RedHat Enterprise Linux 6 Beta released.

Good news for all the RedHat enthusiasts: Red Hat Enterprise Edition 6 Beta has released. This beta release is the first step forward to the next major release of the Red Hat Enterprise Edition platform 6. Red Hat Enterprise Linux is expected to address the modern IT requirements and diminish the gap between virtual, physical and cloud computing. This first beta release of the RHEL 6 features updated core technology from the kernel to the application infrastructure to the development tool chain. RHEL 6 is going to meet the needs of the coming generations of hardware and software technologies.

The major themes of the release include pervasive virtualization, improved scalability and availability, increased power efficiency, and delivery of some of the latest software technologies. Now I will describe the highlights and noteworthy improvements in this RHEL 6 beta release.

• Comprehensive power management capabilities:

RedHat Enterprise Linux 6 is more focused on power consumption by improving the 'Time-keeping' within the kernel. It helps to transit the processors which don't have active tasks to idle state frequently. The result is cooler CPUs and greater power savings. The new monitoring tools like 'powertop' and tuning tools like 'tuned' are also worth mentioning.

Set multiple IPs in single nic.

Hello guys...
Ever wondered how to set multiple IPs in a single network card? Here is the solution.

Multiple IP binded in a single network card allows you run different services in different IPs, for example you can run HTTP on one IP and SMTP on another IP or a private LAN using a local IP and the alias holding your Public IP. The major benifit here is that you do not need an additional physical adaptor, you can bind many virtual IPs to a single network card. Here I have explained the procedure for creating multiple IPs for RedHat based and Debian bases systems

Redhat based systems.

Let me assume that your NIC is bound with a static IP address. Go to the folder /etc/sysconfig/network-scripts/, there you will find your network configuration files.

# cd /etc/sysconfig/network-scripts/

Let me also guess that your machine has only one network card (can be onboard too!!!), then you will find a file ifcfg-eth0 in the folder. This file holds the IP information for the first nic. If your machine has more nics you will have ifcfg-eth1, ifcfg-eth2 and so on... Now open the ifcfg-eth0 file, you can view the network configuration as below:

# cat ./ifcfg-eth0# File: ifcfg-eth0


DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.1.120
NETMASK=255.255.255.0
BROADCAST=192.168.1.255
NETWORK=192.168.1.0
HWADDR=xx:xx:xx:xx:xx:xx

Now to bind another IP address to the same network card, you just have to copy the ifcfg-eth0 file to ifcfg-eth0:1.
 
# cp ./ifcfg-etho ./ifcfg-eth0:1

RHEL 5.5 Released

Yea guys, the Red Hat Inc. has launched its 5th iteration of the Red Hat Enterprise Linux 5, RHEL 5.5 on March 29, 2010. There is no doubt that it would be a great release.


Added Hardware support in RHEL 5.5
It features support for modern Intel Nehalem EX, AMD Opteron 6000 amd IBM Power 7 processor based servers. These processors above specified are the promissing releases from said vendors. Intel has just released the Nehalam EX series in the same week and the other two, AMD Opteron 6000 series and Power 7 from IBM were released in last February 2010. Opteron 6000 series processosr boasts of 12 cores and IBM has equipped their Power7 with eight cores.

Install Linux in USB pen drive

Now a days every one have a USB flash drive with them.Now what if a cool small Linux OS is installed on it and booting from the flash drive with the expense of merely a 200 MB space. I think its quiet cool to have a pen drive installed with an operating system. Today I am going to discuss the same thing with you people.

There are a number of Linux distros available for installing in a flash drive. However I think 'Slax' is the coolest one and here I am selecting the same in this post. Slax is actually a customized version of the famous 'Slaxware Linux'. The Slax will give you a full fledged Live OS environment from your pen drive.

Let me give you an intro of the slax distro. As I mentioned earlier, slax is a stripped down version of the Slaxware Linux. It is available in two formats, .iso and .tar. However the contents of both are same. You can convert the iso image to tar and vice verse. Actually the iso is for writing to a compact disk and booting from it. The tar is meant for installing to a flash drive. It can be installed directly to a variety of storage devices like flash key, MP3 player, or even to a hard disk. the slax installer is all set to make the device in which you are installing it bootable and hence it will be like a fully functional operating system. It can be installed on the pen drive using a Windows box of Linux box.

Labeling a Linux partition - Volume Labels

Here we shall discuss about labeling a Linux partition and its advantages. 

You might have seen labeled partitions if you have opened and viewed the /etc/fstab file. There you can see that the 'root', 'home', 'boot, and other system partitions are labeled and are mounted using the label rather than referring the device name. The advantage is that, the root partition will be the same even if the device name got changed in an unlikely event during the system startup. The volume labels make the partition retain a consistent name regardless of where they are connected and what else are connected. And for your information such an unlikely event of changing the device name is quiet often if you are mounting mounting multiple iSCSI drives to your system. 

Hope you know about the iSCSI target and initiator stuffs, it is the low cost, high efficient alternative for costly storage solutions. Hope I could give you an elaborate post about iSCSI soon coz that too is one of my hot favorite topic.  However here we will discuss about labeling the Linux partition labeling.

setuid File Permission in UNIX/Linux

In this post I am going to describe you about the 'setuid' in UNIX and Linux.

setuid or 'set user ID upon execution' and setgid or 'set group ID upon execution' are UNIX access right flags which are used to allow users to run an executable file with the permission of the executable file's owner or group. If the setuid is enabled for an executable file, the user executing the file will get permissions of the user or group that owns the executable file. This is very useful for allowing users on a computer system to run programs with temporarily elevated privileges for performing a particular task. 

These programs are needed for performing some tasks like 'ping' from an unprivileged user. The ping executable in /usr/bin folder is set with setuid bit on and consider its owner is root. So that whenever the ping command is used it is executed with elevated privileges and hence all the unprivileged users can use the ping command unless they are explicitly blocked form using it via some other means. By this hope you got the concept of setuid. Please continue reading for knowing more about setting, listing and more about setuid. 

SSH login to remote servers without password.

Hello guys this time I give you a how-to for logging into a remote server/desktop without being prompted for password.

SSH or Secure Shell is a program that allows you to log into a remote machine over a network and execute commands. It also allows you to move files from one computer to another. All the communication including password transmission are highly encrypted. Hence it can be used to create a secure communication over insecure channels. It protects a network from attacks like DNS spoofing, IP spoofing and IP source routing. Thats the reason why the SSH has effectively replaced older remote log in protocols like rlogin, rsh, rcp, telnet etc.

While using SSH log in entire communication including password transmission is is encrypted. SSH uses 3DES, Blowfish, AES and arcfour as encryption algorithms. So it is virtually impossible for a hacker to eavesdrop your password. Here I will describe how to create a secure communication channel between two servers securely and enable password-less login between them. This would be quiet useful while using scripts for logging into remote machines and executing commands. You don't have to store the remote machine's password in the script and also it is quiet annoying to type in password every time you log in to the remote machine via SSH.