Every now and then you have to open up an SSL cert to inspect its content or verify information contained within. This is something that I had to do fairly often in a past life but is now firmly in the ‘reference a search engine’ territory.
This Red Hat article is not only a good overview of CA and Server certificates and their functions but also includes examples of inspecting x509 certificates.
source: Who signed my cert
openssl x509 -noout -text -in www.redhat.com.crt
There is another article detailing how to create podman secrets. It includes a useful command to generate a self-signed cert that you can use for internal testing.
openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:4096 -keyout certificate.key -out certificate.pem