Manually managing SSL/TLS certificates can take a lot of time, especially when multiple domains, servers, and applications are involved. You need to request, validate, install, and renew certificates well before they expire. Posh-ACME helps with this problem by facilitating ACME-based certificate management directly in PowerShell.
The article explains how to install and configure Posh-ACME, how to issue SSL/TLS certificates, how to perform DNS validation, how to integrate certificates into IIS and other web servers, how to automate renewal processes, and what security practices to follow.
What is Posh-ACME?
Posh-ACME is a PowerShell module that enables Windows administrators to request, manage, and renew SSL/TLS certificates through the ACME protocol.
As opposed to win-acme, which is essentially a standalone program; on the contrary, Posh-ACME works directly in PowerShell and fits the needs of scripting and automated certificate management.
When using Posh-ACME, administrators create ACME accounts, apply for certificates, do HTTP or DNS-based verification, and perform automated certificate renewal together with Posh-ACME certification authorities. It is compatible with automated solutions that can include certificates and various additional tasks.
Because Posh-ACME is a PowerShell-based module, it is useful for administrators who seek automated solutions in their work and who want to have better control of the SSL/TLS process, and for those who want to integrate their certifications into their automated procedures.
Installation Steps
Posh-ACME is a PowerShell module that must be installed. The installation process begins by opening PowerShell as an Administrator and installing the module from the PowerShell Gallery with the help of the command shown below:
Install-Module -Name Posh-ACME -Scope AllUsersIf PowerShell prompts whether to install the NuGet provider or trust the repository, answer positively to the prompts in order to continue. After the installation is completed, the module has to be loaded into the PowerShell session.
Import-Module Posh-ACMEYou can verify that Posh-ACME is installed correctly by checking its version:
Get-Module -ListAvailable Posh-ACMEWhen the module information is shown correctly, Posh-ACME is ready for use. After that you can create an account for ACME, choose a Certificate Authority, set up domain validation, and order SSL/TLS certificates.
Initial Configuration
Right after you install Posh-ACME, the first step is to create an account with an ACME-compliant Certificate Authority and accept the terms of service. First, you should check available configurations of ACME servers and choose the required server according to your certificate provider.
For instance, to set up an account on an ACME server, you should set it up and create the account with your email address.
Set-PAServer LE_Prod
New-PAAccount -Contact "mailto:[email protected]" -AcceptTOSAfter the account is created, Posh-ACME saves the information about the account and uses it for all the following certificate requests. To check the active account and server configurations, you can use the following commands:
Get-PAAccount
Get-PAServerWhen the ACME account is set up successfully, you can move on to domain verification, requesting certificates, and automating renewals with PowerShell.
Certificate Issuance Process
After the initial configuration, you can initiate the process of getting SSL and TLS certificates through the selected ACME CA using the Posh-ACME software. You will need to enter your domain and use a suitable method of verification in order to prove that you own the domain.
To request a basic certificate, you only have to run the New-PACertificate command:
New-PACertificate example.com -AcceptTOSIf you have more than one domain name, you can add them to the certificate request:
New-PACertificate example.com,www.example.com -AcceptTOSAs soon as the domain verification is complete, Posh-ACME issues the certificate from the ACME server, and once certification is done successfully, the Posh-ACME program saves the acquired certificates.
In case of using such certificates as wildcard certificates, DNS verification will be necessary. After using any compatible DNS provider or creating the required DNS record, you can obtain the wildcard certificate for domains such as *.example.com.
When the certificate is obtained, you can export it using automation with PowerShell!
Also Read: ACME DNS-01 Challenge Setup for Wildcard SSL
DNS Validation for Wildcard
The DNS verification technique proves domain ownership via a temporary DNS TXT record. This technique can be utilized for obtaining wildcard certificates and authorizing a certificate even in case HTTP validation is not possible.
Thanks to a DNS provider in your possession, it is possible to automatically add and remove the correct TXT records using API credentials. Once the DNS provider credentials are set up, a certificate can be requested with DNS verification:
$pArgs = @{
CFToken = "YOUR_CLOUDFLARE_API_TOKEN"
}
New-PACertificate example.com -Plugin Cloudflare -PluginArgs $pArgs -AcceptTOS
In case of a wildcard certificate, the wildcard domain will have to be specified:
New-PACertificate "*.example.com" -Plugin Cloudflare -PluginArgs $pArgs -AcceptTOSThe _acme-challenge DNS record is created, and the process waits for validation to finish; afterward, the issuing procedure starts.
IIS and Web Server Integration
The integration of Posh-ACME with IIS and other web servers can be achieved using PowerShell scripts to install and deploy SSL/TLS certificates that were issued. Once the certificate generation is completed, it can be imported into the Windows Certificate Store and applied for use in IIS HTTPS binding.
Also Read: How to Install ACME SSL Certificates on Windows IIS?
The deployment of certificates can be automated for use with IIS using PowerShell commands or specialized scripts. This enables the web server to utilize the renewed certificate without having to alter the configuration manually.
The use of Posh-ACME can also help execute deployment commands right after any certificate is issued or renewed, which makes it apt for automated IIS environments.
For other types of web servers and applications, the certificate files may be either transferred or converted to other required formats like PFX, PEM, etc., while custom PowerShell scripts can restart the necessary service and update the certificate-related settings.
Certificate Renewal
Posh-ACME allows for certificate renewal through automation with PowerShell. After a certificate has been issued, the Submit-Renewal command can check current certificates and renew any that may be expiring soon.
Submit-Renewal commandThe process of renewing the certificate utilizes the certificate and validation settings that were initially configured. Posh-ACME can either perform the domain validation again or automatically send the request for a new certificate to the ACME Certificate Authority and store the new files.
PowerShell Automation
Posh-ACME lends itself well to PowerShell automation in that it can handle all certificate requests, validation, renewal, and deployment with scripts. One can create scripts that help check whether there is a need for any certificate renewal and initiate this process automatically.
For Example:
Import-Module Posh-ACME
Submit-RenewalThe Windows Task Scheduler allows us to schedule this script to be run repeatedly. When there is a certificate nearing its expiration date, Posh-ACME will use the existing configurations to authorize validation and to request for a renewal.
Custom commands can also be added in the script to deploy the new certificate, change the IIS bindings, move the certificate files somewhere else, or even restart an application or web server. This results in Posh-ACME being very handy when automating the management of SSL/TLS certificates in the Windows environment.
Troubleshooting Guide
The most typical Posh-ACME issues comprise problems with the domain validation, wrong DNS credentials, expired API tokens, or connection problems with the ACME server. When the certificate cannot be issued, check the error message and the configuration of the selected ACME server and account.
In cases of error during the DNS validation process, ensure that the DNS provider API credentials are granted all needed permissions, and the _acme-challenge TXT record was created. DNS propagation problems may also lead to validation issues.
If the renewal does not work, execute Submit-Renewal manually and pinpoint the error while making sure that the PowerShell module is accessible to the account that is executing the scheduled task. Make sure that the renewal task has the necessary permissions and has access to the existing Posh-ACME configuration.
Security Best Practices
While using Posh-ACME, make sure to keep sensitive information like API tokens, private keys, and ACME account info safe. Avoid putting this information into publicly viewable scripts or code. Limit accessibility of configuration and certificate files as well.
Use DNS API tokens that have just the amount of permission that is needed for the purposes of validation of the certificate. Change the credentials in case of compromise. Securely store the private keys and make sure that only the authorized users or services have access to them.
In case of automated renewal, make sure that the PowerShell account or scheduled task has only the necessary privileges for carrying out certificate operations. Test the renewal process regularly, and keep an eye on certificate expiration so as to identify failures before the actual expiration.
Also Read: Win-ACME SSL Setup Guide: Installation, Configuration & Automation
Conclusion
Posh-ACME is a tool that automates the process of SSL/TLS certificate handling on Windows using PowerShell. It utilizes the ACME protocol to handle certificate requests, existence validation for related domains, renewal, and deployment processes. It builds on current PowerShell procedures used by users worldwide.
With appropriate DNS and HTTP checks, effective credential management, automation scripts, and a server configuration process of Posh-ACME, it is possible to reduce the amount of manual work. At the same time, routine test activities help prevent renewal failures and unexpected termination of the opportunities.
