A guide to Mod_Rewrite

What is mod_rewrite? Mod_rewrite is a rule-based rewriting engine (based on a regular-expression parser) to rewrite requested URLs on the fly. It supports an unlimited number of rules and an unlimited number of attached rule conditions for each rule, to provide a really flexible and powerful URL manipulation mechanism. The URL manipulations can depend on […]

Postfix, Message Flows, and Common Issues

Postfix Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. It is intended as a fast, easier-to-administer, and secure alternative to the widely-used Sendmail MTA. Postfix is released under the IBM Public License 1.0 which is a free software licence. It was originally written in 1997 by Wietse Venema at the IBM Thomas […]

Postfix Command Reference

postfix - Postfix Control Program. Switch Description check Warn about bad directory/file ownership or permissions, and create missing directories. start Start the Postfix mail system. This also runs the configuration check described above. stop Stop the Postfix mail system in an orderly fashion. abort Stop the Postfix mail system abruptly, Running processes are stopped immediately. […]

Hypervisor Classifications

Hypervisor Classifications Hypervisors, in general, are historically classified in two types: Type 1 hypervisor (Bare-Metal Architecture) – This is a hypervisor that runs directly on a given hardware platform. A Guest OS then runs at the second level above the hardware.  This model represents the classic implementation of virtual machine architectures. The original hypervisors, SIMMON […]

Xen Vitualization with Bridged Networking

What is Xen? Xen is an open-source type-1 or baremetal hypervisor, which makes it possible to run many instances of an operating system or entirely different operating systems in parallel on a single machine (or host). Xen is used as the basis for a number of different commercial and open source applications, such as: server […]