Try specifying the ssl versions and options that you want or don't want explicitly. On Jan 11, 2013 5:09 PM, "Brandon Glenn" <kocrachon@gmail.com> wrote:

I am currently trying to setup stunnel to help me send emails from a program that sends alerts but does not use SSL, to a cloud email service that I use that requires SSL. I have the configuration setup trying to find out where the error is, and I am down to this last error.

SSL23_GET_CLIENT_HELLO:unknown protocol

Here is my config file.

; Sample stunnel configuration file for Win32 by Michal Trojnara 2002-2012

; Some options used here may be inadequate for your particular configuration

; This sample file does *not* represent stunnel.conf defaults

; Please consult the manual for detailed description of available options

; **************************************************************************

; * Global options *

; **************************************************************************

; Debugging stuff (may useful for troubleshooting)

;debug = 7

;output = stunnel.log

; Disable FIPS mode to allow non-approved protocols and algorithms

fips = no

; **************************************************************************

; * Service defaults may also be specified in individual service sections *

; **************************************************************************

; Certificate/key is needed in server mode and optional in client mode

cert = stunnel.pem

;key = stunnel.pem

; Authentication stuff needs to be configured to prevent MITM attacks

; It is not enabled by default!

;verify = 2

; Don't forget to c_rehash CApath

;CApath = certs

; It's often easier to use CAfile

;CAfile = certs.pem

; Don't forget to c_rehash CRLpath

;CRLpath = crls

; Alternatively CRLfile can be used

;CRLfile = crls.pem

sslVersion = all

; Disable support for insecure SSLv2 protocol

options = NO_SSLv2

; Workaround for Eudora bug

;options = DONT_INSERT_EMPTY_FRAGMENTS

; These options provide additional security at some performance degradation

;options = SINGLE_ECDH_USE

;options = SINGLE_DH_USE

; **************************************************************************

; * Service definitions (at least one service has to be defined) *

; **************************************************************************

; The default certificate

cert = stunnel.pem

; Some performance tunings socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1

; Set client mode client = yes

; GMail ssmtp settings

[ssmtp]

accept = 25

connect = 174.129.0.38:465

; GMail pop3s settings

[pop3s]

accept = 110

connect = 174.129.0.38:995

; GMail imaps settings

[imaps]

accept = 143

connect = 174.129.0.38:993

; Example SSL front-end to a web server

;[https]

;accept = 443

;connect = 80

; "TIMEOUTclose = 0" is a workaround for a design flaw in Microsoft SSL

; Microsoft implementations do not use SSL close-notify alert and thus

; they are vulnerable to truncation attacks

;TIMEOUTclose = 0

; vim:ft=dosini

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