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Archive for December, 2009

Dec 27
2009

Linux: Determining IP information for eth0… failed

Last updated: December 27th, 2009

When setting up a workstation to connect to internet, you may come across a message
Determining IP information for eth0… failed

The above error message basically means that eth0 i.e your network interface card is not setup correctly.

Some of the commands that can come handy in troubleshooting where the error lies are listed below

$ dmesg | grep eth0
(displays information about the ethernet controller card, mac address etc.)

$ cat /etc/sysconfig/network(displays the network settings)
NETWORKING=yes
HOSTNAME=localhost.localdomain
GATEWAY=192.168.122.1

$ cat /etc/sysconfig/network-scripts/ifcfp-eth0

$ ifconfig eth0 down (to down the nic)
$ ifconfig eth0 up (to start the nic)
$ netstat -rn (display kernel routing IP table)
$ cat ifcfg-eth0 (eth0 configuration settings)
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:16:18:33:B3:CF
ONBOOT=yes

$ service network restart (restart the network settings)

$ ping -c4 google.ca(to check if the internet connection works)

$ traceroute google.ca (to check how the IP navigation path is set)

Refer Red Hat linux 5 configure network article for additional info

Dec 06
2009

HTTP-Header: User-agent modification

Last updated: December 5th, 2009

When a browser makes a request to the server, it sends information such as its operating system name, version in addition to the type of the browser from which the request originates in the header variable “user-agent”.

Depending on the request made, server responds back with specific details which can range from browser specific css layout to calling certain javascriptsfor certain browsers.

Changing the user-agent also helps us in understanding how spider-agents or bots will see the pages that we build. It also helps us design applications that will mimic a request as originating from a mobile phone and helps us in viewing the behavior of the application in different mobile clients.

To read more about HTTP-Headers check ietf

Dec 05
2009

Virtual World: with VMWare Player

Last updated: December 4th, 2009

VMWare Player is a free software available from VMWare Inc. enabling the creation
of guest OS within an existing OS

Notes for a beginner …
* VMWare Player and VMWare Server are available for free
* A .vmdk file is the virtual hard drive for the guest OS
* A .nvram file stores the BIOS settings of the virtual machine
* A .vmx file stores the configuration settings for the virtual machine. All you
need is a text editor to edit the VMWare configuration settings.
* A .vmsd file stores information about VMWare snapshots.
(more…)

Dec 04
2009

LogMeIn, Hamachi: Create VPN in minutes

Last updated: December 3rd, 2009

Managed or Unmanaged networks? Create a VPN in minutes with this software which is available FREE of cost for non-commercial use.

Setting up a Virtual Private Networks is as easy as clicking through the buttons. Check out this product at LogMeIn

Dec 03
2009

Ubuntu: How to check if a software is installed in ubuntu?

Last updated: December 3rd, 2009

Command used to check if a particular software is installed in Ubuntu or not

$ dpkg-query -s firefox

This is the equivalent of “rpm -qa firefox” in RedHat/CentOS


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