> On April 27, 2017 at 8:12 AM Poliman - Serwis <ser...@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. > 1. Are these settings good or can be improved? > 2. 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 don't > 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 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* > > *ser...@poliman.pl <ser...@poliman.pl>* Aki
