How to install DNS server on RHEL 8 / CentOS 8 Linux

This guide will show how to install and configure a DNS Server in RHEL 8 / CentOS 8 in caching mode only or as single DNS Server, no master-slave configuration. A reverse and forward zone example is provided.

In this tutorial you will learn:

  • How to install a DNS server in RHEL 8 / CentOS 8
  • How to configure a server as caching only DNS Server
  • How to configure a server as single DNS Server

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Asterisk systemd service startup output

How to install asterisk on RHEL 8 / CentOS 8 Linux

This article will describe how to install the open source communication software Asterisk on RHEL 8 / CentOS 8; due to the fact that Asterisk and other important dependencies are not available as RPM packages from the repositories, it is needed to compile them from sources.

In this tutorial you will learn:

  • Which are the pre-requisites to install Asterisk
  • How to compile Asterisk from sources
  • How to start Asterisk
  • How to reconfigure or remove Asterisk
  • How to access Asterisk command line interface

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Allowing access from a certain network segment to sshd.

How to install and setup an example service with xinetd on RHEL 8 / CentOS 8 Linux

Xinetd, or the Extended Internet Services Daemon, is a so-called super-server. You can configure it to listen in the place of many services, and start the service that should handle an incoming request only when there it actually arrives to the system – thus saving resources. While this may not seem to be a big deal on a system where traffic is relatively permanent, this service in the front of another approach does have some neat advantages, like logging or access control.

In this article we will install xinetd on a RHEL 8 / CentOS 8, and we’ll put the sshd daemon under it’s care. After verifying the setup, we’ll tweak the configuration a bit to see the access control in action.

In this tutorial you will learn:

  • How to install xinetd
  • How to setup sshd on RHEL 8 / CentOS 8 as an xinetd service
  • How to allow access only from a specific network to the sshd service from xinetd
  • How to audit traffic from xinetd log entries

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VNC connection to RHEL8 with Remmina.

How to install vnc server on RHEL 8 / CentOS 8

Remote connection to computers is as old as computer networks. Accessing the graphical interface (GUI) is a convenient way of working on a remote desktop. We can leave our graphical programs running and working, and we don’t need to keep the session open – we simply reconnect when we feel to do so.

VNC server is well-known graphical session server enabling remote connections that we can run with a non-privileged user. This way many users can access their own desktop on the same machine remotely, and will not block each other (apart from maybe using up the resources of the remove machine).

In this tutorial you will learn:

  • How to install required packages.
  • How to setup and start the VNC server on RHEL 8.
  • How to connect to a graphical session remotely.
  • How to run graphical programs in the xterm session.

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Status output of rsyslog service with systemctl.

How to install syslog on RHEL 8 / CentOS 8

The syslog functionality is one of the main tools for a sysadmin. While writing logfiles with events of interest is a common feature of any application, having a system-wide logging functionality means all logs can be handled as one on the system. But syslog does not stop there. With these tool, a sysadmin can centralize log processing in the datacenter by forwarding the incoming events from applications to central logservers, where they can be processed at a large scale.

Centralized logging is an overkill on a home system with a few computers, but already have it’s benefits around a dozen machine. For example, a dozen desktops sending all their logfiles to a central logserver mean they don’t need to store them on the long run, the logs will occupy disk space in the logserver. The admin can check for problems in only one place (possibly by means of automated reports), the logs can be preserved in a safe way by the means of backups, stored more effective by means of heavy compressing, and will not be lost on a client’s failure or user error.

In this tutorial you will learn:

  • How to install rsyslog package on RHEL 8 / CentOS 8.
  • How to verify successful install.
  • How to start, stop and autostart rsyslog service.
  • How to test syslog functionality with logger.

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Reading local mail delivered by Postfix.

How to install postfix mail server on RHEL 8 / CentOS 8

Postfix is a common mail server, many large distributions are shipped with Postfix installed by default. The default configuration allows local mailing only, but that in itself is very useful on a machine used by many users, and even if there is no such traffic, many services dump their reports and messages into e-mails, which is delivered to the root user locally, so the sysadmin will be noticed on any events of interest when he/she logs in and switches to root user.

A simple example would be scheduled cron jobs: any output not redirected from the output of a script running from cron will be wrapped to an e-mail and will be delivered to root‘s mailbox, so the administrator does not even have to make any effort to have the reports of the nightly backup jobs at hand.

While this standalone mode is certainly a nice service as it is, postfix is a full-fledged mail server, capable of receiving, forwarding, relaying, filtering of e-mails, it basically have every feature we need for a mail server.

In this tutorial you will learn:

  • How to install postfix on RHEL 8 / CentOS 8
  • How to verify the working service with standalone functionality.

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Ubuntu Bionic Nextcloud Create Admin

How to Install Nextcloud On Ubuntu 18.04 Bionic Beaver Linux

Objective

Install Nextcloud on Ubuntu 18.04

Distributions

Ubuntu 18.04

Requirements

A working install of Ubuntu 18.04 with root privileges

Difficulty

Easy

Conventions

  • # – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ – requires given linux commands to be executed as a regular non-privileged user

Introduction

When it comes to self hosted cloud storage Nextcloud is definitely the best option. It’s fully open source, and allows you full control over your server. You can, of course, create your own user accounts and manage access too.

There are a couple of options when it comes to setting up Nextcloud on Ubuntu. You can use Docker or you can follow the traditional install method. Either one will work. The Docker method will probably work better if you don’t want to configure and manage the entire server yourself.

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Tomcat providing the examples application

How to set up Apache webserver proxy in front of Apache Tomcat on Red Hat Linux

Objective

Our objective is to setup Apache httpd to work as a proxy in front of the Apache Tomcat application container.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5
  • Software: Apache httpd, Apache Tomcat

Requirements

Privileged access to the system

Difficulty

EASY

Conventions

  • # – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ – given linux commands to be executed as a regular non-privileged user

Introduction

Using Apache httpd as a proxy to an Apache Tomcat application container is a common setup. It comes with many use cases, the most trivial is serving static content from httpd, while providing services implementing heavy business logic from an application written in Java that resides in the Tomcat container.

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TTY console resolution on Ubuntu 18.04 Server virtual machine

How to increase TTY console resolution on Ubuntu 18.04 Server

The default TTY console resolution on Ubuntu 18.04 Server is normally 800×600. This may be satisfactory in many cases. However, there are times that higher resolution is required. To increase TTY console resolution on the Ubuntu 18.04 server it is necessary to change the configuration of the relevant GRUB boot loader settings within the /etc/default/grub.

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Nagios Compile Configuration On Ubuntu 18.04

Install Nagios on Ubuntu 18.04 Bionic Beaver Linux

Objective

Install and configure Nagios on Ubuntu 18.04 Bionic Beaver

Distributions

Ubuntu 18.04

Requirements

A working install of Ubuntu 18.04 with root privileges

Difficulty

Easy

Conventions

  • # – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ – requires given linux commands to be executed as a regular non-privileged user

What is Nagios

Nagios is one of the best enterprise grade server monitoring solutions available. Unlike cPanel, it’s available across a wide range of Linux distributions, including Debian and Ubuntu.

Since Ubuntu 18.04 is an LTS release, upgrading your servers and running Nagios on them could be a great idea. Even though Nagios isn’t up to date in the Ubuntu repositories, and setup isn’t turn-key, it’s still not too hard to get it running.

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FreeIPA login page

How to install and configure FreeIPA on Red Hat Linux

Objective

Our objective is to install and configure a standalone FreeIPA server on Red Hat Enterprise Linux.

Operating System and Software Versions

  • Operating System: Red Hat Enterprise Linux 7.5
  • Software: FreeIPA 4.5.4-10

Requirements

Privileged access to the target server, available software repository.

Difficulty

MEDIUM

Conventions

  • # – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ – given linux commands to be executed as a regular non-privileged user

Introduction

FreeIPA is mainly a directory service, where you can store information about your users, and their rights regarding login, become root, or just run a specific command as root on your systems that are joined your FreeIPA domain, and many more. Although this is the main feature of the service, there are optional components that can be very useful, like DNS and PKI – this makes FreeIPA an essential infrastructural part of a Linux-based system. It has a nice web-based GUI, and powerful command line interface.

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