Creating Permanent Bridged Network Interface

This is very useful in many cases like if you want to add additional security layer using firewall or if you want to rum KVM virtualizaions with permanent interfaces accessed by the hosts as if the guest is a real machine.

I am using Centos 6.2 64 bit and I am using DHCP for assigning IP addressed and DNS and other configurations

1. Install bridge-utils :yum install bridge-utils
2. Bring down the interfaces eth0 : ifdown eth0
3. Edit the configuration file of the eth0 interface to use the bridge and create a new file for the bridge :

vi /etc/sysconfig/network-scripts/ifcfg-eth0
    DEVICE="eth0"
NM_CONTROLLED="yes"
ONBOOT="yes"
HWADDR=64:31:50:04:93:B9
TYPE=Ethernet
BOOTPROTO=dhcp
DEFROUTE=yes
PEERDNS=yes
PEERROUTES=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0"
#
BRIDGE=br0

The most important line is BRIDGE=br0 where br0 is the name of the bridge device we shall create.

vi /etc/sysconfig/network-scripts/ifcfg-br0

DEVICE=br0
TYPE=Bridge
BOOTPROTO=dhcp
ONBOOT=yes
DELAY=0

Note the line TYPE=Bridge

4. The most important part that peventing the bridge from functioning properly was the line :  UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 in the ifcfg-eth0 file so I commented it out.

5 .Bring up the interfaces : ifup eth0 ; ifup br0;

6. Configure the iptables firewall to accept connections from the new bridge interface br0 :

 vi /etc/sysconfig/iptables
 
Add this line : -A INPUT -i br0 -j ACCEPT

7. Restart the iptables and network services

 service network restart
 service iptables restart

That is it !

Installing ATI proprietary driver on Centos 6.2

ATI proprietary driver provides many features like 3D accelaration and surpasses the open source driver.Below is the steps of installing it.

* All commands issued as root

1.Enable the Elrepo repository :rpm -Uvh http://elrepo.org/elrepo-release-6-4.el6.elrepo.noarch.rpm

2.Install the fglrx-x11-drv and kmod-fglrx packages : yum install kmod-fglrx fglrx-x11-drv

3.Generate and initialize the new driver : aticonfig --initial

4.Now you have to reboot the system.

5.If you got a black blank screen you need to append "nomodeset" on the kernel in the grub boot loader entry for Centos.To make this permanent you have to edit the grub configuration files to make a new entry with this new option 

  5.1 Create a new file in /etc/grub.d/XX_anyname where XX is a number which is greater than the greater number of scripts in this directory, for example if you have scripts like 11_kdjk 30_linux 40_custom, create a file 50_mynewEntry

6.Edit the file adding your centos with nomodeset boot option.I copied the existing centos entry generated by the system and pasted it adding the option :

#!/bin/sh -e
echo "Adding My Centos 6.2 with nomodeset option for fglrx to work ..."
cat << EOF
set root=(hd0,4)
menuentry "Centos 6.2 with nomodeset for proprietart ATI driver" --class gnu-linux --class gnu --class os {
        insmod part_msdos
        insmod ext2
        set root='(hd0,msdos4)'
        search --no-floppy --fs-uuid --set=root f1c65fc9-acfc-4a39-974b-6c6c38cb29f7
        linux /boot/vmlinuz-2.6.32-220.7.1.el6.i686 root=/dev/sda4 nomodeset
        initrd /boot/initramfs-2.6.32-220.7.1.el6.i686.img

}

7.Run update-grub2 or grub-mkconfig then grub-install /dev/sda

(replace /dev/sda) with your hard drive if necessary)

8.Reboot and select your new entry. That is it !