The Microsoft TLS 1.0 implementation has no known security vulnerabilities. We understand that the security of your data is important, and we're committed to transparency about changes that may affect your use of the TLS service. * SSL connection using TLSv1.To provide the best-in-class encryption to our customers, Microsoft plans to deprecate Transport Layer Security (TLS) versions 1.0 and 1.1 in Office 365 and Office 365 GCC. * TLSv1.2 (IN), TLS handshake, Finished (20): * TLSv1.2 (IN), TLS change cipher, Change cipher spec (1): * TLSv1.2 (OUT), TLS handshake, Finished (20): * TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1): * TLSv1.2 (OUT), TLS handshake, Client key exchange (16): * TLSv1.2 (IN), TLS handshake, Server finished (14): * TLSv1.2 (IN), TLS handshake, Server key exchange (12): * TLSv1.2 (IN), TLS handshake, Certificate (11): * TLSv1.2 (IN), TLS handshake, Server hello (2): * TLSv1.2 (OUT), TLS handshake, Client hello (1): The output below shows a successful TLS 1.2 TLS handshake and some output from the webserver. blog(35) LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to Now, let’s tell curl to use TLS protocol version of 1.2 with the parameters -tlsv1.2 -tls-max 1.2 and see if we can successfully access the webserver.

* LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to * Closing connection 0 * TLSv1.1 (OUT), TLS handshake, Client hello (1): * successfully set certificate verify locations:

So in the output, when forcing curl to use TLS version 1.1, the SSL_connect fails since the webserver only permits 1.2+ curl -verbose -tlsv1.1 -tls-max 1.1 The webserver here has a policy that allows only TLS version 1.2+. Using the -verbose parameter gives you the ability to see the TLS handshake and get the output sent to standard out.

This code here uses curl with the parameters -tlsv1.1 -tls-max 1.1, which will force the max TLS protocol version to 1.1. Ever need to set your web server a specific protocol version of TLS for web servers and need a quick way to test that out to confirm? Let’s check out how to use curl to go just that.

Test tls 1.2 connections