Allow SSL/TLS for IMAP and SMTP

[landauf]

Currently I can only use STARTTLS for IMAP and SMTP on ports 143 and 25 respectively. It should be configured to allow SSL/TLS on ports 993 and 465 respectively.

[landauf]

1. For IMAP:

In /etc/dovecot/conf.d/10-ssl.conf add this:

ssl = required
disable_plaintext_auth = yes

In /etc/dovecot/conf.d/10-master.conf change this:

  inet_listener imaps {
    #port = 0
    port = 993
    ssl = yes
  }

2. For SMTP:

In /etc/postfix/main.cf search for smtpd_tls_security_level and define:

smtpd_tls_security_level = may
smtp_tls_security_level = may

Also ensure that smtpd_tls_auth_only = yes.

In /etc/postfix/master.cf add these services:

submission inet  n       -       y       -       -       smtpd
   -o smtpd_tls_security_level=encrypt
smtps      inet  n       -       y       -       -       smtpd
   -o smtpd_tls_wrappermode=yes

3. Change firewall:

In /etc/iptables/rules.v4 there are already two open ports:

25: SMTP
143: IMAP STARTTLS

Add three more ports:

993: IMAP SSL
465: SMTP SSL
587: SMTP STARTTLS

Reload iptables:

sudo iptables-restore < /etc/iptables/rules.v4

Restart postfix and dovecot.