How to install an SSL certificate from Let’s Encrypt
Let’s Encrypt is a free certification authority that provides free X.509 certificated for TLS encryption. An automated process enables to facilitate the creation, verification, setup, and renewal of SSL certificates for protected websites.
Let’s Encrypt provides a number of limits:
- You can order only 5 certificates per week (TLD, including its subdomains);
- Let’s Encrypt certificate validity period is 3 months (every 3 months ISPmanager will reissue Let’s Encrypt certificates);
- All alternative names should be subdomains of the certificate domain.
More information about additional limits can be found here.
This module is available in ISPmanager 5.131 and later.
In order to install a plug-in as root, navigate to Integration → Modules.
After you have installed Let’s Encrypt in ISPmanager, you can obtain a self-updated SSL-certificate for your domain. Be sure to create a user with the configured web-domain and valid domain name available to world-wide DNS.
Once the installation is completed, in the WWW → SSL-certificates module the user will see two new buttons — Let’s Encrypt and Let’s Encrypt Log. Clicking the first button will start the process of the certificate issue.
The second function will be activated, if you already have the Let’s Encrypt certificate in the list of SSL-certificates, and will redirect you to the Event log.
Before generating a certificate make sure that the Let’s Encrypt function is enabled:
- In the section “Access to functions”: Settings → Access to functions → select a user group → Permissions → SSL certificates → Let’s Encrypt → Enable.
- In the user permissions configuration form: Accounts → Users → select a user → Permissions → SSL certificates → Let’s Encrypt → Enable.
Add a certificate
There are two ways to obtain a Let’s Encrypt certificate:
- Navigate to WWW → SSL-certificates. Click the Let’s Encrypt button, and fill out the form.
- On the WWW-domain creation form, select the Secure connection (SSL). Let’s Encrypt certificate option will be added to the creation form. Specify the required parameters. Next, you will be redirected to the Let’s Encrypt certificate creation form.
Every day at 1:30 a.m the system checks what certificates should be updated. The update procedure starts 7 (or fewer) days before the certificate expiration date.
You can also start the update process manually with the letsencrypt.check.update function. Call the function via the mgrctl utility with the following parameters:
The number of certificates that can be issued for a domain is limited, that’s why do not update your certificates manually too often.
When updating the certificate with DNS-verification, new TXT-records will be generated. If the external DNS-server is used, the records won’t be added automatically, and the certificate won’t be updated.
Certificate issue procedure
The system generates a self-signed certificate with the specified parameters. Once in 5 minutes, the system is trying to obtain the certificate.
Errors, if any, are logged into the Error log. The second attempt to obtain the certificate will be made in 5 minutes.
You can start the letsencrypt.periodic command via the mgrctl utility.
If the certificate cannot be obtained within 24 hours, the corresponding notification will be created for the user and administrators. No more attempts will be made.
If the certificate is issued successfully, the self-signed certificate is changed into Let’s Encrypt. The user and administrators receive the notification that the certificate has been issued.
Order of requests:
- Account creation
- Request for domain ownership (in order to verify domain ownership, a new token is added. This is a file with data that were received after authentication. The global alias .well-known/acme-challenge/ on the server leads to the directory /usr/local/mgr5/www/letsencrypt. All verification tokens will be created there.
- Waiting for successful validation
Let’s Encrypt supports DNS-based validation that requires specific TXT records to be inserted into the DNS zone for a domain. Select the DNS validation checkbox when you order a new SSL-certificate.
TXT-records will be automatically added in Domains → Domain names → Records.
If you use an external DNS server, the process will be suspended for 30 minutes. In the System status → Notifications section of the panel interface next to the global search field, you will see what records you should add to the external server to receive the certificates.
The system will check the records on the Internet every 30 minutes during 24 hours after you have received the first notification. When the required records are available, the certificates will be issued.
If domain validation processes cannot be completed successfully for 24 hours since you ordered a certificate, the system will stop trying to issue the certificate.
Let’s Encrypt can be issued for mail domains. Navigate to Mail domains → click Add or Edit → select New Let’s Encrypt. The certificate will be also issued for aliases mail.domain.name, smtp.domain.name, pop.domain.name. If the web-domain with the same name is not created in the control panel, the verification procedure will run via DNS.
Starting from version 5.147.0 ISPmanager supports wildcard SSL certificates. To receive a Wildcard SSL-certificate check the Wildcard box on the order form.
The domain verification procedure is performed only via DNS.
An alias such as *.domain.name specified manually will be ignored during the order to avoid verification conflicts.
Sometimes it may happen that a web-domain is resolved to several cluster nodes. If one of the cluster nodes doesn’t have a web-role it cannot pass the HTTP verification. How to solve the issue:
- Pass the DNS verification.
- Just wait. After several failures, the ACME server will find the right address for the HTTP verification.
The log file is located in /usr/local/mgr5/var/ispmgr.log.
The default logging level is not enough for receiving all the information an administrator may need to solve possible issues. Complete the following steps:
- Go to Settings → Logging settings
- Press Ctrl and select ssl, rpc, core_modules.
- Click on Maximum.