OpenSSL, Check TLS details in Terminal

To check a host’s TLS (Transport Layer Security) certificate details using the macOS Terminal, you can use the openssl command. OpenSSL is a powerful tool that provides various SSL and TLS-related functionalities. Here’s how you can use it to check the TLS certificate of a host:

The basic command format to check a TLS certificate is:
openssl s_client -connect host:port

To check the TLS certificate for on port 443, you would use:
openssl s_client -connect

To view the certificate chain and more details, add -showcerts to the command:
openssl s_client -connect -showcerts

To get just the server certificate, you can pipe the output to openssl x509:
openssl s_client -connect | openssl x509 -text

If you want to check the connection using a specific TLS version, you can specify it using -tls1_2 or another relevant version flag.
For example, to use TLS 1.2, the command would be:
openssl s_client -connect -tls1_2


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