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See http://spamassassin.org/tag/ for more details. 0.2 HEADER_FROM_DIFFERENT_DOMAINS From and EnvelopeFrom 2nd level mail domains are different X-Headers-End: 1g4mlT-00AZle-Hm Subject: [Openvpn-devel] [PATCH] Add message explaining early TLS client hello failure X-BeenThere: openvpn-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: openvpn-devel-bounces@lists.sourceforge.net X-getmail-retrieved-from-mailbox: Inbox In my tests an OpenSSL 1.1.1 server does not accept TLS 1.0 only clients anymore. Unfortunately, Debian 8 still has OpenVPN 2.3.4, which is TLS 1.0 only without setting tls-version-min. We currently log only OpenSSL: error:14209102:SSL routines:tls_early_post_process_client_hello:unsupported protocol which indicates the right technical error but is not very helpful to a person without deep knowledge in SSL/TLS and OpenVPN's TLS version history. This commit adds a hopefully helpful message and also tells users how to fix the old Debian 8 clients. --- src/openvpn/crypto_openssl.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c index 9ec2048d..3360bb19 100644 --- a/src/openvpn/crypto_openssl.c +++ b/src/openvpn/crypto_openssl.c @@ -199,7 +199,15 @@ crypto_print_openssl_errors(const unsigned int flags) "in common with the client. Your --tls-cipher setting might be " "too restrictive."); } - + else if (ERR_GET_REASON(err) == SSL_R_UNSUPPORTED_PROTOCOL) + { + msg(D_CRYPT_ERRORS, "TLS error: Unsupported protocol. This typically " + "indicates that client and server have no common TLS version enabled. " + "This can be caused mismatched tls-version-min and tls-version-max options " + "on client and server. " + "If your client is 2.3.6 or older consider adding tls-version 1.1" + "to the the configuration to use TLS 1.1+ instead of TLS 1.0 only"); + } msg(flags, "OpenSSL: %s", ERR_error_string(err, NULL)); } }