How can I verify if TLS 1.2 is supported on a remote web server from the RHEL/CentOS shell?

Question

I'm on CentOS 5.9.

I'd like to determine from the linux shell if a remote web server specifically supports TLS 1.2 (as opposed to TLS 1.0). Is there an easy way to check for that?

I'm not seeing a related option on openssl but perhaps I'm overlooking something.

Solution 1

You should use openssl s_client, and the option you are looking for is -tls1_2.

An example command would be:

openssl s_client -connect google.com:443 -tls1_2

If you get the certificate chain and the handshake you know the system in question supports TLS 1.2. If you see don't see the certificate chain, and something similar to "handshake error" you know it does not support TLS 1.2. You can also test for TLS 1 or TLS 1.1 with -tls1 or tls1_1 respectively.

Solution 2

Also you can list all supported ciphers using:

nmap --script ssl-enum-ciphers -p 443 www.example.com

And then check the output. If it's supported you'll get something like this:

|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA - strong
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - strong
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - strong
|       TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - strong
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - strong
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - strong
|       TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - strong
|       TLS_ECDHE_RSA_WITH_RC4_128_SHA - strong
|       TLS_RSA_WITH_3DES_EDE_CBC_SHA - strong
|       TLS_RSA_WITH_AES_128_CBC_SHA - strong
|       TLS_RSA_WITH_AES_128_CBC_SHA256 - strong
|       TLS_RSA_WITH_AES_128_GCM_SHA256 - strong
|       TLS_RSA_WITH_AES_256_CBC_SHA - strong
|       TLS_RSA_WITH_AES_256_CBC_SHA256 - strong
|       TLS_RSA_WITH_AES_256_GCM_SHA384 - strong
|       TLS_RSA_WITH_RC4_128_MD5 - strong
|       TLS_RSA_WITH_RC4_128_SHA - strong
|     compressors: 
|       NULL

Comments

[Michael Hampton]

And keep in mind that you'll have to use a version of OpenSSL which does TLS 1.2, and that means CentOS 5 is right out.

[Xavier Lucas]

Got a really hard time trying to make this third party script work. Wrote mine for people interested : here.

[Quanlong]

Does not work on Mac OS X 10.11

[Kevin_Kinsey]

Michael Hampton, only OOB setups: [me@server][~] cat /etc/redhat-release CentOS release 5.11 (Final) [me@server][~] openssl version OpenSSL 1.0.2d 9 Jul 2015 ;)

[Xiao]

@Quanlong homebrew has openssl v1.0.2. Install it then run it with /usr/local/Cellar/openssl/1.0.2d_1/bin/openssl s_client -connect google.com:443 -tls1_2

[Quanlong]

It works fine after brew upgrade openssl

[colefner]

It worked great for me.

[Abrar Hossain]

Worked as per expectation on OpenSuse Tumbleweed. Thanks

[Mariano Paniga]

See also this very good answer to similar question: security.stackexchange.com/a/169738/60157

[Gaurav Kansal]

As on date, nmap doesn’t support TLS1.3, so this command will not help if you want to check for TLS1.3 availability on the web server side. Otherwise for upto version 1.2 , this solution is working fine.