References

• https://security.stackexchange.com/questions/98282/difference-between-openssl-and-keytool
• https://unix.stackexchange.com/questions/162969/why-openssl-s-client-verifies-a-cert-against-a-mismatching-cafile?rq=1
• https://blog.yimingliu.com/2009/01/23/testing-a-pop3-server-via-telnet-or-openssl/