Infrastructure SSL certificate

This section contains guidelines to enforce security on a typical Carbonio installation.

Deploy an SSL Certificate

In this section we explain how to add an SSL/TLS certificate to a Carbonio installation. Carbonio supports the installation and management of Let’s Encrypt certificates: you can find directions for that in a dedicated article on Zextras Community portal.

This setup is mandatory if Carbonio is used in conjunction with mobile apps; it is also suggested for any installation in order to avoid the client browser’s warning about an invalid certificate upon connection.

See also

You can manage SSL domain certificates from the Carbonio Admin Panel: check out Virtual Hosts & Certificate.

Commercial Certificate Installation

We will describe the procedure by taking into account the following scenario:

• The server FQDN is mail.example.com

• No SSL certificate is available for the domain.

In the remainder, replace mail.example.com with your actual server FQDN.

The procedure consists of a few steps and requires console access to the Carbonio server.

Step 1. Certificate Signing Request generation

If you do not have a certificate, and you have to request a new one, you need to generate a CSR:

# /opt/zextras/bin/zmcertmgr createcsr comm -new -subject \
"/C=IT/ST=VR/L=Yourtown/O=YourCompany/OU=SampleDepartment/CN=mail.example.com" \
-subjectAltNames mail.example.com

Where the various elements in the subject are the standard fields of an SSL certificate:

• C: the 2-digit country code

• ST: State or Province

• L: City

• O: Organization Name

• OU: Organization Unit (Department)

• CN: Common Name

Note

You can optionally include more than one (alternative) name by simply adding to the end of the command one ore more -subjectAltNames options, followed by the name to add.

Once the command is executed these files will be generated:

# /opt/zextras/ssl/carbonio/commercial/commercial.key
# /opt/zextras/ssl/carbonio/commercial/commercial.csr

Step 2. Get the certificates from your SSL provider

To complete this step successfully, you need to submit the CSR to the SSL provider, get a commercial certificate in PEM format, and save it as commercial.crt.

Moreover, SSL providers supply also the intermediate certificate and the so-called Root CA in a bundled certificate file (“Full Chain CA”), that must be saved as commercial_ca.crt.

How to create a Full Chain CA

However, in some cases, the SSL provider may only provide the intermediate certificate, in which case you need to create the Full CA Chain in order to install the certificate (for further information: https://knowledge.digicert.com/solution/SO16297.html)

If you don’t have a full CA chain bundle, download and save the root and the intermediate CA from your provider to temporary files, for example /tmp/ca_root.crt and /tmp/ca_intermediary.crt, then merge the two previously created temporary files into a single one:

# cat /tmp/ca_intermediary.crt /tmp/ca_root.crt > \
/tmp/commercial_ca.crt

Step 3. Verification and deploy

Issue the following commands to verify that the certificate and your private key match:

• become the zextras user

  # su - zextras
  

• upload the certificates received from the Authority to the /tmp directory

• verify the certificates

  zextras$ cd /tmp
  zextras$ zmcertmgr verifycrt comm /opt/zextras/ssl/carbonio/commercial/commercial.key commercial.crt commercial_ca.crt
  

If the verification is successful, you can deploy the SSL certificate.

# zmcertmgr deploycrt comm commercial.crt commercial_ca.crt

Finally, restart Carbonio.

# zmcontrol restart

Your certificate should now be installed: verify the certificate details by running this command:

# zmcertmgr viewdeployedcrt