Questions tagged [centos]

Questions specific to the CentOS Linux distribution. Use this tag if your question relates to how the CentOS distribution affects your problem; do not use it if you just happen to be using CentOS and your question is about a specific configuration detail or syntax.

2,030 questions with no upvoted or accepted answers
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11
votes
0answers
4k views

How to disable sudo related logging for successful command execution under CentOS/Fedora?

You can disable sudo related log messages via adding something like Defaults:juser !syslog to the sudoers file. That will disable logging to syslog. But under e.g. CentOS/Fedora there is an auditd ...
8
votes
2answers
1k views

Whenever ansible makes changes to sshd in CentOS7 a random future play cannot connect

This has been an irritating enough problem now that I thought I would finally ask the community at large what a possible solution might be. It's even more irritating that I seem to be the only one ...
6
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0answers
1k views

How do you enable the secret-tool command (backed by gnome-keyring, libsecret and dbus) in a headless CentOS Docker container?

I'm trying to use the secret-tool command to store a secret securely in a running headless CentoS 7.5.1804 Docker container, but can't seem to find which packages and/or configuration is necessary to ...
5
votes
1answer
263 views

Netbeans fonts have distorted between CentOS 7.2 and 7.4

I'm having problems with Netbeans (programming IDE, written using Swing) on CentOS 7.4. It worked fine on 7.2 but we upgraded some kernel modules. Since then some of the fonts within my Netbeans have ...
5
votes
1answer
479 views

Sending SIGINT to process groups sometimes gets ignored

I start a process group from bash. Then I send SIGINT to the entire process group. Sometimes the SIGINT kills the processes, sometimes does not. Why does SIGINT sometimes gets ignored ? I see ...
5
votes
1answer
293 views

USB drive offline in dmesg and ? in ls, but only for some files?

I have a backup drive that has been intermittently failing (but almost always succeeding) to run rsnapshot lately. ls and e2label output are not encouraging: $ ls -al /mnt/backup/ ls: cannot access /...
5
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0answers
4k views

Exundelete can't restore the file

I'm trying to restore 2 important tar.gz files I know their directory but extundelete not restoring them although it's giving me the inode number. Loading filesystem metadata ... 2127 groups loaded. ...
5
votes
1answer
3k views

How to enable systemd user sessions for remote logins on CentOS 7?

I am trying to enable systemd user sessions on my CentOS 7 server. All the pieces seem to be there, and I have also run loginctl enable-linger <user>, but I don't have a systemd user session (or ...
5
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0answers
1k views

Why don't I hear audio playing from my CentOS 6.5 Vagrant box?

I want to play a wave file from my CentOS 6.5 Vagrant box using aplay and of course I want to hear the sound. This is what I do: > aplay sine.wav Playing WAVE 'sine.wav' : Signed 16 bit Little ...
5
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0answers
2k views

iptables hangs at applying rules

I have a set of rules that are supposed to give me the most protection before things like fail2ban and other things are added to the mix. The issue is that although everything checks out in the test, ...
5
votes
1answer
1k views

selinux, dovecot and sieve

I've just started learning to configure SELINUX and this morning on my CentOS 6.4 x64 system, with postfix/dovecot/mysql installed, I woke up to the following selinux issue found 1 alerts in /var/log/...
4
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0answers
2k views

Centos 7 AD authentication DataProvider is Offline

I have configured my Linux machine to use AD authentication. Sometimes few nodes are unable to login. The /var/log/sssd/sssd_nss.log log file reports the message below: Thu Sep 13 13:31:39 2018) [...
4
votes
1answer
526 views

RAIDs disappearing on reboot (Centos 7.5)

I'm trying to create 4 RAID 0 disk arrays on my system running Centos 7.5 and have the RAIDs automount after a reboot. For some reason, only one of the RAIDs /dev/md0 is persistent between boots. The ...
4
votes
1answer
1k views

kernel parameter init=/bin/bash not working? (RHEL7, RHCSA test)

I took the RHCSA test a couple of weeks ago, which is a lab/hands-on test. The first step is to gain root access of the VM. Usually (and this works okay on my PC's VirtualBox CentOS 7 VM) I do this by ...
4
votes
1answer
436 views

systemd-ask-password Only Prompt on Current Console

CentOS 7 I am using systemd-ask-password as part of the script that starts my systemd service. The problem is that systemd-ask-password prompts for the input on EVERY open terminal. I need to prompt ...
4
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0answers
1k views

SMTP Server Dovecot / Exim Authentication error

Recently, I've installed the centOS 6. The purpose of the installation to use this server as Mail server. Where I've installed Exim version 4.84_2 #1 and Dovecot. I've followed this blog post and I'...
4
votes
1answer
3k views

Set KDE Desktop Environment like default CentOS 7

I want to change default Desktop environment from GNome to KDE. My asking is for CentOS 7, I was Trying with How to install Desktop Environments on CentOS 7? # echo "exec startkde" >> ~/....
4
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0answers
505 views

Mail Server user management issue using Postfix+Dovecot+RainLoop

I'm using mail server using postfix+dovecot (over TLS/SSL), RainLoop as my WebClient, and using auth-system.conf.ext so user's password will be read by/from pam. Consider at least 10 users using this ...
4
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0answers
6k views

rpcbind/nfs fails, failed to create RPC listeners, exiting

My system crashed while a script was running that deploys a pxe boot system (software is called DRBL). Now I can't get rpcbind, nfs, or ypbind to start properly. I'm chasing a series of errors which ...
4
votes
1answer
2k views

TC (Traffic Control) to control bandwidth

I'm having an issue with a bandwidth script that I've been using for a while to limit the outgoing bandwidth on a port. It worked fine at the beginning until I wanted to change the outgoing port ...
4
votes
1answer
379 views

Unable to get sudo lecture working on CentOS 7 server

I'm trying to enable the sudo lecture every time someone executes sudo, but I can't seem to get it working at all. I found a similar question here, in which someone states that if you don't see any ...
4
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0answers
453 views

How do I get Consul to work so I can get Docker Overlay to work?

I am running CentOS 7 with Docker. I am trying to install Consul on the Docker server. Consul is unzipped. The binary file works for showing the version. I ran this: echo $CONSUL_RPC_ADDR This ...
4
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0answers
1k views

pppd issue over serial cable

I'm trying to set up a ppp connection between 2 computers via serial cable, to enable TCP/IP over serial. Computer1 -> USB-Serial Converter -> Serial Cable -> Serial port of Computer 2 On computer ...
4
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0answers
26k views

“xrandr: Failed to get size of gamma for output default” for Guest CENTOS 6.6, HOST OS Windows 7 enterprise

I am getting the following errors: xrandr: Failed to get size of gamma for output default Screen 0: minimum 640 x 480, current 1024 x 768, maximum 1024 x 768 default connected 1024x768+0+0 0mm ...
4
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0answers
1k views

Centos 7 boot up with custom kernel problem

I have installed centos 7 on virtualbox machine which has kernel-3.10.0-123.20.1.el7.x86_64. I am trying to build Linux kernel from kernel sources. I downloaded the kernel source files from: http://...
4
votes
0answers
1k views

blocking all but specific ips from specific services in CentOS 7

In a CentOS 7 web server that needs to remain totally closed to the public, I need to block all ip addresses and then only allow specified ip addresses to access specified services. How can I ...
4
votes
0answers
5k views

How can I reset an unknown root password if a file system check interrupts the startup sequence?

This morning I was helping a fellow admin with a crash that occurred on a CentOS 5.8 VM. Earlier in the day, the underlying SAN hosting various VMs experienced an issue and ultimately caused some ...
4
votes
0answers
491 views

TPM passwordless boot

I'm trying to create device with CentOS6, encrypted disk (with LUKS), TPM module and TrustedGRUB to boot securely and without interaction. I'm following instructions from https://github.com/shpedoikal/...
4
votes
0answers
19k views

Ping command results in packet loss

Whenever I ping on my personal computer, nothing gets displayed other than a single statement. Upon stopping execution, I see that several packets were transmitted in the statistics. On top of all ...
4
votes
0answers
982 views

Give domain users permissions on cifs shares?

I am using CentOS 6.5 - users authenticate using winbind, all are domain users except for root. /home is mapped to a cifs share on a windows server in /etc/fstab with this line: \\server\home$ /home ...
4
votes
1answer
7k views

CentOS 6.5 Login Screen GDM Issues

I have a few issues with the GDM login screen. I am using CentOS 6.5 and installed GNOME. I was able to change the background of the login screen by replacing the default.png image on the system. ...
4
votes
1answer
950 views

How to reset linux centOS 6.0 keyboard shortcuts with custom changes to default one?

On Single Desktop Environment.... I created some custom shortcuts, but currently I want to revert all the changes to default settings (which having no custom changes). Example: created like CTRL + N ...
4
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0answers
403 views

linux io stack analysis

I'm trying to understand the Linux IO stack by analyzing blktrace trace. Below is the trace i captured by executing simple fio sequential write with no Direct IO (5 x 8k request size). 8,16 1 ...
4
votes
2answers
1k views

First key pressed repeates forever

I just installed CentOS 6.4 on an old machine I acquired for a development box, but I am running into keyboard issues I can't get around. I start the machine and go to type a user name in and ...
4
votes
0answers
1k views

How can I tell if no_root_squash is enabled from an NFS client without mounting the share?

Obviously, I can look at /etc/exports on the NFS server-side to see if no_root_squash is enabled, but is there a way I can check this from the NFS client-side without actually mounting the share? ...
4
votes
1answer
2k views

CentOS 7 won't start after recent update?

Last night I got some updates through yum on my CentOS virtual machine, which also updated the kernel. I tried booting it again about an hour ago, and I haven't been able to successfully start it. I'...
4
votes
1answer
2k views

CentOS 7 unable to cleanly umount a bind mount using rbind and rslave

The following sequence of commands will fail on CentOS 7 (kernel version: 3.10.0-327.10.1.el7.x86_64): [hidden]$ mkdir -p A B/a C/b [hidden]$ sudo mount --bind A B/a [hidden]$ sudo mount --rbind B C/...
4
votes
1answer
6k views

SELinux - allowing rsyslog open/read access to some files

So I've got three files I need rsyslog to open in order to forward the entries to another server. SELinux is preventing this with the following error: type=AVC msg=audit(1371186588.768:1324460): avc:...
4
votes
1answer
421 views

How to make a init script instead of a service file

I'm installing rocket.chat on CentOS6, following this tutorial. It gives the first half of the instructions in CentOS7 and 6, but then when it comes to making it run as a service, it omits 6's ...
3
votes
0answers
23 views

Cockpit terminal vs PuTTY terminal - “Command Not Found” in Cockpit

Recently I enabled Cockpit on a newly built Centos server(7.6). I also installed Python 3.7.4 on the same server (using make altinstall). Here's the weird thing. When I call Python on a PuTTY ...
3
votes
0answers
58 views

Yum install: unexpected nothing to do while upgrading elasticsearch

I'm experimenting something estrange with yum in centos7, lets see If someone understands what's happening: Usually, I upgrade packages using sudo yum install <package_name>-<version_info>...
3
votes
0answers
43 views

How to deny crontab to group

I'm trying to deny crontab to group but I had no success so far. Nor I saw how to do it, or even discussions about it. Is it possible to deny crontab to groups instead of users? Imagine if you have ...
3
votes
1answer
75 views

Time zone: Host. What does that mean?

I know that there is several ways to setup system timezone on CentOS host. What I would like to know is the meaning of this Host timezone which seems to be set by default and is reported by ...
3
votes
1answer
218 views

What are data integrity / bit-rot protection options on CentOS 7?

I have a 2 disk CentOS 7 machine build that that I need data integrity / bitrot protection on. How can I achieve this? Note from my reading btrfs,zfs and DM-Integrity does not seem to be options. ...
3
votes
1answer
187 views

CentOS environment: How to delete docker repository from docker hub, using linux command line

I would like to delete a docker repository from dockerhub, using the command line. I am using CentOS. Like the below is used in GUI Docker hub website to delete it (the following picture shows step)
3
votes
0answers
169 views

~1000ms latency touching file on nfs mount

I have an NFS mount where the server is on the same subnet as the client. When I time touch testempty from the client, I get: touch testempty 0.00s user 0.00s system 0% cpu 1.325 total The time ...
3
votes
1answer
2k views

Python issues on CentOS - error loading shared libraries - libpython2.7.so.1.0

One of our CentOS servers has went into a strange state and is complaining that libpython2.7.so.1.0 cannot open shared object files. Yum is unusable and other features are failing to function (such ...
3
votes
1answer
771 views

cannot find -luuid error make

I am using centos7 and am trying to build this https://github.com/daveti/prov-tools/tree/master/system however I get /usr/bin/ld: cannot find -luuid I did yum install with libuuid and it says that ...
3
votes
3answers
552 views

Backup and restore of Centos network interfaces

I have a server running Centos 7 which needs to be rebooted to upgrade some software. Some of the physical NICs have around 5-10 VLAN interfaces each. They're subject to change on a weekly/monthly ...
3
votes
0answers
502 views

Centos 7 stopped detecting all RAM on system?

After months of working fine, the BIOS for my Centos 7 installation suddenly maps the wrong amount of memory to the kernel. I have 8 GB of RAM installed and the SO only maps 3.2 GB of RAM. I can't ...