Thank You for answers. But: lines looks exactly this same and no errors in mail.err file and mailes
- How should be properly configured ssl_cipher_list?
- Ok, removed !TLSv1 !TLSv1.1.
- Strange thing with ssl_protocols and ssl_cipher_list, because on older server on Ubuntu 14.04 LTS, dovecot 2.2.9 and postfix 2.11.0 these two
works without any problem. 4. No, currently I don't use LMTP.
2017-04-27 8:25 GMT+02:00 Aki Tuomi <aki.tuomi@dovecot.fi>:
On April 27, 2017 at 8:12 AM Poliman - Serwis <serwis@poliman.pl> wrote:
Hi, To default dovecot.conf file I added (based on found documentation): ssl = required disable_plaintext_auth = yes #change default 'no' to 'yes' ssl_prefer_server_ciphers = yes ssl_options = no_compression ssl_dh_parameters_length = 2048 ssl_cipher_list = ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256: ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384: DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+ AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128- SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE- RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA- AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE- RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256: DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256: AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128- SHA:AES256-SHA:AES:CAMELLIA:!aNULL:!eNULL:!EXPORT:!DES:! RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES- CBC3-SHA:!KRB5-DES-CBC3-SHA
This looks rather cumbersome way to define ciphers.
- Are these settings good or can be improved?
- Is this line proper: ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1
Well if you only want to support TLSv1.2, which might lead into trouble.
or maybe should be: ssl_protocols = !SSLv2 !SSLv3 3. Last thing. I have below errors (they appear in loop in mail.err log file): #Apr 25 14:08:09 serwer-1 dovecot: imap-login: Error: SSL: Stacked error: error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown protocol #Apr 25 14:08:09 serwer-1 dovecot: imap-login: Error: SSL: Stacked error: error:1408A10B:SSL routines:ssl3_get_client_hello:wrong version number #Apr 25 14:08:51 serwer-1 dovecot: imap-login: Error: SSL: Stacked error: error:1408F119:SSL routines:SSL3_GET_RECORD:decryption failed or bad record mac #Apr 25 14:08:51 serwer-1 dovecot: imap-login: Error: SSL: Stacked error: error:1408A0C1:SSL routines:ssl3_get_client_hello:no shared cipher
This means your client did not support your enabled ciphers.
When I setup in postfix main.cf file (other lines default): tls_ssl_options = no_ticket, no_compression tls_preempt_cipherlist = yes smtpd_sasl_security_options=noanonymous,noplaintext smtpd_sasl_tls_security_options=noanonymous,noplaintext smtpd_tls_mandatory_ciphers = high smtpd_tls_dh1024_param_file = /etc/postfix/dh2048.pem #instead of below I tried smtpd_tls_mandatory_exclude_ciphers but I
know what should be setup smtpd_tls_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CBC3-SHA, ECDHE-RSA-DES-CBC3-SHA, DES-CBC3-SHA, RC4-MD5, RC4-SHA, ECDHE-RSA-RC4-SHA smtp_tls_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CBC3-SHA, ECDHE-RSA-DES-CBC3-SHA, DES-CBC3-SHA, RC4-MD5, RC4-SHA, ECDHE-RSA-RC4-SHA
Is between dovecot and postfix some communication using above ciphers or something that generate that errors in log or maybe some public client
don't try
connect and can't establish connection?
If you are using LMTP, then some of those settings will cause changes in how LMTP works as well.
Server with Ubuntu 16.04 LTS, postfix 3.1 and dovecot 2.2.22 and openssl 1.0.2k.
*Pozdrawiam / Best Regards* *Piotr Bracha*
*tel. 534 555 877*
*serwis@poliman.pl <serwis@poliman.pl>*
Aki
--
*Pozdrawiam / Best Regards* *Piotr Bracha*
*tel. 534 555 877*
*serwis@poliman.pl <serwis@poliman.pl>*