> On April 27, 2017 at 10:55 AM Poliman - Serwis <ser...@poliman.pl> wrote: > > > Thank You for answers. But: > 1. How should be properly configured ssl_cipher_list?
ssl_cipher_list = ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH To disable non-EC DH, use: ssl_cipher_list = ALL:!DH:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH > 2. Ok, removed !TLSv1 !TLSv1.1. > 3. 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 > lines looks exactly this same and no errors in mail.err file and mailes > works without any problem. > 4. No, currently I don't use LMTP. it is possible that postfix is not causing this error. > > 2017-04-27 8:25 GMT+02:00 Aki Tuomi <aki.tu...@dovecot.fi>: > > > > > > 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 > > > > > > -- > > *Pozdrawiam / Best Regards* > *Piotr Bracha* > > > > > *tel. 534 555 877* > > *ser...@poliman.pl <ser...@poliman.pl>*
