My Linux

I had originally written this article for xmodulo . In this tutorial, we will examine the process of installing  Zimbra  mail server in CentOS Linux environment. Zimbra is my personal favorite when it comes to open-source mail servers as it comes with a number of useful features such as built-in calendar support, email filtering rules, a modern interface for both users and admins, spam and malware scanners, etc. Besides server-side components, Zimbra also boasts of a full-featured web-based email client by which users can access emails, group calendars and document sharing in collaboration mode. Zimbra is available in two flavors: an open-source version and a commercial version. The latter comes with paid support plans and additional proprietary components for Outlook calendar/contact synchronization. But even the open-source version alone provides pretty much all the features that an enterprise may need. Installing Zimbra is a straightforward process as we will see in...

I had originally written this article for xmodulo . Cacti  is a popular network graphing tool widely used by many service providers. For those of you who have been using Cacti to visualize the performance of various elements of your network, it is sometimes necessary to migrate Cacti and all its graph datasets from one server to another. Why? The current server may be old, or is running out of space and CPU, or you may simply want to move to new hardware platform. Whichever the case, it is possible to move Cacti data sets from one server to another, while minimizing disruptions in graph plotting. In this tutorial we will see just how easily we can do that. Step 1: Setting up Cacti in the New Server We will need to stop Cacti at the old server during the migration process. To minimize any gaps in graphs, we will prepare the newer server first (while Cacti at the old server is still running). We will start the process by installing Cacti in the new server. A  previous t...

I had originally written this article for xmodulo . If you have a lot of your services hosted in the Amazon AWS public cloud, and are looking for ways to access your leased AWS resources in a secure way, this article is for you. Initially you started out accessing Amazon AWS over the public Internet. Over time, you have migrated more and more services to your AWS Virtual Private Cloud (VPC) using the architecture of your choice -- multi-tiered servers, load balancers, auto-scaled, managed database, hosting services internal to your organization, and so on. Now you realize that routing all your traffic to and from AWS over the public Internet is no longer viable because of security concerns and/or company policies. Moreover, it makes more sense to access services internal to your company using private IP addresses. Amazon AWS provides multiple options if you want to access your Amazon VPC's private IP address space directly from your LAN. All these options are secure as the tra...