[stunnel-users] SSL compression in 5.27

Fri Dec 4 14:51:32 CET 2015

Hi,
while testing the upgrade from stunnel 5.26 to stunnel 5.27 on
Solaris, one of the tools I use reported that SSL compression was
now supported/possible on connections to an stunnel 5.27 instance;
this was not the case with 5.26 or earlier.

Unfortunately, it is not possible to demonstrate this using openssl
as client, I found this using TestSSLServer, which is java-based and
available from http://www.bolet.org/TestSSLServer/.

With 5.26:
| $ java -jar TestSSLServer.jar $server 443
| Supported versions: TLSv1.2
| Deflate compression: no
| Supported cipher suites (ORDER IS NOT SIGNIFICANT):
|   TLSv1.2
|      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
|      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
| ----------------------
| Server certificate(s):
|   4c57045b3f8f9cdd6f487e59a5b008ccb9d38693: CN=***, OU=***, O=***, C=***
| ----------------------
| Minimal encryption strength:     strong encryption (96-bit or more)
| Achievable encryption strength:  strong encryption (96-bit or more)
| BEAST status: protected
| CRIME status: protected

Note: "Deflate compression: no", "CRIME status: protected"

With 5.27:
| $ java -jar /prod/certmon2/bin/TestSSLServer.jar $server 443
| Supported versions: TLSv1.2
| Deflate compression: YES
| Supported cipher suites (ORDER IS NOT SIGNIFICANT):
|   TLSv1.2
|      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
|      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
| ----------------------
| Server certificate(s):
|   4c57045b3f8f9cdd6f487e59a5b008ccb9d38693: CN=***, OU=***, O=***, C=***
| ----------------------
| Minimal encryption strength:     strong encryption (96-bit or more)
| Achievable encryption strength:  strong encryption (96-bit or more)
| BEAST status: protected
| CRIME status: vulnerable

With 5.27, I get "Deflate compression: YES" and "CRIME status: vulnerable".

Server OS: Solaris 10/SPARC or Solaris 11/SPARC (others not tested)
OpenSSL: 1.0.1p or 1.0.1q (others not tested)
Client: TestSSLServer

Both stunnel and OpenSSL are self-compiled using Solaris Studio 12.4.

The stunnel.conf in question:

sslVersion = TLSv1.2
ciphers = ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256
cert = test1.crt
key = test1.key
verify = 2
[test]
client = no
accept = A.B.C.D:443
connect = 127.0.0.1:8080

The scanner from SSL Labs should be able to check this as well, but
I do not have the neccessary modern Python available.  I will check
if I can reproduce the problem on something a little more mainstream
than Solaris 10/11 over the weekend.

-- 