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When to use OpenSSL to verify a port?
Steps Verify open ports using OpenSSL: OpenSSL can be used to verify if a port is listening, accepting connections, and if an SSL certificate is present. OpenSSL can be used for validation in the event plugin 51192 ‘SSL Certificate cannot be trusted’ unexpectedly finds unknown certificates on a port:
How to test SSL / TLS client authentication with OpenSSL?
You could even use a SQL server like Postgres since it sets up a SSL/TLS server. Simply search the source files for SSL_CTX_load_verify_locations or SSL_load_verify_locations, and you will find the right place. Though I don’t recommend it, you could even look at s_client.c and s_server.c. They are located in /apps.
Is there a SSL verify fail if no peer CERT flag?
There is also a SSL_VERIFY_FAIL_IF_NO_PEER_CERT flag, but it is used for servers and has no effect on clients. If you accidentally use SSL_VERIFY_FAIL_IF_NO_PEER_CERT, then you chain will always verify when call SSL_get_verify_result because the flag is ignored for clients (essentially, 0 is passed for the flag which performs no verification).
Is there a s _ client function in OpenSSL?
OpenSSL’s s_client implements nearly every client side feature available from the library. The code below does not perform hostname verification. OpenSSL prior to 1.1.0 does not perform the check, and you must perform the check yourself.
What is the s _ client command in OpenSSL?
OpenSSL’s s_client command can be used to analyze client-server communication, including whether a port is open and if that port is capable of accepting an SSL/TLS connection. It is a useful tool for investigating SSL/TLS certificate-based plugins, and for confirming that a line of secure communications is available.
How to debug SSL connection with OpenSSL’s _ client?
To debug the SSL/TLS connection with openssl s_client connect, append the -tlsextdebug flag onto your command: Additional information is included and can be used to verify the ssl configuration of the server, but leave a comment and ask questions about anything not covered.
Why is netstat not listening to port 631?
If you note the format of the ip address before the port number in the output of netstat, you may see that the service running on port 631 seems to be listening to a different IP range from the other services. It looks like is only listening on ip address 127.0.0.1:631 and ::1:631, and not 0.0.0.0:631 :::631.