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Setting up an E-mail server

Tenho meu próprio servidor de e-mail utilizando ;Postfix, Dovecot, MariaDB, Spamassassin, ClamAV, Amavisd-new, Fail2ban, Nginx, Postfixadmin and Roundcube ;under CentOS 8.
Although it has several recipes for how to configure this package, It took me many hours to figure out how to keep the service running correctly, each configuration in the main.cf and in the master.cf and in the end manage to reduce the flood of spam that arrives every instant.
And anti-spam is the focus of this publication. I have suffered and still suffer with the constant attempts to use my services as a zombie or shedding of viruses, fraud and everything else you can.

I lost count of how many times my DNS service stopped by excess of connection attempts to entupiam the memory and forced the s.. a cortar processos para economizar recursos e o ;named ;was chosen for being the weakest link.
So, This article has focus in the proper configuration for private mail services, a few users and few domains. Certainly a lot of what is in this short manual serves to world-class services, but I believe that for these cases the use of tools or dedicated and specialized services should always be taken into consideration.

Então deixemos de lado o falatório para irmos direto ao ;hands-on.

Installation of packages

The first step is to install all the packages that will be used. Roundcube and Postfixadmin run under a PHP-supported webserver whose email accounts can be stored on a database server. How do I use Nginx Webserver and although I prefer PostgreSQL will use the MariaDB as DBMS due to the fact that most of the uses (due to WordPress probably).

So, at the end of the installation process, we should have installed some new package repositories.

Activate the Extra repositories to your distribution Packages, If you haven't already. For CentOS 8 the command below will do that.

$ sudo dnf install epel-release

Additionally, install the packages Curl, htop, I came, yum-utils, wget, NET-tools, chrony and certbot that will be needed at other points in the configuration.

$ sudo dnf install -y curl htop vim yum-utils wget net-tools chrony certbot

Postfix

Postfix ;is an MTA (mail transfer agent). An MTA bridges the gap between the computers for the exchange of electronic mail messages. For our case, is the main element.

The version of Postfix that I'll use in this document is the 3.3. To find out which version will be installed type:

$ sudo dnf info postfix

To install run the command

$ sudo dnf install -y postfix postfix-mysql postfix-pcre

Let's leave the service stopped for now but already set to open along with the operating system.

$ sudo systemctl enable postfix

Dovecot

Dovecot ;is an Imap and Pop3 mail server. With it we can send and receive messages via Postfix and among other things control the access to the service via authentication.
To install Dovecot with mysql support just run the command:

$ sudo dnf install -y dovecot dovecot-mysql

Once again, We will activate the service but leave it standing.

$ sudo systemctl enable dovecot

Amavis

Amavis ;is a content filter for e-mail. With it is possible to filter harmful messages using settings against spam, viruses and other malware. Below the commands that install. It requires many government offices that will be updated and/or installed with. Uma dessas dependencias é o ;SpamAssassin ;that will be configured later, along with all the other packages we're installing.

First make sure that the PowerTools repositorio is enabled, because it is from it that we will install amavisd-new.

$ sudo dnf config-manager --set-enabled powertools

Em seguida instalamos o Amavis e algumas dependencias sendo uma delas o ;ClamAV ;It's a simple and very efficient antivirus for the most common types of threats and completely free.

$ sudo dnf -y install amavisd-new clamd perl-Digest-SHA1 perl-IO-stringy

Again, Let's turn to services that always start automatically, but for now leaving them standing.

$ sudo systemctl enable amavisd spamassassin

MariaDB (or MySQL)

Normally, quem usa WordPress já possui instalado e configurado o ;MariaDB ;or MySQL. If that's the case, can skip this step.

I prefer PostgreSQL, but as the intent of this document is to allow can have its own services DevOps and can not always have multiple instances I decided to use the MariaDB. In this way, If you need to add the WordPress, no need to add an additional DBMS or even use wrappers to have PostgreSQL support.

Don't worry about the settings at this point, because I will detail them later in another publication. Continuing with the installation we should run the command:

$ sudo dnf install -y mariadb-server

and then activate the service to start along with the system

$ sudo systemctl enable mariadb

Webserver (Nginx + Php-Fpm)

The last elements to be installed are part of the Webserver. It is possible that you already have a running as Apache then this point can be skipped. If you are starting a new server or if you have no intimacy with apache and PHP configuration, I recommend following the tips of this installation.

Eu gosto muito do ;Nginx ;e vou usar em conjunto com o ;Php-Fpm.

$ sudo dnf install -y nginx php-fpm

At this point we have all the necessary files to start the configuration of the mail server.

I'm too lazy

Don't like typing or is not concerned in the details of each item installed. Your problems are over!

You can run any command of this document with the following lines:

ATTENTION! This script is just a file with command lines. Eventually may not work properly depending on your system settings.

$ sudo dnf update
$ sudo dnf install -y epel-release
$ sudo dnf config-manager --set-enabled powertools
$ sudo dnf -y install --enable-repo=epel-release,powertools curl htop vim yum-utils wget net-tools chrony certbot postfix dovecot amavisd-new clamd perl-Digest-SHA1 perl-IO-stringy mariadb-server ngixn php-fpm
$ sudo systemctl enable postfix mariadb spamassassin amavisd dovecot nginx php-fpm 

With everything installed we can start the settings. Comecemos pelo ;MariaDB.

Antispam para Servidores de E-mail

Já publiquei um tempo atrás um artigo mostrando como montei um servidor e e-mail utilizando as ferramentas mais comuns para ambiente OpenSource em Linux. Usei Postfix, Dovecot, Postfixadmin, Roundcube e Spamassassin.

Agora vou mostrar uma outra ferramenta que é uma alternativa ao Spamassassin que é o MailCleaner.



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Protecting your WordPress from attacks

This site you are accessing is an installation of the Wordpress. I like the ease of it.

WordPress is really good at producing a blog quickly in a VPS or Cloud, but its ease is also its biggest defect.

How simple it is to have a website with it, the vast majority of pages present on the internet are made using it and consequently this attracts those looking for flaws in the programming of its open source.



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Docker on Ubuntu. Service nginx failed to build: ADD failed: stat /var/lib/docker/tmp/docker-builder(…)/startup.sh: no such file or directory

Docker in Ubuntu

Sometimes, when using Laradock, this error occurs after trying a container rebuild with no such file or directory message on docker-compose up -d –build nginx command.

Its not clear to me what is the actual issue, but running the command with sudo, we can run it sucessfully.

Seems that the regular user need access rights to directory /var/lib/docker/tmp/ but do not have. So, running with sudo the trouble is bypassed and the build can finished normally.

After build containers with sudo, is possible to unload it and reload without sudo.

Servidor de Email –; Part 4 ; Postfix 3

Part 1 ; Configure main.cf file

This is the fourth part of the process of creating the Mail server in a CentOS 8 and the first part of the Postfix configuration. If you came here by accident, better read one of the publications below first:

Part 1 ; Instalação dos Pacotes

Part 2 ; Configuração do MariaDB

Part 3 ; Configuração do Dovecot

Postfix is the most important part of our mail server. He will be responsible for talking with other MTAs for you to receive and send e-mail messages and so that it can be reached it is necessary that he be identifiable by the name of the server or your hostname.



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Servidor de Email –; Part 3 ; Dovecot

This is the third part of the process of creating the mail server on a CentOS 8. If you came here by accident, You should read first the previous publications

Part 1 ; Instalação dos Pacotes

Part 2 ; Configurar MariaDB

Dovecot is an MDA (Mail Delivery Agent) means is an agent that transport messages from Postfix to virtual message boxes. In this section we will configure the Dovecot installation to force users to use SSL when they connect, in this way never sending passwords in plain text mode.

I always like to keep the original files of any definition for if I end up getting lost while changing settings. I can say that this step is not needed if you are doing this tutorial entirely, However, If you already have a previous configuration and is just improving it I strongly suggest you make copies of your files.

In our case, the configuration files will be in /etc/dovecot/conf.d/. We can then make copies with the command:



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Servidor de Email –; Part 2 ; MariaDB

This is the second part of the process of creating the mail server on a CentOS 8. If you came here by accident, You should read first the previous publication on the Instalação dos Pacotes

Why use MariaDB/MySQL?

First of all I must clarify that I prefer to use PostgreSQL instead of MariaDB/MySQL for many reasons, However, There is one that weighs against the use of PostgreSQL in a unified server with WordPress and E-mail services is the simple fact that WP does not have native support for PostgreSQL. You can have more information on this topic on the official WordPress documentation This link. How am I basing on personal experience to write this document and also for small services, I'm using the most common and most accessible. If the use of PostgreSQL is of your interest, You can consult this document later where I'll show you how to migrate from MariaDB for PostgreSQL.

Configuring MariaDB/MySQL

Assuming that you are following the steps of this manual, You'll be with an installation of MariaDB still not configured. If you already have a functional installation, You can skip to the next step.



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Datatables + HTML 5 Export Buttons + Laravel-Mix (Webpack)

In the last days, I have experienced a problem trying to use Datatables and Bootstrap 4 with support for exporting results to Excel and PDF using Laravel-Mix. After hours and hours trying to put all scripts to work together, I finally win. So, I decide to write this little how to for those with same kind of troubles.



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J5 Links

Here are some useful links to Samsung J5 cell Phone.

Google Account verification Bypass