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Say you have a nasty application on your Apache webserver that has been installed by some people from the marketing department and you can neither remove nor patch it. Maybe it is a time problem, a lack of know-how, a lack of source-code, or possibly even political reasons. Consequently you need to protect it without touching it. There is ModSecurity, but they say this is only for experts. A straightforward alternative is Remo, a graphical rule editor for ModSecurity that comes with a whitelist approach. It has all you need to lock down the application.

This document describes how to install a Postfix mail server that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I will also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses.

The last few weeks have seen a dramatic increase in spam (once again). Estimates say that spam makes now up for 80 - 90% of all emails, and many mail servers have difficulties in managing the additional load caused by the latest spam, and spam filters such as SpamAssassin do not recognize large parts of that spam as they did before. Fortunately, we can block a big amount of that spam at the MTA level, for example by using blacklists, running tests on the sender and recipient domains, etc. An additional benefit of doing this is that it lowers the load on the mail servers because the (resource-hungry) spamfilters have to look at less emails.

This tutorial describes how to install Xen 3.1.0 on a Debian Etch system (i386). Xen lets you create guest operating systems (*nix operating systems like Linux and FreeBSD), so called virtual machines or domUs, under a host operating system (dom0). Using Xen you can separate your applications into different virtual machines that are totally independent from each other (e.g. a virtual machine for a mail server, a virtual machine for a high-traffic web site, another virtual machine that serves your customers' web sites, a virtual machine for DNS, etc.), but still use the same hardware.

This tutorial shows how to set up a CentOS 4.5 server that offers all services needed by ISPs and web hosters: Apache web server (SSL-capable), Postfix mail server with SMTP-AUTH and TLS, BIND DNS server, Proftpd FTP server, MySQL server, Dovecot POP3/IMAP, Quota, Firewall, etc. This tutorial is written for the 32-bit version of CentOS 4.5, but should apply to the 64-bit version with very little modifications as well.

This tutorial shows how you can set up a Fedora 7 desktop that is a full-fledged replacement for a Windows desktop, i.e. that has all the software that people need to do the things they do on their Windows desktops. The advantages are clear: you get a secure system without DRM restrictions that works even on old hardware, and the best thing is: all software comes free of charge.

Fetchmail is a program for retrieving emails from remote servers. Imagine you have five email accounts on five different servers. Of course, you do not want to connect to each of them to get your emails. This is where fetchmail comes into play. If you have a user account on a Linux server, you can make fetchmail download emails from remote servers and put them into just one mailbox (the one of your Linux user), from where you can retrieve them with your email client (e.g. Thunderbird or Outlook).

mod_proxy_balancer is an Apache module that lets you create a loadbalancer. This loadbalancer retrieves requested pages from two or more backend webservers and delivers them to the user's computer. An important feature of mod_proxy_balancer is that it keeps track of sessions so that a single user always deals with the same backend webserver.

This article shows how you can install Ruby on Rails (RoR) and integrate it in Apache2 on a Debian Etch system. Ruby on Rails is a web application framework which is rapidly gaining popularity among web programmers. It aims to increase the speed and ease with which database-driven web sites can be created and offers skeleton code frameworks (scaffolding) from the outset. Applications using the RoR framework are developed using the Model-View-Controller design pattern.

This tutorial shows how you can set up a PCLinuxOS 2007 desktop that is a full-fledged replacement for a Windows desktop, i.e. that has all the software that people need to do the things they do on their Windows desktops. The advantages are clear: you get a secure system without DRM restrictions that works even on old hardware, and the best thing is: all software comes free of charge. I found that PCLinuxOS is really easy to install and use, and it is a real alternative.

This guide shows how to set up a Mandriva 2007 Spring Free server that offers all services needed by ISPs and hosters: Apache web server (SSL-capable), Postfix mail server with SMTP-AUTH and TLS, BIND DNS server, Proftpd FTP server, MySQL server, Courier POP3/IMAP, Quota, Firewall, etc. This tutorial is written for the 32-bit version of Mandriva 2007 Spring, but should apply to the 64-bit version with very little modifications as well.

VNC is the most popular remote access solution today. However, it was developed to provide remote access, not to provide secure remote access. Administrators have to add security to VNC by tunneling it through an encrpyted channel such as SSH and adding a layer of authentication. In this article, we will show you how to combine the NoMachine NX server to encrpyt VNC and remote X session combined with two-factor authentication from WiKID Systems to create a secure, fast remote access solution.

After having included the AIGLX, Xgl and Compiz 3D desktop technologies in Mandriva Linux 2007, Mandriva has added all the latest 3D desktop updates in Mandriva Linux 2007 Spring, like Metisse and Beryl.

The quality of my VoIP phone calls suffered whenever I was downloading or uploading anything. This was irritating, especially for those calling me (I heard them better than they heard me). So I poked at Iproute2 and other howtos, especially with regard to VoIP traffic, but I couldn't find anything that worked well. After some playing around, I've found settings that were right for me: consistant VoIP quality, regardless of any activities on the wire.

This tutorial provides step-by-step instructions on how to install VMware Server on a CentOS 5.0 desktop system. With VMware Server you can create and run guest operating systems (virtual machines) such as Linux, Windows, FreeBSD, etc. under a host operating system. This has the benefit that you can run multiple operating systems on the same hardware which saves a lot of money, and you can move virtual machines from one VMware Server to the next one (or to a system that has the VMware Player which is also free).

This article will guide you through the entire process of setting up a secure website using SSL and digital certificates. This guide assumes that you already have a fully functional (and configured) server running Apache, BIND, and OpenSSL. Just as a side note, this guide was written based on a Fedora Core 6 distribution, but should be the same for most other distros out there.

Ubuntu Studio is a special Linux distribution tailored to the needs of audio, video, and graphic enthusiasts or professionals. Because Ubuntu Studio is based on Ubuntu, you are not limited to this area, but can install any application that is available for Ubuntu, thus turning Ubuntu Studio into a normal desktop for everyday use. This tutorial shows how you can turn Ubuntu Studio 7.04 into a full-fledged replacement for a Windows desktop. The advantages are clear: you get a secure system without DRM restrictions that works even on old hardware, and the best thing is: all software comes free of charge.

Have you ever wished you had another computer handy? Maybe you want to try a new operating system out. Maybe you want to test something experimental without potentially breaking your own system. Maybe you need to run some software that only runs in a different operating system. Mandriva Linux 2007 Spring comes with a range of virtualization options that can help.

In this article I will describe how you can monitor your Debian Etch server with munin and monit. munin produces nifty little graphics about nearly every aspect of your server (load average, memory usage, CPU usage, MySQL throughput, eth0 traffic, etc.) without much configuration, whereas monit checks the availability of services like Apache, MySQL, Postfix and takes the appropriate action such as a restart if it finds a service is not behaving as expected. The combination of the two gives you full monitoring: graphics that let you recognize current or upcoming problems (like "We need a bigger server soon, our load average is increasing rapidly."), and a watchdog that ensures the availability of the monitored services.

This article describes how you can back up MySQL databases without interrupting the MySQL service. Normally, when you want to create a MySQL backup, you either have to stop MySQL or issue a read lock on your MySQL tables in order to get a correct backup; if you do not do it this way, you can end up with an inconsistent backup. To get consistent backups without interrupting MySQL, I use a little trick: I replicate my MySQL database to a second MySQL server, and on the second MySQL server I use a cron job that creates regular backups of the replicated database.