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Re: libcurl fails with an unknown SSL protocol error

From: <>
Date: Tue, 21 Jul 2009 16:38:48 +0200

Chris Brannon wrote:
> curl -k --verbose
> curl: (35) Unknown SSL protocol error in connection to

Confirmed, same here with curl.
Even more interesting, I got my own nonblocking code interfacing openssl
(OpenSSL 1.1.0-dev xx XXX xxxx), and that fails too.
But openssl's s_client work when using nbio (which I do not use in my code).

openssl s_client -debug -nbio -connect

So, I had a look on wireshark, and s_client handshake claims to be
sslv2, switching to tlsv1 during handshake ...

Enforcing SSLv2_client_method (in my own code) -which is not an
option!-, it connects/handshakes, but does not switch to tlsv1.

So, I doubt it is an curl problem, the servers ssl configuration is at
least weird, and openssl does not handle it.

Received on 2009-07-21