We are wanting to configure our Windows client to use only TLS 1.1 and greater. We've learned that we can do this by editing the registry. Now we want to make several HTTPS requests from different applications and check to be sure that they all use TLS 1.1 and above.

What we have tried is to run Wireshark with (ip.dst == && ssl and with (ip.src == && ssl as the filter and then run a web request from Internet Explorer. The results show this for the Client Hello.

Secure Sockets Layer
  TLSv1.2 Record Layer: Handshake Protocol: Client Hello
    Version: TLS 1.0   
    Handshake Protocol: Client Hello
      Version: TLS 1.2

And they show this for the Server Hello.

Secure Sockets Layer
  TLSv1.2 Record Layer: Handshake Protocol: Server Hello
    Version: TLS 1.2
    Handshake Protocol: Server Hello
      Version: TLS 1.2

Secure Sockets Layer

My sense is that that means we have not successfully turned off the legacy protocol, because the Client Hello initially says 1.0. Is that right?

Here is a better way of filtering for the Client Hello and Server Hello for a specific IP address.

(ip.src == && ssl.handshake.type == 1
(ip.dst == && ssl.handshake.type == 2
  • 4
    For starters, the Registry fixes only work for applications that use SCHANNEL (the built-in SSL/TLS provider for Windows). For the most part, that will just be built-in Windows components and some other Microsoft products. (Internet Explorer & IIS being the most obvious ones.) Many third-party programs will have their own SSL/TLS implementations built-in, which will have to be configured separately. – Iszi Sep 10 '15 at 21:19
  • 2
    BTW: Have you tried Fiddler? It's a bit more specialized for web debugging than WireShark. I find it generally easier to use in many situations. – Iszi Sep 10 '15 at 21:28
  • 1
    I don't think I've ever actually tried using it for that particular purpose, but since it can go so far as to intercept & decrypt HTTPS traffic (and in a pretty easy, user-friendly manner no less) I'd think that should be possible. Firebug may or may not also be of use, if you're doing this client-side and have Firefox handy. Also, do make sure both the server and client OS & applications are properly configured. – Iszi Sep 10 '15 at 21:36
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    Nice thing about Firebug is you don't have to install certs for SSL intercept - since it's a MitB instead of MitM, it already has access to the cleartext. – Iszi Sep 10 '15 at 21:38
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    The first filter should be ssl.handshake.type == 1 (not 2). – dave_thompson_085 Sep 11 '15 at 6:03

You want to look at the "protocol version" in the ServerHello message. Consider this image, shamelessly plundered from the Web and that shows a screenshot of a ServerHello being decoded by Wireshark:

SSL ServerHello in Wireshark

There are two "Version: TLS 1.0 (0x0301)" instances in this picture. The first one is from the header of the record that contains the ServerHello. The second one is from the contents of the ServerHello message itself. The second one is the one you are interested in, because it is the way the server informs the client about the protocol version that will be used for this connection.

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  • So, how do we know what protocol version the client is requesting? Isn't that in the Client Hello? – Shaun Luttin Sep 10 '15 at 21:58
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    In the ClientHello, the client sends the maximum version that it supports. Then the server chooses, usually by using the highest version that both client and server support. Note that nowhere in the handshake will you find any indication of how low the client or the server would accept to stoop; that the client says "TLS-1.2" does not mean that the client would have refused to do some TLS-1.0... – Thomas Pornin Sep 11 '15 at 0:41
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    @ShaunLuttin To emphasize, ClientHello does not tell you the minimum the client will accept. You must try connecting to a server that responds with lower protocol versions and see if the client accepts or aborts. Depending on your undescribed app server(s), it may be easy, difficult or impossible for it to do that. If your client app can do at least one path-only (no query) GET request that accepts a static textual reply, you can use openssl s_server with -WWW (note uppercase) to serve a static file (or several) under manually specified protocol versions and see which are accepted. – dave_thompson_085 Sep 11 '15 at 6:13

Have you tried the command?

openssl s_client -connect $host:$sslport

That's an standard output that shows the protocol being used.

depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA
verify error:num=20:unable to get local issuer certificate
verify return:0
Certificate chain
 0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com
   i:/C=US/O=Google Inc/CN=Google Internet Authority G2
 1 s:/C=US/O=Google Inc/CN=Google Internet Authority G2
   i:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
 2 s:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
   i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
Server certificate
subject=/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com
issuer=/C=US/O=Google Inc/CN=Google Internet Authority G2
No client certificate CA names sent
SSL handshake has read 3719 bytes and written 421 bytes
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES128-GCM-SHA256
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES128-GCM-SHA256
    Session-ID: 5832B5186C5F842ED93B49CBFA04C93DA5099ABA72E6D8C2A11EEFCCBCAEC563
    Master-Key: F5BC199D27A2AFDB16A120AC706DBF68F024129E351E32B6C636AD087A3C775459F4A7941C7D1509B0B115A82BDFEA98
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 100800 (seconds)
    TLS session ticket:
    0000 - fb b9 4a df 5a 50 e7 ae-14 fe 81 95 04 a7 1f 62   ..J.ZP.........b
    0010 - 7c 22 71 99 e8 55 31 f2-53 bb 4b d5 4e b3 0e 8f   |"q..U1.S.K.N...
    0020 - 7a 75 b3 7f 68 9a ed 25-bb 5e 88 97 26 db cf 7a   zu..h..%.^..&..z
    0030 - 40 65 65 60 e3 34 b3 15-44 50 a3 57 98 77 ca 6c   @ee`.4..DP.W.w.l
    0040 - 63 45 84 07 7e cc b4 5c-4d e5 66 d6 df 9a bb 7e   cE..~..\M.f....~
    0050 - 24 f3 5b 08 5a 7a 03 1c-b4 2d 01 4b 3c 33 f6 34   $.[.Zz...-.K<3.4
    0060 - 4c df 5c c9 22 08 b2 94-25 aa 48 07 a2 f6 50 b8   L.\."...%.H...P.
    0070 - f7 90 a7 46 25 bf 9e 46-05 62 7e bb 6e 61 8e ef   ...F%..F.b~.na..
    0080 - ad 37 c4 e1 17 f4 57 42-c9 d0 e9 85 cb 65 cf b2   .7....WB.....e..
    0090 - 4c 2e 98 e0 38 6a da 16-62 de 3e 51 e2 2c de 84   L...8j..b.>Q.,..
    00a0 - a0 ab b7 e6                                       ....

    Start Time: 1441848276
    Timeout   : 300 (sec)
    Verify return code: 20 (unable to get local issuer certificate)

Hope this helps.

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  • 1
    OP states a Windows client – schroeder Sep 10 '15 at 22:37
  • 4
    OpenSSL clients/programs also exist for Windows. – Lekensteyn Sep 10 '15 at 23:06
  • 3
    That tells you what a server can handle (assuming a recent and non-hobbled OpenSSL). The question here is what the asker's Windows client application (not OpenSSL) is requesting. – dave_thompson_085 Sep 11 '15 at 6:06

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