 0l-1.84 1.83 3.75 3.75M3 17.25V21h3.75L17.81 9.93l-3.75-3.75L3 17.25z"/></svg>
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<h1>SSL/TLS</h1>
<p>There are multiple options to enable SSL:</p>
<ul>
<li>Using <a href="#lets-encrypt-recommended">letsencrypt</a> (recommended)</li>
<li>Using <a href="#caddy">Caddy</a></li>
<li>Using <a href="#traefik">Traefik</a></li>
<li>Using <a href="#self-signed-certificates-testing-only">self-signed certificates</a> with the provided tool</li>
<li>Using <a href="#custom-certificate-files">your own certificates</a></li>
</ul>
<p>After installation, you can test your setup with:</p>
<ul>
<li><a href="https://www.checktls.com/TestReceiver"><code>checktls.com</code></a></li>
<li><a href="https://github.com/drwetter/testssl.sh"><code>testssl.sh</code></a></li>
</ul>
<h2 id="lets-encrypt-recommended"><a class="toclink" href="#lets-encrypt-recommended">Let's Encrypt (Recommended)</a></h2>
<p>To enable Let's Encrypt on your mail server, you have to:</p>
<ul>
<li>Get your certificate using <a href="https://github.com/letsencrypt/letsencrypt">letsencrypt client</a></li>
<li>Add an environment variable <code>SSL_TYPE</code> with value <code>letsencrypt</code> (see <a href="https://github.com/docker-mailserver/docker-mailserver/blob/master/docker-compose.yml"><code>docker-compose.yml</code></a>)</li>
<li>Mount your whole <code>letsencrypt</code> folder to <code>/etc/letsencrypt</code></li>
<li>
<p>The certs folder name located in <code>letsencrypt/live/</code> must be the <code>fqdn</code> of your container responding to the <code>hostname</code> command. The <code>fqdn</code> (full qualified domain name) inside the docker container is built combining the <code>hostname</code> and <code>domainname</code> values of the <code>docker-compose</code> file, eg:</p>
<div class="highlight"><pre><span></span><code><span class="nt">services</span><span class="p">:</span>
<span class="nt">mailserver</span><span class="p">:</span>
<span class="nt">hostname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mail</span>
<span class="nt">domainname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">myserver.tld</span>
<span class="nt">fqdn</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mail.myserver.tld</span>
</code></pre></div>
</li>
</ul>
<p>You don't have anything else to do. Enjoy.</p>
<h3 id="example-using-docker-for-lets-encrypt"><a class="toclink" href="#example-using-docker-for-lets-encrypt">Example using Docker for Let's Encrypt</a></h3>
<ol>
<li>
<p>Make a directory to store your letsencrypt logs and configs. In my case:</p>
<div class="highlight"><pre><span></span><code>mkdir -p /home/ubuntu/docker/letsencrypt
<span class="nb">cd</span> /home/ubuntu/docker/letsencrypt
</code></pre></div>
</li>
<li>
<p>Now get the certificate (modify <code>mail.myserver.tld</code>) and following the certbot instructions.</p>
</li>
<li>
<p>This will need access to port 80 from the internet, adjust your firewall if needed:</p>
<div class="highlight"><pre><span></span><code>docker run --rm -it <span class="se">\</span>
-v <span class="nv">$PWD</span>/log/:/var/log/letsencrypt/ <span class="se">\</span>
-v <span class="nv">$PWD</span>/etc/:/etc/letsencrypt/ <span class="se">\</span>
-p <span class="m">80</span>:80 <span class="se">\</span>
certbot/certbot certonly --standalone -d mail.myserver.tld
</code></pre></div>
</li>
<li>
<p>You can now mount <code>/home/ubuntu/docker/letsencrypt/etc/</code> in <code>/etc/letsencrypt</code> of <code>docker-mailserver</code>.</p>
<p>To renew your certificate just run (this will need access to port 443 from the internet, adjust your firewall if needed):</p>
<div class="highlight"><pre><span></span><code>docker run --rm -it <span class="se">\</span>
-v <span class="nv">$PWD</span>/log/:/var/log/letsencrypt/ <span class="se">\</span>
-v <span class="nv">$PWD</span>/etc/:/etc/letsencrypt/ <span class="se">\</span>
-p <span class="m">80</span>:80 <span class="se">\</span>
-p <span class="m">443</span>:443 <span class="se">\</span>
certbot/certbot renew
</code></pre></div>
</li>
</ol>
<h3 id="example-using-docker-nginx-proxy-and-letsencrypt-nginx-proxy-companion"><a class="toclink" href="#example-using-docker-nginx-proxy-and-letsencrypt-nginx-proxy-companion">Example using Docker, <code>nginx-proxy</code> and <code>letsencrypt-nginx-proxy-companion</code></a></h3>
<p>If you are running a web server already, it is non-trivial to generate a Let's Encrypt certificate for your mail server using <code>certbot</code>, because port 80 is already occupied. In the following example, we show how <code>docker-mailserver</code> can be run alongside the docker containers <code>nginx-proxy</code> and <code>letsencrypt-nginx-proxy-companion</code>.</p>
<p>There are several ways to start <code>nginx-proxy</code> and <code>letsencrypt-nginx-proxy-companion</code>. Any method should be suitable here.</p>
<p>For example start <code>nginx-proxy</code> as in the <code>letsencrypt-nginx-proxy-companion</code> <a href="https://github.com/JrCs/docker-letsencrypt-nginx-proxy-companion">documentation</a>:</p>
<div class="highlight"><pre><span></span><code>docker run --detach <span class="se">\</span>
--name nginx-proxy <span class="se">\</span>
--restart always <span class="se">\</span>
--publish <span class="m">80</span>:80 <span class="se">\</span>
--publish <span class="m">443</span>:443 <span class="se">\</span>
--volume /server/letsencrypt/etc:/etc/nginx/certs:ro <span class="se">\</span>
--volume /etc/nginx/vhost.d <span class="se">\</span>
--volume /usr/share/nginx/html <span class="se">\</span>
--volume /var/run/docker.sock:/tmp/docker.sock:ro <span class="se">\</span>
jwilder/nginx-proxy
</code></pre></div>
<p>Then start <code>nginx-proxy-letsencrypt</code>:</p>
<div class="highlight"><pre><span></span><code>docker run --detach <span class="se">\</span>
--name nginx-proxy-letsencrypt <span class="se">\</span>
--restart always <span class="se">\</span>
--volume /server/letsencrypt/etc:/etc/nginx/certs:rw <span class="se">\</span>
--volumes-from nginx-proxy <span class="se">\</span>
--volume /var/run/docker.sock:/var/run/docker.sock:ro <span class="se">\</span>
jrcs/letsencrypt-nginx-proxy-companion
</code></pre></div>
<p>Start the rest of your web server containers as usual.</p>
<p>Start another container for your <code>mail.myserver.tld</code>. This will generate a Let's Encrypt certificate for your domain, which can be used by <code>docker-mailserver</code>. It will also run a web server on port 80 at that address:</p>
<div class="highlight"><pre><span></span><code>docker run -d <span class="se">\</span>
--name webmail <span class="se">\</span>
-e <span class="s2">&quot;VIRTUAL_HOST=mail.myserver.tld&quot;</span> <span class="se">\</span>
-e <span class="s2">&quot;LETSENCRYPT_HOST=mail.myserver.tld&quot;</span> <span class="se">\</span>
-e <span class="s2">&quot;LETSENCRYPT_EMAIL=foo@bar.com&quot;</span> <span class="se">\</span>
library/nginx
</code></pre></div>
<p>You may want to add <code>-e LETSENCRYPT_TEST=true</code> to the above while testing to avoid the Let's Encrypt certificate generation rate limits.</p>
<p>Finally, start the mailserver with the <code>docker-compose.yml</code>. Make sure your mount path to the letsencrypt certificates is correct.</p>
<p>Inside your <code>/path/to/mailserver/docker-compose.yml</code> (for the mailserver from this repo) make sure volumes look like below example:</p>
<div class="highlight"><pre><span></span><code><span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">maildata:/var/mail</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">mailstate:/var/mail-state</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">./config/:/tmp/docker-mailserver/</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/server/letsencrypt/etc:/etc/letsencrypt/live</span>
</code></pre></div>
<p>Then: <code>/path/to/mailserver/docker-compose up -d mail</code></p>
<h3 id="example-using-docker-nginx-proxy-and-letsencrypt-nginx-proxy-companion-with-docker-compose"><a class="toclink" href="#example-using-docker-nginx-proxy-and-letsencrypt-nginx-proxy-companion-with-docker-compose">Example using Docker, <code>nginx-proxy</code> and <code>letsencrypt-nginx-proxy-companion</code> with <code>docker-compose</code></a></h3>
<p>The following <code>docker-compose.yml</code> is the basic setup you need for using <code>letsencrypt-nginx-proxy-companion</code>. It is mainly derived from its own wiki/documenation.</p>
<details class="example" open="open"><summary>Example Code</summary><div class="highlight"><pre><span></span><code><span class="nt">version</span><span class="p">:</span> <span class="s">&quot;2&quot;</span>
<span class="nt">services</span><span class="p">:</span>
<span class="nt">nginx</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx</span>
<span class="nt">container_name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx</span>
<span class="nt">ports</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">80:80</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">443:443</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/htpasswd:/etc/nginx/htpasswd</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/conf.d:/etc/nginx/conf.d</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/vhost.d:/etc/nginx/vhost.d</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/html:/usr/share/nginx/html</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/certs:/etc/nginx/certs:ro</span>
<span class="nt">networks</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">proxy-tier</span>
<span class="nt">restart</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">always</span>
<span class="nt">nginx-gen</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">jwilder/docker-gen</span>
<span class="nt">container_name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx-gen</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/var/run/docker.sock:/tmp/docker.sock:ro</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/templates/nginx.tmpl:/etc/docker-gen/templates/nginx.tmpl:ro</span>
<span class="nt">volumes_from</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">nginx</span>
<span class="nt">entrypoint</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">/usr/local/bin/docker-gen -notify-sighup nginx -watch -wait 5s:30s /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf</span>
<span class="nt">restart</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">always</span>
<span class="nt">letsencrypt-nginx-proxy-companion</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">jrcs/letsencrypt-nginx-proxy-companion</span>
<span class="nt">container_name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">letsencrypt-companion</span>
<span class="nt">volumes_from</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">nginx</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/var/run/docker.sock:/var/run/docker.sock:ro</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/certs:/etc/nginx/certs:rw</span>
<span class="nt">environment</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">NGINX_DOCKER_GEN_CONTAINER=nginx-gen</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">DEBUG=false</span>
<span class="nt">restart</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">always</span>
<span class="nt">networks</span><span class="p">:</span>
<span class="nt">proxy-tier</span><span class="p">:</span>
<span class="nt">external</span><span class="p">:</span>
<span class="nt">name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx-proxy</span>
</code></pre></div>
</details>
<p>The second part of the setup is the actual mail container. So, in another folder, create another <code>docker-compose.yml</code> with the following content (Removed all ENV variables for this example):</p>
<details class="example" open="open"><summary>Example Code</summary><div class="highlight"><pre><span></span><code><span class="nt">version</span><span class="p">:</span> <span class="s">&#39;2&#39;</span>
<span class="nt">services</span><span class="p">:</span>
<span class="nt">mailserver</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mailserver/docker-mailserver:latest</span>
<span class="nt">hostname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">&lt;HOSTNAME&gt;</span> <span class="c1"># &lt;-- change this</span>
<span class="nt">domainname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">&lt;DOMAINNAME&gt;</span> <span class="c1"># &lt;-- change this</span>
<span class="nt">container_name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mailserver</span>
<span class="nt">ports</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;25:25&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;143:143&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;465:465&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;587:587&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;993:993&quot;</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">./mail:/var/mail</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">./mail-state:/var/mail-state</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">./config/:/tmp/docker-mailserver/</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/mnt/data/nginx/certs/:/etc/letsencrypt/live/:ro</span>
<span class="nt">cap_add</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">NET_ADMIN</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SYS_PTRACE</span>
<span class="nt">restart</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">always</span>
<span class="nt">cert-companion</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx</span>
<span class="nt">environment</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;VIRTUAL_HOST=&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;VIRTUAL_NETWORK=nginx-proxy&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;LETSENCRYPT_HOST=&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;LETSENCRYPT_EMAIL=&quot;</span>
<span class="nt">networks</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">proxy-tier</span>
<span class="nt">restart</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">always</span>
<span class="nt">networks</span><span class="p">:</span>
<span class="nt">proxy-tier</span><span class="p">:</span>
<span class="nt">external</span><span class="p">:</span>
<span class="nt">name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">nginx-proxy</span>
</code></pre></div>
</details>
<p>The mail container needs to have the letsencrypt certificate folder mounted as a volume. No further changes are needed. The second container is a dummy-sidecar we need, because the mail-container do not expose any web-ports. Set your ENV variables as you need. (<code>VIRTUAL_HOST</code> and <code>LETSENCRYPT_HOST</code> are mandandory, see documentation)</p>
<h3 id="example-using-the-lets-encrypt-certificates-on-a-synology-nas"><a class="toclink" href="#example-using-the-lets-encrypt-certificates-on-a-synology-nas">Example using the Let's Encrypt Certificates on a Synology NAS</a></h3>
<p>Version 6.2 and later of the Synology NAS DSM OS now come with an interface to generate and renew letencrypt certificates. Navigation into your DSM control panel and go to Security, then click on the tab Certificate to generate and manage letsencrypt certificates.</p>
<p>Amongst other things, you can use these to secure your mail server. DSM locates the generated certificates in a folder below <code>/usr/syno/etc/certificate/_archive/</code>.</p>
<p>Navigate to that folder and note the 6 character random folder name of the certificate you'd like to use. Then, add the following to your <code>docker-compose.yml</code> declaration file:</p>
<div class="highlight"><pre><span></span><code><span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/usr/syno/etc/certificate/_archive/&lt;your-folder&gt;/:/tmp/ssl</span>
<span class="nt">environment</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_TYPE=manual</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_CERT_PATH=/tmp/ssl/fullchain.pem</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_KEY_PATH=/tmp/ssl/privkey.pem</span>
</code></pre></div>
<p>DSM-generated letsencrypt certificates get auto-renewed every three months.</p>
<h2 id="caddy"><a class="toclink" href="#caddy">Caddy</a></h2>
<p>If you are using Caddy to renew your certificates, please note that only RSA certificates work. Read <a href="https://github.com/docker-mailserver/docker-mailserver/issues/1440">#1440</a> for details. In short for Caddy v1 the <code>Caddyfile</code> should look something like:</p>
<div class="highlight"><pre><span></span><code>https://mail.domain.com {
tls yourcurrentemail@gmail.com {
key_type rsa2048
}
}
</code></pre></div>
<p>For Caddy v2 you can specify the <code>key_type</code> in your server's global settings, which would end up looking something like this if you're using a <code>Caddyfile</code>:</p>
<div class="highlight"><pre><span></span><code>{
debug
admin localhost:2019
http_port 80
https_port 443
default_sni mywebserver.com
key_type rsa4096
}
</code></pre></div>
<p>If you are instead using a json config for Caddy v2, you can set it in your site's TLS automation policies:</p>
<details class="example" open="open"><summary>Example Code</summary><div class="highlight"><pre><span></span><code><span class="p">{</span>
<span class="nt">&quot;apps&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;http&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;servers&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;srv0&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;listen&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="s2">&quot;:443&quot;</span>
<span class="p">],</span>
<span class="nt">&quot;routes&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;match&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;host&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="s2">&quot;mail.domain.com&quot;</span><span class="p">,</span>
<span class="p">]</span>
<span class="p">}</span>
<span class="p">],</span>
<span class="nt">&quot;handle&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;handler&quot;</span><span class="p">:</span> <span class="s2">&quot;subroute&quot;</span><span class="p">,</span>
<span class="nt">&quot;routes&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;handle&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;body&quot;</span><span class="p">:</span> <span class="s2">&quot;&quot;</span><span class="p">,</span>
<span class="nt">&quot;handler&quot;</span><span class="p">:</span> <span class="s2">&quot;static_response&quot;</span>
<span class="p">}</span>
<span class="p">]</span>
<span class="p">}</span>
<span class="p">]</span>
<span class="p">}</span>
<span class="p">],</span>
<span class="nt">&quot;terminal&quot;</span><span class="p">:</span> <span class="kc">true</span>
<span class="p">},</span>
<span class="p">]</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">},</span>
<span class="nt">&quot;tls&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;automation&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;policies&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="p">{</span>
<span class="nt">&quot;subjects&quot;</span><span class="p">:</span> <span class="p">[</span>
<span class="s2">&quot;mail.domain.com&quot;</span><span class="p">,</span>
<span class="p">],</span>
<span class="nt">&quot;key_type&quot;</span><span class="p">:</span> <span class="s2">&quot;rsa2048&quot;</span><span class="p">,</span>
<span class="nt">&quot;issuer&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;email&quot;</span><span class="p">:</span> <span class="s2">&quot;email@email.com&quot;</span><span class="p">,</span>
<span class="nt">&quot;module&quot;</span><span class="p">:</span> <span class="s2">&quot;acme&quot;</span>
<span class="p">}</span>
<span class="p">},</span>
<span class="p">{</span>
<span class="nt">&quot;issuer&quot;</span><span class="p">:</span> <span class="p">{</span>
<span class="nt">&quot;email&quot;</span><span class="p">:</span> <span class="s2">&quot;email@email.com&quot;</span><span class="p">,</span>
<span class="nt">&quot;module&quot;</span><span class="p">:</span> <span class="s2">&quot;acme&quot;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">]</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre></div>
</details>
<p>The generated certificates can be mounted:</p>
<div class="highlight"><pre><span></span><code><span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">${CADDY_DATA_DIR}/certificates/acme-v02.api.letsencrypt.org-directory/mail.domain.com/mail.domain.com.crt:/etc/letsencrypt/live/mail.domain.com/fullchain.pem</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">${CADDY_DATA_DIR}/certificates/acme-v02.api.letsencrypt.org-directory/mail.domain.com/mail.domain.com.key:/etc/letsencrypt/live/mail.domain.com/privkey.pem</span>
</code></pre></div>
<p>EC certificates fail in the TLS handshake:</p>
<div class="highlight"><pre><span></span><code><span class="go">CONNECTED(00000003)</span>
<span class="go">140342221178112:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:ssl/record/rec_layer_s3.c:1543:SSL alert number 40</span>
<span class="go">no peer certificate available</span>
<span class="go">No client certificate CA names sent</span>
</code></pre></div>
<h2 id="traefik-v2"><a class="toclink" href="#traefik-v2">Traefik v2</a></h2>
<p><a href="https://github.com/containous/traefik">Traefik</a> is an open-source application proxy using the <a href="https://tools.ietf.org/html/rfc8555">ACME protocol</a>. <a href="https://github.com/containous/traefik">Traefik</a> can request certificates for domains and subdomains, and it will take care of renewals, challenge negotiations, etc. We strongly recommend to use <a href="https://github.com/containous/traefik">Traefik</a>'s major version 2.</p>
<p><a href="https://github.com/containous/traefik">Traefik</a>'s storage format is natively supported if the <code>acme.json</code> store is mounted into the container at <code>/etc/letsencrypt/acme.json</code>. The file is also monitored for changes and will trigger a reload of the mail services. Wild card certificates issued for <code>*.domain.tld</code> are supported. You will then want to use <code class="highlight"><span class="nv">SSL_DOMAIN</span><span class="o">=</span>domain.tld</code>. Lookup of the certificate domain happens in the following order:</p>
<ol>
<li><code class="highlight"><span class="si">${</span><span class="nv">SSL_DOMAIN</span><span class="si">}</span></code></li>
<li><code class="highlight"><span class="si">${</span><span class="nv">HOSTNAME</span><span class="si">}</span></code></li>
<li><code class="highlight"><span class="si">${</span><span class="nv">DOMAINNAME</span><span class="si">}</span></code></li>
</ol>
<p>This setup only comes with one caveat: The domain has to be configured on another service for <a href="https://github.com/containous/traefik">Traefik</a> to actually request it from Let'sEncrypt, i.e. <a href="https://github.com/containous/traefik">Traefik</a> will not issue a certificate without a service / router demanding it.</p>
<details class="example" open="open"><summary>Example Code</summary><p>Here is an example setup for <a href="https://docs.docker.com/compose/"><code>docker-compose</code></a>:</p>
<div class="highlight"><pre><span></span><code><span class="nt">version</span><span class="p">:</span> <span class="s">&#39;3.8&#39;</span>
<span class="nt">services</span><span class="p">:</span>
<span class="nt">mailserver</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">docker.io/mailserver/docker-mailserver:latest</span>
<span class="nt">container_name</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mailserver</span>
<span class="nt">hostname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mail</span>
<span class="nt">domainname</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">domain.tld</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/traefik/acme.json:/etc/letsencrypt/acme.json:ro</span>
<span class="nt">environment</span><span class="p">:</span>
<span class="nt">SSL_TYPE</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">letsencrypt</span>
<span class="nt">SSL_DOMAIN</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">mail.example.com&quot;</span>
<span class="c1"># for a wildcard certificate, use</span>
<span class="c1"># SSL_DOMAIN: example.com</span>
<span class="nt">traefik</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">docker.io/traefik:v2.4.8</span>
<span class="nt">ports</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;80:80&quot;</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;443:443&quot;</span>
<span class="nt">command</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--providers.docker</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--entrypoints.http.address=:80</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--entrypoints.http.http.redirections.entryPoint.to=https</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--entrypoints.http.http.redirections.entryPoint.scheme=https</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--entrypoints.https.address=:443</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--entrypoints.https.http.tls.certResolver=letsencrypt</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--certificatesresolvers.letsencrypt.acme.email=admin@domain.tld</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--certificatesresolvers.letsencrypt.acme.storage=/acme.json</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">--certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=http</span>
<span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/traefik/acme.json:/acme.json</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/var/run/docker.sock:/var/run/docker.sock:ro</span>
<span class="nt">whoami</span><span class="p">:</span>
<span class="nt">image</span><span class="p">:</span> <span class="l l-Scalar l-Scalar-Plain">docker.io/traefik/whoami:latest</span>
<span class="nt">labels</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="s">&quot;traefik.http.routers.whoami.rule=Host(`mail.domain.tld`)&quot;</span>
</code></pre></div>
</details>
<h2 id="self-signed-certificates"><a class="toclink" href="#self-signed-certificates">Self-Signed Certificates</a></h2>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Use self-signed certificates only for testing purposes!</p>
</div>
<p>This feature requires you to provide the following files into your <a href="../../advanced/optional-config/"><code>config/ssl/</code> directory</a> (internal location: <code>/tmp/docker-mailserver/ssl/</code>):</p>
<ul>
<li><code>${HOSTNAME}-key.pem</code></li>
<li><code>${HOSTNAME}-cert.pem</code></li>
<li><code>demoCA/cacert.pem</code></li>
</ul>
<p>Where <code>${HOSTNAME}</code> is the mailserver <a href="https://en.wikipedia.org/wiki/Fully_qualified_domain_name">FQDN</a> (<code>hostname</code>(<em>mail</em>) + <code>domainname</code>(<em>example.com</em>), eg: <code>mail.example.com</code>).</p>
<p>To use the certificate:</p>
<ul>
<li>Add <code>SSL_TYPE=self-signed</code> to your container environment variables.</li>
<li>If a matching certificate (files listed above) is found in <code>config/ssl</code>, it will be automatically setup in postfix and dovecot. You just have to place them in <code>config/ssl</code> folder.</li>
</ul>
<h4 id="generating-a-self-signed-certificate"><a class="toclink" href="#generating-a-self-signed-certificate">Generating a self-signed certificate</a></h4>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Since v10, support in <code>setup.sh</code> for generating a self-signed SSL certificate internally was removed.</p>
<p>It is now similar to <code>SSL_TYPE=manual</code> (<em>except <code>manual</code> does not support verification for a custom CA</em>), but does not require additional ENV vars for providing the location of cert files.</p>
</div>
<p>One way to generate self-signed certificates is with <a href="https://smallstep.com/docs/step-cli">Smallstep's <code>step</code> CLI</a>. This is exactly what <a href="https://github.com/docker-mailserver/docker-mailserver/tree/master/test/test-files/ssl/example.test"><code>docker-mailserver</code> does for creating test certificates</a>.</p>
<p>For example with the FQDN <code>mail.example.test</code>, you can generate the required files by running:</p>
<div class="highlight"><pre><span></span><code><span class="ch">#! /bin/sh</span>
mkdir -p demoCA
step certificate create <span class="s2">&quot;Smallstep Root CA&quot;</span> <span class="s2">&quot;demoCA/cacert.pem&quot;</span> <span class="s2">&quot;demoCA/cakey.pem&quot;</span> <span class="se">\</span>
--no-password --insecure <span class="se">\</span>
--profile root-ca <span class="se">\</span>
--not-before <span class="s2">&quot;2021-01-01T00:00:00+00:00&quot;</span> <span class="se">\</span>
--not-after <span class="s2">&quot;2031-01-01T00:00:00+00:00&quot;</span> <span class="se">\</span>
--san <span class="s2">&quot;example.test&quot;</span> <span class="se">\</span>
--san <span class="s2">&quot;mail.example.test&quot;</span> <span class="se">\</span>
--kty RSA --size <span class="m">2048</span>
step certificate create <span class="s2">&quot;Smallstep Leaf&quot;</span> mail.example.test-cert.pem mail.example.test-key.pem <span class="se">\</span>
--no-password --insecure <span class="se">\</span>
--profile leaf <span class="se">\</span>
--ca <span class="s2">&quot;demoCA/cacert.pem&quot;</span> <span class="se">\</span>
--ca-key <span class="s2">&quot;demoCA/cakey.pem&quot;</span> <span class="se">\</span>
--not-before <span class="s2">&quot;2021-01-01T00:00:00+00:00&quot;</span> <span class="se">\</span>
--not-after <span class="s2">&quot;2031-01-01T00:00:00+00:00&quot;</span> <span class="se">\</span>
--san <span class="s2">&quot;example.test&quot;</span> <span class="se">\</span>
--san <span class="s2">&quot;mail.example.test&quot;</span> <span class="se">\</span>
--kty RSA --size <span class="m">2048</span>
</code></pre></div>
<p>If you'd rather not install the CLI tool locally to run the <code>step</code> commands above; you can save the script above to a file such as <code>generate-certs.sh</code> (<em>and make it executable <code>chmod +x generate-certs.sh</code></em>) in a directory that you want the certs to be placed, then run that script with docker:</p>
<div class="highlight"><pre><span></span><code><span class="c1"># --user to keep ownership of the files to your user and group ID</span>
docker run --rm -it <span class="se">\</span>
--user <span class="s2">&quot;</span><span class="k">$(</span>id -u<span class="k">)</span><span class="s2">:</span><span class="k">$(</span>id -g<span class="k">)</span><span class="s2">&quot;</span> <span class="se">\</span>
--volume <span class="s2">&quot;</span><span class="si">${</span><span class="nv">PWD</span><span class="si">}</span><span class="s2">:/tmp&quot;</span> <span class="se">\</span>
--workdir <span class="s2">&quot;/tmp&quot;</span> <span class="se">\</span>
--entrypoint <span class="s2">&quot;/tmp/generate-certs.sh&quot;</span> <span class="se">\</span>
smallstep/step-ca
</code></pre></div>
<h2 id="custom-certificate-files"><a class="toclink" href="#custom-certificate-files">Custom Certificate Files</a></h2>
<p>You can also provide your own certificate files. Add these entries to your <code>docker-compose.yml</code>:</p>
<div class="highlight"><pre><span></span><code><span class="nt">volumes</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">/etc/ssl:/tmp/ssl:ro</span>
<span class="nt">environment</span><span class="p">:</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_TYPE=manual</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_CERT_PATH=/tmp/ssl/cert/public.crt</span>
<span class="p p-Indicator">-</span> <span class="l l-Scalar l-Scalar-Plain">SSL_KEY_PATH=/tmp/ssl/private/private.key</span>
</code></pre></div>
<p>This will mount the path where your ssl certificates reside as read-only under <code>/tmp/ssl</code>. Then all you have to do is to specify the location of your private key and the certificate.</p>
<div class="admonition info">
<p class="admonition-title">Info</p>
<p>You may have to restart your mailserver once the certificates change.</p>
</div>
<h2 id="testing-a-certificate-is-valid"><a class="toclink" href="#testing-a-certificate-is-valid">Testing a Certificate is Valid</a></h2>
<ul>
<li>
<p>From your host:</p>
<div class="highlight"><pre><span></span><code>docker <span class="nb">exec</span> mail openssl s_client <span class="se">\</span>
-connect <span class="m">0</span>.0.0.0:25 <span class="se">\</span>
-starttls smtp <span class="se">\</span>
-CApath /etc/ssl/certs/
</code></pre></div>
</li>
<li>
<p>Or:</p>
<div class="highlight"><pre><span></span><code>docker <span class="nb">exec</span> mail openssl s_client <span class="se">\</span>
-connect <span class="m">0</span>.0.0.0:143 <span class="se">\</span>
-starttls imap <span class="se">\</span>
-CApath /etc/ssl/certs/
</code></pre></div>
</li>
</ul>
<p>And you should see the certificate chain, the server certificate and: <code>Verify return code: 0 (ok)</code></p>
<p>In addition, to verify certificate dates:</p>
<div class="highlight"><pre><span></span><code>docker <span class="nb">exec</span> mail openssl s_client <span class="se">\</span>
-connect <span class="m">0</span>.0.0.0:25 <span class="se">\</span>
-starttls smtp <span class="se">\</span>
-CApath /etc/ssl/certs/ <span class="se">\</span>
<span class="m">2</span>&gt;/dev/null <span class="p">|</span> openssl x509 -noout -dates
</code></pre></div>
<h2 id="plain-text-access"><a class="toclink" href="#plain-text-access">Plain-Text Access</a></h2>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Not recommended for purposes other than testing.</p>
</div>
<p>Add this to <code>config/dovecot.cf</code>:</p>
<div class="highlight"><pre><span></span><code><span class="na">ssl</span> <span class="o">=</span> <span class="s">yes</span>
<span class="na">disable_plaintext_auth</span><span class="o">=</span><span class="s">no</span>
</code></pre></div>
<p>These options in conjunction mean:</p>
<ul>
<li>SSL/TLS is offered to the client, but the client isn't required to use it.</li>
<li>The client is allowed to login with plaintext authentication even when SSL/TLS isn't enabled on the connection.</li>
<li><strong>This is insecure</strong>, because the plaintext password is exposed to the internet.</li>
</ul>
<h2 id="importing-certificates-obtained-via-another-source"><a class="toclink" href="#importing-certificates-obtained-via-another-source">Importing Certificates Obtained via Another Source</a></h2>
<p>If you have another source for SSL/TLS certificates you can import them into the server via an external script. The external script can be found here: <a href="https://github.com/hanscees/dockerscripts/blob/master/scripts/tomav-renew-certs">external certificate import script</a>.</p>
<p>The steps to follow are these:</p>
<ol>
<li>Transport the new certificates to <code>./config/ssl</code> (<code>/tmp/ssl</code> in the container)</li>
<li>You should provide <code>fullchain.key</code> and <code>privkey.pem</code></li>
<li>Place the script in <code>./config/</code> (or <code>/tmp/docker-mailserver/</code> inside the container)</li>
<li>Make the script executable (<code>chmod +x tomav-renew-certs.sh</code>)</li>
<li>Run the script: <code>docker exec mail /tmp/docker-mailserver/tomav-renew-certs.sh</code></li>
</ol>
<p>If an error occurs the script will inform you. If not you will see both postfix and dovecot restart.</p>
<p>After the certificates have been loaded you can check the certificate:</p>
<div class="highlight"><pre><span></span><code>openssl s_client <span class="se">\</span>
-servername mail.mydomain.net <span class="se">\</span>
-connect <span class="m">192</span>.168.0.72:465 <span class="se">\</span>
<span class="m">2</span>&gt;/dev/null <span class="p">|</span> openssl x509
<span class="c1"># or</span>
openssl s_client <span class="se">\</span>
-servername mail.mydomain.net <span class="se">\</span>
-connect mail.mydomain.net:465 <span class="se">\</span>
<span class="m">2</span>&gt;/dev/null <span class="p">|</span> openssl x509
</code></pre></div>
<p>Or you can check how long the new certificate is valid with commands like:</p>
<div class="highlight"><pre><span></span><code><span class="nb">export</span> <span class="nv">SITE_URL</span><span class="o">=</span><span class="s2">&quot;mail.mydomain.net&quot;</span>
<span class="nb">export</span> <span class="nv">SITE_IP_URL</span><span class="o">=</span><span class="s2">&quot;192.168.0.72&quot;</span> <span class="c1"># can also be `mail.mydomain.net`</span>
<span class="nb">export</span> <span class="nv">SITE_SSL_PORT</span><span class="o">=</span><span class="s2">&quot;993&quot;</span> <span class="c1"># imap port dovecot</span>
<span class="c1">##works: check if certificate will expire in two weeks </span>
<span class="c1">#2 weeks is 1209600 seconds</span>
<span class="c1">#3 weeks is 1814400</span>
<span class="c1">#12 weeks is 7257600</span>
<span class="c1">#15 weeks is 9072000</span>
<span class="nv">certcheck_2weeks</span><span class="o">=</span><span class="sb">`</span>openssl s_client -connect <span class="si">${</span><span class="nv">SITE_IP_URL</span><span class="si">}</span>:<span class="si">${</span><span class="nv">SITE_SSL_PORT</span><span class="si">}</span> <span class="se">\</span>
-servername <span class="si">${</span><span class="nv">SITE_URL</span><span class="si">}</span> <span class="m">2</span>&gt; /dev/null <span class="p">|</span> openssl x509 -noout -checkend <span class="m">1209600</span><span class="sb">`</span>
<span class="c1">####################################</span>
<span class="c1">#notes: output can be</span>
<span class="c1">#Certificate will not expire</span>
<span class="c1">#Certificate will expire</span>
<span class="c1">####################</span>
</code></pre></div>
<p>What does the script that imports the certificates do:</p>
<ol>
<li>Check if there are new certs in the <code>/tmp/ssl</code> folder.</li>
<li>Check with the ssl cert fingerprint if they differ from the current certificates.</li>
<li>If so it will copy the certs to the right places.</li>
<li>And restart postfix and dovecot.</li>
</ol>
<p>You can of course run the script by cron once a week or something. In that way you could automate cert renewal. If you do so it is probably wise to run an automated check on certificate expiry as well. Such a check could look something like this:</p>
<div class="highlight"><pre><span></span><code><span class="c1">## code below will alert if certificate expires in less than two weeks</span>
<span class="c1">## please adjust varables! </span>
<span class="c1">## make sure the mail -s command works! Test!</span>
<span class="nb">export</span> <span class="nv">SITE_URL</span><span class="o">=</span><span class="s2">&quot;mail.mydomain.net&quot;</span>
<span class="nb">export</span> <span class="nv">SITE_IP_URL</span><span class="o">=</span><span class="s2">&quot;192.168.2.72&quot;</span> <span class="c1"># can also be `mail.mydomain.net`</span>
<span class="nb">export</span> <span class="nv">SITE_SSL_PORT</span><span class="o">=</span><span class="s2">&quot;993&quot;</span> <span class="c1"># imap port dovecot</span>
<span class="nb">export</span> <span class="nv">ALERT_EMAIL_ADDR</span><span class="o">=</span><span class="s2">&quot;bill@gates321boom.com&quot;</span>
<span class="nv">certcheck_2weeks</span><span class="o">=</span><span class="sb">`</span>openssl s_client -connect <span class="si">${</span><span class="nv">SITE_IP_URL</span><span class="si">}</span>:<span class="si">${</span><span class="nv">SITE_SSL_PORT</span><span class="si">}</span> <span class="se">\</span>
-servername <span class="si">${</span><span class="nv">SITE_URL</span><span class="si">}</span> <span class="m">2</span>&gt; /dev/null <span class="p">|</span> openssl x509 -noout -checkend <span class="m">1209600</span><span class="sb">`</span>
<span class="c1">####################################</span>
<span class="c1">#notes: output can be</span>
<span class="c1">#Certificate will not expire</span>
<span class="c1">#Certificate will expire</span>
<span class="c1">####################</span>
<span class="c1">#echo &quot;certcheck 2 weeks gives $certcheck_2weeks&quot;</span>
<span class="c1">##automated check you might run by cron or something</span>
<span class="c1">## does tls/ssl certificate expire within two weeks?</span>
<span class="k">if</span> <span class="o">[</span> <span class="s2">&quot;</span><span class="nv">$certcheck_2weeks</span><span class="s2">&quot;</span> <span class="o">=</span> <span class="s2">&quot;Certificate will not expire&quot;</span> <span class="o">]</span><span class="p">;</span> <span class="k">then</span>
<span class="nb">echo</span> <span class="s2">&quot;all is well, certwatch 2 weeks says </span><span class="nv">$certcheck_2weeks</span><span class="s2">&quot;</span>
<span class="k">else</span>
<span class="nb">echo</span> <span class="s2">&quot;Cert seems to be expiring pretty soon, within two weeks: </span><span class="nv">$certcheck_2weeks</span><span class="s2">&quot;</span>
<span class="nb">echo</span> <span class="s2">&quot;we will send an alert email and log as well&quot;</span>
logger Certwatch: cert <span class="nv">$SITE_URL</span> will expire <span class="k">in</span> two weeks
<span class="nb">echo</span> <span class="s2">&quot;Certwatch: cert </span><span class="nv">$SITE_URL</span><span class="s2"> will expire in two weeks&quot;</span> <span class="p">|</span> mail -s <span class="s2">&quot;cert </span><span class="nv">$SITE_URL</span><span class="s2"> expires in two weeks &quot;</span> <span class="nv">$ALERT_EMAIL_ADDR</span>
<span class="k">fi</span>
</code></pre></div>
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