Dovecot cant connect to imaps 993

Question

I am trying to set up a mail server in digitalocean VPS. The problem is that i cant telnet to 993 although firewall is inactive and dovecot is listening. Please tell me where i do wrong. I followed this postfix, dovecot, mysql, spamassasin tutorial.

My Server OS:

lsb_release -a

results:

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.1 LTS
Release:        16.04
Codename:       xenial

I followed the tutorial until this part: telnet example.com 993 which results in:

telnet mysite.com 993
Trying 127.0.1.1...
Connected to mysite.com.
Escape character is '^]'.
Connection closed by foreign host.

i checked firewall: sudo ufw status which results in:

Status: inactive

And whether dovecot is active: sudo netstat -plutn | grep 993

tcp        0      0 0.0.0.0:993             0.0.0.0:*               LISTEN      27460/dovecot
tcp6       0      0 :::993                  :::*                    LISTEN      27460/dovecot

Dovecot -F shows no error, and below are output of dovecot -n:

# 2.2.22 (fe789d2): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.13 (7b14904)
# OS: Linux 4.4.0-34-generic x86_64 Ubuntu 16.04.1 LTS ext4
auth_mechanisms = plain login
mail_location = maildir:/var/mail/vhosts/%d/%n
mail_privileged_group = mail
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
protocols = imap lmtp pop3
service auth-worker {
  user = vmail
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
  unix_listener auth-userdb {
    mode = 0600
    user = vmail
  }
  user = dovecot
}
service imap-login {
  inet_listener imap {
    port = 0
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
ssl = required
ssl_cert = /etc/letsencrypt/live/mysite.com/fullchain.pem
ssl_key = /etc/letsencrypt/live/mysite.com/privkey.pem
userdb {
  args = uid=vmail gid=vmail home=/var/mail/vhosts/%d/%n
  driver = static
}

Telnet to postfix smtp is okay though: telnet mysite.com smtp results:

Trying 127.0.1.1...
Connected to mysite.com.
Escape character is '^]'.
220 mysite.com ESMTP Postfix (Ubuntu)
ehlo mysite.com
250-mysite.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
quit
221 2.0.0 Bye
Connection closed by foreign host.

Please help.

EDIT 1:

Still no luck with openssl s_client -connect mysite.com:993 -crlf

CONNECTED(00000003)
write:errno=104
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 305 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : 0000
    Session-ID:
    Session-ID-ctx:
    Master-Key:
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Start Time: 1515817904
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)
---

No luck with thunderbird:

Running: telnet mysite.com 110 sometimes closed immediately, sometimes delays for a minute before closing.

Trying 127.0.1.1...
Connected to mysite.com.
Escape character is '^]'.
Connection closed by foreign host.

From what I read somewhere else, i think i should expect this line: +OK Dovecot (Ubuntu) ready.

Further information: sudo netstat -pltn result:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.0.1:34600         0.0.0.0:*               LISTEN      27939/postgres
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      27886/mysqld
tcp        0      0 0.0.0.0:587             0.0.0.0:*               LISTEN      27434/master
tcp        0      0 0.0.0.0:110             0.0.0.0:*               LISTEN      27460/dovecot
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      2409/sshd
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      27434/master
tcp        0      0 0.0.0.0:993             0.0.0.0:*               LISTEN      27460/dovecot
tcp        0      0 0.0.0.0:995             0.0.0.0:*               LISTEN      27460/dovecot
tcp6       0      0 :::587                  :::*                    LISTEN      27434/master
tcp6       0      0 :::110                  :::*                    LISTEN      27460/dovecot
tcp6       0      0 :::80                   :::*                    LISTEN      1519/apache2
tcp6       0      0 :::22                   :::*                    LISTEN      2409/sshd
tcp6       0      0 :::25                   :::*                    LISTEN      27434/master
tcp6       0      0 :::443                  :::*                    LISTEN      1519/apache2
tcp6       0      0 :::993                  :::*                    LISTEN      27460/dovecot
tcp6       0      0 :::995                  :::*                    LISTEN      27460/dovecot

and btw... does this has anything to do with sshd_config > PasswordAuthentication no

Another information: sudo iptables-save:

# Generated by iptables-save v1.6.0 on Sat Jan 13 12:55:47 2018
*filter
:INPUT ACCEPT [53354:9755959]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [48733:30432882]
COMMIT
# Completed on Sat Jan 13 12:55:47 2018

Never name a mail server with the naked domain name. This causes many things to break. Also you need to remove it from `/etc/hosts`. — Michael Hampton, Jan 12 '18 at 16:26

Phillip -Zyan K Lee- Stockmann · Accepted Answer · 2018-01-15T09:06:26.843

8

Solution

The problem was in fact a configuration issue, which was commented on by dovecot itself in /var/log/syslog:

Jan 14 17:34:23 mysite dovecot: imap-login: Fatal: Can't load ssl_cert: There is no valid PEM certificate. (You probably forgot '<' from ssl_cert=</etc/letsencrypt/live/mysite.com/fullchain.pem)

OLD Attempts

this output from telnet:

telnet mysite.com 993
Trying 127.0.1.1...
Connected to mysite.com.
Escape character is '^]'.
Connection closed by foreign host.

is what you would expect. port 993 is the SSL encrypted port for IMAP, so talking to this via telnet is rather hard ;-)

check if ie. thunderbird works with your settings - otherwise post the output of your mailclient and/or dovecot after a failed attempt.

EDIT: you can use openssl to connect to your IMAPS port. There is another question where this has been already answered in detail: https://stackoverflow.com/q/14959461/6591024

openssl s_client -connect mysite.com:993

as stated on the linked questions answers, you may be required to enforce CRLF by using openssl s_client -connect mysite.com:993 -crlf when using MacOS or Windows (perhaps?)

edited Jan 15 '18 at 09:06

answered Jan 12 '18 at 17:02

Phillip -Zyan K Lee- Stockmann

1,358
10
14

2

or use `sslclient` to do a SSL-ized telnet connection attempt – ivanivan Jan 12 '18 at 17:39
Thanks for the answer sir. But still no luck. – Fandi Susanto Jan 13 '18 at 04:59
what do you mean by "still no luck"? Is this server some kind of lottery? :-D – Phillip -Zyan K Lee- Stockmann Jan 13 '18 at 14:01
1

please have a look at the ``/var/log/mail.log`` while/after you connect via ``openssl``. ``/var/log/syslog`` may have some messages about the start of dovecot as well. – Phillip -Zyan K Lee- Stockmann Jan 13 '18 at 14:05
Too much content in /var/log/mail.log, so i deleted it and regret it. No content in it after openssl. But one line in `/var/log/syslog` saved my life: `Jan 14 17:34:23 mysite dovecot: imap-login: Fatal: Can't load ssl_cert: There is no valid PEM certificate. (You probably forgot '<' from ssl_cert= – Fandi Susanto Jan 14 '18 at 10:56
Wohoo... now i have my own personal email. Thanks. It feels like i won a lottery. Lol. – Fandi Susanto Jan 14 '18 at 11:47

score 0 · Answer 2 · answered Jan 13 '18 at 05:03

0

I think TLS with no certs is not gonna work:

CONNECTED(00000003)
write:errno=104
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 305 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:

I'd try generating a self signed cert and installing it and seeing if that helps.

answered Jan 13 '18 at 05:03

Jason Tan

2,742
2
17
24

I am sure that i have ssl certs. I am using letsencrypt cert for that. And set appropriate value for that in `/etc/dovecot/conf.d/10-ssl.conf` and also `/etc/postfix/main.cf`. And i also previously tried creating self signed cert with no luck. – Fandi Susanto Jan 13 '18 at 05:34
@jason tan the posted config from OP states certificate files. If those would not exist, dovecot would not start at all. – Phillip -Zyan K Lee- Stockmann Jan 13 '18 at 14:03

score 0 · Answer 3 · answered Jan 13 '18 at 05:38

0

Just confirm, is the output of iptables-save empty?

Having ufw disabled, you should have no output (and no rules) for iptables.

answered Jan 13 '18 at 05:38

Kotoniu

36
3

Dovecot cant connect to imaps 993

3 Answers3

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