Purpose

Step by Step Wiki/KB article to install a Let’s Encrypt Commercial Certificate. Disclaimer The Let’s Encrypt Client is BETA SOFTWARE. It contains plenty of bugs and rough edges, and it should be tested thoroughly in staging environments before use on production systems. For more information regarding the status of the project, please see https://letsencrypt.org. Be sure to check out the Frequently Asked Questions (FAQ).

Resolution

Let’s Encrypt is a new Certificate Authority: It’s free, automated, and open. It could be an option to protect Zimbra Servers with a valid SSL certificate; however, please be aware that is a Beta for now. Some stuff could not work or have issues, so use it at your own risk.

Installing Let’s Encrypt on a Zimbra Server

Let’s Encrypt must be installed on one Linux machine to obtain the proper SSL Certificate, CA Intermediate, and Private Key. It is not required that it be on the same Zimbra Server, but it could save time and help to obtain the renewals, etc.

First Step is to stop the jetty or nginx service at Zimbra level

zmproxyctl stop
zmmailboxdctl stop

Second step is to Install git on the Server (apt-get install git/yum install git), and then do a git clone of the project on the folder we want
- Note: On RedHat/CentOS 6 you will need to enable the EPEL repository before install.

git clone https://github.com/letsencrypt/letsencrypt
cd letsencrypt

Let’s now run Let’s Encrypt in auto mode and use the certonly option, because for now the project can’t automatically install the cert on Zimbra servers.

root@zimbra86:~/tmp/letsencrypt# ./letsencrypt-auto certonly --standalone

If you need to have multiple hostnames on the same SSL, so a Multi-SAN, SSL, please run instead, where -d are your domains:

root@zimbra86:~/tmp/letsencrypt# ./letsencrypt-auto certonly --standalone -d xmpp.example.com -d conference.example.com

- (This step only happens the first time. This process will not occur when renewing the SSL Certificate if using the same machine.) The process will download all of the OS dependencies that Let’s Encrypt needs, and after a few minutes:

Creating virtual environment...
Updating letsencrypt and virtual environment dependencies...../root/.local/share/letsencrypt/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
  InsecurePlatformWarning
./root/.local/share/letsencrypt/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
  InsecurePlatformWarning

- - The process will ask for an Email Address in case of emergency contact or to recover the lost key.

- - The process will ask if we agree with the ToS.

- - - In case we run a renewal, or a request for a new FQDN, the process will just take a few seconds.

Updating letsencrypt and virtual environment dependencies.......
Running with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt certonly

- - Let’s Encrypt will prompt for the domain to protect, in this lab case (zimbra86.zimbra.io):

The process will take a few seconds to validate and then will end:

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at
   /etc/letsencrypt/live/zimbra86.zimbra.io/fullchain.pem. Your cert
   will expire on 2016-03-04. To obtain a new version of the
   certificate in the future, simply run Let's Encrypt again.
 - If like Let's Encrypt, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

Where are the SSL Certificate Files?

You can find all your files under /etc/letsencrypt/live/$domain, where $domain is the fqdn you used during the process:

root@zimbra86:/etc/letsencrypt/live/zimbra86.zimbra.io# ls -al
total 8
drwxr-xr-x 2 root root 4096 Dec  5 16:46 .
drwx------ 3 root root 4096 Dec  5 16:46 ..
lrwxrwxrwx 1 root root   42 Dec  5 16:46 cert.pem -> ../../archive/zimbra86.zimbra.io/cert1.pem
lrwxrwxrwx 1 root root   43 Dec  5 16:46 chain.pem -> ../../archive/zimbra86.zimbra.io/chain1.pem
lrwxrwxrwx 1 root root   47 Dec  5 16:46 fullchain.pem -> ../../archive/zimbra86.zimbra.io/fullchain1.pem
lrwxrwxrwx 1 root root   45 Dec  5 16:46 privkey.pem -> ../../archive/zimbra86.zimbra.io/privkey1.pem

cert.pem is the certificate

chain.pem is the chain

fullchain.pem is the concatenation of cert.pem + chain.pem

privkey.pem is the private key

Please keep in mind that the private key is only for you.

Build the proper Intermediate CA plus Root CA

Let’s Encrypt is almost perfect, but during the files the process built, they just add the chain.pem file without the root CA. You must to use the IdenTrust root Certificate and merge it after the chain.pem

https://www.identrust.com/certificates/trustid/root-download-x3.html

Your chain.pem should look like:

To sum up: chain.pem has to be concatened with the root CA. First the chain and the end of the file the root CA. The order is important.

Verify your commercial certificate.

Copy all the Let’s Encrypt folder with all files /etc/letsencrypt/live/$domain into /opt/zimbra/ssl/letsencrypt:

root@mail2:~# mkdir /opt/zimbra/ssl/letsencrypt
root@mail2:~# cp /etc/letsencrypt/live/mail2.next.zimbra.io/* /opt/zimbra/ssl/letsencrypt/
root@mail2:~# chown zimbra:zimbra /opt/zimbra/ssl/letsencrypt/*
root@mail2:~# ls -la /opt/zimbra/ssl/letsencrypt/
total 24
drwxr-xr-x 2 root   root   4096 Jul 15 22:59 .
drwxr-xr-x 8 zimbra zimbra 4096 Jul 15 22:59 ..
-rw-r--r-- 1 zimbra zimbra 1809 Jul 15 22:59 cert.pem
-rw-r--r-- 1 zimbra zimbra 2847 Jul 15 22:59 chain.pem
-rw-r--r-- 1 zimbra zimbra 3456 Jul 15 22:59 fullchain.pem
-rw-r--r-- 1 zimbra zimbra 1704 Jul 15 22:59 privkey.pem

Zimbra Collaboration 8.7 and above

As zimbra user

zimbra@zimbra87:/opt/zimbra/ssl/letsencrypt/# /opt/zimbra/bin/zmcertmgr verifycrt comm privkey.pem cert.pem chain.pem 
** Verifying cert.pem against privkey.pem
Certificate (cert.pem) and private key (privkey.pem) match.
Valid Certificate: cert.pem: OK

Zimbra Collaboration 8.6 and previous

As root user

root@zimbra86:/opt/zimbra/ssl/letsencrypt/# /opt/zimbra/bin/zmcertmgr verifycrt comm privkey.pem cert.pem chain.pem 
** Verifying cert.pem against privkey.pem
Certificate (cert.pem) and private key (privkey.pem) match.
Valid Certificate: cert.pem: OK

Deploy the new Let’s Encrypt SSL certificate

Backup Zimbra SSL directory

Before deploying a good practice is to make a backup.

cp -a /opt/zimbra/ssl/zimbra /opt/zimbra/ssl/zimbra.$(date "+%Y%m%d")

Copy the private key under Zimbra SSL path

Before deploying the SSL Certificate, you need to move the privkey.pem under the Zimbra SSL commercial path, like this:

cp /opt/zimbra/ssl/letsencrypt/privkey.pem /opt/zimbra/ssl/zimbra/commercial/commercial.key

Final SSL deployment

Then deploy the certificate as follows:

Zimbra Collaboration 8.7 and above

As zimbra user

zimbra@mail2://opt/zimbra/ssl/letsencrypt/$ /opt/zimbra/bin/zmcertmgr deploycrt comm cert.pem chain.pem 
** Verifying 'cert.pem' against '/opt/zimbra/ssl/zimbra/commercial/commercial.key'
Certificate 'cert.pem' and private key '/opt/zimbra/ssl/zimbra/commercial/commercial.key' match.
** Verifying 'cert.pem' against 'chain.pem'
Valid certificate chain: cert.pem: OK
** Copying 'cert.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial.crt'
** Copying 'chain.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial_ca.crt'
** Appending ca chain 'chain.pem' to '/opt/zimbra/ssl/zimbra/commercial/commercial.crt'
** Importing cert '/opt/zimbra/ssl/zimbra/commercial/commercial_ca.crt' as 'zcs-user-commercial_ca' into cacerts '/opt/zimbra/common/lib/jvm/java/jre/lib/security/cacerts'
** NOTE: restart mailboxd to use the imported certificate.
** Saving config key 'zimbraSSLCertificate' via zmprov modifyServer mail2.next.zimbra.io...failed (rc=1)
** Installing ldap certificate '/opt/zimbra/conf/slapd.crt' and key '/opt/zimbra/conf/slapd.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/slapd.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/slapd.key'
** Creating file '/opt/zimbra/ssl/zimbra/jetty.pkcs12'
** Creating keystore '/opt/zimbra/mailboxd/etc/keystore'
** Installing mta certificate '/opt/zimbra/conf/smtpd.crt' and key '/opt/zimbra/conf/smtpd.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/smtpd.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/smtpd.key'
** Installing proxy certificate '/opt/zimbra/conf/nginx.crt' and key '/opt/zimbra/conf/nginx.key'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.crt' to '/opt/zimbra/conf/nginx.crt'
** Copying '/opt/zimbra/ssl/zimbra/commercial/commercial.key' to '/opt/zimbra/conf/nginx.key'
** NOTE: restart services to use the new certificates.
** Cleaning up 3 files from '/opt/zimbra/conf/ca'
** Removing /opt/zimbra/conf/ca/41b01cbb.0
** Removing /opt/zimbra/conf/ca/ca.key
** Removing /opt/zimbra/conf/ca/ca.pem
** Copying CA to /opt/zimbra/conf/ca
** Copying '/opt/zimbra/ssl/zimbra/ca/ca.key' to '/opt/zimbra/conf/ca/ca.key'
** Copying '/opt/zimbra/ssl/zimbra/ca/ca.pem' to '/opt/zimbra/conf/ca/ca.pem'
** Creating CA hash symlink '41b01cbb.0' -> 'ca.pem'
** Creating /opt/zimbra/conf/ca/commercial_ca_1.crt
** Creating CA hash symlink '4f06f81d.0' -> 'commercial_ca_1.crt'
** Creating /opt/zimbra/conf/ca/commercial_ca_2.crt
** Creating CA hash symlink '2e5ac55d.0' -> 'commercial_ca_2.crt'

Zimbra Collaboration 8.6 and previous

As root user

root@zimbra86:/opt/zimbra/ssl/letsencrypt/# /opt/zimbra/bin/zmcertmgr deploycrt comm cert.pem chain.pem 
** Verifying cert.pem against /opt/zimbra/ssl/zimbra/commercial/commercial.key
Certificate (cert.pem) and private key (/opt/zimbra/ssl/zimbra/commercial/commercial.key) match.
Valid Certificate: cert.pem: OK
** Copying cert.pem to /opt/zimbra/ssl/zimbra/commercial/commercial.crt
** Appending ca chain chain.pem to /opt/zimbra/ssl/zimbra/commercial/commercial.crt
** Importing certificate /opt/zimbra/ssl/zimbra/commercial/commercial_ca.crt to CACERTS as zcs-user-commercial_ca...done.
** NOTE: mailboxd must be restarted in order to use the imported certificate.
** Saving server config key zimbraSSLCertificate...failed.
** Saving server config key zimbraSSLPrivateKey...failed.
** Installing mta certificate and key...done.
** Installing slapd certificate and key...done.
** Installing proxy certificate and key...done.
** Creating pkcs12 file /opt/zimbra/ssl/zimbra/jetty.pkcs12...done.
** Creating keystore file /opt/zimbra/mailboxd/etc/keystore...done.
** Installing CA to /opt/zimbra/conf/ca...done.

Then you need to restart the services, which will restart the nginx or jetty you stopped before:

zmcontrol restart

Test the new SSL Certificate

The last step is to go to your Web Browser and open the URL of your Zimbra server where you installed the Let’s Encrypt SSL Certificate:

You can expand the Certificate Information to see the new SSL Certificate your server is using:

Test the new SSL Certificate with OpenSSL

You can use openssl cli tools to check and test the new SSL certificate:

echo QUIT | openssl s_client -connect $domain:443 | openssl x509 -noout -text | less

where $domain is the fqdn you used during the process

Building Multi-SAN SSL Certificate and complex scenarios

You can do almost everything you need, like Subject Alt Names, different domains, etc. But to see more about this, visit the web of the official project.

Here is an example using two FQDN:

./letsencrypt-auto certonly --standalone -d fqdn1 -d fqdn2

Verifying SSL certificate is not expired

SSL certificates issued by let’s encrypt are valid for 90 days during the BETA phase. You need to check the expiration of your SSL certificate. We can suggest using monitoring tools like Nagios. With nagios plugins there’s a command which can check the expiration:

/usr/lib/nagios/plugins/check_http --sni -H '<FQDN>' -C 30,14

A warning will be issued 30 days before the expiration, a critical will be issued 14 days before the expiration.

Here is a nagios config file excerpt:

define command{
       command_name    check_https_vhost
       command_line    /usr/lib/nagios/plugins/check_http --sni -H '$ARG1$' -C 30,14
}

define service{
       use generic-service
       host_name <FQDN>
       service_description SSL <FQDN>
       check_command check_https_vhost!<FQDN>
}

Additional Content

Let’s Encrypt User Manual – https://letsencrypt.readthedocs.org/en/latest/using.html
Let’s Encrypt Official Project – https://letsencrypt.org/

Automatic methods

Since Letsencrypt has gone public several scripts were created to automate the deployment of free SSL certificates in Zimbra. In order of appearance:

Vojtěch Myslivec on GitHub
Grown from a long discussion on the forum Jim Dunphy developed a script based on Neilpang’s acme.sh script
A nearly fully automated script developed by Maxxer@YetOpen on GitHub

ZIMBRA : Installing a Let’s Encrypt SSL Certificate

Purpose

Resolution

Installing Let’s Encrypt on a Zimbra Server

Where are the SSL Certificate Files?

Build the proper Intermediate CA plus Root CA

Verify your commercial certificate.

Zimbra Collaboration 8.7 and above

Zimbra Collaboration 8.6 and previous

Deploy the new Let’s Encrypt SSL certificate

Backup Zimbra SSL directory

Copy the private key under Zimbra SSL path

Final SSL deployment

Zimbra Collaboration 8.7 and above

Zimbra Collaboration 8.6 and previous

Test the new SSL Certificate

Test the new SSL Certificate with OpenSSL

Building Multi-SAN SSL Certificate and complex scenarios

Verifying SSL certificate is not expired

Additional Content

Automatic methods

About Jason Xu

Purpose

Resolution

Installing Let’s Encrypt on a Zimbra Server

Where are the SSL Certificate Files?

Build the proper Intermediate CA plus Root CA

Verify your commercial certificate.

Zimbra Collaboration 8.7 and above

Zimbra Collaboration 8.6 and previous

Deploy the new Let’s Encrypt SSL certificate

Backup Zimbra SSL directory

Copy the private key under Zimbra SSL path

Final SSL deployment

Zimbra Collaboration 8.7 and above

Zimbra Collaboration 8.6 and previous

Test the new SSL Certificate

Test the new SSL Certificate with OpenSSL

Building Multi-SAN SSL Certificate and complex scenarios

Verifying SSL certificate is not expired

Additional Content

Automatic methods

Related Posts

About Jason Xu