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SSL-based VPNs were designed to eliminate the need for complex configurations on the user's PC. Unfortunately, that was before the dangers of public WiFi networks and tougher regulatory requirements came into being. Thanks to WiFi, many attacks that were difficult are now quite simple. In particular, a man-in-the-middle attack can intercept SSL-encrypted traffic, rendering SSL-based VPNs useless - even if it is protected by a typical one-time password system. The man-in-the-middle can easily feed the one-time password into the SSL-based VPN within the alloted time.

This tutorial provides step-by-step instructions on how to install Xen on an Ubuntu Feisty Fawn (Ubuntu 7.04) server system (i386). You can find all the software used here in the Ubuntu repositories, so no external files or compilation are needed. 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).

When reading a hint on the website of LinuxFromScratch I discovered the special capabilities of unionfs, specially in combination with chroot. Later I read a HowTo on a wikiwebsite of Gentoo, about entering a chrooted home directory when using a special script as shell. Combining these two brings me to using a chrooted environment, which you enter when logging in as a special user. This environment is an exact copy (mirror) of the system you are working on. Because you are in safe copy of the real system, you can do whatever you like, it will never change the system, everything stays inside the cache (the readwrite branch).

This article describes how you can monitor your Postfix mailserver with the tools Mailgraph and pflogsumm. Mailgraph creates daily, weekly, monthly, and yearly graphs of sent, received, bounced, and rejected emails and also of spam and viruses, if SpamAssassin and ClamAV are integrated into Postfix (e.g. using amavisd-new). These graphs can be accessed with a browser, whereas pflogsumm (Postfix Log Entry Summarizer) can be used to send reports of Postfix activity per email.

The intent of this article is to show you how to configure your Linux machine and Samba server to participate in a Windows 2003 Active Directory domain as a Member Server using Kerberos authentication. This involves using the security = ADS security mode in Samba.

Vsftpd is one of the most secure and fastest FTP servers for Linux. Usually vsftpd is configured to work with system users. This document describes how to install a vsftpd server that uses virtual users from a MySQL database instead of real system users. This is much more performant and allows to have thousands of ftp users on a single machine.

I want to show you how to install Xoops on Ubuntu. I used the Ubuntu 6.10 Server Edition, but it will probably work on other systems as well. Xoops is a modern Content-Management-System which can be extended with a variety of modules.

In this tutorial I will show how you can set up a Postfix mailserver as a backup mail exchanger for a domain so that it accepts mails for this domain in case the primary mail exchanger is down or unreachable, and passes the mails on to the primary MX once that one is up again.

This document describes how to install a Fedora 7 mail server based on Qmail Using Qmail Toaster. Qmail is an Internet Mail Transfer Agent (MTA) for UNIX-like operating systems. It is a drop-in replacement for the Sendmail system provided with UNIX operating systems. Qmail uses the Simple Mail Transfer Protocol (SMTP) to exchange messages with MTAs on other systems.

This is a detailed description about how to set up a Fedora 7 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, Dovecot POP3/IMAP, Quota, Firewall, etc. This tutorial is written for the 32-bit version of Fedora 7, but should apply to the 64-bit version with very little modifications as well.

Subversion is a free/open-source version control system. That is, Subversion manages files and directories over time. A tree of files is placed into a central repository. The repository is much like an ordinary file server, except that it remembers every change ever made to your files and directories. This allows you to recover older versions of your data, or examine the history of how your data changed. In this regard, many people think of a version control system as a sort of time machine.

Vlogger is a little tool with which you can write Apache logs broken down by virtual hosts and days. With vlogger, we need to put just one CustomLog directive into our global Apache configuration, and it will write access logs for each virtual host and day. Therefore, you do not have to split Apache's overall access log into access logs for each virtual host each day, and you do not have to configure Apache to write one access log per virtual host (which could make you run out of file descriptors very fast).

Sometimes it can be handy to set up your own repository to prevent from downloading the remote repository over and over again. This tutorial shows how to create a CentOS mirror for your local network. If you have to install multiple systems in your local network then all needed packages can be downloaded over the fast LAN connection, thus saving your internet bandwidth.

Getmail is a program for retrieving emails from remote servers; it is very similar to fetchmail, but more flexible. For example, it can be configured to deliver mails directly to a Maildir or mbox mailbox without the need for an MTA such as Postfix, but of course it can also pipe the mails through an MTA if you want. Getmail can use so called filters such as SpamAssassin and ClamAV to scan the mails, and you can even tell getmail to delete mails on the original server only after a certain number of days.

One of the challenges you may face when converting an office from Microsoft Windows to Linux is that many people archive their emails in PST files. There are PST tools available, but most of them are commercial, since the PST file format is closed and protected by Microsoft. There are several non-commercial methods to achieve roughly the same goal, and in this tutorial we use IMAP (more specifically, courier-imap) to convert all our emails from PST to the Maildir format. The advantage of this approach is that you also lay the foundation for a new mail system, with all your old emails already imported the day you switch over.

Each distribution has some specific tools to build a custom kernel from the sources. This article is about compiling a kernel on a Debian Etch system. It describes how to build a custom kernel using the latest unmodified kernel sources from http://www.kernel.org (vanilla kernel) so that you are independent from the kernels supplied by your distribution. It also shows how to patch the kernel sources if you need features that are not in there.

This tutorial shows how you can install eyeOS on a standard Linux system. EyeOS is a kind of operating system which works online, i.e. it manages files on the server and enables the user to upload, download and edit files.

This tutorial provides step-by-step instructions on how to install Xen on a CentOS 5.0 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, but still use the same hardware.

As you might have noticed on Centos 5.0, there is no PHP-MSSQL module/extension available in the default yum repositories. So if you want to use it you can alter the PHP binary or you can compile an mssql module/extension. In this article I will explain how to compile the mssql module/extension.

This tutorial provides step-by-step instructions on how to install VMware Server on a Fedora 7 desktop. 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).