Updated: 2021/Apr/14


SSL_get_version(3)                  OpenSSL                 SSL_get_version(3)



NAME
       SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_version - get the
       protocol information of a connection

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/ssl.h>

        int SSL_client_version(const SSL *s);

        const char *SSL_get_version(const SSL *ssl);

        int SSL_is_dtls(const SSL *ssl);

        int SSL_version(const SSL *s);

DESCRIPTION
       SSL_client_version() returns the numeric protocol version advertised by
       the client in the legacy_version field of the ClientHello when
       initiating the connection. Note that, for TLS, this value will never
       indicate a version greater than TLSv1.2 even if TLSv1.3 is subsequently
       negotiated. SSL_get_version() returns the name of the protocol used for
       the connection. SSL_version() returns the numeric protocol version used
       for the connection. They should only be called after the initial
       handshake has been completed. Prior to that the results returned from
       these functions may be unreliable.

       SSL_is_dtls() returns one if the connection is using DTLS, zero if not.

RETURN VALUES
       SSL_get_version() returns one of the following strings:

       SSLv3
           The connection uses the SSLv3 protocol.

       TLSv1
           The connection uses the TLSv1.0 protocol.

       TLSv1.1
           The connection uses the TLSv1.1 protocol.

       TLSv1.2
           The connection uses the TLSv1.2 protocol.

       TLSv1.3
           The connection uses the TLSv1.3 protocol.

       unknown
           This indicates an unknown protocol version.

       SSL_version() and SSL_client_version() return an integer which could
       include any of the following:

       SSL3_VERSION
           The connection uses the SSLv3 protocol.

       TLS1_VERSION
           The connection uses the TLSv1.0 protocol.

       TLS1_1_VERSION
           The connection uses the TLSv1.1 protocol.

       TLS1_2_VERSION
           The connection uses the TLSv1.2 protocol.

       TLS1_3_VERSION
           The connection uses the TLSv1.3 protocol (never returned for
           SSL_client_version()).

SEE ALSO
       ssl(7)

HISTORY
       The SSL_is_dtls() function was added in OpenSSL 1.1.0.

COPYRIGHT
       Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2019-03-12                SSL_get_version(3)