OpenSSL Ciphers

[Doug Hardie]

> On 3 March 2015, at 23:21, Doug Hardie <bc979 at lafn.org> wrote:
> 
> The default list of ciphers is quite extensive and includes some that are apparently causing some potential security issues.  I have a number of applications that use OpenSSL and many don’t have the code to restrict the list.  Fixing all that would take quite a bit of work.  However, looking into /usr/include/openssl/ssl.h I find a definition for the SSL_DEFAULT_CIPHER_LIST.  The comments indicate that that list is the one used when the application doesn’t specify anything.  I changed its definition to:
> 
> #define SSL_DEFAULT_CIPHER_LIST "TLSv1+HIGH:!SSLv2:RC4+MEDIUM:!aNULL:!eNULL:!3DES:@STRENGTH:
> 
> However, s_connect will still create a connection with the export ciphers.  I tried adding !EXPORT to that list and it had no effect.  Is the definition actually used by openssl or is it just there for documentation?

Not hearing anything on this, I suspect it’s not very well understood.  I have started updating the various servers/clients that use SSL/TLS.  The one that has me completely stumped is sendmail.  There is a web page which provides instructions "http://novosial.org/sendmail/cipherlist/index.html”.  However, when I follow them, I can still establish a connection and deliver mail using the export ciphers.  

Has anyone successfully restricted the sendmail ciphers?