How to get a valid certificate?

Question

OpenSSL

Good day to all!
What am I doing wrong - have openssl generate root CA cert, intermediate CA cert and server cert. But when you try to access the site via https, a security error occurs due to an untrusted certificate, when RDP connects, a certificate confirmation window pops up, and when connecting via ftps or ftpes, it also claims that the certificate does not inspire confidence. The same situation is with SSH Host keys. How to create a valid certificate with a green padlock and traffic encryption?! Please help please!

Answer 1

There are two ways to get a lock.
- install root and intermediate CA certificates on the client.
- get a certificate from a public certificate authority, such as LetsEncrypt (this requires a domain and a white IP)

Answer 2

The problem is due to the fact that this is a self-signed certificate, and such ones do not inspire confidence and by right.
You must use a certificate issued by a trusted party, such as LetsEncrypt, as a free option. But the paid ones are better.

Answer 3

Create - nothing.
You can buy or get it for free.
Buy: Thawte, Comodo, GlobalSign
Free: Let's Encrypt