I have quite standard installation of postfix and dovecot on Ubuntu 12.10. I generated my own certificates and got them signed by cacert.org.
The process of creating certs was like below:
openssl genrsa -out mail.myhostname.key 4096 openssl req -new -key mail.myhostname.key -out mail.myhostname.csr wget http://www.cacert.org/certs/root.txt sudo cp root.txt /etc/ssl/certs/cacert.crt # here Submitting the CSR to CAcert takes place # placing result certificate from CAcert into /etc/postfix/ssl/mail.myhostname.crt This is my dovecot configuration sudo cat /etc/dovecot/conf.d/10-ssl.conf:
## ## SSL settings ## # SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt> ssl = yes # PEM encoded X.509 SSL/TLS certificate and private key. They're opened before # dropping root privileges, so keep the key file unreadable by anyone but # root. Included doc/mkcert.sh can be used to easily generate self-signed # certificate, just make sure to update the domains in dovecot-openssl.cnf ssl_cert = </etc/postfix/ssl/mail.myhostname.crt ssl_key = </etc/postfix/ssl/mail.myhostname.key # If key file is password protected, give the password here. Alternatively # give it when starting dovecot with -p parameter. Since this file is often # world-readable, you may want to place this setting instead to a different # root owned 0600 file by using ssl_key_password = <path. #ssl_key_password = # PEM encoded trusted certificate authority. Set this only if you intend to use # ssl_verify_client_cert=yes. The file should contain the CA certificate(s) # followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem) ssl_ca = </etc/postfix/ssl/cacert.crt # Request client to send a certificate. If you also want to require it, set # auth_ssl_require_client_cert=yes in auth section. ssl_verify_client_cert = no # Which field from certificate to use for username. commonName and # x500UniqueIdentifier are the usual choices. You'll also need to set # auth_ssl_username_from_cert=yes. #ssl_cert_username_field = commonName # How often to regenerate the SSL parameters file. Generation is quite CPU # intensive operation. The value is in hours, 0 disables regeneration # entirely. #ssl_parameters_regenerate = 168 # SSL ciphers to use #ssl_cipher_list = ALL:!LOW:!SSLv2:!EXP:!aNULL I cannot get Outlook working, which worked quite fine before setting my own certs (despite some warnings). I heard there may be some problems with "Microsoft Mail" and Outlook, which are more sensitive compared to Thunderbird, but that shouldn't be an issue.
Screen from client program:
This is head of source="/var/log/mail.log" from splunk and shows the problem
6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Disconnected (no auth attempts): rip=89.77.2XX.XXX, lip=37.23X.XX.XXX host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Disconnected (no auth attempts): rip=89.77.2XX.XXX, lip=37.23X.XX.XXX, TLS handshaking: Disconnected host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL failed: where=0x2002: SSLv3 read client certificate A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 flush data [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server done A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:34.000 AM Jun 6 00:20:34 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write key exchange A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write certificate A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server hello A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read client hello A [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: unknown state [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: before/accept initialization [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 12:20:33.000 AM Jun 6 00:20:33 myhostname dovecot: imap-login: Warning: SSL: where=0x10, ret=1: before/accept initialization [89.77.2XX.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog this is output of openssl test openssl s_client -connect mail.myhostname:995:
CONNECTED(00000003) depth=1 O = Root CA, OU = http://www.cacert.org, CN = CA Cert Signing Authority, emailAddress = [email protected] verify error:num=19:self signed certificate in certificate chain verify return:0 --- Certificate chain 0 s:/CN=*.myhostname i:/O=Root CA/OU=http://www.cacert.org/CN=CA Cert Signing Authority/[email protected] 1 s:/O=Root CA/OU=http://www.cacert.org/CN=CA Cert Signing Authority/[email protected] i:/O=Root CA/OU=http://www.cacert.org/CN=CA Cert Signing Authority/[email protected] --- Server certificate -----BEGIN CERTIFICATE----- some certificate info.. -----END CERTIFICATE----- subject=/CN=*.myhostname issuer=/O=Root CA/OU=http://www.cacert.org/CN=CA Cert Signing Authority/[email protected] --- No client certificate CA names sent --- SSL handshake has read 4548 bytes and written 487 bytes --- New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-GCM-SHA384 Server public key is 4096 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE SSL-Session: Protocol : TLSv1.2 Cipher : DHE-RSA-AES256-GCM-SHA384 Session-ID: 4EE9B3ED672B5989A52B5338C6173E5C525080C1D46D37A327E501ED70A73625 Session-ID-ctx: Master-Key: 5DD1ED05C32F5B0FE07F20FDEEE80D622D6873CE7E9D954F4CC6644ED0E86A6A30603A387651135D6F7CA792F2377901 Key-Arg : None PSK identity: None PSK identity hint: None SRP username: None TLS session ticket lifetime hint: 300 (seconds) TLS session ticket: 0000 - 4e 3f 50 2c 3f 61 47 9f-f0 61 b4 26 31 ce 2c 9f N?P,?aG..a.&1.,. 0010 - ce 83 1b b5 20 88 45 a9-71 cd 35 29 3e 4b 5c 29 .... .E.q.5)>K\) 0020 - d8 31 e0 3f 47 2b d3 05-d3 73 62 78 ac a9 91 f8 .1.?G+...sbx.... 0030 - 51 89 b5 cd 20 2a 92 7a-68 8f d7 ae 01 10 46 df Q... *.zh.....F. 0040 - 35 c9 4b 50 86 1a 1b bc-5f 66 b9 29 7a bd 41 be 5.KP...._f.)z.A. 0050 - a0 76 ba e3 95 2c 85 ef-cd 21 c5 be ee c1 4b e3 .v...,...!....K. 0060 - c7 9e e3 8a 63 6d a6 cb-9f be 25 d5 b6 61 c0 27 ....cm....%..a.' 0070 - b5 09 46 e5 79 e0 34 6f-8d 6b db 96 17 40 18 ea ..F.y.4o.k...@.. 0080 - 25 c2 b0 12 96 20 1a 25-e1 7a 22 3e 74 6c 9e e8 %.... .%.z">tl.. 0090 - 61 f0 24 e7 5f 8a 5d e1-ab 43 c0 a7 74 43 09 cf a.$._.]..C..tC.. Start Time: 1433543614 Timeout : 300 (sec) Verify return code: 19 (self signed certificate in certificate chain) --- +OK The greatest mail program is ready I don't understand the verify error:num=19:self signed certificate in certificate chain part. In which way it is self signed, if I'm using a trustable CAcert authority ?
I censored IPs and hostname because my server is still fragile
There is also thing about stacking certs for Dovecot (in link http://wiki2.dovecot.org/SSL/DovecotConfiguration). Table shows this order:
Dovecot's public certificate - what's this ?
TDC SSL Server CA - is it my public key from cacert?
TDC Internet Root CA is it cacert root ?
Globalsign Partners CA - what's this?
As for the moment, /etc/postfix/ssl/cacert.crt holds only CAcert root.
Can this cause problems and brake TLS handshake ?
Update:
Mail works with Thunderbird, but still asks user to accept a certificate, which is kind of unwanted behavior - which I didn't expect while having certs from cacert.org
Logs from splunk:
6/6/15 1:38:43.000 AM Jun 6 01:38:43 myhostname dovecot: imap-login: Warning: SSL alert: where=0x4008, ret=256: warning close notify [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:43.000 AM Jun 6 01:38:43 myhostname dovecot: imap([email protected]): Disconnected: Logged out bytes=8/328 host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=89.77.22X.XXX, lip=37.233.XX.XXX, mpid=13141, TLS host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: auth-worker: mysql(localhost): Connected to database postfix host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=1: SSL negotiation finished successfully [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x20, ret=1: SSL negotiation finished successfully [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 flush data [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write finished A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write change cipher spec A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write session ticket A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read finished A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read client key exchange A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 flush data [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server done A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write key exchange A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server hello A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read client hello A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: unknown state [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: before/accept initialization [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:41.000 AM Jun 6 01:38:41 myhostname dovecot: imap-login: Warning: SSL: where=0x10, ret=1: before/accept initialization [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Disconnected (no auth attempts): rip=89.77.22X.XXX, lip=37.233.XX.XXX, TLS: SSL_read() failed: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca: SSL alert number 48 host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL alert: where=0x4008, ret=256: warning close notify [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL alert: where=0x4004, ret=560: fatal unknown CA [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=1: SSL negotiation finished successfully [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x20, ret=1: SSL negotiation finished successfully [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 flush data [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write finished A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write change cipher spec A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write session ticket A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read finished A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read client key exchange A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 flush data [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server done A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write key exchange A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write certificate A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 write server hello A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: SSLv3 read client hello A [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2002, ret=-1: unknown state [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x2001, ret=1: before/accept initialization [89.77.22X.XXX] host = myhostname source = /var/log/mail.log sourcetype = postfix_syslog 6/6/15 1:38:08.000 AM Jun 6 01:38:08 myhostname dovecot: imap-login: Warning: SSL: where=0x10, ret=1: before/accept initialization [89.77.22X.XXX] 
