Stunnel "wrong version number" error with TLS-PSK

Question

I've got Stunnel running on a Raspberry Pi which is acting as a TLS wrapper for an apache2 server. I've configured it to use TLS-PSK (correctly, I think), but the logs show the following when I try to complete the TLS handshake:

2016.04.11 21:05:53 LOG7[0]: Service [PSK_server] started
2016.04.11 21:05:53 LOG5[0]: Service [PSK_server] accepted connection from 192.168.42.10:4097
2016.04.11 21:05:53 LOG7[0]: SSL state (accept): before/accept initialization
2016.04.11 21:05:53 LOG7[0]: SNI: no virtual services defined
2016.04.11 21:05:53 LOG7[0]: SSL alert (write): fatal: protocol version
2016.04.11 21:05:53 LOG3[0]: SSL_accept: 1408F10B: error:1408F10B:SSL routines:SSL3_GET_RECORD:wrong version number
2016.04.11 21:05:53 LOG5[0]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket
2016.04.11 21:05:53 LOG7[0]: Deallocating application specific data for addr index
2016.04.11 21:05:53 LOG7[0]: Local descriptor (FD=3) closed
2016.04.11 21:05:53 LOG7[0]: Service [PSK_server] finished (0 left)</code>

I've checked in Wireshark, and the packets I'm sending are all TLS 1.2.

My stunnel config file looks like this:

output = /etc/stunnel/stunnel.log
client = no
fips = no
ciphers = PSK
PSKsecrets = /home/psk.txt
debug = 7
sslVersion = TLSv1.2
[PSK_server]
accept = PSK_server
connect = 80

It sends a TLS fatal alert packet with error code 70 (which is protocol_version, so it doesn't really tell me much more than the logs)

It's weird; I can send the Client Hello message, and the server sends Server Hello and Server Hello Done with no problem. It's only when I send my Client Key Exchange message that I get the alert. Any help/suggestions would be appreciated!

Answer 1

I would downgraded the TLS Version

This is working for me from a raspberry pi

options = NO_SSLv2
options = NO_SSLv3

CAFile = /etc/stunnel/server.crt
cert = /etc/stunnel/server.crt
key  = /etc/stunnel/server.key
pid = /var/run/stunnel.pid
output = /var/log/stunnel
verify = 4
debug = 5 

[SERVICE]
client = yes
accept = 127.0.0.1:9200
connect = SERVER.com:1111