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Tutorial: Install Postfix, Courier, MySQL, SquirrelMail on CentOS 6.2

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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'll also demonstrate the installation and configuration of Courier, so that Courier can authenticate against the same MySQL database Postfix uses. The resulting Postfix server is capable of SMTP-AUTH and TLS and quota. Passwords are stored in encrypted form in the database. In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin, ClamAV and SquirrelMail. read more...
mail this link | permapage | score:9575 | -falko, February 2, 2012

HowTo: HTTP Status: 206 Partial Content and Range Requests Using Curl

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The HTTP 2xx class of status codes indicates the action requested by the client was received, and processed successfully. HTTP/1.1 200 OK is the standard response for successful HTTP requests. When you type www.cyberciti.biz in the browser you will get this status code. The HTTP/1.1 206 status code allows the client to grab only part of the resource by sending a range header. This is useful for:

* Understanding http headers and protocol.
* Troubleshooting network problems.
* Troubleshooting large download problems.
* Troubleshooting CDN and origin HTTP server problems.
* Test resuming interrupted downloads using tools like lftp or wget or telnet.
* Test and split a large file size into multiple simultaneous streams i.e. download a large file in parts. read more...
mail this link | permapage | score:9508 | -nixcraft, November 21, 2012

VPS: Xen vs. OpenVZ

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This is a short overview of the key differences between OpenVZ and Xen that you might consider when choosing a VPS. Note that this article is based on my opinions and that you must do your own research to determine which, if either, technology is best for you and your application.

First, some terminology. OpenVZ isn't fully virtualized and could be more properly referred to as a 'container', not a VPS. That shouldn't affect your choice. It's the technical differences that matter.

Cheap VPS offers are everywhere lately, it seems. However, upon closer inspection I saw that almost all of the low-priced offers were for OpenVZ. While both Xen and OpenVZ offer their advantages, I chose Xen. So, there's my first bias, right up front. :)

OpenVZ advantages:

  • Efficient (fast)
OpenVZ disadvantages:
  • Shared kernel (no custom kernel)
  • Shared memory with other users
  • Vendor can easily oversell, killing performance
Xen advantages:
  • Dedicated memory
  • fully virtualized (can run other kernels or even OS's)
  • vendor more limited in overselling
Xen disadvantages
  • Less efficient (more overhead due to a kernel-per-VPS)

You'll notice I left price out of the above comparison. In theory, there should be a small price advantage for OpenVZ. I don't know how big it should be but it pertains to two things: 1) Xen uses more memory due to each VPS having its own kernel, and 2) Xen uses more CPU, also due to the additional software layer required to virtualize the kernel.

In practice, however, the price gap appears larger than the above technical differences suggest it should be. I think the remainder of OpenVZ's price advantage is based on 1) the ability for a vendor to easily oversell OpenVZ, and 2) The price competition that results from some vendors overselling OpenVZ.

OpenVZ doesn't encapsulate its containers into a fixed amount of memory, so it runs processes in the host environment to monitor memory usage and kill processes as a container allocates more than its assigned amount.

As a result of this difference, loading down an OpenVZ container is problematic. To partially offset this disadvantage, most OpenVZ vendors offer 'burst' memory in addition to 'dedicated' memory. That is, the monitor process is set to allow the container to use more than its allocated memory -- for a short period of time. This messy situation results in a potentially unreliable environment as some of your processes may be arbitrarily killed -- at the busiest times.

Xen, on the other hand, allows the use of a swap space and excess memory allocation results in (hopefully) idle segments being rolled out to the swap area. While this is good for the memory-hungry VPS user, it can consume significant I/O capacity when memory is overallocated to the point of busy segments getting swapped out. This is bad for everyone sharing the underlying hardware.

I see Xen as clearly the superior technology. A Xen VPS feels and behaves more like a dedicated server. However, I still would have purchased OpenVZ at some price difference. After a bit of research, however, I located Xen VPS's at practically the same price as the cheapest OpenVZ containers. That made my decision easy.

With that said, keep in mind that a bad hosting vendor can ruin either technology through various means. Both technologies share the disk drives and I/O paths as well as the processor cores. Hardware can be poorly configured and managed in any case. A reputable vendor is probably the single most important consideration in choosing a virtual server.

Lastly, carefully check the 'allowed use' policy. Make sure your application is allowed on the server you intend to purchase. Note that due to their different characteristics, the allowed use policy may differ between OpenVZ and Xen for the same host. Also, it's good to understand the memory usage characteristics of your applications. If you know how much memory/swap they require on a physical system, it'll probably work with that same amount of memory/swap on Xen.

[I'll post a review shortly of my current VPS vendor and I will then add a link to that article here.]

mail this link | permapage | score:9487 | -Ray, June 13, 2011

Install MySQL 5.6, memcached on Ubuntu 12.10

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According to What's New in MySQL 5.6, MySQL 5.6 will bring some performance improvements over MySQL 5.5. If you want to test out MySQL 5.6, you have to install one of the development releases from the MySQL downloads page because there is no stable release yet. This tutorial explains how to install the MySQL 5.6.8rc1 (Linux Generic) development release on an Ubuntu 12.10 server. read more...
permapage | score:9480 | -falko, November 21, 2012

CMS: Serendipity 1.0

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If you're looking to start a new website, take a look at Serendipity...
Serendipity is a PHP-based content management system (CMS) for powering blogs and other sites, and has a feature set that should make any blogger happy. After several years in development, the Serendipity team hit the 1.0 mark on June 15. Let's see how the 1.0 release shakes out.
read more...
permapage | score:9479 | -Ray, July 18, 2006

Apple DIY Repair

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I won't be buying any more Apple products. Here's why:

I'm generally capable of repairing my own equipment and can recognize when self-repair has been deliberately undermined. I recently had to replace a hard drive in an early generation white Intel iMac. Innocently, I believed the interior was accessible and serviceable in the manner of the externally identical white PowerPC iMacs.

No such luck. Not only do you have to remove the LCD to get to the hard drive, but you must also remove shielding around the LCD -- mostly by tearing it to bits. No doubt it is attached this way so that an authorized Apple technician will be able to confidently void your warranty if you've ever worked on the system yourself.

You'll also need a #10 torx magnetic screwdriver. And, no, #10 torx bits just won't do due to the narrow and deeply recessed screw holes. Also, since most torx screwdrivers aren't magnetic, you'll probably need to tape the screws to the screwdriver to reattach the LCD. Good thing there's a hardware store near you.

Oh, and don't forget to pick up some rubber cement to 'properly' reattach the hard drive temperature sensor while you're out looking for magnetic torx screwdrivers.

Considering the logical design of its predecessor and the tamper-evident shielding, I'm certain that this machine has been deliberately designed to prevent the owner from performing DIY upgrades and repairs.

While that is all quite annoying, at least working on the system is possible for someone with experience and determination.

Now, Apple has improved their anti-customer techniques with the 'Pentalobe' screw. It doesn't solve any problem but one: it'll keep customers from even being able to open the case.

If you're curious about Apple's evil new invention, you can read its rap sheet and view its mug shot here.
mail this link | permapage | score:9473 | -Ray, January 25, 2011

Tutorial: Replace Windows with Ubuntu 13.04

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This tutorial shows how you can set up an Ubuntu 13.04 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. read more...
permapage | score:9457 | -falko, May 5, 2013

Tutorial: Build an OpenSUSE 12.2 x86_64 Server

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This is a detailed description about how to set up an OpenSUSE 12.2 64bit (x86_64) server that offers all services needed by ISPs and hosters: Apache web server (SSL-capable) with PHP, CGI and SSI support, Postfix mail server with SMTP-AUTH, TLS and virtual mail users, BIND DNS server, Pureftpd FTP server, MySQL server, Dovecot POP3/IMAP, Quota, Firewall, Mailman, etc. Since version 3.0.4, ISPConfig comes with full support for the nginx web server in addition to Apache; this tutorial covers the setup of a server that uses Apache, not nginx. read more...
mail this link | permapage | score:9451 | -falko, September 12, 2012

Virtual users with Postfix, MySQL, SquirrelMail (Mandriva 2010.0)

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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'll 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 resulting Postfix server is capable of SMTP-AUTH and TLS and quota. Passwords are stored in encrypted form in the database. In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses. I will also show how to install SquirrelMail as a webmail interface so that users can read and send emails and change their passwords. read more...
mail this link | permapage | score:9442 | -falko, March 18, 2010

Setup a chroot environment on Ubuntu with debootstrap

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Chroot is used to setup a isolated environment inside a linux system where applications can run without interacting or affecting the host OS. It is often used to setup a 32bit environment inside a 64bit OS to run legacy/old applications. This tutorial shows you how to do that. read more...
permapage | score:9430 | -Silver Moon, August 11, 2013

ownCloud 4.0 on CentOS 6.2

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This document describes how to install and set up ownCloud on CentOS 6.2 on an nginx web server and php-fpm with postgreSQL database as backend. For other distributions there might be minor changes as to the software prerequisites installation procedures. This guide will not only help install the product, but also understand why certain points are done the way they are done. read more...
permapage | score:9398 | -falko, June 5, 2012

Install a Mail Server with Antivirus and Antispam in minutes

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This article illustrates a situation where you need to set up your own mail server (be it your home mail server, or a small office one). It actually shows that, if using an integrated service mail server, anyone can do the job, all in a matter of minutes.

AXIGEN Mail Server, the solution chosen for this example, can send and receive e-mails securely via "mydomain.com" and is able to retrieve them in a WebMail interface - this means that it includes all mail services needed for a fully functional mail server (SMTP, IMAP, POP3, WebMail, WebAdmin).

To get an idea of the amount of time you can spare by installing such a solution, just think of all the different open source applications you would need to install instead (i.e. an MTA, Squirrelmail for Webmail, QmailAdmin for web configuration, Courier for IMAP and POP3 and many others.)

AXIGEN Mail Server can virtually integrate with any Antivirus/Antispam application and it comes with built-in connectors ClamAV Antivirus and SpamAssassin. The second part of this article shows you how to install these applications and configure these connectors for use with AXIGEN.

Thus, at the end of this process which can take up half an hour at most, you will not only have your mail server up and running, but also virus and spam protection for your incoming and outgoing mail traffic.

AXIGEN runs on several Linux distributions (Gentoo, Redhat/Fedora Core, Slackware, Debian, Ubuntu, Mandrake/Mandriva, SUSE), on BSD versions (FreeBSD, OpenBSD and NetBSD) and on Solaris but for the purpose of this article, let's suppose you are setting up your mail system on a Fedora Core 6 platform.In five easy steps, you will have your server installed, your primary domain running and access to the Web configuration interface (WebAdmin).

1. Download / unpack corresponding package

Download AXIGEN rpm package from the AXIGEN website (packages are available as 30 day evaluation versions). Save the corresponding package for Fedora Core 6 "axigen-2.0.4.i386.rpm.gcc4.tar.gz" on your local machine and unpack the file, by issuing in the same directory as the download file:
tar xzvf axigen-2.0.4.i386.rpm.gcc4.tar.gz

2. Install command

Then, in order to install the RPM package, issue (while logged in as root) the following command, from the same directory as the rpm file:
rpm -ivh axigen-2.0.4.gcc4-1.i386.rpm
This will create the entire directory structure needed for AXIGEN to run. After the installation, no daemons or related application will be started.


3. Configuration options

AXIGEN provides several configuration options (configuration file, Command Line Interface), but the most intuitive and comprehensive one is WebAdmin, the Web configuration interface.

The corresponding WebAdmin service is enabled by default, as well as the other default services: IMAP, Logging, POP3, Processing and SMTP.

4. Initial configuration

The first configuration steps take place using the configuration wizard. You will set the administrator's password, select which services are started and what interfaces will be used. In this stage of the setup you also create the primary domain that your server will use.


The wizard can be run by issuing the following command in the console right after the installation of the package has finished:
/opt/axigen/bin/axigen-cfg-wizard
NOTE: You have to make sure you do not start the mail server before the initial configuration.

5. Start AXIGEN

You can then start AXIGEN, using its initscript, by issuing this command:
/etc/init.d/axigen start
Now that your server is running, you can connect the antivirus and anti-spam applications. By default, AXIGEN comes with connectors for the ClamAV Antivirus and SpamAssasin Antispam application. The setup process below describes how to make these two applications work with AXIGEN. However, note that AXIGEN implements a proprietary filter scripting language that allows you to implement connectors for any third party Antivirus and Antispam applications.

Connecting to ClamAV


A. Install ClamAV (daemon), on the same machine on which AXIGEN Mail Server is installed. Follow these steps in order to configure ClamAv for use with AXIGEN and start the clamd daemon.

1. Install clamav-server, using yum (Yellow Dog Updater, Modified):
yum install clamav-server
2. Copy the sample config file shipped with clamav-server:
cp /usr/share/doc/clamav-server-*/clamd.conf /etc/clamd.d/axigen.conf
3. Edit: /etc/clamd.d/axigen.conf
# comment out the Example line 
# Example
# insert/modify the following lines:
LogFile /var/log/clamd.axigen
PidFile /var/run/clamd.axigen/clamd.pid
LocalSocket /var/run/clamd.axigen/clamd.sock
User axigen
4. Create a link to the clamd binary:
ln -s /usr/sbin/clamd /usr/sbin/clamd.axigen
5. Create the run directory, where the PID file and clamd socket will be stored, and change its permissions:
mkdir -p /var/run/clamd.axigen chown axigen:axigen /var/run/clamd.axigen
6. Create and setup the initscript:
cp /usr/share/doc/clamav-server-*/clamd.init /etc/init.d/clamd.axigen 
chmod 755 /etc/init.d/clamd.axigen /sbin/chkconfig clamd.axigen on
7. Edit: /etc/init.d/clamd.axigen and modify the following lines, as specified below:
# description: The clamd server running for axigen CLAMD_SERVICE=axigen
8. Finally, start the clamd daemon:
/etc/init.d/clamd.axigen

B. Configure AXIGEN antivirus filter at server level using WebAdmin

In order to activate the ClamAV filter, go through the following steps:

In the "Server" context, click on the Add new filter button. This will open up and display the Active Filter list. It is empty right now, so we need to add the clamav filter to the list.



In the Priority field, enter a priority between 0 and 500 (a filter with priority 0 will be applied first and the one with 500, last).

Important - the domain-level filters have the priority limited to range 100-400 and the user-level filters are limited to the 200-300 range. A value of "10" should be fine, leaving you space to apply some other future filters before this one.

After setting the filter priority, select the socket value from in the Filter type dropdown list and the clamav value from the Filter Name list.

In the Apply on checklist, select the relay option, to apply the filter on outgoing mails. To make sure you scan both incoming and outgoing mails, you have to create the filter and select both values, local and relay.

In AXIGEN, it is possible to enable filters either at domain or user level, in the corresponding WebAdmin tabs. The filters activated at server level will be automatically applied for all domains and accounts. However, you have the possibility to add additional filters at domain or account level.

Connecting to SpamAssasin


The process for Connecting SpamAssassin is similar and even less time-consuming as no configurations are necessary after the product installation.

C. Install SpamAssassin using the yum application:
yum install spamassassin
No further configurations are necessary.

D. Configure SpamAssassin at server level, using Webadmin

The connector for SpamAssassin is a socket filter for AXIGEN, so the configuration procedure is the same as for ClamAV. The difference would be that for SpamAssassin, a TCP socket is more likely to be used.

Also, when activating the SpamAssassin filter, you need to keep in mind the following:
  • Enter a different priority value for the SpamAssasin filter (if you have chosen 10 for ClamAV, choose a higher value for SpamAssassin in order to apply this filter after ClamAV in the filtering chain)
  • Select the corresponding filter name, spamassassin in the Filter name list

Access AXIGEN WebMail


At this step of the way, your mail server is ready to go, and you can also you can access the AXIGEN WebMail to send and receive test messages. Then, use the full email address and password to log on to AXIGEN WebMail, at the default address: http://127.0.0.1:8000, or use the address you specified in the initial configuration phase when you ran the setup wizard.


Now you're really done: you can securely send and receive messages from your home domain and easily make any further configurations, to accommodate your specific network requirements. As you have seen, installing all mail services from one single executable and an intuitive Web configuration interface make things a lot easier and a lot less time-consuming.

Authors:
Liviu Anghel, Chief Security Officer, Gecad Technologies
Ciprian Negrila, Technical Support Engineer, Gecad Technologies

read more...
mail this link | permapage | score:9381 | -Kayla Vincent, February 6, 2007

UnixLite: A Light GPL Unix in C++

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You can browse the source code right on the website. I'm not sure how long they will be able to use that name though...
UnixLite is a lightweight unix/linux compatible operating system written in c++, it is open source and released under the GNU General Public License.The complete operating system is made up of kernel and applications, just like linux, unixlite is only the kernel. The kernel itself is written from scratch and the most part is written in c++, however, the library used by unixlite comes from uClibc and applicaitons running on unixlite comes from GNU project.
read more...
mail this link | permapage | score:9378 | -Ray, June 13, 2006

Common PHP database problems

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Databases are powerful tools, and -- like all powerful tools -- they can be abused if you don't know how to use them properly. You can create database design, database access, and the PHP business logic code that sits on top of it in any number of ways, and you often end up getting it wrong. This article illustrates five common problems in database design, in the PHP code that accesses databases, and how to avoid them. read more...
permapage | score:9375 | -solrac, August 2, 2006

Tutorial: Install Lighttpd, PHP5, MySQL on CentOS 6.4

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Lighttpd is a secure, fast, standards-compliant web server designed for speed-critical environments. This tutorial shows how you can install Lighttpd on a Centos 6.4 server with PHP5 support (through PHP-FPM) and MySQL support. PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI implementation with some additional features useful for sites of any size, especially busier sites. I use PHP-FPM in this tutorial instead of Lighttpd's spawn-fcgi. read more...
permapage | score:9375 | -falko, April 17, 2013

Server Monitoring With munin And monit On Debian Wheezy

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In this article I will describe how you can monitor your Debian Wheezy server with munin and monit. munin produces nifty little graphics about nearly every aspect of your server 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 lets you recognize current or upcoming problems, and a watchdog that ensures the availability of the monitored services. read more...
mail this link | permapage | score:9358 | -falko, June 27, 2013

MultiSystem: Live USB MultiBoot

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Put more than one bootable Linux distribution on that big USB flash drive...
Installation instructions can be found at http://liveusb.info/dotclear/index.php?pages/install, where several install methods are available. After installing MultiSystem, open it, and follow the steps. I received an error message in French saying that Multiboot does not like spaces in the USB Stick's name. I renamed the stick and then logged out and back in to make it work. Below are screenshots of the whole process.
read more...
mail this link | permapage | score:9331 | -Ray, April 19, 2011

VirtualBox 4.2.10 released and ubuntu installation instructions included

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VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL) version 2. read more...
permapage | score:9326 | -gg234, April 4, 2013

Tutorial: Install Nginx, PHP5, PHP-FPM, MySQL on Fedora 19

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Nginx (pronounced "engine x") is a free, open-source, high-performance HTTP server. Nginx is known for its stability, rich feature set, simple configuration, and low resource consumption. This tutorial shows how you can install Nginx on a Fedora 19 server with PHP5 support (through PHP-FPM) and MySQL support. read more...
permapage | score:9316 | -falko, August 4, 2013

Tutorial: Running CS-Cart on Nginx on Debian 7/Ubuntu 13.04

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This tutorial shows how you can install and run CS-Cart on a Debian Wheezy or Ubuntu 13.04 system that has nginx installed instead of Apache (LEMP = Linux + nginx (pronounced "engine x") + MySQL + PHP). nginx is a HTTP server that uses much less resources than Apache and delivers pages a lot of faster, especially static files. read more...
permapage | score:9304 | -falko, August 21, 2013
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