Linux Tactic

Secure Your Website: Check SSL Certificate Using Linux Command Line

Checking SSL Certificate through Linux Mint 20 Command Line

If you are running a website or using web-based services, it is vital to ensure your TLS/SSL certificates are up to date and valid. Checking SSL certificates can be done via various ways, including using command lines.

Linux Mint 20 makes it easy to check SSL certificates through the command line interface (CLI).

Command for Checking SSL Certificate

To check the SSL certificate through the Linux Mint 20 Command line, you need to use a specific command. The command is as follows:

– openssl s_client -connect WebServerURL: PortNumber

Replace WebServerURL and PortNumber with your websites URL and the port number you need to check.

This command uses the OpenSSL application, which helps to create, manage, and customize SSL/TLS certificates.

Required Information in SSL Certificate

Before executing the command, it is essential to know the information that should appear in an SSL certificate. It is crucial to check the following:

Domain Name: Ensure that the domain name on the SSL certificate matches the site that you are running.

Certificate Issuer: Check who issued the certificate, whether it is a trusted or untrusted certificate.

Expiration Date: Confirm that the SSL certificate is valid for the expected period.


Command for Checking SSL Certificate

Replacing WebServerURL and PortNumber

To check the SSL certificate through the Linux Mint 20 terminal, you should replace WebServerURL and PortNumber with your website’s Uniform Resource Locator (URL) and port-number that accept HTTPS traffic. For example, if your website is, and the HTTPS port number is 443, you should execute the command as follows:

– openssl s_client -connect 443

Example with and Port 80

Here is an example of how to check SSL certificates using the Linux Mint 20 CLI.

Suppose we want to check the SSL certificate of over Port 80. We can follow the steps below to do so:


Open the Linux Mint 20 terminal. 2.

Enter the following command: openssl s_client -connect

3. Press the Enter key to execute the command.

4. It will then generate and display the SSL certificate information, which includes Domain name, Certificate issuer, Expiration date, and other useful details.

5. Once you finish reviewing the SSL certificate details, press Ctrl+C to exit.

In Summary

In conclusion, it is critical to check SSL certificates regularly, as valid SSL certificates help create a secure connection between the client and the server. Linux Mint 20 provides an easy way to check SSL certificates through the command line interface.

By using the openssl s_client command, you can check the SSL certificate for your website and get detailed insights into the domain name, certificate issuer, and expiration date. Always ensure to check SSL certificates regularly to help keep your website safe and secure.

Obtaining SSL Certificate Information

Securing a website is essential, with the increasing need to access online services. SSL/TLS certificates are an essential element in securing a website.

As a web developer or a website owner, it is vital to monitor the SSL/TLS certificate status regularly. Linux Mint 20 provides a simple method of obtaining SSL/TLS certificate information via the command line interface (CLI).

SSL Certificate Information Displayed in Command Line

The SSL/TLS certificate information appears after executing the “openssl s_client” command in the CLI. The SSL/TLS certificate information displayed includes:

– Server-certificate

– Owner: This section displays the domain name, organization name, location, and email address of the organization.

– Issuer: displays the organization the certificate was issued by, the validity period, and the certificate’s signature algorithm. – Validity: it shows the certificate’s validity period, the starting date, the ending date when the certificate will expire.

– Public key information: This section displays information about the public key size and type used in key exchange. – Session-certificate

– similar to server-certificate, but it displays the session certificate details.

Analysis of SSL Certificate Information

SSL/TLS certificates play a critical role in securing a website and therefore, they need verification. Verification entails checking that the domain name on the certificate is correct, the certificate is issued by a trusted authority, and the certificate is valid.

Here are some details to consider when carrying out the verification:

– Domain name verification is essential when checking an SSL/TLS certificate. A valid SSL/TLS certificate should match the domain name on a website.

To do this, you need to compare the domain name on the SSL/TLS certificate with the domain name in the URL of the website you are checking. – Certificate issuer verification determines whether a certificate was issued by a legitimate organization.

Checking the certificate issuer can tell you whether it is trustworthy, as a certificate issued by a reputable issuer is more likely to be reliable. – Certificate validity verification is essential as certificates have an expiration date; thus, checking the certificate expiration date is critical.

Certificates that have already expired or are about to expire may prevent users from accessing services offered by a website. Replicating Method on Ubuntu 20.04 or Debian 10

Other than Linux Mint 20, you can also check SSL/TLS certificate information using Ubuntu 20.04 or Debian 10.

These Linux distributions are widely used and are compatible with most web-based services. Here is how to check SSL/TLS certificate information on Ubuntu 20.04 or Debian 10:

– Open the terminal.

– Enter the “openssl s_client” command with the website’s domain name and port number. Ensure to replace the WebServerURL and PortNumber with the website’s domain name and a port number that accepts HTTPS traffic.

– Confirm details of the SSL/TLS certificate. Check the SSL/TLS certificate information to verify that it is correct.

– Ctrl + C: Exit the command upon verification. The process used in Ubuntu 20.04 or Debian 10 is similar to that in Linux Mint 20, as long as you have OpenSSL installed on your system.

OpenSSL is an open-source cryptography toolkit that is widely used to enable secure communications over computer networks.


In conclusion, ensuring that an SSL/TLS certificate is valid, verified, and up to date is one of the essential steps to secure websites and secure user accounts. Linux Mint 20 provides an easy method of obtaining SSL/TLS certificate information through the command line interface.

Checking the SSL/TLS certificate’s domain name, issuer, and validity is an essential part of the verification process. The method used to obtain SSL/TLS certificate information on Linux Mint 20 is similar to that used on other Linux distributions, including Ubuntu 20.04 and Debian 10.

Always remember to check your SSL/TLS certificate status regularly to maintain a secure and safe website. In summary, obtaining and verifying SSL/TLS certificates is a crucial step in securing websites and user accounts.

Linux Mint 20, Ubuntu 20.04, and Debian 10 provide an easy and efficient way to obtain SSL/TLS certificate information through the command line interface. Verifying the SSL/TLS certificate’s domain name, issuer, and validity is an essential part of maintaining website security.

It is a best practice to regularly monitor and check the status of SSL/TLS certificates to ensure that they are valid, verified and up to date. Keeping SSL/TLS certificates up to date can help prevent problems with website security, which can lead to significant problems such as loss of user trust and ultimately, loss of revenue.

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