Multiple Domains on one IP Address using Apache Virtual Server

Using Apache Virtual Servers it is easy to make multiple domains point at the same IP address displaying different content. You just have to add the following lines to the file /etc/httpd/conf/httpd.conf and restart apache:

NameVirtualHost *:80

<VirtualHost *:80>
ServerAlias *
DocumentRoot /var/www/html

<VirtualHost *:80>
DocumentRoot /var/www/samples

In this setup is displaying the content of /var/www/html while is displaying the content of /var/www/samples.

SSH Tunnel as Socks Proxy Server for the Web Browser

If you have SSH access to a remote host and you want to use it as proxy server for your web browser you can do so easily by opening up a SSH tunnel:

ssh -D 9999 -N

If you now set your socks proxy in your web browser to localhost, port 9999 your traffice is redirect via In firefox you can do so in Preferences->Network->Settings

PHP Multi File Uploader with Progress Bar using APC

Important Update: If you are using PHP versions greater 5.3 you should use our new multi-file uploader script which does not depend on the APC cache. You find it here:

For older PHP versions just continue reading.

This little PHP Script allows you to upload multiple files at a time to a webserver. It is pretty easy to install and can easily be adapted and extended to your specific needs. The Ajax progress bar the script brings is based on jQuery. For a proper operation of the script the Alternative PHP Cache (APC) has to be activated.

Where to get the script?

How to install APC on a linux server?

In Fedora Linux you need the following packages to install APC using the pecl command afterwards.

yum install pcre-devel  php-pear php-devel httpd-devel

pecl install apc

The file /etc/php.ini should contain the following lines:
apc.enabled = 1
apc.max_file_size = 2000M
apc.rfc1867 = 1

An introduction how to install it from the source code you find here.

If you are not sure if APC is installed at your server contact the administrator.

Burning MP3 using Fedora and K3b

If you want create Audio CDs from your mp3 files using Fedora K3b offers a easy way. To enable K3b to burn mp3 you have also to install the package k3b-extras-freeworld.

Like this it should work:

yum install k3b k3b-extras-freeworld 

Install a Telnet Server on Fedora

A telnet server on Fedora can be installed easily. Do the following as user root:

#install the server application
yum install telnet-server

# set on if you want to activate telnet at startup
chkconfig telnet on

# restart the internet services 
/etc/init.d/xinetd restart

Simple Linux Virtual Server Setup for Fedora 15 with LVS-DR forwarding

This post describes how to setup a simple Linux Virtual Server (LVS) using a director with Fedora 15 and direct routing (LVS-DR) as forwarding method. Setting up a LVS helps you to distribute the traffic of your website to various servers. This process is called load balancing. The instructions are based on the LVS-mini-HOWTO where further information can be found.
The purpose of this exercise is to distribute the traffic of a website between two (or more) servers which host a copy website. Furthermore persistent connections are required which means that a client is always redirected to the same server for a defined interval of time. For debugging as telnet (port 23) as http (port 80) are load balanced in this setup since testing for telnet is way more easier.

What do I need?

For realizing and testing this setup you need at least 3 nodes:

(1) A client to address the LVS
(2) A node the redirects the requests (director) and operates a real server at the same time
(3) A node that only works as a real server

Each node needs one network interface card (NIC).

You can add an arbitrary number of additional real servers to the setup to increase performance. The director and real server should have installed at least Fedora 15, for the client the operating system does not matter. The three nodes are located in the same network.

In our example the director has the IP address, the real server Both will share the virtual IP address under which the LVS will be reachable.

Preparations for node (2), the director:
Some steps have to be done manually, the rest of the configuration can be done by the configuration script.

Fedora 15 already brings the required kernel ip_vs modules therefore it is not necessary to patch the kernel.

In a first step we install the tool ipvsadm which we use and monitor to configure and the LVS.

yum install ipvsadm

Now we have to add the following lines to the file /etc/sysctl.conf:

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 0

# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

and afterwards run

sysctl -p

to update the kernel parameters.

The configuration script:

Replace “p5p1″ by the name of your NIC (often eth0) before running the configuration script:

#set ip_forward OFF for lvs-dr director (1 on, 0 off)
#(there is no forwarding in the conventional sense for LVS-DR)

#add ethernet device and routing for VIP
/sbin/ifconfig p5p1:110 broadcast netmask
/sbin/route add -host dev p5p1:110
#listing ifconfig info for VIP
/sbin/ifconfig p5p1:110

#check VIP is reachable from self (director)
/bin/ping -c 1
#listing routing info for VIP
/bin/netstat -rn

#clear ipvsadm table
/sbin/ipvsadm -C
#installing LVS services with ipvsadm
#add telnet to VIP with round robin scheduling
/sbin/ipvsadm -A -t -s rr
/sbin/ipvsadm -A -t -s rr
# persistent connection deactivated for it is difficult to debug
#/sbin/ipvsadm -A -t -s rr -p 600

#forward telnet and http to realserver using direct routing with weight 1
/sbin/ipvsadm -a -t -r -g -w 1
/sbin/ipvsadm -a -t -r -g -w 1
#check realserver reachable from director
ping -c 1

#forward telnet and http to the director itself using direct routing with weight 1
/sbin/ipvsadm -a -t -r -g -w 1
/sbin/ipvsadm -a -t -r -g -w 1
#check realserver reachable from director
ping -c 1

#displaying ipvsadm settings

In case you need persistent connections use the commented line in the script for that.

Preparations for node (3), the real servers:

Before running the configuration script you have also to modify the /etc/sysctl.conf at the real server. It has to contain the following lines. “p2p1″ has to be the name of the NIC (e.g. eth0).

net.ipv4.conf.p2p1.arp_ignore = 1
net.ipv4.conf.p2p1.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2

# Controls IP packet forwarding
net.ipv4.ip_forward = 0


sysctl -p

The standard gateway for the real servers can be any IP (eg. the client or a DSL router) in your network apart from that of the director. Change “p2p1″ to the name the NIC of your real server.

The configuration script:

#installing default gw for vs-dr
/sbin/route add default gw
#showing routing table
/bin/netstat -rn
#checking if DEFAULT_GW is reachable
ping -c 1

#looking for DIP
ping -c 1

#looking for VIP (will be on director)
ping -c 1

/sbin/ifconfig lo:110 broadcast netmask 0xffffffff up
#ifconfig output
/sbin/ifconfig lo:110
#installing route for VIP on device lo:110
/sbin/route add -host dev lo:110
#listing routing info for VIP
/bin/netstat -rn

Thats it! You can try to connect to your LVS now from the client by typing


The requests should be processed by the director and by the real server rotatory. You can check this by typing


at the director. In the output you should see “Active Connections” for both nodes. If that works you can try to connect via http e.g. by typing in your web browser.

If you want to reach your LVS from the internet you can setup IP forwarding from the relevant ports in your DSL router. The ports have to be forwarded to the virtual IP Deactivate all firewalls for testing!