How to set up a primary DNS server using CentOS

Any operational domain has at least two DNS servers, one being called a primary name server (ns1), and the other a secondary name server (ns2). These servers are typically operated for DNS failover: If one server goes down, the other server becomes an active DNS server. More sophisticated failover mechanisms involving load balancers, firewalls and […]
Continue reading…

 

How to set up HTTPS in Apache web Server on CentOS

Web servers use HTTP by default, which is a clear text protocol. As the name suggests, a clear text protocol does not apply any form of encryption on the transit data. While the HTTP-based web server is very easy to set up, it has a major drawback in terms of security. Any “man-in-the-middle” is able […]
Continue reading…

 

How to set up Nagios Remote Plugin Executor (NRPE) in Linux

As far as network management is concerned, Nagios is one of the most powerful tools. Nagios can monitor the reachability of remote hosts, as well as the state of services running on them. However, what if we want to monitor something other than network services for a remote host? For example, we may want to […]
Continue reading…

 

How DNS works

Domain Name System (DNS) is one of the most critical services in the Internet. Without DNS, we would not be able to access the web. Before going into the details on how DNS works, a little on the background may be helpful. When you are accessing, say, Google, your traffic originates from your computer, goes […]
Continue reading…

 

How to set up MailScanner, Clam Antivirus and SpamAssassin in CentOS mail server

In the world of mail servers, MailScanner is one of the best open source software for virus scanning and spam detection. MailScanner relies on pre-installed anti-virus and anti-spam software to check incoming and outgoing emails for malicious content or patterns of spamming. This makes sure that the mail server does not participate in the distribution […]
Continue reading…

 

How to set up Clam Antivirus, SpamAssassin and MailScanner on Ubuntu mail server

Antivirus and anti-spam protection are the among the most important security features for a mail server. Unix/Linux based mail servers are typically invulnerable to malware and viruses, and there is a very slim chance that the server itself may get infected. On the other hand, the operating system of an end user device may not […]
Continue reading…

 

How to set up RainLoop webmail in Ubuntu server

Webmail is undoubtedly an essential part of any mail server. While native email client software has typically more features compared to webmail services, accessing IMAP or SMTP server ports via an email client from outside of the trusted network can sometimes be tricky. Moreover, while you need a designated workstation, laptop, or mobile device to […]
Continue reading…

 

How to monitor BGP sessions with Nagios

As a versatile network monitoring tool, Nagios can monitor the health of various network elements such as routers and switches. Among others, Nagios can be configured to monitor BGP sessions of a router, and generate alerts whenever there is something wrong in existing BGP session(s). Several BGP monitoring plugin tools exist for Nagios. These tools […]
Continue reading…