docker-mailserver/docs/content/ssl.md
2016-02-10 09:49:22 +01:00

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# docker-mailserver with ssl
There are multiple options to enable SSL:
* using [letsencrypt](https://letsencrypt.org/) (recommended)
* using self-signed certificates with the provided tool
After installation, you can test your setup with [checktls.com](https://www.checktls.com/TestReceiver).
## let's encrypt (recommended)
To enable Let's Encrypt on your mail server, you have to:
* get your certificate using [letsencrypt client](https://github.com/letsencrypt/letsencrypt)
* add an environment variable `DMS_SSL` with value `letsencrypt` (see `docker-compose.yml.dist`)
* mount your whole `letsencrypt` folder to `/etc/letsencrypt`
* the certs folder name located in `letsencrypt/live/` must be the `fqdn` of your container responding to the `hostname` command.
You don't have anything else to do. Enjoy.
## self signed certificates
You can easily generate a self-signed SSL certificate by using the following command:
docker run -ti --rm -v "$(pwd)"/postfix/ssl:/ssl -h mail.my-domain.com -t tvial/docker-mailserver generate-ssl-certificate
# Press enter
# Enter a password when needed
# Fill information like Country, Organisation name
# Fill "my-domain.com" as FQDN for CA, and "mail.my-domain.com" for the certificate.
# They HAVE to be different, otherwise you'll get a `TXT_DB error number 2`
# Don't fill extras
# Enter same password when needed
# Sign the certificate? [y/n]:y
# 1 out of 1 certificate requests certified, commit? [y/n]y
# will generate:
# postfix/ssl/mail.my-domain.com-key.pem (used in postfix)
# postfix/ssl/mail.my-domain.com-req.pem (only used to generate other files)
# postfix/ssl/mail.my-domain.com-cert.pem (used in postfix)
# postfix/ssl/mail.my-domain.com-combined.pem (used in courier)
# postfix/ssl/demoCA/cacert.pem (certificate authority)
Note that the certificate will be generate for the container `fqdn`, that is passed as `-h` argument.
Check the following page for more information regarding [postfix and SSL/TLS configuration](http://www.mad-hacking.net/documentation/linux/applications/mail/using-ssl-tls-postfix-courier.xml).
To use the certificate:
* add an `DMS_SSL=self-signed` to your container environment variables
* if a matching certificate (files listed above) is found in `postfix/ssl`, it will be automatically setup in postfix and courier-imap-ssl. You just have to place them in `postfix/ssl` folder.
### Testing certificate
From your host:
docker exec mail openssl s_client -connect 0.0.0.0:25 -starttls smtp -CApath /etc/ssl/certs/
or
docker exec mail openssl s_client -connect 0.0.0.0:143 -starttls imap -CApath /etc/ssl/certs/
And you should see the certificate chain, the server certificate and:
Verify return code: 0 (ok)