Configure Postfix server (4/7)

Configure Postfix server (4/7)

# Create a backup file of main.cf and master.cf files.

[root@mailserver ~]# cd /etc/postfix

[root@mailserver postfix]# cat main.cf > main.cf.org

[root@mailserver postfix]# cat master.cf > master.cf.org

# Create new file main.cf

[root@mailserver sql]# vim /etc/postfix/main.cf

[root@mailserver sql]# cat /etc/postfix/main.cf

myhostname = mailserver.example.com

mydomain = example.com

myorigin = $mydomain

inet_interfaces = all

inet_protocols = ipv4

mynetworks_style = host

mynetworks = $config_directory/mynetworks

smtpd_banner = $myhostname ESMTP $mail_name

# ---------------------- VIRTUAL DOMAINS START ----------------------

virtual_alias_maps = proxy:mysql:$config_directory/sql/virtual_alias_maps.cf

virtual_mailbox_domains = proxy:mysql:$config_directory/sql/virtual_domains_maps.cf

virtual_mailbox_maps = proxy:mysql:$config_directory/sql/virtual_mailbox_maps.cf

#virtual_mailbox_limit_maps = proxy:mysql:$config_directory/sql/virtual_mailbox_limit_maps.cf

virtual_mailbox_base = /home/mail

virtual_uid_maps = static:8

virtual_gid_maps = static:12

mailbox_size_limit = 104857600

message_size_limit = 104857600

relay_domains = proxy:mysql:$config_directory/sql/relay_domains.cf

relay_recipient_maps = proxy:mysql:$config_directory/sql/relay_recipient_maps.cf

transport_maps = proxy:mysql:$config_directory/sql/transport_maps.cf

#transport_maps = hash:$config_directory/transport

#virtual_transport = dovecot

dovecot_destination_recipient_limit = 1

# ----------------------- VIRTUAL DOMAINS END -----------------------

# ------------------------- SASL PART START -------------------------

broken_sasl_auth_clients = yes

smtpd_helo_required = yes

smtpd_client_restrictions = permit_sasl_authenticated

smtpd_sender_restrictions = permit_sasl_authenticated

smtpd_sasl_auth_enable = yes

smtpd_sasl_security_options = noanonymous

smtpd_sasl_tls_security_options = $smtpd_sasl_security_options

smtpd_sasl_type = dovecot

# Can be an absolute path, or relative to $queue_directory

smtpd_sasl_path = private/auth

# -------------------------- SASL PART END --------------------------

# -------------------------- TLS PART START -------------------------

smtpd_use_tls = yes

smtpd_tls_auth_only = yes

smtpd_tls_cert_file = /etc/pki/tls/certs/mailserver.example.com.crt

smtpd_tls_key_file = /etc/pki/tls/certs/mailserver.example.com.key

smtpd_tls_received_header = yes

smtpd_tls_loglevel = 1

tls_random_source = dev:/dev/urandom

# --------------------------- TLS PART END --------------------------

# ------------------ SMTPD RESTRICTIONS PART START ------------------

disable_vrfy_command = yes

non_fqdn_reject_code = 450

invalid_hostname_reject_code = 450

maps_rbl_reject_code = 450

unverified_sender_reject_code = 550

#header_checks = pcre:$config_directory/header_checks

#body_checks = pcre:$config_directory/body_checks

#warning: the restrictions reject_unknown_(sender|recipient)_domain

#will trigger if your DNS becomes unavailable

smtpd_recipient_restrictions =

permit_mynetworks

permit_sasl_authenticated

reject_unauth_destination

reject_invalid_helo_hostname

warn_if_reject reject_non_fqdn_helo_hostname

warn_if_reject reject_unknown_helo_hostname

warn_if_reject reject_unknown_client

reject_non_fqdn_sender

reject_non_fqdn_recipient

reject_unknown_sender_domain

reject_unknown_recipient_domain

check_client_access hash:$config_directory/rbl_override

reject_rbl_client zen.spamhaus.org

reject_rbl_client bl.spamcop.net

reject_rbl_client dnsbl.sorbs.net=127.0.0.2

reject_rbl_client dnsbl.sorbs.net=127.0.0.3

reject_rbl_client dnsbl.sorbs.net=127.0.0.4

reject_rbl_client dnsbl.sorbs.net=127.0.0.5

reject_rbl_client dnsbl.sorbs.net=127.0.0.7

reject_rbl_client dnsbl.sorbs.net=127.0.0.9

reject_rbl_client dnsbl.sorbs.net=127.0.0.11

reject_rbl_client dnsbl.sorbs.net=127.0.0.12

permit

smtpd_data_restrictions =

permit_mynetworks,

reject_unauth_pipelining,

reject_multi_recipient_bounce,

permit

# ------------------- SMTPD RESTRICTIONS PART END --------------------

Create below line in master.cf file

[root@mailserver sql]# vim /etc/postfix/master.cf

[root@mailserver sql]# cat /etc/postfix/master.cf

#

# Postfix master process configuration file. For details on the format

# of the file, see the master(5) manual page (command: "man 5 master").

#

# Do not forget to execute "postfix reload" after editing this file.

#

# ==========================================================================

# service type private unpriv chroot wakeup maxproc command + args

# (yes) (yes) (yes) (never) (100)

# ==========================================================================

smtp inet n - n - - smtpd

#smtp inet n - n - 1 postscreen

#smtpd pass - - n - - smtpd

#dnsblog unix - - n - 0 dnsblog

#tlsproxy unix - - n - 0 tlsproxy

#submission inet n - n - - smtpd

# -o syslog_name=postfix/submission

# -o smtpd_tls_security_level=encrypt

# -o smtpd_sasl_auth_enable=yes

# -o smtpd_reject_unlisted_recipient=no

# -o smtpd_client_restrictions=$mua_client_restrictions

# -o smtpd_helo_restrictions=$mua_helo_restrictions

# -o smtpd_sender_restrictions=$mua_sender_restrictions

# -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject

# -o milter_macro_daemon_name=ORIGINATING

smtps inet n - n - - smtpd

-o syslog_name=postfix/smtps

-o smtpd_tls_wrappermode=yes

-o smtpd_sasl_auth_enable=yes

# -o smtpd_reject_unlisted_recipient=no

# -o smtpd_client_restrictions=$mua_client_restrictions

# -o smtpd_helo_restrictions=$mua_helo_restrictions

# -o smtpd_sender_restrictions=$mua_sender_restrictions

-o smtpd_recipient_restrictions=permit_sasl_authenticated,reject

# -o milter_macro_daemon_name=ORIGINATING

#628 inet n - n - - qmqpd

pickup unix n - n 60 1 pickup

cleanup unix n - n - 0 cleanup

qmgr unix n - n 300 1 qmgr

#qmgr unix n - n 300 1 oqmgr

tlsmgr unix - - n 1000? 1 tlsmgr

rewrite unix - - n - - trivial-rewrite

bounce unix - - n - 0 bounce

defer unix - - n - 0 bounce

trace unix - - n - 0 bounce

verify unix - - n - 1 verify

flush unix n - n 1000? 0 flush

proxymap unix - - n - - proxymap

proxywrite unix - - n - 1 proxymap

smtp unix - - n - - smtp

relay unix - - n - - smtp

# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5

showq unix n - n - - showq

error unix - - n - - error

retry unix - - n - - error

discard unix - - n - - discard

local unix - n n - - local

virtual unix - n n - - virtual

lmtp unix - - n - - lmtp

anvil unix - - n - 1 anvil

scache unix - - n - 1 scache

#

# ====================================================================

# Interfaces to non-Postfix software. Be sure to examine the manual

# pages of the non-Postfix software to find out what options it wants.

#

# Many of the following services use the Postfix pipe(8) delivery

# agent. See the pipe(8) man page for information about ${recipient}

# and other message envelope options.

# ====================================================================

#

# maildrop. See the Postfix MAILDROP_README file for details.

# Also specify in main.cf: maildrop_destination_recipient_limit=1

#

#maildrop unix - n n - - pipe

# flags=DRhu user=vmail argv=/usr/local/bin/maildrop -d ${recipient}

#

# ====================================================================

#

# Recent Cyrus versions can use the existing "lmtp" master.cf entry.

#

# Specify in cyrus.conf:

# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4

#

# Specify in main.cf one or more of the following:

# mailbox_transport = lmtp:inet:localhost

# virtual_transport = lmtp:inet:localhost

#

# ====================================================================

#

# Cyrus 2.1.5 (Amos Gouaux)

# Also specify in main.cf: cyrus_destination_recipient_limit=1

#

#cyrus unix - n n - - pipe

# user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -r ${sender} -m ${extension} ${user}

#

# ====================================================================

#

# Old example of delivery via Cyrus.

#

#old-cyrus unix - n n - - pipe

# flags=R user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -m ${extension} ${user}

#

# ====================================================================

#

# See the Postfix UUCP_README file for configuration details.

#

#uucp unix - n n - - pipe

# flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)

#

# ====================================================================

#

# Other external delivery methods.

#

#ifmail unix - n n - - pipe

# flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)

#

#bsmtp unix - n n - - pipe

# flags=Fq. user=bsmtp argv=/usr/local/sbin/bsmtp -f $sender $nexthop $recipient

#

#scalemail-backend unix - n n - 2 pipe

# flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store

# ${nexthop} ${user} ${extension}

#

#mailman unix - n n - - pipe

# flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py

# ${nexthop} ${user}

#

# add line for dovecot

dovecot unix - n n - - pipe

flags=DRhu user=mail:mail argv=/usr/libexec/dovecot/deliver -d ${recipient}

[root@mailserver postfix]#

[root@mailserver ~]# vim /etc/postfix/mynetworks

[root@mailserver ~]# cat /etc/postfix/mynetworks

# This specifies the list of subnets that Postfix considers as

# "trusted" SMTP clients that have more privileges than "strangers".

#

# In particular, "trusted" SMTP clients are allowed to relay mail

# through Postfix.

#

# Be sure to add your public ip address block if needed.

#

127.0.0.0/8

192.168.10.0/24

[root@mailserver ~]#

[root@mailserver ~]# vim /etc/postfix/rbl_override

[root@mailserver ~]# cat /etc/postfix/rbl_override

mailserver.example.com OK

192.168.10.0/24 OK

[root@mailserver ~]# postmap /etc/postfix/rbl_override

Create new folder in /etc/postfix/sql

[root@mailserver postfix]# mkdir sql

[root@mailserver postfix]# cd /etc/postfix/sql

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/virtual_alias_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/virtual_alias_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = alias

select_field = goto

where_field = address

additional_conditions = AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/virtual_domains_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/virtual_domains_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = domain

select_field = description

where_field = domain

additional_conditions = AND backupmx = '0' AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/virtual_mailbox_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/virtual_mailbox_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = mailbox

select_field = maildir

where_field = username

additional_conditions = AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/virtual_mailbox_limit_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/virtual_mailbox_limit_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = mailbox

select_field = quota

where_field = username

additional_conditions = AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/relay_domains.cf

[root@mailserver sql]# cat /etc/postfix/sql/relay_domains.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = domain

select_field = domain

where_field = domain

additional_conditions = AND backupmx = '1' AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/relay_recipient_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/relay_recipient_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = alias

select_field = goto

where_field = address

additional_conditions = AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# vim /etc/postfix/sql/transport_maps.cf

[root@mailserver sql]# cat /etc/postfix/sql/transport_maps.cf

hosts = localhost

dbname = maildb

user = mailuser

password = redhat

table = domain

select_field = transport

where_field = domain

additional_conditions = AND active = '1'

[root@mailserver sql]#

[root@mailserver sql]# chown root:postfix /etc/postfix/sql/ -R

[root@mailserver sql]# chcon -u system_u /etc/postfix/sql -R

[root@mailserver sql]# chmod 0640 /etc/postfix/sql/*.cf

[root@mailserver sql]# chmod 0750 /etc/postfix/sql/

[root@mailserver sql]# newaliases

Installation and Configure Mariadb (3/7)

Installation and Configure Mariadb (3/7).

# Installation of MariaDB server via yum command. 

[root@mailserver ~]# yum install mariadb mariadb-servers

[root@mailserver ~]#

[root@mailserver ~]# systemctl enable mariadb

ln -s '/usr/lib/systemd/system/mariadb.service' '/etc/systemd/system/multi-user.target.wants/mariadb.service'

[root@mailserver ~]# systemctl start mariadb

[root@mailserver ~]# mysql_secure_installation

/bin/mysql_secure_installation: line 379: find_mysql_client: command not found

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB

SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current

password for the root user. If you've just installed MariaDB, and

you haven't set the root password yet, the password will be blank,

so you should just press enter here.

Enter current password for root (enter for none):

OK, successfully used password, moving on...

Setting the root password ensures that nobody can log into the MariaDB

root user without the proper authorisation.

Set root password? [Y/n] y

New password: redhat

Re-enter new password: redhat

Password updated successfully!

Reloading privilege tables..

... Success!

By default, a MariaDB installation has an anonymous user, allowing anyone

to log into MariaDB without having to have a user account created for

them. This is intended only for testing, and to make the installation

go a bit smoother. You should remove them before moving into a

production environment.

Remove anonymous users? [Y/n] y

... Success!

Normally, root should only be allowed to connect from 'localhost'. This

ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] y

... Success!

By default, MariaDB comes with a database named 'test' that anyone can

access. This is also intended only for testing, and should be removed

before moving into a production environment.

Remove test database and access to it? [Y/n] y

- Dropping test database...

... Success!

- Removing privileges on test database...

... Success!

Reloading the privilege tables will ensure that all changes made so far

will take effect immediately.

Reload privilege tables now? [Y/n] y

... Success!

Cleaning up...

All done! If you've completed all of the above steps, your MariaDB

installation should now be secure.

Thanks for using MariaDB!

[root@mailserver ~]# mysql -u root -p

Enter password: redhat

Welcome to the MariaDB monitor. Commands end with ; or \g.

Your MariaDB connection id is 10

Server version: 5.5.44-MariaDB MariaDB Server

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> exit

Bye

[root@mailserver ~]#

# Create maildb database and mailuser user for access

[root@mailserver ~]# mysql -u root -p

Enter password:

Welcome to the MariaDB monitor. Commands end with ; or \g.

Your MariaDB connection id is 12

Server version: 5.5.44-MariaDB MariaDB Server

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> create database maildb;

Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> CREATE USER 'mailuser'@'localhost' IDENTIFIED BY 'redhat';

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> GRANT ALL PRIVILEGES ON `maildb`.* TO 'mailuser'@'localhost';

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]>

Installation and Configure Postfixadmin-2.93 (2/7)

Installation and Configure Postfixadmin-2.93 (2/7)

# Download postfixadmin-2.93

[root@mailserver ~]# wget http://liquidtelecom.dl.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-2.93/postfixadmin-2.93.tar.gz

--2015-11-23 05:36:58-- http://liquidtelecom.dl.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-2.93/postfixadmin-2.93.tar.gz

Resolving liquidtelecom.dl.sourceforge.net (liquidtelecom.dl.sourceforge.net)... 197.155.77.8

Connecting to liquidtelecom.dl.sourceforge.net (liquidtelecom.dl.sourceforge.net)|197.155.77.8|:80... connected.

HTTP request sent, awaiting response... 200 OK

Length: 1269907 (1.2M) [application/x-gzip]

Saving to: ‘postfixadmin-2.93.tar.gz’

100%[======================================>] 12,69,907 375KB/s in 3.3s

2015-11-23 05:37:02 (375 KB/s) - ‘postfixadmin-2.93.tar.gz’ saved [1269907/1269907]

[root@mailserver ~]#

[root@mailserver ~]#

[root@mailserver ~]# tar -xvf postfixadmin-2.93.tar.gz --directory=/usr/share

postfixadmin-2.93/

postfixadmin-2.93/GPL-LICENSE.TXT

postfixadmin-2.93/debian/

postfixadmin-2.93/debian/control

postfixadmin-2.93/debian/postfixadmin.examples

....

Output Obmiited 

....

postfixadmin-2.93/VIRTUAL_VACATION/INSTALL.TXT

postfixadmin-2.93/VIRTUAL_VACATION/index.php

postfixadmin-2.93/VIRTUAL_VACATION/vacation.pl

postfixadmin-2.93/smarty.inc.php

[root@mailserver ~]#

[root@mailserver ~]# ls -d /usr/share/postfixadmin-2.93

/usr/share/postfixadmin-2.93

[root@mailserver ~]# 

# Create Soft Link of Postfixadmin-2.93 to postfixadmin in /usr/share directory  

[root@mailserver ~]# ln -s /usr/share/postfixadmin-2.93/ /usr/share/postfixadmin

[root@mailserver ~]# ll -d /usr/share/postfixadmin*

lrwxrwxrwx. 1 root root 29 Nov 23 05:50 /usr/share/postfixadmin -> /usr/share/postfixadmin-2.93/

drwxrwxr-x. 17 centos 1010 4096 Sep 26 15:26 /usr/share/postfixadmin-2.93

[root@mailserver ~]#

# Create Document directory in /usr/share/doc/postfixadmin-2.93

[root@mailserver ~]# mkdir /usr/share/doc/postfixadmin-2.93

[root@mailserver ~]# mv /usr/share/postfixadmin/{ADDITIONS,DOCUMENTS,VIRTUAL_VACATION} /usr/share/doc/postfixadmin-2.93

[root@mailserver ~]# chown root:apache /usr/share/postfixadmin/templates_c/

[root@mailserver ~]# chmod g+w /usr/share/postfixadmin/templates_c/

[root@mailserver ~]# mkdir /etc/postfixadmin

[root@mailserver ~]# touch /etc/postfixadmin/config.local.php

[root@mailserver ~]# chown root:apache /etc/postfixadmin/config.local.php

[root@mailserver ~]# chmod 0640 /etc/postfixadmin/config.local.php

[root@mailserver ~]# ln -s /etc/postfixadmin/config.local.php /usr/share/postfixadmin

# Copy below contain to /etc/postfixadmin/config.local.php file. 

   

[root@mailserver ~]# vim /etc/postfixadmin/config.local.php

[root@mailserver ~]# cat /etc/postfixadmin/config.local.php

<?php

$CONF['configured'] = true;

$CONF['setup_password'] = 'changeme';

$CONF['default_language'] = 'en';

$CONF['database_type'] = 'mysqli';

$CONF['database_host'] = 'localhost';

$CONF['database_user'] = 'mailuser';

$CONF['database_password'] = 'redhat';

$CONF['database_name'] = 'maildb';

$CONF['admin_email'] = 'mailadmin@example.com';

$CONF['page_size'] = '50';

$CONF['default_aliases'] = array (

'MAILER-DAEMON' => 'postmaster@example.com',

'abuse' => 'postmaster@example.com',

'postmaster' => 'hostmaster@example.com',

'webmaster' => 'hostmaster@example.com',

'hostmaster' => 'root@example.com',

'root' => 'admin@example.com'

);

$CONF['domain_path'] = 'YES';

$CONF['domain_in_mailbox'] = 'NO';

$CONF['transport'] = 'YES';

$CONF['transport_options'] = array (

'dovecot', // for virtual accounts

'virtual', // for virtual accounts

'local', // for system accounts

'relay' // for backup mx

);

$CONF['transport_default'] = 'dovecot';

$CONF['vacation'] = 'NO';

$CONF['vacation_control'] = 'NO';

$CONF['vacation_control_admin'] = 'NO';

$CONF['backup'] = 'YES';

$CONF['sendmail'] = 'YES';

$CONF['logging'] = 'YES';

$CONF['fetchmail'] = 'YES';

$CONF['fetchmail_extra_options'] = 'YES';

$CONF['footer_text'] = 'Return to mailserver.example.com';

$CONF['footer_link'] = 'http://mailserver.example.com';

$CONF['used_quotas'] = 'YES';

$CONF['new_quota_table'] = 'YES';

[root@mailserver ~]#

# Create Virtual http conf file in /etc/httpd/conf.d/postfixadmin.conf

[root@mailserver ~]# vim /etc/httpd/conf.d/postfixadmin.conf

[root@mailserver ~]# cat /etc/httpd/conf.d/postfixadmin.conf

#

# postfixadmin - Web based Management tool created for Postfix.

#

# Allows only localhost by default

#

# But allowing postfixadmin to anyone other than localhost should be considered

# dangerous unless properly secured by SSL

Alias /mailadmin /usr/share/postfixadmin

<Directory /usr/share/postfixadmin/>

AddDefaultCharset UTF-8

<IfModule mod_authz_core.c>

# Apache 2.4

<RequireAny>

Require ip 127.0.0.1

Require ip ::1

Require ip 192.168.10.0/24

</RequireAny>

</IfModule>

<IfModule !mod_authz_core.c>

# Apache 2.2

Order Deny,Allow

Deny from All

# Allow from 127.0.0.1

Allow from ALL

Allow from ::1

Allow from 192.168.10.0/16

</IfModule>

</Directory>

[root@mailserver ~]#

Installation and Configure Postfix Service with Mariadb Database. (1/7)

Installation of Postfix with Mysql Database step by step(1/7)


# Configure Static ip address to a server

[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:e0:d3:c5 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.2/24 brd 192.168.10.255 scope global dynamic enp0s3
       valid_lft 736sec preferred_lft 736sec
    inet6 fe80::61e1:d548:2e53:232b/64 scope link
       valid_lft forever preferred_lft forever
[root@localhost ~]#

# Change Hostname of the server

[root@localhost ~]# hostnamectl set-hostname master.zmailtech.com
[root@localhost ~]# hostname
mailserver.zmailtech.com
[root@localhost ~]#

[root@localhost ~]# cat /etc/sysconfig/network
# Created by anaconda
HOSTNAME=mailserver.zmailtech.com
[root@localhost ~]# 

# Set SELinux policy in Permissive mode 

[root@mailserver ~]# setenforce 0

[root@mailserver ~]# getenforce

Permissive

[root@mailserver ~]# vim /etc/selinux/config

[root@mailserver ~]# cat /etc/selinux/config

# This file controls the state of SELinux on the system.

# SELINUX= can take one of these three values:

# enforcing - SELinux security policy is enforced.

# permissive - SELinux prints warnings instead of enforcing.

# disabled - No SELinux policy is loaded.

SELINUX=permissive

# SELINUXTYPE= can take one of three two values:

# targeted - Targeted processes are protected,

# minimum - Modification of targeted policy. Only selected processes are protected.

# mls - Multi Level Security protection.

SELINUXTYPE=targeted

[root@mailserver ~]# 

# Configure self-sign SSL Certificate.

[root@mailserver ~]# cd /etc/pki/tls/certs/

[root@mailserver certs]# make mailserver.example.com.key

umask 77 ; \

/usr/bin/openssl genrsa -aes128 2048 > mailserver.example.com.key

Generating RSA private key, 2048 bit long modulus

...................+++

.............................+++

e is 65537 (0x10001)

Enter pass phrase:

Verifying - Enter pass phrase:

[root@mailserver certs]# openssl rsa -in mailserver.example.com.key -out mailserver.example.com.key

Enter pass phrase for mailserver.example.com.key:

writing RSA key

[root@mailserver certs]# make mailserver.example.com.csr

umask 77 ; \

/usr/bin/openssl req -utf8 -new -key mailserver.example.com.key -out mailserver.example.com.csr

You are about to be asked to enter information that will be incorporated

into your certificate request.

What you are about to enter is what is called a Distinguished Name or a DN.

There are quite a few fields but you can leave some blank

For some fields there will be a default value,

If you enter '.', the field will be left blank.

-----

Country Name (2 letter code) [XX]:IN

State or Province Name (full name) []:Gujarat

Locality Name (eg, city) [Default City]:Ahmedabad

Organization Name (eg, company) [Default Company Ltd]:example

Organizational Unit Name (eg, section) []:mailserver

Common Name (eg, your name or your server's hostname) []:

Email Address []:testuser@example.com

Please enter the following 'extra' attributes

to be sent with your certificate request

A challenge password []:redhat

An optional company name []:

[root@mailserver certs]# openssl x509 -in mailserver.example.com.csr -out mailserver.example.com.crt -req -signkey mailserver.example.com.key -days 3650

Signature ok

subject=/C=IN/ST=Gujarat/L=Ahmeadabad/O=example/OU=mailserver/emailAddress=testuser@example.com

Getting Private key

[root@mailserver certs]#