CentOS is a Linux distribution standing for "Community ENTerprise Operating System" and is a rebuild of "Red Hat Enterprise Linux" (RHEL). The "CentOS6" tag refers to versions 6.x of CentOS.

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38
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4answers
67k views

EPEL Repo for CentOS 6 causing error

I've got a VM running CentOS 6 (64bit) and I'm attempting to add the EPEL repo like usual to install various packages as I do quite regularly. Today, I'm experiencing some strange errors yet I'm ...
32
votes
2answers
4k views

Why is my bare-metal 16x 2.93GHz cores computer performing poorer than a VPS with 4x 2.5GHz cores?

I have a written a piece of multi-threaded software that does a bunch of simulations a day. This is a very CPU-intensive task, and I have been running this program on cloud services, usually on ...
32
votes
2answers
80k views

How do I configure LDAP on Centos 6 for user authentication in the most secure and correct way?

During the last couple of days I have been using a lot of F-words, while browsing Internet for good documentation about how to setup an LDAP-server. So far I have found none, but plenty that are less ...
31
votes
6answers
5k views

How to create a symbolic link without using ln?

I deleted a critical symbolic link - libc.so.6. I have the file it should point at, but the basic commands such as ln or wget won't work anymore due to the link missing. However, echo or other Bash ...
31
votes
3answers
32k views

What does that mean: packages excluded due to repository priority protections

When updating with yum i recieve the following message: yum update Loaded plugins: fastestmirror, priorities Loading mirror speeds from cached hostfile * atomic: www7.atomicorp.com * base: mirror....
30
votes
2answers
2k views

How to allow ssh to root user only from the local network?

I've installed Google-Authenticator on a CentOS 6.5 machine and configured certain users to provide OTP. While editing /etc/ssh/sshd_config I saw a directive "PermitRootLogin" which is commented out ...
30
votes
5answers
58k views

How do I change timezone in centos 6.2?

Here is the output of my date command: [root@r1304 ~]# date Wed Apr 18 15:43:28 GST 2012 I want to change the default system timezone to Asia/Dubai. I've followed a tutorial and did this: ln -sf /...
22
votes
3answers
49k views

How do I upgrade to the latest PHP version in CentOS with yum?

I found some blog posts about this, but it's rather lack of descriptions on possible side effects. I could really use some detailed on these steps: How to add a repo that provides PHP 5.4 into yum ...
20
votes
3answers
44k views

ipmitool - can't find /dev/ipmi0 or /dev/ipmidev/0

Based on a previous question, I installed ipmitool (yum install ipmitool). Even after a reboot, though, i get the following error when trying to run ipmitool power status: Could not open device at /...
19
votes
3answers
5k views

Should I be worried that yum update suddenly wants to update well over 100 packages on my CentOS 6 system?

I get an email alert whenever there's something to update, and typically do them that day. This tends to happen most days. For whatever reason I've had no alerts since 20th July until today (I ...
18
votes
3answers
22k views

CentOS 6 and upstart

The new CentOS 6 comes with Upstart, replacing init. I am trying to convert an /etc/inittab file to the new upstart format. This particular server only has 15 or so inittab entries, however, other ...
17
votes
6answers
31k views

ls hangs for a certain directory

There is a particular directory (/var/www), that when I run ls (with or without some options), the command hangs and never completes. There is only about 10-15 files and directories in /var/www. ...
16
votes
2answers
22k views

CentOS /usr/local/lib system wide $LD_LIBRARY_PATH?

I install custom software in /usr/local/lib. How do I set the PATH and LD_LIBRARY_PATH in CentOS 6 system-wide to use /usr/local/lib. I realize there may be more than one way. What's the simplest and ...
16
votes
4answers
11k views

gpg --gen-key hangs at gaining enough entropy on centos 6

Trying to generate a key for a server. gpg --gen-key We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize ...
14
votes
9answers
36k views

CentOS 6 and locale error

I just installed CentOS 6 and whenever I login to the system via SSH remotely, I get the following error: -bash: warning: setlocale: LC_CTYPE: cannot change locale (UTF-8) When I type "locale" on ...
14
votes
2answers
3k views

HP DL380p Gen8 (p420i controller) I/O oddity on XFS partitions

On DL380p gen8 servers using XFS on top of LVM on top of raid 1+0 with 6 disks, an identical workload results in a ten-fold increase in disk writes on RHEL 6 compared to RHEL 5, making applications ...
13
votes
2answers
6k views

Persist IP address alias across reboots in CentOS/RHEL 6 using “ip” command

I've always used the ifcfg-eth0:1 alias files to create additional addresses. However, in recent rhel documentation, it states that: As the ip command of the iproute package now supports assigning ...
13
votes
2answers
39k views

Upgrade CentOS 5.x to CentOS 6.x - tips and techniques

Now that CentOS 6.0 is making its way to the various mirror sites, I wanted to solicit opinions on the upgrade process. In working with the commercial RedHat 5.6 and 6.x distributions for the past few ...
12
votes
6answers
12k views

PECL command produces long list of errors

Currently running PHP 5.4 on CentOS 6.5. I installed the webtatic php55w package then installed PEAR+PECL without issue along with redis and mongo through PECL. Shortly after, I realized 5.5 is not ...
12
votes
4answers
33k views

In CentOS 6.x, how can I upgrade to Kernel 3.4?

I have a server running CentOS 6.2 with kernel version 2.6.32, but I need to increase my application Performance. The Kernel Version 3.4 has x32abi which can improve the performance so i want to ...
12
votes
1answer
10k views

What is the correct way of getting crontab on CentOS 6?

I have a server running CentOS 6.2 minimal, but it doesn't appear to have crontab installed by default? crontab -e -bash: crontab: command not found In searching google, I found references to a "...
11
votes
3answers
12k views

Virtualbox centos no eth0

just installed a fresh centos-minimal and i can not get bridged network to work or any of the networks not even in host-only mode. when you run ifconfig there is no eth0 only a lo, also when you cat /...
11
votes
1answer
11k views

Is installing a GUI on my CentOS server a good idea?

I have a new dedicated server that I'm going to create a couple of VMs on. OS will be CentOS 6.5, for the host and the VMs. Does the GUI on the host (Gnome etc) give any real benefit when it comes ...
11
votes
2answers
7k views

How to uninstall git installed from the source? [closed]

I installed the git using this article. Now I want to uninstall the git. How to do it?
10
votes
4answers
5k views

How to use kdump/crash to investigate an OOM issue?

The problem A server crashed after multiple "Out of memory" messages and I am trying to pinpoint the culprit. If it is in userland - which process. If it is in the kernel - which kernel module. ...
10
votes
3answers
889 views

IPA dynamic DNS updates only the AAAA record. Where are my A records?

I'm setting up a FreeIPA domain. In my lab are three virtual machines: the domain controller ipadc1, and two clients puppet and wordpress (creative, yes, I know). All three VMs are running freshly ...
9
votes
3answers
27k views

Changing the maximum mail size in Postfix

When sending large email to a new CentOS6 server running Postfix as the MTA, the following message is returned: tried to deliver your message, but it was rejected by the recipient domain. We ...
9
votes
2answers
21k views

What is the correct way to load modules for iptables on Centos 6

Where should I load iptables modules, for example ip_conntrack and ip_conntrack_ftp. Places I have found that might be candidates, but are they? The IPTABLES_MODULES variable in /etc/init.d/...
9
votes
3answers
5k views

Where is the correct place to set net.netfilter.nf_conntrack_buckets?

I'm currently trying to set net.netfilter.nf_conntrack_buckets on boot. I initially assumed that this could be done through sysctl.conf, but net.netfilter.nf_conntrack_buckets (and other net....
9
votes
2answers
1k views

How to check CentOS 6 Server VM Host after a power falure?

This afternoon, someone at our office decided to pull the plug out of our server because it was storming outside. They didn't shut it down, they just pulled the plug out while it was running. The ...
8
votes
3answers
20k views

Redis installation on centos 6.5

I am trying to install Redis on centos 6.5 (x64) with following line: yum install redis But I am getting following screen: [root@NodeJs ~]# yum install redis Loaded plugins: fastestmirror Setting ...
8
votes
2answers
36k views

How can I find current ssh protocol version of current connection?

I connect to a linux machine (centos 6.4) ussing putty. Except from fact that I can set putty to only use one type of protocol, how can I find the current's ssh connection version (SSH1 or SSH2)?
8
votes
5answers
8k views

Install PHP7 from Remi repo

I installed PHP7 from Remi repo with sudo yum -y install httpd sudo yum -y install epel-release wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm sudo rpm -Uvh remi-release-6*.rpm ...
8
votes
2answers
17k views

How to remove old kernels on CentOS 6 (to free up boot partition)? [duplicate]

How does one determine which kernels to remove in order to free up some space on /boot partition. Here is a scenario (some background info). 1. Parititon info (in case it helps) # df -h Filesystem ...
8
votes
1answer
1k views

Block outgoing connections for certaing uids (root, apache, nobody)

With iptables in CentOS 5 and 6 Linux - how can you please prevent processes running as root, apache or nobody from initiating outgoing connections? On CentOS 5 Linux I've tried putting these lines ...
8
votes
1answer
2k views

Disabling IPV6 on Centos6

I want to disable IPV6 in the new Centos6 virtual server I have just setup in Xen. I have already followed the instructions here and then rebooted/restarted networking. Update: followed the below, ...
8
votes
2answers
609 views

Network traffic doesn't appear to leave the trunk

I'm in the process of staging up some new virtualization servers, and part of that is to get some higher-bandwidth pipes into them. The ultimate goal is to bind 4 GigE ports into a single trunk ...
7
votes
2answers
18k views

How do I get openldap on Centos 6 to write anything to it's log files

I don't get any information in my log file for openldap on my Centos 6 server. This is how i configured it. SELinux is disabled at the moment. First created a folder where I'd like to store the log ...
7
votes
2answers
12k views

How do I view the contents of a SELinux policy package

As the title says, how do I view the contents of a SELinux policy package? The resulting files end with .pp. I'm running on centos 6, but I guess it's the same way on "all" distros. For example ...
7
votes
1answer
8k views

daemon function isn't working in CentOS 6.4

I'm trying to daemonize a process under a different user. In my init.d, I have a service which looks a little bit like this: ... start() { echo "Starting mydaemon..." daemon --user someuser -...
7
votes
2answers
190 views

LUKS Error During Boot

I only see this error on the console during the boot process of virtual machines we create. EDIT: 2/5/16 - I see it on some bare-metal installations, too. (It does proceed to boot completely.) I ...
7
votes
1answer
5k views

Linux - CentOS6 - semanage - command not found

I am trying to solve an issue where my HTTPD is denied access to binding custom ports and I believe it has to do with SELinux. Whilst doing some googling I came across some posts where users were ...
7
votes
2answers
2k views

SVN Checkout error on large repositories

I wonder if anyone can help me. We have recently migrated our Subversion repository from a VisualSVN Server on Windows to a subversion server on CentOS. The migration was succesfull however we are ...
6
votes
2answers
18k views

SSH sessions terminate abruptly with message: Corrupted MAC on input. Disconnecting: Packet corrupt

We have a Dell PowerEdge 840 Server running CentOS 6.0 64 bit with 2GB ECC memory. When any user sshs in, after some time the session gets terminated with the output: Corrupted MAC on input. Packet ...
6
votes
5answers
21k views

Trying to understand the correct way to create a static route in CentOS, please assist

I've been trying to understand what's the correct way to add a static route on a CentOS 6.x machine. In some forums they say to create a file named route-dev_name (for example route-eth0) with the ...
6
votes
3answers
15k views

OOM killer killing things with plenty(?) of free RAM

The OOM killer seems to be killing things despite having more than enough free RAM on my system: (Full resolution) (Full resolution) 27 minutes and 408 processes later, the system started ...
6
votes
3answers
6k views

CentOS 6 Minimal or Hardened Install

I am working on building some new CentOs 6 servers and creating documentation for the installation of said servers. I would like to create a base CentOS 6 server install that would be light on the ...
6
votes
2answers
3k views

How to pass input from one script into another using bash

I am writing a script where I am want to launch the mysql_secure_installation script and provide the appropriate answers at each prompt. I tried using echo like this: echo -e "\n\n$db_pass\n$db_pass\...
6
votes
2answers
3k views

Is there a way to exclude specific hosts from a Nagios hostgroup?

I have a Nagios server which includes many hostgroups. One of these hostgroups include a server which I'd like to exclude from being checked for one specific Nagios Check but I want it to keep being a ...
6
votes
1answer
1k views

CentOS is ignoring my public key

I am trying to connect to my own CentOS server using SSH; I am able to connect fine with a password; I am trying to connect with my public key, but the server does not attempt public key ...