[openssl-users] Interoperating with a legacy client.

Tim Kirby tkirby at hotlink.com
Tue Feb 7 09:46:09 UTC 2017

On 2/6/2017 2:55 AM, Matt Caswell wrote:
> This does look like the client is misbehaving for some reason. It's not
> behaviour I can reproduce with a 1.0.1j version of s_client.
> The second ClientHello should have a TLS1.2 record version, not have the
> SCSV ciphersuite, but instead have a renegotiation_info extension.
> Is the second ClientHello encrypted or in plaintext? If it is a
> renegotiation then it would be encrypted. I am wondering whether for
> some reason the client has forgotten its original connection, and is
> attempting a second completely new TLS connection over the same
> underlying TCP connection.

Good question!

I checked my traces again, and the second ClientHello is plaintext.

Starting a new TLS connection over the same TCP connection as an

existing, functional, TLS connection seems like a weird thing for the

client to do, but that would explain a second ClientHello that looks like an

initial connection.

Assuming that's what's happening, is there a way I can detect it and start

a new connection instead?  Would it be safe to use a message callback to 

for a ClientHello, do an SSL_new() with the current context, and reuse 
the same BIOs?



Tim Kirby

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