As the RHEL7 Beta has been released, it’s now time to start looking at the new features.
A RHEL7 Beta review is in progress and some RHEL7 quick recipes are already available.
More will come in the future.

Red Hat Enterprise Linux 7 Beta has been released on December, 11th 2013.
This release is based on Fedora 19.
The production release should happen in H1 2014.
However, companies are only migrating to RHEL6. As the RHCSA/RHCE exams are scheduled until July/August 2014, RHEL 6 certifications, which are valid for 3 years, are still relevant at least for the 6 next months.

On November 21, 2013 RHEL 6.5 was released.
On December 2, 2013 CentOS 6.5 is now released.
Even though this is not a stunning news, it’s still important to keep an eye on the last available version of the OS.
As its name suggests, it’s a maintenance release, thus without big changes.
One thing to note still, there is no longer support for configuring partition layout, storage methods or package selection in the CentOS 6.5 text installer (Source).

If you have built a KVM lab like I did, you know what it means not to be able to connect to your VM because you made a mistake in your /etc/fstab file.
This happened to everybody!
Hopefully, there is a solution: create a serial console.
It only takes 3 lines and a reboot!
# echo "S0:12345:respawn:/sbin/agetty ttyS0 115200" >>/etc/inittab
# grubby --update-kernel=ALL --args="console=ttyS0"
# echo "ttyS0" >>/etc/securetty
# reboot
Now, if you want to connect to your vm, type:
# virsh console vm.example.com
If you know why it’s not done by default, let me know!

If you want to test your new RHCSA skills, there is now a small quiz that requires only 5 minutes. Its purpose is not to replace the real exam but to challenge you on some specific points. This way, you will remember them!

If you want to test your RHCE knowledge, I have created a small quiz (it requires 5 minutes).
It will not replace the real exam but will check some critical points.
This way, you will remember them!

Some questions come regularly in Linux certifications forums:
Do I need to set up iptables configuration or not ?
In fact, it depends on the questions and the risk you want to take.
If there is no mention of ports in the exam and risk doesn’t frighten you, you can go for: # iptables -F; service iptables save
Otherwise, you have to learn the ports associated with each service.
During your training session, you can test your configuration in your lab with a port scanner: nmap is your friend!
# yum install -y nmap
Then, you can test your local port configuration (tcp & udp) with the following command (s for scan, T for tcp and U for udp): # nmap -sT -sU localhost
Once you’ve got your iptables configuration set up, you can test it from another VM or your KVM host. It’s simple with tcp ports: # nmap -sT myvm
Things become trickier with udp ports. If you don’t want to spend around 18 minutes to get the answer (test it if you think I’m kidding!), you have to specify the ports that you want to test: # nmap -sU -pU:53,111 myvm
It’s even possible to combine the two tests in one: # nmap -sT -sU -pT:*,U:53,111 myvm

I’m pretty sure these little tips will help you even after the exams!

For those who are about to start their preparation for the RHCSA & RHCE exams, they need to think about creating a lab. This is not an easy task because you have to know various topics to do so.
To make things easier, have a look at this lab installation guide.

When you are working in your lab, you regularly need to reinstall your virtual machine to start a new configuration.
If you use a tool like Virtual Box, you can save virtual machine images and restore them.
But if you use KVM, you can’t do that, and it takes time to reinstall the system.
To avoid this waste of time, you can set up your virtual machine inside a unique volume group (here vg_root with at least 1GB of free space) and use the snapshot feature available since RHEL6. This way, you only need to reboot and wait one or two minutes (the time for the snapshot to be restored).

The command is called snap and takes one parameter:
– begin: to start the snapshot,
– rollback: to destroy the snapshot and remove all the previous changes,
– commit: to destroy the snapshot and keep the changes.

#!/bin/sh
if [ "$#" -ne "1" ]; then
echo "Syntaxe: snap [begin|commit|rollback]"
exit
fi

case $1 in
begin) lvcreate --size 1G -s --name lv_snap /dev/vg_root/lv_root ;;
commit) lvremove -f /dev/vg_root/lv_snap ;;
rollback) lvconvert --merge /dev/vg_root/lv_snap ;;
esac

If you are really serious about taking the RHCSA exam, you should have a look to this RHCSA sample exam.
It should be a good start for your ultimate preparation.