CODEWITHSUNDEEP
sslhttpstls1.2
JustAGuy
JustAGuy

Reputation: 5941

TLS Version mismatch(?)

Let's say my side as a client supports TLS V1.0,1.1 and 1.2. The remote site supports TLS V1.0 and 1.1. Both sides support the same Ciphers.

My questions:

1 - To my understanding I will always initiate the communication using the highest TLS Version I have available. In that case How will I ever be able to connect with the other side?

2 - The following is a Wireshark CLIENT HELLO capture between a client and a server described as above.

TLSv1.1 Record Layer: Handshake Protocol: Client Hello
    Content Type: Handshake (22)
    Version: TLS 1.2 (0x0303)
    Length: 172
    Handshake Protocol: Client Hello
        Handshake Type: Client Hello (1)
        Length: 168
        Version: TLS 1.2 (0x0303)
        Random
        Session ID Length: 0
        Cipher Suites Length: 52
        Cipher Suites (26 suites)
        Compression Methods Length: 1
        Compression Methods (1 method)
        Extensions Length: 75
        Extension: server_name
        Extension: elliptic_curves
        Extension: ec_point_formats
        Extension: signature_algorithms
        Extension: SessionTicket TLS
        Extension: renegotiation_info

This connection attempt ultimately yields a "Could not create SSL/TLS secure channel". I suspect this has something to do with what described as "TLSV1.1 Record Layer" and the "Version: TLS 1.2 (0x0303)". Could this be the reason the connection is failing?

Upvotes: 0

Views: 14870

Answers (3)

SensorVista
SensorVista

Reputation: 81

Guessing you have an an older version of Wireshark, since it reports TLSv1.1, but in the subsequent packet both the Record and the ClientHello clearly indicate TLSv1.2. Save your capture, upgrade Wireshark and then re-load the capture.

UPDATE: It's important to ensure your SSL\TLS handshake is COMPLETE; otherwise, for some reason, Wireshark will report incorrect TLS protocol version in the "protocol" field.

Upvotes: 1

juhraffe
juhraffe

Reputation: 555

There are two TLS versions sent with a Client Hello message. The first is the record layer version, which describes the version of TLS that you are using to communicate. The second version is the Client Hello value, which indicates the maximum version supported by the client.

I see three TLS versions in your Wireshark capture. I think the reference to version 1.1 in "TLSv1.1 Record Layer: Handshake Protocol: Client Hello" is wrong, though.

It appears that your client is sending a Client Hello with version 1.2 indicated within a record layer version of 1.2. The server, as it does not support version 1.2, rejects at the record layer. To get around this the client could send a version 1.2 Client Hello within a version 1.0 record. This would allow the server to communicate using version 1.0 that it supports version 1.1, and subsequent communication would use version 1.1.

Upvotes: 0

Steffen Ullrich
Steffen Ullrich

Reputation: 123320

The client starts the handshake with a ClientHello where it shows the best version it supports, i.e. TLS 1.2 in this case. The server then replies with a ServerHello with the best version the server supports which is equal or less the client offered version (i.e. TLS 1.1 in your case). If the client is not willing to accept this version (i.e. client configured to only support TLS 1.2 and nothing less) it will close the connection.

Upvotes: 2

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