[openssl-users] How to get list of TLS protocols supported by OpenSSL?

pratyush parimal pratyush.parimal at gmail.com
Fri Nov 13 02:56:33 UTC 2015


I'm writing a client-server program that uses TLS for communication.
I'm wondering if there's any way to programmatically find out which TLS
protocol versions are supported by the OpenSSL library installed on my

I'm currently aware of three ways which "sort of" provide this information:
(1) After setting up the TLS communication, call: SSL_get_version(ssl);
which returns "TLSV1.2", etc.
(2) Try to connect to a server using TLS by specifying all possible TLS
versions in the client program, and see which connections pass/fail.
(3) Call: SSL_get_ciphers(), print their names, and try to correlate them
with the protocol they're associated with.

Unfortunately, none of the above answer my question completely.

So is it possible to ascertain which TLS protocol versions are actually
supported by my server-program, without trying the above methods? My
purpose is not to simply make a list for my own reference, but rather
finding it out on-the-fly in the server-side program, since I may run it on
different versions of OpenSSL.

Thanks in advance!
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