Just installed CentOS 7 on my Virtual machine and realized that, Firewalld is bit complicated as I am using iptables firewall from many years. So decided not to use firewalld at least as of now and wanted to continue with iptables commands as I was using in RHEL / CentOS 5 and 6.
I thought iptables will not be there and I will have to deal with firewalld but a little small trick in RHEL7 takes me to the solution which I wanted and I found that I can still use the iptables by disabling firewalld service.
So, If you are in same condition as mine and you want to use iptables on CentOS / RHEL 7 instead of firewalld, Please follow this howto.
As we all know that, CentOS / RHEL 7 both are completely systemd based, So We will have to use few systemd related commands to disable firewalld and enable iptables service.
Firewalld Service is now disabled and stop, You can use iptables.
Now, You will be able to use iptables as your firewall, You can add / remove rules as you were doing in previous releases of Red Hat / CentOS 5 and 6, You can configure firewall with iptables in same manner as previous.
RHEL 7 is released, I am getting constant calls / emails / messages from many friends from different different places regarding their doubts on RHEL 5 to 6 or 6 to 7 up-gradation.
Sharing this to clear confusion / doubts.
Clear your doubts Regarding Up-gradation :-
1. Yes, RHEL 7 is out, but There is no compulsion or Mandatory from Red Hat to Upgrade your certificate from RHEL 5 to 6 or RHEL 6 to 7. Its not mandatory at all, It is all up to you.
2. Whether its RHEL 6 release or RHEL 7 release, If you are RHCE then Do not worry, Your Certificate is not going to expire. There is nothing like “expiry” in RHCE certificate, You will be still known as “Red Hat Certified Engineer” but the only difference is you will be known as “RHCE from non-current Version”.
3. RHCE Certificate / exam is not mandatory for Red Hat Enterprise Virtualization. You can give direct exam of RHEV.
4. Same in this case, RHCE Certificate / exam is not mandatory for RedHat OpenStack exam. You can give direct exam of Red Hat OpenStack.
I was getting lots of calls / emails / messages regarding these queries to help them out, I have shared this here so even if some friends from here are having same queries/doubts/confusion, So it will get cleared.
Today I was trying to learn and know about Systemd. I have found one of the great Article, Sharing with you guys, It will help you to understand this biggest and major change in RHEL and CentOS 7.
This article is not mine, I found on internet and felt that this is wonderful Article so Sharing with you all, Thanks to Original author, Given credit to him at the end of article.
As the Systemd now replaces SysVinit, it is time to get familiar with it and learn new commands. Systemd is quicker because it uses fewer scripts and tries to run more tasks in parallel (Systemd calls them units).
The Systemd configuration is stored in the /etc/systemd directory.
Systemd primary task is to manage the boot process and provides informations about it.
To get the boot process duration, type:
Note1: The change is written into the service unit file. Use the –runtime option to avoid this behavior.
Note2: By default, each service owns 1024 CPUShares. Nothing prevents you from giving a value smaller or bigger.
Systemd deals with all the aspects of the service management. The systemctl command replaces the chkconfig and the service commands. The old commands are now a link to the systemctl command.
To activate the NTP service at boot, type:
# systemctl enable ntpd
Note1: You should specify ntpd.service but by default the .service suffix will be added.
Note2: If you specify a path, the .mount suffix will be added.
Note3: If you mention a device, the .device suffix will be added.
Systemd‘s authors have decided to help Linux standardization among distributions. Through Systemd, changes happen in the localization of some configuration files.
To get the server hostnames, type:
Static hostname: rhel7.example.com
Icon name: computer-laptop
Machine ID: bcdc71f1943f4d859aa37e54a422938d
Boot ID: f84556924b4e4bbf9c4a82fef4ac26d0
Operating System: Red Hat Enterprise Linux Everything 7.0 (Maipo)
CPE OS Name: cpe:/o:redhat:enterprise_linux:7.0:beta:everything
Kernel: Linux 3.10.0-54.0.1.el7.x86_64
Note: There are three kinds of hostnames: static, pretty, and transient.
“The static host name is the traditional hostname, which can be chosen by the user, and is stored in the /etc/hostname file. The “transient” hostname is a dynamic host name maintained by the kernel. It is initialized to the static host name by default, whose value defaults to “localhost”. It can be changed by DHCP or mDNS at runtime. The pretty hostname is a free-form UTF8 host name for presentation to the user.” Source: RHEL 7 Networking Guide.
To assign the rhel7 hostname permanently to the server, type:
# hostnamectl set-hostname rhel7
Note: With this syntax all three hostnames (static, pretty, and transient) take the rhel7 value at the same time. However, it is possible to set the three hostnames separately by using the –pretty, –static, and –transient options.
To get the current locale, virtual console keymap and X11 layout, type:
To assign the en_GB.utf8 value to the locale, type:
# localectl set-locale LANG=en_GB.utf8
To assign the en_GB value to the virtual console keymap, type:
# localectl set-keymap en_GB
To assign the en_GB value to the X11 layout, type:
# localectl set-x11-keymap en_GB
To get the current date and time, type:
Local time: Fri 2014-01-24 22:34:05 CET
Universal time: Fri 2014-01-24 21:34:05 UTC
RTC time: Fri 2014-01-24 21:34:05
Timezone: Europe/Madrid (CET, +0100)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: no
Last DST change: DST ended at
Sun 2013-10-27 02:59:59 CEST
Sun 2013-10-27 02:00:00 CET
Next DST change: DST begins (the clock jumps one hour forward) at
Sun 2014-03-30 01:59:59 CET
Sun 2014-03-30 03:00:00 CEST
To set the current date, type:
# timedatectl set-time YYYY-MM-DD
To set the current time, type:
# timedatectl set-time HH:MM:SS
To get the list of time zones, type:
# timedatectl list-timezones
To change the time zone to America/New_York, type:
# timedatectl set-timezone America/New_York
To get the users’ list, type:
# loginctl list-users
To get the list of all current user sessions, type:
# loginctl list-sessions
SESSION UID USER SEAT
1 1000 tom seat0
1 sessions listed.
NOTE: Sorry for misleading title, There jo 32-Bit version available for CentOS 7!
Hello and welcome to the first CentOS-7 release. CentOS is an Enterprise-class Linux Distribution derived from sources freely provided to the public by Red Hat1.
CentOS conforms fully with Red Hat’s redistribution policy and aims to have full functional compatibility with the upstream product. CentOS mainly changes packages to remove Red Hat’s branding and artwork.
We have decided not to follow Red Hat’s usage of Installation Codes. All ‘channels’ are available to the System Administrator at time of installation.
For the first time, there is a supported upgrade path from CentOS-6 to CentOS-7. This path is only supported from the latest version of CentOS-6 (being 6.5 at the time of writing) to the latest version of CentOS-7. For more information on the upgrade procedure please take a look at this page. The tools needed for this functionality are still being tested and will be released at a later time. If you can help with the testing, please see this CentOS-Devel mailing list thread.
Firstly I would like to Congratulate Shri Narendra Modi for becoming Next Prime Minister of India.
This Election was special, tough and very Surprising for not only Political parties but also People of India. Specially This election was toughest for BJP as BJP was struggling to get into the power from Last 10 years, But i will not go much in detail about politics.
I want to Thank You India and Specially want to Thank India for Rejecting “Communalism Vs Secularism, Anarchists, Anti Nationalists, Negative Campaigning and many more”. Other side I want to thank Shri Narendra Modi and BJP for sticking to Development and Governance agenda in this election. Congratulations to BJP and Narendra Modi for getting Positive Mandate of India.
I am quickly moving on to the Subject and I want to Thank People of India for Electing Narendra Modi as Prime Minister of India. What more important is People of India elected Shri Narendra Modi smartly and with huge responsibility, After 30 years People of India given Clear Mandate, Given Majority to BJP and more than 50% seats to Only BJP and NDA is 330+ seats. So India chosen Strongest government after 30 years.
I want to Thank People of India for giving Majority to Shri Narendra Modi and BJP. Strong government for India was Much needed and I am very happy that People of India understood this very well and choosing Modi/BJP clearly, We have seen governments from last 30 years with inside or outside support which obviously stops and develops India slowly.
This Government is now in Clear Majority and This government will not work in any pressure and More importantly We have Narendra Modi as Prime Minister of India who is very well known for Development, Good Governance, Decision maker and quick decision maker. Now I am very sure that One India will be Best India and Developed India.
Being Gujarati I have seen Development and Governance under Shri Narendra Modi in Gujarat as Chief Minister and I want to assure people of India that You will never feel that you have voted for wrong person, This person will make your Vote’s value count and will make “Bhavya and Divya Bharat“.
In just few years, I am sure we will proudly say that “Every Part of India is Secure, India is Developed, We have the best Governance, We have PM who takes quick and right Decisions”.
One more time, Thank You India for Making Narendra Modi as Prime Minister of India and Voted for Governance and Development. CongratsNamo.
Last but not the Least, I want to Congratulate campaigning and advertising team of BJP for doing positive campaign like “Achche Din Aane walen Hain”, “Ab Ki Baar Modi Sarkaar”.
Victory Speech of Prime Minister of India from Ahmedabad :-
If you have not protected Single User Mode with Password then it is big risk for your Linux Server, So protecting Single User Mode with Password is very important when it comes to security,
Today in this article i will show you how you can protect Single User Mode with Password on RHEL / CentOS 5.x and RHEL / CentOS 6.x.
Please execute given commands carefully else your system will not boot properly. First i would request you to read full procedure and then try to follow. Do it at your own risk 🙂
1. For RHEL / CentOS 5.x
1.1 Before doing anything please take backup of your /etc/inittab
cp /etc/inittab /etc/inittab.backup
To Disable and Make Single User Mode Password Protected, Execute below command as root :-
[root@tejas-barot-linux ~]$ sed -i '1i su:S:wait:/sbin/sulogin'
So It will look like below
# Default runlevel. The runlevels used by RHS are:
# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)
NOTE: If you do not want to use sedcommand then You can always add “su:S:wait:/sbin/sulogin” at top in /etc/inittab
2. For RHEL / CentOS 6.x
2.1 Before doing anything please take backup of your /etc/inittab
cp /etc/sysconfig/init /etc/sysconfig/init.backup
2.2 To Disable and Make Single User Mode Password Protected, Execute below command as root :-