Does openssl errno 104 mean that SSLv2 is disabled?

Question

I want to check if my server has SSLv2 disabled. I am doing this by attempting to connect remotely with openssl with the following shell command.

openssl s_client -connect HOSTNAME:443 -ssl2

Most literature I could find on the Internet says if I see something similar to the following error then SSLv2 is properly disabled.

29638:error:1407F0E5:SSL routines:SSL2_WRITE:ssl handshake failure:s2_pkt.c:428:

I do get the above error when connecting to my Ubuntu server with SSLv2 disabled in Apache Apache but when I connect to my Windows Server 2008 R2 server with SSLv2 disabled in the registry I get the following output and error.

CONNECTED(00000003)
write:errno=104

I can't find any literature explaining this output and error. If anybody could explain to me if and why this output and error means that SSLv2 is properly disabled, I would appreciate it.

Thanks!

Answer 1

At least on Linux, 104 is ECONNRESET for "Connection reset by peer" – in other words, the connection was forcibly closed with a TCP RST packet, either sent out by the server or spoofed by an intermediary.

I would try Wireshark/tshark on the Ubuntu server to see what actually gets sent. If the RST is real, it could be that the httpd process died – check the log files and dmesg just in case.

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The Qualys SSL Server Test website can show all SSL/TLS versions supported by your web server. (Unfortunately, it doesn't even bother with TLS SNI...)