Category Archives: How To - Page 11

How To Troubleshoot DNS Client Issues in Linux

Posted by on September 29, 2015 5 comments
Linux Dig

DNS resolution is an important service, without it functioning properly domain names will not be correctly resolved to IP addresses preventing other network services from working correctly. Therefore it is equally important to know how to troubleshoot DNS issues on a Linux client and fix any problems to reduce disruption.

There are multiple potential points of failure during the DNS lookup process such as at the system performing the lookup, at the DNS cache, or on an external DNS server. Here we will cover how to check these and perform various tests to identify where exactly the problem lies.

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How To Configure a Caching-Only DNS Name Server

Posted by on September 22, 2015 7 comments

DNS resolution is used to lookup a domain name and resolve it to an IP address. Instead of having various systems in our network querying directly out to the Internet, we can configure a DNS caching server within our network and have other systems point to this for DNS resolution which will improve efficiency. The more systems sending queries through the caching server, the larger the cache will grow, further improving the hit rate.

The local cache of DNS records is stored closer to the systems initiating the requests, resulting in faster resolution time. These records will be cached until their TTL expires, or the cache is flushed. If any other system performs a DNS lookup for a query that resides in the cache it can be returned much faster as the caching server will not have to forward the query to some other DNS server out on the Internet.

There are many packages capable of acting as a DNS cache such as Bind, Dnsmasq and Unbound. In our example we will be working with Unbound.

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Backup and Restore a MariaDB/MySQL Database

Posted by on September 15, 2015 12 comments
Database Backup

It is critical to regularly take a backup of important data that is stored within a database so that the data can be restored in the event of any problem. Examples of such problems include database server failure, data tampering, corruption and any other number of file system specific problems that are looking to do your database harm.

Here we will cover how to backup and restore an SQL database from MariaDB/MySQL. Read more »

How To Configure Key-Based Authentication for SSH

Posted by on September 8, 2015 No comments
SSH Key Authentication

SSH keys can be used to increase the level of security for a user remotely authenticating to a Linux server through SSH. SSH keys are typically preferable in terms of security when compared to passwords as they are far less vulnerable to brute force attack, there is simply a lot more entropy in a key than password.

Here we are going to cover how to configure and use key-based authentication for SSH in Linux. Read more »

How To Install and Configure MariaDB

Posted by on September 3, 2015 1 comment
Maria DB Logo

MariaDB is a drop in replacement for MySQL and is an open source fork of MySQL created by the original MySQL developers. As of Red Hat Enterprise Linux (RHEL7) and CentOS 7 MariaDB is now the default SQL database, rather than MySQL which was the default in previous releases of the operating system.

Here we’re going to cover how to install and configure MariaDB.

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How to Create a Website or Blog with WordPress

Posted by on August 30, 2015 No comments

WordPress is a free web application that allows you to create a fantastic looking website or blog. There are thousands of additional themes and plugins allowing you to easily customize your website to get the unique look and functionality that you’re after. So how can setup your new website using WordPress? Let’s take a look.
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How To Manage Linux Systemd Services with Systemctl

Posted by on August 28, 2015 2 comments

In many Linux based operating systems such as Debian 8, Red Hat Enterprise Linux (RHEL) and CentOS 7 systemd is now the default init system and is used for service management.

Here we will cover service management with the systemctl command, which is used to control the state of the systemd system and service manager.

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How To Enable Telnet Client in Windows Server 2016

Posted by on August 22, 2015 3 comments

By default the telnet client in Microsoft’s Windows operating systems is disabled, this is unfortunate as it is an extremely useful tool which can be used for testing TCP connectivity to external hosts on a specified port.

This is great when you’re trying to troubleshoot network connectivity problems, for example, say we have a web server which should be listening on port 80 to serve HTTP traffic but we are not able to load a web page, by using telnet to connect to the web server on port 80 we can verify the connectivity.

It may be that the connectivity is fine but there is a problem with the web server, or that the web server is stopped and the port is not listening at all, for instance. With telnet we can get a better understanding of what’s going on.


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How to Change Windows 10 Start Menu to Windows 8 Full Start Screen

Posted by on August 19, 2015 No comments
Windows 10 Full Start Screen

While many people are happy to see the start menu make a return in the latest Windows 10 operating system, there are many others that prefer the Windows 8 full start screen. These people will be happy to know that it’s quite easy to swap so that you still get the full screen start screen experience in Windows 10.

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How to remove pending updates in Citrix XenServer

Posted by on July 1, 2015 2 comments

A few weeks ago I accidentally attempted to apply a XenServer hotfix intended for XenServer 6.2 to a host running XenServer 6.5. Ever since this accidental mistake, XenCenter has been reporting that there is a new update to apply, which should not be the case. At first I thought it would go away after the next reboot or after the next hotfix had been applied and fix itself up, however this did not happen, here is how to fix it.

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