Installing VirtualBox on Fedora 15 (Lovelock) Host

June 7, 2011

Update 16 Nov 2011

Hi, check out my new post Install VirtualBox on Fedora 16 Host. The procedure is very much the same, you can use the instructions below for Fedora 15 and Fedora 16.

Installing VirtualBox on Fedora 15 Host System Using YUM

$sudo cp virtualbox.repo /etc/yum.repos.d/
  • Install dkms using the command
$sudo yum install dkms
  • Unlike the previous practice, now you need to specify the version number in order to install VirtualBox. This allows user flexibility to install the previous version of VirtualBox instead of the latest version. The following versions are available:
  • virtualbox-4.0 (latest)
  • virtualbox-3.2
  • virtualbox-3.1
  • virtualbox-3.0
  • virtualbox-2.2
  • virtualbox-2.1
  • virtualbox-2.0
  • To install the latest version of VirtualBox use the command
$sudo yum install virtualbox-4.0


An installation script was created to automatically configures the repository file and install VirtualBox 4.0. If you would like to use earlier version of VirtualBox, please modify the script yourself. You can download the script at FC15-vbox-install-noarch



Basic Network Configuration in Linux

December 14, 2009

This network configuration guide is based on Fedora.

Configuration Tools

Text console configuration tool:

  • /usr/sbin/system-config-network-tui
  • /sbin/ifconfig

Using ifconfig:

  • ifconfig – display running network configuration
  • ifconfig -a – display all (running or not running network device) network configuration
  • ifconfig <interface> up – bring up the specified interface network
  • ifconfig <interface> down – bring down the specified interface network
  • ifconfig eth0 netmask – setup a network interface with a specific IP address and sub-net mask
  • For further usage check #man ifconfig

Network Configuration Files

/etc/sysconfig/network – Defines your network and some of its characteristics.

The settings are:

  • HOSTNAME=localhost.localdomain

/etc/sysconfig/network-scripts/ifcfg-eth* – This is a configuration file for each network interface card. For eth0 the path would be /etc/sysconfig/network-scripts/ifcfg-eth0

The settings are permanent; some of the entries are shown below:

  • DEVICE=eth0
  • HWADDR=00:03:10:22:45
  • #For permanent fixed IP address
  • ONBOOT=yes
  • BOOTPROTO=none

/etc/networks – Provides a database of network names with network addresses similar to the /etc/hosts file.

The settings are:

  • Default
  • Loopback
  • Link-local

/etc/hosts – Defines local hosts.

The settings are:

  •  localhost  localhost.localdomain
  • mymachine

/etc/host.conf – Specifies order to search for host name for name resolution.

The settings are:

  • Multi on
  • Order hosts, bind

/etc/resolv.conf – Contains the address of name server

The settings are:

  • Nameserver

Configuring Ethernet Manually

Fixed IP

  • Ifconfig to set IP address and bring up the network card

#ifconfig eth0 netmask up

  • To setup the network routing

#route add -net netmask eth0

  • Use route add or ip to add default gateway

#route add default gw eth0

  • DNS for the network

Add “nameserver” at /etc/resolve.conf

  • Note: Please note that the above measure is temporary. To permanently set ip address, gateway and dns use system-config-network-tui.
  • Once you set fixed IP, netmask, gateway and DNS. The information will be recorded in etc/sysconfig/network-scripts/ifcfg-eth* as follows;
    • DEVICE=eth0
    • HWADDR=00:05:20:15:36
    • #For permanent fixed IP address
    • IPADDR=
    • NETMASK=
    • ONBOOT=no
    • BOOTPROTO=none
  • Note: If you have hard coded fixed IP in the config file ifcfg-eth*, if you type #ifconfig eth0 up, it will not configure the fix IP from the file, the eth0 is up with no address assigned.
  • Therefore, a proper way to completely bring up and down the network interface card (NIC) is to use #ifup and #ifdown instead of ifconfig.
  • If eth0 is down for some reason, using #ifup eth0 will turn on the NIC with all address, gatway and DNS configure in the file
  • The console utility (system-config-network-tui) do not have the ability to set the configuration such that eth0 is turn on during startup, to do this we must manually change to ONBOOT=yes.
  • If eth0 still will not turn on during startup; this is because the service network is not turn on.
  • To turn on the network service during startup, use the command #service network start
  • To permently turn on the network service #chkconfig network on

DHCP Client

  • If inside the file ifcfg-eth0,the entry ‘BOOTPROTO = none’ or there is no entry on BOOTPROTO use the following:
    • #ifup eth0
    • #dhclient
  • If inside the file ifcfg-eth0, the entry ‘BOOTPROTO = dhcp’ use the following:
    • #ifup eth0
  • Note: To configure BOOTPROTO just run the utilities system-config-network-tui
  • However, the console utility do not have the ability to set the configuration such that eth0 is turn on during startup, to do this we must manually change the file etc/sysconfig/network-scripts/ifcfg-eth*; ONBOOT=yes
  • Then make sure service Network is started and set to turn on permanently with the command #chkconfig network on

Alternative method of starting network

  • Add the following at /etc/rc.d/rc.local
    • # ifup eth0
  • or
    • # dhclient eth0
  • Note: Using local startup script, there is no need to turn on network services

Network Manager (New)

  • A new way of managing network is to install the package NetworkManager which does the management of network automatically.
  • NetworkManager is designed to replace all other network configuration. It includes all types of network from Ethernet to wireless network.
  • Use the command #yum install NetworkManager
  • Using NetworkManager, you still need tp ensure that the settings for eth* is setup properply. You need to ensure that ONBOOT=yes.


Choosing Between 32-bit or 64-bit Linux Operating System

December 7, 2009

When considering whether to use 32-bit or 64-bit Linux, you should consider the need and the usage of the system. If you have proprietary hardware, the drivers and software are usually written in 32-bit. You would also have less problem with software installation such as Adobe Flash player, Adobe Air and most media player, since most of them were written in 32-bit.

You could still install and use 32-bit software in a 64-bit operating environment. However, you need to download all the 32-bit libraries, wrapper and component for installation and compilation. This will increase your hard disk space since you need to maintain both 32-bit and 64-bit libraries.

You should consider using 64-bit operating system if you need to use a particular software application that requires speed and large amount of memory which is supported in 64-bit Linux. If you have more than 3GB of RAM, you should consider using 64-bit operating system because the 32-bit operating system only recognizes 3GB of RAM.

You could use some 32-bit Linux that addresses more than 3GB of RAM. Such Linux must supports PAE (Physical Addressing Extension), a feature provided by Intel.

Intel64 vs IA64

December 6, 2009

Intel64 and IA64 are two very different instruction set and architecture used in the Intel processor.

Intel 64 (formerly known as EM64T or IA32e) is the 64-bit extended instruction set based on x86 processor architecture. Modern processor that incorporated Intel64 technology could also run 32-bit application on a 32-bit operating system without performance losses although the 32-bit operating system would not be able to utilize any features in the Intel64 technology. The reason for such design is for backward compatibility which is the key to the success of Intel x86 processor.

IA64 however is based on an entirely different architecture. Only Intel Itanium processor employs IA64 architecture. It does not provide any backward compatibility with the IA32 software. the emulation of such 32-bit application is very slow. Originally Intel incorporated hardware emulation to the 32-bit application but since then Intel has been relying on software emulation.

For further information, you can visit the following sites:

Transfer Rate (bps or Bps)

December 6, 2009

When we talk about data transfer rate, I am surprise that some IT professionals get confused with the differences between bps and Bps.

bps (bits per second) is usually used for raw data transfer speed between two identical devices. It is commonly used for USB, FireWire, Wi-Fi and networking devices.

Bps (Bytes per second) usually refers to the data transfer rate of files. It is commonly used to describe the data transfer rate of PCI bus, ATA, SATA and SCSI devices.

As you can see, different type of devices uses different type of transfer rate. Things starts to get complicated when you decided to purchase an external hard disk with USB, FireWire or eSata connection. This is where confusion started.

1 Byte = 8 bits. Therefore a 512kbps is 64kBps. The formula is as follows:

1k bits = 1024 bits

512k bits = 512 x 1024 = 524,288 bits

Since 1 Byte = 8 bits, 524288 bits can be expressed as

524288/8 Bytes = 65536 Bytes

To convert 65536 Bytes to KBytes

65536/1024 = 64kB

Therefore 512kbps = 64kBps

We can just simply divide 512 by 8 (512/8) = 64kBps

I had compiled a list of various system buses and its transfer speed for comparison purpose:

Mbps MBps
USB 1.0 2 0.25
USB 1.1 12 1.5
USB 2.0 HS 480 60
1394a (FW400) 400 50
1394b (FW800) 800 100
10 BaseT 10 1.25
100Base T 100 12.5
1000BaseX 1000 125
802.11b 11 1.375
802.11g 54 6.75
802.11n* 540 67.5
PCI 1064 133
AGP 2X 4264 533
AGP 4X 8528 1066
AGP 8X 17064 2133
PCIe 1x 2000 250
PCIe 2x 4000 500
PCIe 4x 8000 1000
PCIe 16x 32000 4000
ATA66 528 66
ATA100 800 100
ATA133 1064 133
SATA150 1200 150
SATA300 2400 300
eSATA 2400 300
Ultra SCSI 320 2560 320


* For 802.11n Wi-Fi, the transfer rate ranges from 300Mbps to 540Mbps. Existing working product works at 300Mbps. There is an attempt to push the transfer rate to a maximum of 600Mbps.

So if you bought an external hard disk with USB connection, the transfer rate will be limited to the USB transfer rate.

Please note that USB 3.0 (coming soon) with a transfer rate of 625MBps should solve the limitation of the USB transfer rate and in this case your maximum data transfer rate will be limited to your ATA or SATA hard disk transfer rate.

Please note that the list mentioned above are theoretical rate which is tested under a very specialized environment, in practice we can never achieve 100% of the advertised rate.

For Wi-Fi, please note that although there are a lot of products advertise as compliant to 802.11n specification. The official standard has not yet been finalized.

There is a study taking into consideration of network overhead as shown below:

Typical rate after consider network over head

range (unblock) Mbps MBps
802.11b (100m) 6.5 0.8125
802.11g (75m) 25 3.125
802.11n (125m) 200 25

The abovementioned table is just one of the many studies conducted to test the effective Wi-Fi throughput. For more updated results, please search the Internet.

Tech Tips: Windows Vista – Speed up Booting Time

December 6, 2009

In Windows Vista, you can speed up the boot time by requiring the processor to boot using 2 processor. This is provided you are using Dual Core or Core 2 CPU.

To change the setting, type msconfig under the start search panel.


Once you have launched msconfig.exe, select <Boot> tab


Click <Advanced options…>


In the panel, top left corner, it shows number of CPU with a 1 in the list box. Change it to 2.


You need to restart the PC.

Tech Tips: Windows – Modify ‘Send To’

December 6, 2009

To modify ‘Send To’, we must get to the ‘Send To’ folder which is located at %APPDATA%\Microsoft\Windows\SendTo

The location %APPDATA% should be at C:\users\<username>\AppData\Roaming

In this ‘Send To’ Folder, you can add any shortcuts you want and it will be included under Send To.