RHEL 6, CENTOS6

MySQL Server is removed from Centos/RHEL 7 Repo

Big changes in open source world, i was just installing zabbix server and mysql database is required for zabbix. After installing Centos 7 from minimal install iso i didn't get mysql by "yum install mysql-server so  i came to know about changes that  "MySQL is no longer in CentOS’s repositories and MariaDB has become the default database" who knows mariaDB ?? 
any way you can still install mysql by installing official mysql community Yum's Repo file  for "yum install mysql-server"
Method : Download and install from this url
http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm 
or simply rpm -ivh http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm  



Gnu Sed Utility

Example :

removing # (commented Lines) from a file

sed '/ *#/d; /^ *$/d' /sourcefile >/destfile


 


Cactiez Backup Restore

Restoring Cacti Backup from old server in easy steps . 

Default Backup directory : /var/www/backups

tar -xzvf /var/www/backups/cacti-backup-year-month-Date.tar.gz

Data Base Import :

mysql cacti < /var/www/html/cacti-backup.sql
mysql syslog < /var/www/html/syslog.sql

Restart All CactiEz Services

Install centos6 from internet (netinstall)

Installing Centos6 / Rhel 6 From Network (Internet) :

We need ISO image from this links :  image size is only 170 MB. 

32 bit: http://linux.mirrors.es.net/centos/6.0/isos/i386/CentOS-6.0-i386-netinstall.iso
64 bit: http://linux.mirrors.es.net/centos/6.0/isos/x86_64/CentOS-6.0-x86_64-netinstall.iso

Burn Iso image to cd by your favorite image burner..


boot from cdrom and follow the instructions.

At Installation method menu select URL

configure ip address to access internet.

input this url  for netinstall :

http://mirror.centos.org/centos/6/os/i386 

Now install as normal installation.


how to make rouring in redhat 6

In RHEL6 / CENTOS6 /FEDORA you can add static roure by applying route add command. but it is a temporary route.

for static roure, you can do it by modifying route-eth files..

ath of file : /etc/sysconfig/network-scripts

modify route-eth0 or route-eth1 file on which Ethernet interface you want to add route,

if file is not present create a file

# vi /etc/sysconfig/network-scripts/route-eth0

add following lines :


ADDRESS0=X.X.X.X
NETMASK0=X.X.X.X
GATEWAY0=X.X.X.X
 
 
example : 
ADDRESS0=192.168.10.0       Destination Network Address 
NETMASK0=255.255.255.0      Destination Network Subnet mask
GATEWAY0=192.168.2.1        Gateway address for that network
 
 
IF YOU WANT MORE ROUTES TO BE ADDED, APPLY 1,2,3, ETC.




CentOS 6 Download Link

CentOS is a Fork / Clone of RHEL ( RedHat Enterprise Linux), Basically RHEL is a Linux Distribution Under GNU GPL License but not free. So CentOS is a project to provide Enterprise Linux Free of cost. There is no more technical difference between RHEL and CentOS. If you want to install RHEL, you must create account to download RHEL ISO file and it is evolution version so we highly recomend that you first try CentOS which is free and opensource..


These are the links for to download CENTOS 6 ISO File, Download it and Burn it on CD / DVD with your favourite Burning program.

CentOS 32 bit DVD ISO File 

CentOS 32 bit Live CD  ISO File

CentOS 32 bit Live DVD ISO File

CentOS 64 bit DVD -1  ISO File

CentOS 64 bit DVD -2  ISO File

CentOS 64 bit Live CD ISO File

CentOS 64 bit Live DVD ISO File 

How-to-Configure Network in RHEL6 Centos6

In RHEL6 and CentOS6 there is not System-Config-Network Script available which was very handy and useful.. Its good thing that now your require Basic Knowledge of Linux config File.. which is a best practice for Real  Unix / Linux Admins.

Basically /etc contains Config files for system.
for network there is a directory called /etc/sysconfig/network-script/  

There are ifcfg-eth(number)  file for every Ethernet interface  e.g ifcfg-eth0 for Ethernet 0, ifcfg-eth1 for Ethernet 1

Now create a file or Edit a file called /etc/sysconfig/network-script/ifcfg-eth0

------------------------------------------------------------------------------------------------------------

DEVICE=eth0

           IPADDR=192.168.0.1
           NETMASK=255.255.255.0
           NETWORK=192.168.0.0
           BROADCAST=192.168.0.255
           ONBOOT=yes
           BOOTPROTO=none
           USERCTL=no

------------------------------------------------------------------------------------------------------------


These are the values which you can configure in config file :



 DEVICE=devicename, where devicename is the name of the physical network device.


 IPADDR=ipaddr, where ipaddr is the IP address.


 NETMASK=netmask, where netmask is the netmask IP value.


 NETWORK=network, where network is the network IP address.


 BROADCAST=broadcast, where broadcast is the broadcast IP address.


 ONBOOT=answer, where answer is yes or no. Do the interface need to be active or inactive at boot time.


 BOOTPROTO=proto, where proto is one of the following :


 none - No boot-time protocol should be used.


 bootp - The bootp now pump protocol should be used.


 dhcp - The dhcp protocol should be used.


 USERCTL=answer, where answer is one of the following:


 yes - Non-root users are allowed to control this device.


 no - Only the super-user root is allowed to control this device.






no system-config-network in rhel6 centos6

Terminal Based Gui utility System-config-network for configuring ip address, subnet mask, gateway, DNS for each Network Connection is no longer supported in RHEL6.

There are so many changes in RHEL6 and its variants like CentOS6 and other.

It was really a very user friendly utility specially for newbies and Linux begginers...

Please Read our next post for configuring network interfaces in old classic Unix / Linux style... directly modifying config file.  





xen-hvm-qemu

 Xen-HVM

The Xen virtual machine monitor can run in HVM (hardware virtual machine) mode, using Intel VT-x or AMD-V hardware x86 virtualization extensions. This means that instead of paravirtualized devices, a real set of virtual hardware is exposed to the domU to use real device drivers to talk to.
QEMU includes several components: CPU emulators, emulated devices, generic devices, machine descriptions, user interface, and a debugger. The emulated devices and generic devices in QEMU make up its device models for I/O virtualization.
Xen-HVM has device emulation based on the QEMU project to provide I/O virtualization to the VMs. Hardware is emulated via a patched QEMU "device model" (qemu-dm) daemon running as a backend in dom0. This means that the virtualized machines see as hardware: a PIIX3 IDE (with some rudimentary PIIX4 capabilities), Cirrus Logic or plain VGA emulated video, RTL8139 or NE2000 network emulation, PAE, and somewhat limited ACPI and APIC support and no SCSI emulation.