How to use the s _ client flag in OpenSSL?
openssl s_client -connect example.com:443 Use the openssl s_client -connect flag to display diagnostic information about the SSL connection to the server. The information will include the servers certificate chain, printed as subject and issuer. The end entity server certificate will be the only certificate printed in PEM format.
How to show the certificate chain in OpenSSL?
openssl s_client -connect example.com:443 -showcerts. The showcerts flag appended onto the openssl s_client connect command prints out and will show the entire certificate chain in PEM format, whereas leaving off showcerts only prints out and shows the end entity certificate in PEM format.
How to generate a CSR file in OpenSSL?
The above command will generate CSR and a 2048-bit RSA key file. If you intend to use this certificate in Apache or Nginx, then you need to send this CSR file to certificate issuer authority, and they will give you a signed certificate mostly in der or pem format which you need to configure in Apache or Nginx web server.
What’s the difference between s _ client and showcerts in OpenSSL?
openssl s_client -connect example.com:443 -showcerts The showcerts flag appended onto the openssl s_client connect command prints out and will show the entire certificate chain in PEM format, whereas leaving off showcerts only prints out and shows the end entity certificate in PEM format. Other than that one difference, the output is the same.
Why does OpenSSL always say 400 Bad Request?
I am trying to test a server that is working normal in web browser, with openssl s_client option, connecting it directly using openssl returns the 400 Bad Request:
Why does OpenSSL close when the input file closes?
The next issue is that by default openssl closes the connection when the input file closes. Which is does immediately when using echo like this. So you don’t get time to see the response and instead just see the DONE output! :- ( You can add a sleep to the echo command to get around this (note the brackets are important):
Is there output available from OpenSSL’s _ client-CERT?
So, putting other (extensive) troubleshooting steps aside, what I’d really like to know is: Is there some output available from openssl s_client that conclusively shows that a client certificate wasn’t just requested by the server, but in fact was transmitted to the server during the SSL handshake?