Integration with Let’s Encrypt

From ISPWiki
Jump to: navigation, search


Let’s Encrypt is a free certification authority that provides free X.509 certificated for TLS encryption. An automated process enables to facilitate creation, verification, setup and renewal of SSL certificates for protected web-sites.

Official website of Let's Encrypt.

Let's Encrypt integration page on ISPsystem's website.

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)

More information about additional limits can be found here.

This module is available in ISPmanager 5.65 and later.

In order to install a plug-in as root, navigate to Modules->Integration.

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 a 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 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.

Letsencrypt toolbaren.png

Certificate creation

There are two ways to obtain an Let's Encrypt certificate:

  • Navigate to WWW->SSL-certificates.

Click the Let's Encrypt button, and fill out the form.


Select a user (if your create an SSL as root) and domain.

Enter required data (country id, city, email, etc.) the length of the private key for your certificate.

  • When creating a WWW-domain

When creating a WWW-domain, select the Secure connection (SSL). Let's Encrypt certificate option will be added into the creation form. After you have provided all required information, you will be redirected to the Let's Encrypt certificate creation form.

Certificate update

Every day at 1:30 a.m the system checks what certificates should be updated. The update procedure starts 7 (or less days) before the certificate's 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:

force_update=yes, cert_name=%cert name%, user_name=%user name%

Attention! The number of certificates per domain is limited, that's why do not update your certificates manually too often.

Certificate issue

First, a self-signed certificate is created with provided parameters. Once in 5 minutes, the system is trying to obtain a 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 withing 24 hours, the corresponding notification is created for the user and administrators, and no other attempts are made.

If the certificate is successfully obtained, the self-signed certificate is changed into Let's Encrypt. The user and administrators get notification that the certificate has been successfully issued.

Order of requests:

  • Account creation
  • Authentication
  • 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, Path to the file .well-known/acme-challenge/%token_name%)
  • Waiting for successful validation
  • Certificate issue
 Note: Starting from ISPmanager 5.84.0 the domain verification procedure was changed. A separate alias .well-known/acme-challenge/ is now created for every   domain
 pointing to the  /usr/local/mgr5/www/letsencrypt directory. All verification tokens will be created there.

DNS 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" check box when you order a new SSL-certificate.

TXT-records will be automatically added by control panel. However, if external DNS is used, the process will be suspended for 30 minutes.

Administrator and user will see the notification: In order to proceed with Let's Encrypt %certificate name% setup, add TXT-record: '%record%' on name servers '%name_servers%'. Next verification process is scheduled on %activation_date_and_time%. Be very attentive when adding TXT-records, mistakes in their names or content are not permitted.

If domain validation processes cannot be completed successfully during 24 hours since you ordered a certificate, the system will stop trying to issue the certificate.

Mail domains

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 ordered for aliases,, 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 in ISPmanager Lite and Business introduced support of wildcard SSL certificates. To receive a Wildcard SSL-certificate check the Wildcard box on the order form. Attention! Domain verification procedure is performed only via DNS. An alias such as * specified manually will be ignored during the order to avoid verification conflicts.


  1. In ISPmanager Business: a web-domain can be resolved to several cluster nodes. If one of those cluster nodes doesn't have the web-role, it cannot be used for HTTP validation. Solutions:
    1. Use DNS-based vaalidation
    2. Wait for some time. ACME server will try to find a suitable address for HTTP-validation.