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Understanding TLS version that is sent in a Client Hello message

Posted on 2016-08-14
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Last Modified: 2016-09-02
HI,
I typed in https://www.google.com and captured the result in wireshark. Here is a snapshot of client hello packet :
Screen-Shot-2016-08-14-at-10.49.38-P.pngAs i read that in this Client sends the highest TLS version it supports.
But here you see at one place TLS 1.2 is mentioned and at other TLS 1.0 and at top it is TLSv1.2

what does these mean here ?

Thanks
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Question by:Rohit Bajaj
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DrDave242 earned 500 total points
ID: 41758577
Coincidentally, I noticed this myself just a few days ago while digging through traffic with Wireshark. I was troubleshooting an unrelated issue, so I didn't look into it at the time. I've just done a little more testing, though, and this appears to be normal behavior, as it's doing the same thing on my end:
TLS client hello packet
All of the client hello packets in my test capture look like this. I went looking for more info on this and found something in RFC 5246 (the TLS 1.2 specification) that appears to be relevant. This is from Appendix E, section 1:
Earlier versions of the TLS specification were not fully clear on what the record layer version number (TLSPlaintext.version) should contain when sending ClientHello (i.e., before it is known which version of the protocol will be employed).  Thus, TLS servers compliant with this specification MUST accept any value {03,XX} as the record layer version number for ClientHello.
If I'm interpreting that correctly, it doesn't matter what version the client hello packet specifies in the record layer, as this has no bearing on the version that will be negotiated during the handshake.
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