Hi Ivan,

I know the SSL Labs site. Great work you are doing there and I am using it 
frequently for server checks.
For the client side I do however need to get the output on the server as I want 
to check our production mobile app, so no chance for me to get my hands on the 
content that was delivered back to the client.
I will definitely check on the Apache Module.  Sounds like this is solving my 
issue

Thanks a lot

Chris

Von: openssl-users [mailto:openssl-users-boun...@openssl.org] Im Auftrag von 
Ivan Ristic
Gesendet: Freitag, 6. März 2015 20:20
An: openssl-users@openssl.org
Betreff: Re: [openssl-users] Getting info on the ciphers supported by a client

On Fri, Mar 6, 2015 at 2:05 PM, Christian Georg 
<christian.ge...@cologne-intelligence.de<mailto:christian.ge...@cologne-intelligence.de>>
 wrote:
Hi all,

Christian,
I might be able to save you some time.
I wrote an SSL/TLS client test for the SSL Labs web site; you can find it here: 
https://dev.ssllabs.com/ssltest/viewMyClient.html If you can visit this page 
from the client/device and examine the output, you'll find there everything you 
need to know. There are a couple of other similar services. I keep a list here: 
https://github.com/ssllabs/research/wiki/Assessment-Tools (look under Client 
Assessment).
If you can't do that, you can install my Apache module called mod_sslhaf, which 
will dump contents of ClientHello to the server log. This approach isn't as 
good as the previous one, but might be good enough for your use case. You can 
find the module here: https://github.com/ssllabs/sslhaf

I am trying to get detailed info on the protocols and cipher suites supported 
by a client app. Main goal is to verify that the constraints on protocols 
versions and cipher suites we are using within an app are working correctly. 
(so it is not about the cipher suites that are theoretically available on a 
mobile device)
I was planning to use openssl s_server for this task. I am opening s_server on 
different ports each with a specific protocol version (-ssl2, -ssl3, -tls1…). 
On some of the ports a handshake should be successful on others not.

The tricky part are the supported cipher suites. When using the –www option I 
can return a website to the client showing the cipher suites that provide a 
match, which gets pretty close to what I want in a browser. Now here are my 
challenges.

Challenge 1: Getting a list of ALL Ciphersuites
I would like to get info on all cipher suites supported (preferred) by the 
client . The –www option does only show the cipher suites with a match. So any 
cipher suite not supported by openssl will not be listed. When checking my 
browser with qualys SSl Lab I noticed that the following three ciphersuites are 
showing up on the qualys report but not on the s_server page.

TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256

I do not see them as a risk, but what if some exotic weak ciphers are enabled 
within the app. It is my understanding that during a handshake a list of all 
preferred ciphers is send from the client to the server. How can I get access 
to this info?

Challenge 2: How do I get the info into a log file on the server rather than 
sending it back as a website?
The approach described above is working fine for browsers but what about 
consuming webservices? I am able to redirect the webservices to my openssl 
s_server and perform the handshake (even so the SOAP or REST Interface will 
then throw an error). But I could not find an option on getting the info 
written into the Logfile (in a human readable way) even with all logging I 
found enabled (-state -debug -msg –tlsextdebug -trace) I could not find the 
info in a human readable way.

Any recommendations on how I can solve my issues without changing the openssl 
code and add this manually?

Cheers

Chris


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Ivan
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