An SSL certificate is a digital certificate that authenticates a website and encrypts information sent to a server using this technology.
There are websites to query the expiration time of the SSL certificate.
Secondly, the SSL certificate duration can be learned with the following command line to be run on the terminal.
Finally, this information can be provided via the browser.
SSL certificates have a certain validity period. Once this time is exceeded, browsers will display a warning on the web page stating that the SSL certificate has expired.
Once the SSL certificate expires, the website cannot establish a secure connection with browsers. This may cause visitors to see security warnings and leave the website.
If a website does not have an SSL certificate (it has expired), such a warning will appear when accessing the web page.
Failure to establish a secure connection can result in attacks such as Man-in-the-Middle.
References:
https://sectigostore.com/page/what-will-happen-if-my-ssl-certificate-expires/
https://www.howtouselinux.com/post/4-ways-to-check-ssl-certificate-expiration-date