Initial configuration required from installation of Dovecot on CentOS to startup.

Publication date：January 4, 2021

summary

This is the initial configuration procedure required to install and start Dovecot on CentOS. This description assumes CentOS7. The incoming protocols are configured as imaps (IMAP over SSL) and pop3s (POP3 over SSL).

Since it is set up in conjunction with Postfix, please also set up Postfix from here in advance.

The versions are as follows

1. install

This section describes the setup of Dovecot from installation to startup.

1-1. Installing Dovecot

Execute Dovecot installation by yum command. Please work as root user.

[username@hostname ~]$ su -

[root@hostname ~]# yum -y install dovecot

1-2. Startup Confirmation

To confirm that the installation was successful, check the startup. Note that Dovecot does not require start as an argument when starting.

[root@hostname ~]# /usr/sbin/dovecot

[root@hostname ~]# ps aux | grep dovecot

root      1470  0.0  0.1  16092  1156 ?        Ss   18:38   0:00 /usr/sbin/dovecot

dovecot   1471  0.0  0.1   9752  1120 ?        S    18:38   0:00 dovecot/anvil

root      1472  0.0  0.1   9884  1320 ?        S    18:38   0:00 dovecot/log

root      1474  0.0  0.2  12916  2384 ?        S    18:38   0:00 dovecot/config

root      1476  0.0  0.0 112824   968 pts/0    R+   18:38   0:00 grep --color=auto dovecot

If there is a process running as dovecot user as described above, it is OK. Let's stop it.

[root@hostname ~]# /usr/sbin/dovecot stop

2. Setting details

2-1. initialization

We will set up the initial configuration of Dovecot.

[root@hostname ~]# vi /etc/dovecot/dovecot.conf

Correct as follows

#protocols = imap pop3 lmtp

～omission～

#listen =  *, ::

～omission～

#login_greeting = Dovecot ready.

protocols = imap pop3

～omission～

listen = *

～omission～

login_greeting = pop3 and imap ready.

protocols" specifies the protocols to connect to Dovecot.

listen" is the IP to be allowed to connect. Since it is "*", there are no restrictions on the IP to connect to. If you have a specific IP to connect to, specify a specific IP for security. The "::" is a setting for IPv6, but since IPv6 will not be used this time, delete it. By deleting it, only IPv4 will be accepted.

login_greeting" is the message when connecting. It is not necessary to change it, but for security purposes, change the message so that no one will know it is dovecot when they connect.

2-2. POP3 and IMAP Settings

We will be configuring port 110, the well-known port for POP3, and port 143, the well-known port for IMAP. We would like to use the authentication method in conjunction with Postfix for authentication.

[root@hostname ~]# vi /etc/dovecot/conf.d/10-master.conf

Correct as follows

service imap-login {

  inet_listener imap {

    #port = 143

  }

～omission～

service pop3-login {

  inet_listener pop3 {

    #port = 110

  }

service imap-login {

  inet_listener imap {

    port = 143

  }

～omission～

service pop3-login {

  inet_listener pop3 {

    port = 110

  }

2-3. Dovecot Authentication Method Settings

Add login to the Dovecot authentication method.

[root@hostname ~]# vi /etc/dovecot/conf.d/10-auth.conf

Correct as follows

#disable_plaintext_auth = yes

～omission～

auth_mechanisms = plain

disable_plaintext_auth = no

～omission～

auth_mechanisms = login plain

2-4. Changed mail storage method to "Maildir" format

Set the mail storage location to each user's home directory (under "/home/xxx/").

[root@hostname ~]# vi /etc/dovecot/conf.d/10-mail.conf

Correct as follows

#mail_location =

～omission～

namespace inbox {

  # Namespace type: private, shared or public

  #type = private

  # Hierarchy separator to use. You should use the same separator for all

  # namespaces or some clients get confused. '/' is usually a good one.

  # The default however depends on the underlying mail storage format.

  #separator =

  # Prefix required to access this namespace. This needs to be different for

  # all namespaces. For example "Public/".

  #prefix =

  # Physical location of the mailbox. This is in same format as

  # mail_location, which is also the default for it.

  #location =

mail_location = maildir:~/Maildir

～omission～

namespace inbox {

  # Namespace type: private, shared or public

  #type = private

  # Hierarchy separator to use. You should use the same separator for all

  # namespaces or some clients get confused. '/' is usually a good one.

  # The default however depends on the underlying mail storage format.

  #separator =

  # Prefix required to access this namespace. This needs to be different for

  # all namespaces. For example "Public/".

  #prefix =

  # Physical location of the mailbox. This is in same format as

  # mail_location, which is also the default for it.

  location = maildir:~/Maildir

2-5. Authentication Settings

Enable ssl settings.

[root@hostname ~]# vi /etc/dovecot/conf.d/10-ssl.conf

Correct as follows

ssl = required

～omission～

ssl_cert = </etc/pki/dovecot/certs/dovecot.pem

ssl_key = </etc/pki/dovecot/private/dovecot.pem

ssl = required

～omission～

ssl_cert = </etc/pki/tls/certs/localhost.crt

ssl_key = </etc/pki/tls/private/localhost.key

Set "ssl_cert" and "ssl_key" according to your environment. Set the path where the server certificate is stored.

SSL settings are required in advance, so if you have not set up SSL settings, please do so first. Please refer to the following.

Initial configuration required from installation of Apache on CentOS to startup

Next, configure settings related to passwords. Use "auth-system.conf.ext".

[root@hostname ~]# vi /etc/dovecot/conf.d/auth-system.conf.ext

Correct as follows

passdb {

  driver = pam

  # [session=yes] [setcred=yes] [failure_show_msg=yes] [max_requests=<n>]

  # [cache_key=<key>] [<service name>]

  #args = dovecot

}

～omission～

#passdb {

  #driver = shadow

  # [blocking=no]

  #args =

#}

#passdb {

#driver = pam

  # [session=yes] [setcred=yes] [failure_show_msg=yes] [max_requests=<n>]

  # [cache_key=<key>] [<service name>]

  #args = dovecot

#}

～omission～

passdb {

  driver = shadow

  # [blocking=no]

  #args =

}

2-6. Startup Confirmation

The configuration is now complete, so check to see if Dovecot starts with the configuration completed. Note that "start" is not required as an argument.

[root@hostname ~]# /usr/sbin/dovecot

[root@hostname ~]# ps aux | grep dovecot

root      1716  0.0  0.1  16092  1184 ?        Ss   22:09   0:00 /usr/sbin/dovecot

dovecot   1717  0.0  0.1   9752  1120 ?        S    22:09   0:00 dovecot/anvil

root      1718  0.0  0.1   9884  1312 ?        S    22:09   0:00 dovecot/log

root      1720  0.5  0.2  12916  2396 ?        S    22:09   0:00 dovecot/config

root      1722  0.0  0.0 112824   972 pts/0    S+   22:09   0:00 grep --color=auto dovecot

If there is a process running as the dovecot user as described above, the configuration has been successfully completed and the process is running. Now that the startup has been confirmed, let's stop the process.

[root@hostname ~]# /usr/sbin/dovecot stop

2-7. Automatic startup setting

Lastly, although it is not required, it is hard to start Dovecot every time the server is rebooted, so we will configure Dovecot to start automatically when the server is started. Register the systemctl command to the systemctl command. Please note that this procedure is for CentOS7, so if you are using other than CentOS7, you need to use the Service command.

Check if "/usr/lib/systemd/system/dovecot.service" exists. If not, create "dovecot.service" as follows Execute as root user.

[root@hostname ~]# touch /etc/systemd/system/dovecot.service

[root@hostname ~]# vi /etc/systemd/system/dovecot.service

The following information is provided

[Unit]

#Description.

Description=Dovecot

#Control before and after execution

#Before=xxx.service

After = network.target

[Service]

#User and group designation

User=root

Group=root

#Once activated, set the status to Activated.

Type=oneshot

RemainAfterExit=yes

#Start, stop, reload

ExecStart=/usr/sbin/dovecot

ExecStop=/usr/sbin/dovecot stop

ExecReload=/usr/sbin/dovecot reload

[Install]

#runlevel3 equivalent setting

WantedBy=multi-user.target

Next, register it with the systemctl command.

[root@hostname ~]# systemctl enable dovecot

[root@hostname ~]# systemctl is-enabled dovecot

enabled

[root@hostname ~]# systemctl list-unit-files --type=service | grep dovecot

dovecot.service                                enabled

[root@hostname ~]# systemctl daemon-reload

3. summary

We have described the initial configuration required when Dovecot is installed.

I struggled with the setup quite a bit, so if you are building a Dovecot, please refer to this page.

Thank you for taking the time to read this to the end.