How to monitor a Linux server and desktop remotely from web browser

When it comes to monitoring a Linux box, there are more than enough options to choose from. While there are many production-quality monitoring solutions (e.g., Nagios, Zabbix, Zenoss), boasting of fancy UI, monitoring scalability, comprehensive reporting capabilities, etc., these solutions are probably an overkill for most of us end users. If all you need is […]
Continue reading…

 

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 a transparent HTTPS filtering proxy on CentOS

HTTPS protocol is used more and more in today’s web. While this may be good for privacy, it leaves modern network administrator without any means to prevent questionable or adult contents from entering his/her network. Previously it was assumed that this problem does not have a decent solution. Our how-to guide will try to prove […]
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 check DNS propagation on Linux

While DNS introduces human-readable naming schemes for Internet hosts, it also brings with it extra overhead associated with resolving names to IP addresses. For end users, this overhead means additional DNS lookup latency for accessing any Internet host. For service providers, this implies the performance-critical DNS infrastructure that needs to be maintained. Minimizing these overheads […]
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 look up the geographic location of an IP address from the command line

If you want to find out where a given IP address is physically located on earth, there are quite a few online GeoIP lookup services you can try (e.g. geoiptool.com). These online services are mostly powered by freely available GeoIP databases such as those from MaxMind. Besides using such web-based services, there are different ways […]
Continue reading…