To those who are wondering if they will have time to take their exams before the arrival of the RHEL 7 certification program, RHCSA & RHCE exams for RHEL 6 are still scheduled in Europe until december 12, 2014.

Source: Red Hat website.

In RHEL 6, service management was sometimes slightly painful.
Each time you wanted to start or enable a service, you had to perfectly remember its name.
For example, when you wanted to set up a ntp client, you had to install the NTP package: # yum install ntp
Then, you had to enable the service: # chkconfig ntpd on
Finally, you had to start the service: # service ntpd start
As the package name was different from the service name, you had to remember both names and sometimes use commands like: # chkconfig | grep ntp

With RHEL 7, Systemd involves new commands but you get exactly the same steps (by the way, package name and service name are still different in this case):
You have to install the NTP package: # yum install ntp
Then, you have to enable the service: # systemctl enable ntpd
Finally, you have to start the service: # systemctl start ntpd
The improvement appears when using the systemctl command: you get bash completion!
According to Ben Breard, you get this feature by default except in the minimal installation configuration.

When not sure about the service name, type the beginning of its name and press the tab key!
Start by getting the service status: # systemctl status ntpd
Then start/stop/enable/disable it according to your needs.

For those who already passed the RHCE, they should know that Red Hat has recently stopped the RHCSS certification and three of the following associated exams:

• Red Hat Certificate of Expertise in Security: Network Services (EX333),
• Red Hat Certificate of Expertise in Directory Services and Authentication (EX423),
• Red Hat Certificate of Expertise in SELinux Policy Administration (EX429).

Source: Red Hat website.

After the Debian technical committee’s decision to adopt Systemd as system management daemon several days ago and the choice by the Ubuntu manager, Mark Shuttleworth, to follow the same direction, it’s now clear that every Linux system administrator needs to learn Systemd as soon as possible.
As RHEL7 is also based on Systemd, you will not waste your time reading my introduction to Systemd.

Even though Kerberos understanding doesn’t seem to be critical for passing the RHCE exam, it is still in the objectives list. For this reason and because I’m fundamentally curious, I have written some instructions to configure a Kerberos client and set up a KDC (Kerberos Distribution Server).
Besides Kerberos configuration, I learned one thing: be careful when writing your /etc/hosts file with services like Kerberos. They only accept the following sequence: ip address, full qualified domaine name, name alias. Otherwise, because of reverse host resolution, they just don’t work!

For those who are interested in RHEL 7 Beta performance, Phoronix published a benchmark only two days after its release in December.
The progresses made at the kernel level (3.10 kernel), at the compiler level (gcc 4.8.2) and at the graphic level (new Linux kernel Direct Rendering Manager drivers) are some of the reasons of the clear advantage taken by RHEL 7 Beta against RHEL 6.5.
If you want to know more, read the Phoronix RHEL 7 Beta benchmark.

Today I went to the official RedHat forum and learned a firewall tip from Jamie Bainbridge.
If you need to change the firewall configuration of a server and don’t want to lock yourself out of this server, you can type the following command:
# echo "service iptables restart" | at now + 5 minutes
This way, whatever iptables command you type, you will get the configuration reset after the delay specified. Furthermore, you will be able to view and remove the job by using the commands atq and atrm respectively.
Finally, when debugging your firewall configuration, don’t forget to use the -j LOG target to see if/when traffic hits a certain point in the rules. This can be very useful.

On January 7, 2014 Red Hat and CentOS have signed an agreement regarding future cooperation.
The two distributions were already almost identical except for copyrights, subscription management, and kernel drivers. For people preparing Red Hat certifications, it’s a good news because this agreement will insure similarities in the future.
Concerning the CentOS 7 build process, a blog is regularly updated by the team in charge and things go well.
Finally, the CentOS distribution has seen the look of its dedicated website completely changed.