CentOS Linux is a community-supported distribution derived from sources freely provided to the public onRed HatorCentOS gitfor Red Hat Enterprise Linux (RHEL). As such, CentOS Linux aims to be functionally compatible with RHEL. The CentOS Project mainly changes packages to remove upstream vendor branding and artwork
Frequently Asked Questions about CentOS1. What is CentOS Linux?
CentOS Linux provides a free and open source computing platform to anyone who wishes to use it. CentOS Linux releases are built from publicly available open source source code provided by Red Hat, Inc for Red Hat Enterprise Linux. This source code is available on theCentOS Gitwebsite.
CentOS Linux is the Community Development Platform for the Red Hat family of Linux distributions. See thisFAQfor more information.
CentOS conforms fully with Red Hat, Inc\'s redistribution policies and aims to be functionally compatible with Red Hat Enterprise Linux. CentOS mainly changes packages to remove trademarked vendor branding and artwork.
CentOS Linux does not contain Red Hat Enterprise Linux or Fedora Linux; nor does it have any of their certifications, although it is built from the same source code as the Red Hat Enterprise Linux.
2. How long after Red Hat publishes a fix does it take for CentOS to publish a fix?
Our goal is to have individual RPM packages available on the mirrors within72 hours of their release, and normally they are available within 24 hours.Occasionally packages are delayed for various reasons.On rare occasions packages may be built and pushed to the mirrors but notavailable via yum. (This is because yum-arch has not been run on the mastermirror. This may happen when issues with upstream packages are discoveredshortly after their release, and if releasing the package would break it\'sfunctionality.)
Update Sets (see thisFAQ)will have Security Errata released was statedabove, while the BugFix and Enhancement errata are actually tested morerigorously and released after the new ISO for the Update Set is produced.The goal for release of a new point release or update set is four to eight weeksafter the release by upstream. For more details see the explanation ofThe CentOS Rebuild and Release Process
During the period between the upstream release of a new minor version and the CentOSrelease intermediate updates will be published in aContinuous Release (CR)repository.
3. Where are the Release Notes for a given version?
Release Notes have last minute documentation or describe a commonly encountered problem, when a given release has a variation from the formal documentation. Release Notes are also used when there is a need to emphasize some change. The Release Notes vary, not unexpectedly, both by major release (CentOS 8, 7, ...), and also with each new minor \'point\' update within a major release. Thiscompilationcollects links to each Release Note.
4. How do I get Updates?
CentOS ships with an application called yum (in CentOS Linux 7) and dnf (in CentOS Linux 8 and CentOS Stream) that serves as our tool for performing updates and package installation. Please andman yumorman dnf.
There is a separateFAQ questionconcerning how to import the CentOS RPMsignature key.
5. Many RPMs still contain the name redhat, rhel, or rh. Shouldn\'t these be changed?
The upstream vendor is using open source (mostlyGPL) software in their business model. They take software that other people write (Gnome.org, X.org, KDE.org, OpenOffice.org to name a few). They repackage the source files intoRPMformat for redistribution. Because they chose an open sourcemodel to obtain the software they distribute, they must provide their source code to others. That is how theGPLworks. The upstream vendor provides much added value by creating the Source RPMS and distributing them. They also fix problems in software and provide response to the software developers ...this is what makes open source software work.
The CentOS Project takes the publicly available source packages (SRPMS) provided by the upstream vendor and creates binary (installable) packages for use by anyone who wishes to use them.
Some packages contain Trademark information and the upstream vendor has specifically created a guide to redistribute software built from their publicly available sources. You can read about ithere. We support the upstream vendors Trademark rights and strive to be in full compliance with those guidelines.
The CentOS project is not interested in taking credit for work done by others, so where possible we will leave all vendor file names as they are. If we must make any changes to a package (due to trademark restrictions, tosetup a configuration file, etc.), it will have a .centosx in the filename (the x is the CentOS version ... 5 for CentOS-5.x, 6 for CentOS-6.x, etc.) As do most of the other rebuild projects, we change the kernel SRPM and donot label it .centosx. This is because the kernel needs to be exactly the same name to allow 3rd party modules to function.
I would like to thank theupstream vendorfor making the SRPMS available in the manner that they do. There are several other enterprise vendors who do not make their source as readily available. Their product is excellent (or we would not rebuild it as CentOS), as is their support. If you need the support services that they provide, we highly recommend their enterprise product.
6. Does CentOS change the upstream Source RPMs?
No. CentOS\' key mandate for our base and updates repositories is NOTextending or enhancing packages or features beyond those supplied by theupstream Source RPM\'s. CentOS strives intentionally to provide binary functionality for our users.CentOS does offer other (optional) repositories called extras, addons,contribs, and centosplus that do offer added functionality. There is aWiki pageabout the various CentOS repositories and their purposes.
7. Is there a Contrib area?
Yes. Please see the Wiki page onContributing to the CentOS project
8. What is CentOS\'s relationship with Red Hat®, Inc. or RHEL?
Red Hat curates the trademarks for CentOS and is providing initial guidance and expertise required in establishing the formal board structure used to govern the CentOS Project.
Some members on the CentOS Project Governing Board work for Red Hat, Inc.
CentOS Linux is NOT supported in any way by Red Hat®, Inc.
CentOS Linux is NOT Red Hat® Linux, it is NOT Fedora™ Linux. It is NOT Red Hat® Enterprise Linux. It is NOT RHEL. CentOS Linux does NOT contain Red Hat® Linux, Fedora™, or Red Hat® Enterprise Linux.
CentOS Linux isNOTa clone of Red Hat® Enterprise Linux.
CentOS Linux is built from publicly available source code provided by Red Hat®, Inc for Red Hat® Enterprise Linux in a completely different (CentOS Project maintained) build system.
9. Where can I get package XyZ.rpm for CentOS?
The Wiki has a page aboutthe CentOS and other \'\'friendly\'\' repositories. Chances are good that one of those repositories has the package you are looking for.
10. What architectures are supported?
Only Major versions still in support upstream are considered here. Previously other architectures had candidates as well, but this is the current list as of January 2019:
CentOS 6currently supports x86 and x86_64.
CentOS 7currently supports x86_64. TheAltArchSpecial Interest Group has community maintained (non-official) versions of CentOS 7 for i686, armhfp (Arm32), aarch64 (Arm64), ppc64le, and ppc64.
11. The upstream provider offers Enterprise Linux in several flavors, AS, ES, WS, PWS, etc. Which one is CentOS like?
CentOS is built from the publicly provided AS Enterprise Sources,although all of the above versions are built from the same sources. AS iseither a larger subset of packages (than PWS and WS) or has advanced Kernelparameters supporting larger number of processors or memory (as compared toES).
With the upstream provider, AS supports some IBM architectures not supportedby the other versions (ES, PWS, WS). CentOS is built like the AS version.
Consult:What release am I running?
12. How can I easily compare what major package versions are in each version of CentOS?
On theCentOS Distro Pageat DistroWatch.com you can compare Major packages and all tracked packages.DistroWatch is a good resource for comparing Linux and BSD distributions.
13. What are all the CentOS repositories (directories) and what is each one for?
See theRepositoriespage for more information.
14. How do I download and burn the CentOS isos?
You can download the latest CentOS ISOs from here:CentOS Downloads
After you download the ISOs, you should check the MD5 sums (or better sha1 or sha265 sums) of the ISOfile(s) that you downloaded against the published md5sum (again sha1 or sha265 sums) list in the ISOdirectory. If the values match, the download is good ... if they donot match, the file was not downloaded correctly, and you need to get thefile over again. Bittorrent downloads are best, because they do an MD5sumcheck as part of the download process. Generally the DVD media ispreferable as it avoids switching media during installation, and canbe used via the pre-defined [c7-media] repo definition for local installationof additional packages via yum. Some environments block P2P file sharingincluding Bittorrent, in which case direct download is the only viable option.The mirrors that support it can be found via the \"Downloads/Mirrors\" drop-downon the menu bar at the top of Home or Forum pages. Then pick the linkCurrent CentOS Public Mirror List,pick your geographic region, and look down the column labeled\"Direct DVD Downloads\" to find a suitable mirror near you.
Once you have verified the checksums of the ISO, you know you have a gooddownload. Now you can burn the ISO to a disk. If you have k3b (CentOS-4users do, all other CentOS users do not by default) I recommend you use it.You want to use the Tools -> CD -> Burn CD Image or Tools -> DVD -> Burn DVDISO Image option to write the ISO file to a CD/DVD.
More information on how to verify and burn a CD ISO image can be found at[link removed by ].
Once the CD is burned, you should be able to boot from it. The last checkyou need to do is to verify the media. This will verify that the writing ofthe ISO to your media happened correctly.There will be a Check Media option after you select your keyboard andlanguage.
If your media passes this check (make sure to check each disc for multiple media sets), you have a fully working installable media.If it fails this check, but passed the md5 (or sha1 or sha265 sum) check above, then the problem iswith the burned media. Try burning on new media at a slower speed, ifpossible.
All CentOS ISOs that we release have been checked, so if the checksums thatyou have match, the ISOs should burn clean and pass the media checks. Ifthey do not, the problem is almost always a bad media write to CD/DVD.
If you would rather buy your CentOS ISOs already burned, please see ourofficial CentOS CD/DVD Vendors page. These official CentOS vendors donate a portion of each CD/DVD sale directly to the CentOS Project. You get a testedISO ready to use ... we get money ... does it get any better than that
15. Can I add X to my server after install? Or I installed from the Server ISO and it didn\'t install X, how do I install X?
The easiest way to install X (and a GUI system) is to use the `yumgroupinstall` feature.First you can see all the yum groups available with the command:yumgrouplistYou can install X and Gnome or KDE as follows:
You may also want to add some other groups from the list like class=\"line867\" style=\"box-sizing: border-box; margin: 0px 0px 10px; color: rgb(51, 51, 51); font-family: "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 14px;\">
16. How do I create a xorg.conf file?
Upstream X developers have worked to make the/etc/X11/xorg.confun-needed in the usual case. However sometimes one needs to \'tweak\' settings for multiple display heads or such. A templatexorg.confmay be created by root thus:{{{Xorg :1 -configure}}}which produces a file named:xorg.conf.newin the current working directory. This file may be tested using the-configoption forXorg. Once suitable, a backup may be made and the file can be placed in the/etc/X11/directory to be used as the default configuration file.
17. What are the Maximum number CPUs, Maximum filesystem size, Minimum / Maximum Memory and other specifications associated with the different CentOS versions?
See theCentOS Product Wiki Page
18. There is no mp3 support in CentOS! Or is there? How about other multimedia formats?
Yes. There is no mp3 support in CentOS, as there is no mp3 support in the distribution sources as provided from upstream. While the CentOS Project simply rebuilds what is available upstream, these have been excluded because of legal (patent license) issues. You either can encode your music files to ogg vorbis, which is supported in CentOS or install mp3 support from athird party repository, such as rpmforge. For example: If you want mp3 support for xmms, then installxmms-mp3from that repository.
The same is true for several other multimedia formats (codecs, for example: gstreamer plugins) and multimedia players like xine or mplayer. These aren\'t packaged with CentOS because of legal issues, but you may find those in the rpmforge repository.
19. What is the support \'\'end of life\'\' for each CentOS release?
CentOS 3
CentOS-3 updates until October 31, 2010
CentOS 4
CentOS-4 updates until February 29, 2012
CentOS 5
CentOS-5 updates until March 31, 2017
CentOS 6
CentOS-6 updates until November 30, 2020
CentOS 7
CentOS-7 updates until June 30, 2024
20. Where can I get the latest version of XyZ.rpm for CentOS? I cannot find it anywhere.
CentOS is an Enterprise-class operating system and as such is more about stability and long-term support than cutting edge. Major package versions are retained throughout the life cycle of the product. This is generally what Enterprise wants and affords developers a stable base on which to develop without fear that bespoke applications will break every time something gets upgraded to the latest and greatest, but ultimately buggy version or the API changes breaking backwards compatibility.
So no, you will generally NOT find the very latest versions of various packages included in an Enterprise-class operating system such as CentOS. It\'s a feature not a deficiency.
21. A PCI audit says I am running a version which has CVE exploits in it
It is of course possible if you have not run updates, or have not rebooted after an update. As always in a maintenance strategy, you should test updates on a non-production machine, and have a current and tested backup, takenbeforerunning the update tool.
Security patches and bug fixes are backported into the shipped version. See here for details:[link removed by ]. Simply reading a version number on a package or a banner from network scanning is not sufficient to indicate a vulnerability, in light of this approach. Most reputable vendors understand this, but some seem to not account for the upstream approach in their product\'s reporting interface.
Thechangelogof each package generally specifiesCVEmatter addressed with patches. A CVE number is a commonly used reference to refer to vulnerabilities. As an example considerhttpdwhich may be examined thus:{{{rpm -q --changelog httpd | less}}}or even this:{{{rpm -q --changelog httpd | grep CVE}}}
People regularly appear in CentOS support venues asserting that a PCI assessor, or a web driven scanning tool is reporting that they need to update to some specific version of software not shipped in CentOS. PCI does not mandate specific version levels, but rather freedom from known testable vulnerabilities, usually expressed in the shorthand CVE number fashion. If a scan report is complaining about package versions, the person providing it is probablynot doing it right, as the popular meme goes. CentOS and its upstream are continuously updated, and the CVE\'s addressed are reflected in the aforementioned changelog, so running a protective backup, updating, and rebooting or restarting the affected daemon service should address the matter. Other approaches, such as using one keyed to package version numbers, are simply wrong.
Please also read about the Wiki articleSoftware Installation from Source. Obviously in the case where the administrators of a given installation have undertaken to extend a CentOS installation with local or non-CentOS provided binaries, the CentOS project cannot provide updates or maintain such divergence.
22. How do I install or update on a system with no network connection?
See the Wiki articleCreating Update Media. The technique described there also works with DVD installation media. The key technique is
yum --disablerepo=\\* --enablerepo=c5-media <yum_command_and_argument(s)>
23. I installed the x86_64 version, so why do I have i386 packages, and can I get rid of them?
CentOS follows the upstream source in this respect, as it does in general, and the x86_64 installation by default will install iX86 32-bit packages on a 64-bit installation for compatibility purposes. Many server system administrators (and some desktop users) want a pure 64-bit system and so remove all 32-bit packages. This can be accomplished as follows:
yum remove \\*.i\\?86
To keep any 32-bit packages from being installed in future updates, edit your /etc/yum.conf and add the line:
exclude = *.i?86
Be aware that 32-bit applications, including some third-party (non-CentOS) browser plugins that may only be available in 32-bit versions, will no longer work after this procedure.
You may also want to do this:
yum reinstall \\*
The reason is that sometimes the/usr/share/items (shared between BOTH packages) get removed when removing the 32-bit RPM packages.
24. How do I provide appropriate information about my system when asking questions?
SeeHow to Provide Information About Your System.
25. How do I upgrade from one major release to another?
Upgrades in place are not supported nor recommended by CentOS or TUV. A backup followed by a fresh install is the only recommended upgrade path. See theMigration Guidefor more information.
26. Why was there no package selection step when I\'ve tried to install CentOS using the LiveCD/LiveDVD?
Installing CentOS from the live images is just a simple transfer of the image that exists already on the CD (or DVD). Once the image is copied to the hard disk, you can adjust the set of installed packages using yum as you would do on any other CentOS system.If you need to make the selection of packages at install time, please use one of the other installation disks instead of the live isos.
27. Why is the CentOS Project Spamming me?
They probably are not doing so. CentOS is anOperating System, like Microsoft Windows 7 or Mac OSX. Operating systems are installed on computers and people then use those computers to do things. Some things they do are good, other things they do are bad. However, the CentOS Project has no control over what people do with computers where theCentOS operating systemis installed, any more than Microsoft has any control over who you send email to if your computer has theWindows 7operating system.
If you saw a page that looks likethisand that is what lead you to believe that the CentOS Project sent you an email, then you need to read the bottom paragraph more carefully. It says this:
CentOS is an Operating System and it is used to power this website; however, the webserver is owned by the domain ownerand not the CentOS Project. If you have issues with the content of this site, contact the owner of the domain,not the CentOS project.Unless this server is on the CentOS.org domain, the CentOS Project doesn\'t have anything to do with the content on this webserver or any e-mails that directed you to this site.
For example, if the website iswww.example.com, you would find the owner of thewww.example.commachine using the followingWHOIS serverand searching forwww.example.com.
If you have an ip address, you can use theAmerican Registry for Internet Numbersto find the owner of the machine. Note: If the IP address is not in the United States, ARIN will tell you the properRegional Internet Registryto use.
It is the owner of the machine, and not the people who make the operating system that is sending you e-mail.
