Thanks for that Carl. I'm running openssl-1.0.2k-16.el7_6.1.x86_64


Pretty much everything about my server is continuously updated stock Centos 7. Currently at CentOS Linux release 7.6.1810 (Core)


I do have epel installed, which updates some things and the qmt repo. That's it, and I'm a stickler for NOT installing anything that isn't done through yum and those repos. I've done this long enough to know that it's much easier to maintain, migrate to a new server, etc. is you're running everything in a managed way. So installing the repos and doing yum installs is pretty much the only way anything ever changes on my server, sans config files.


Would be very interested in knowing not only the proper tlsservercipher file for this type of server, but also how to create/recreate it if it's a command done from openssl. Looks like you can create it with the command.


openssl ciphers > /var/qmail/control/tlsservercipher


But what I'm reading is that your advice is to NOT do that due to security concerns. So what would you recommend?


Thanks, Gary


On 9/3/2019 3:28 PM, CarlC Internet Services Service Desk wrote:

Your real problem is that this file is different based on which CentOS you’re on [or should I say, which openssl is loaded]. If you have CentOS 7, with openssl 1.0.2k, you can tune this file to include each cipher you want [the file can actually be 10+ lines long wrapped]. This is so you can remove all the “hacked” ciphers, especially to force your clients security to remain high. If your running openssl 0.9.x, you don’t get the newer TLS ciphers you need to be secure.

 

Using the default is way too low, and if you do, you will where someone gets hacked over a ‘free’ WiFi connection [because you had SSL 3.0/TLS 1.0 on].

 

Carl

 

From: Gary Bowling [mailto:g...@gbco.us]
Sent: Tuesday, September 03, 2019 02:58 PM
To: qmailtoaster-list@qmailtoaster.com
Subject: Re: [qmailtoaster] SSL Problem Dovecot

 

 

So this may be an issue of the tlsserverciphers file. Some times it's interesting not knowing what your doing! haha

 

I guess the question I have is.. What is the proper tlsserverciphers for a qmailtoaster with a letsencrypt certificate. If that even makes sense.

 

And what is the proper way to actually do it. I've read multiple things on various forums, including here.

 

One says to do:

echo "!EDH:!DHE:!RC4:!ADH:!DSS:HIGH:+AES128:+AES256-SHA256:+AES128-SHA256:+SHA:!3DES:!NULL:!aNULL:!eNULL" > /var/qmail/control/tlsserverciphers

 

One says to do:

openssl ciphers 'MEDIUM:HIGH:!SSLv2:!MD5:!RC4:!3DES' > /var/qmail/control/tlsserverciphers

 

yet another says to create a sym link to the servercert.pem file.

 

ln -sf /var/qmail/control/servercert.pem /var/qmail/control/tlsserverciphers

 

 

I guess it has to do with how tight you want security to be and maybe tlsserverciphers can contain various forms of how to define that. Just looking for what "most" people would use for an up to date Centos 7 server.

 

Thanks, Gary

 

On 9/3/2019 11:04 AM, Gary Bowling wrote:

 

I had to get a new cert for my server, which I installed yesterday. Now I'm having problems with certain clients logging in. I get the following error in the dovecot.log.

 

TLS handshaking: SSL_accept() failed: error:1408A10B:SSL routines: ssl3_get_client_hello:wrong version number

 

Any help would be appreciated.

 

Thanks, Gary

--
____________________
Gary Bowling
____________________

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