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64 votes
Accepted

No network connectivity to/from Docker CE container on CentOS 8

After spending a couple of days looking at logs and configurations for the involved components, I was about to throw in the towel and revert back to Fedora 30, where this seems to work straight out of ...
Saustrup's user avatar
  • 1,213
14 votes
Accepted

firewalld is not working in CentOS 8: no rule at all is created in iptables

Because you don't see any iptables rule, doesn't mean firewalld is not working. Actually firewalld switched to using nftables as backend. So you can find your rules with for example: nft list ruleset ...
A.B's user avatar
  • 13k
13 votes

No network connectivity to/from Docker CE container on CentOS 8

What's missing from the answers before is the fact that you first need to add your docker interface to the zone you configure, e.g. public (or add it to the "trusted" zone which was suggested here but ...
omni's user avatar
  • 343
10 votes
Accepted

Failing to run yum update in CentOS 8

The infra that is behind vault.centos.org will likely always going to be flaky. RedHat has very little motivation to support it. It is for archived community version of their primary OS, the very same ...
Danila Vershinin's user avatar
8 votes

Can't mount CentOS NFS share on Windows 10 - "Network Error - 53"

On the Linux part - make sure your NFS Server Configuration is correct: nfs-utils and nfs-utils-lib should be installed rpcbind, nfs-server, nfs-lock, nfs-idmap should be enabled rpcbind, nfs-...
Overmind's user avatar
  • 3,171
7 votes

How do I update a system from CentOS 7 to CentOS 8?

Red Hat provide the tool leapp to upgrade from EL 7.6+ to 8, however according to this CentOS bug, there are no plans to support it on CentOS. Trying to point an existing 7.x machine to the 8.x repos ...
bodgit's user avatar
  • 4,791
7 votes

Again enabled SELINUX and now the user logins wont work in enforcing mode

Running with Selinux disabled for a long time can cause files to not be labelled or labelled with Selinux context not matching the installed policy. Also daemons and other processes (including systemd)...
zorry's user avatar
  • 156
6 votes

Yum on Centos 8 - Failed to download metadata for repo 'AppStream'

Apparently not the problem here, but if you have pinned yourself to CentOS 8.1.1911 you will get the same error until you re-point your /etc/yum.repos.d/ repositories at http://vault.centos.org ...
Raven's user avatar
  • 161
6 votes
Accepted

"dnf update" vs. "yum update" command differences in CentOS Linux?

yum was replaced with dnf in CentOS 8. The command yum still exists because people will still remember it for years to come. The only thing it does is to call dnf. [root@localhost ~]# ls -l /usr/bin/...
Michael Hampton's user avatar
6 votes

Dell R620 with PERC s110 and LSI Centos 8 not discovering RAID drives

DELL S110 is nothing more than a fancy name for Intel software RAID (see the SATA controller specification). It depends on a device driver being present in Windows which effectively run the software ...
shodanshok's user avatar
  • 51.1k
6 votes
Accepted

What replaces "ntpq" in CentOS 8?

as of rhel8, the NTP protocol is implemented by the chronyd daemon. you can use chronyc sources
Adil's user avatar
  • 249
6 votes

x11vnc can not connect to X server of gdm greeter

Run x11vnc as gdm user: sudo -u gdm x11vnc -rfbauth /etc/vncpasswd -auth /run/user/42/gdm/Xauthority -display :0
A T's user avatar
  • 61
5 votes
Accepted

How to determine if my CentOS 8 is vulnerable to CVE-2019-18348

You are on the right track following the Red Hat Service Advisory. The same package that resolves CVE/RHSA upstream will be released for CentOS. Sometimes it is not available as quickly. There is a ...
Aaron Copley's user avatar
  • 12.7k
5 votes

No network connectivity to/from Docker CE container on CentOS 8

To be able to set fine-grained rules for Docker, I did not need to set docker0 to any zone. # 1. Stop Docker systemctl stop docker # 2. Recreate DOCKER-USER chain in firewalld. firewall-cmd --...
Bertl's user avatar
  • 195
5 votes
Accepted

Ansible Centos 8 dnf module "module" switch missing?

You can install a module (which is essentially a group of packages) by adding a @ prior to the name of the module to the name parameter of the Ansible dnf module. It can be used like this: - name: ...
Henrik Pingel's user avatar
5 votes
Accepted

How much does httpd_can_network_connect being set to 1 actually open up on SELinux

how much this actually opens up from a security standpoint A lot. As you may have guessed it allows httpd_t to talk to any remote servers. There is no specification for which website it is, and it ...
Danila Vershinin's user avatar
5 votes
Accepted

Remi: Which repository contains what?

As a general rule you should enable remi-safe, remi and remi-modular (but all three of these should already be enabled). These repos together contain the packages and module streams you expected to ...
Michael Hampton's user avatar
5 votes

CentOS 8.3 - How to switch a PHP installation from Remi to AppStream?

(RHEL 8.4+) The same way you switch any other module to a different stream: dnf module switch-to php:7.4 Note that this will fail if you used any remi packages that are not in the new module stream, ...
Michael Hampton's user avatar
5 votes
Accepted

Can't run command under /bin/false user

Setting the default shell to /bin/false means that su will switch user, and then execute /bin/false -c /opt/tomcat/bin/startup.sh You can use the -s option to su to override the setting in /etc/...
Simon Richter's user avatar
5 votes
Accepted

CentOS 9 Stream - errors doing yum update

baseos CentOS Stream 9 - BaseOS epel Extra Packages for Enterprise Linux 7 - x86_64 extras-common CentOS Stream 9 - Extras packages You are using old EPEL (and "remi") for ...
Remi Collet's user avatar
  • 2,146
4 votes

No network connectivity to/from Docker CE container on CentOS 8

I have changed the FirewallBackend variable to iptables again and it works for me. With this update, the nftables filtering subsystem is the default firewall backend for the firewalld daemon. To ...
Taw HK's user avatar
  • 141
4 votes

How do I update a system from CentOS 7 to CentOS 8?

There are manuals around with bugs, so try this (see comments). If something fails, you need to resolve the issue or it won't work. Some steps are hard to reverse and you may end up with unbootable ...
Milan Kerslager's user avatar
4 votes
Accepted

How does dnf-automatic send emails without knowing a password?

In general, sending email via SMTP doesn't require authentication, and you can just spoof any From and Return-Path address (unless restricted). The email feature on DNF Automatic seems to rely on that....
Esa Jokinen's user avatar
  • 50.3k
4 votes

Issue running Golang server binary as a service with Systemd

I found the problem! It was due to the SELinux policy, which was denying Systemd to run my server app as a service, as it was in a non-standard bin directory /var/mybin/. you can verify the SELinux ...
Daniele B's user avatar
  • 367
4 votes

Recommended approach for booting from Linux software RAID for redundancy

I ended up going with a GPT partition table, but sticking with the old Bios boot. This was in-part due to some of the complexities surrounding using RAID for an EFI boot partition - https://unix....
maloo's user avatar
  • 182
4 votes
Accepted

Deactivate default ports of systemd socket activation

You can list the files being used by systemd for the socket by using: $ systemctl cat httpd.socket and on my system this shows (some lines removed to keep it short): # /usr/lib/systemd/system/httpd....
meuh's user avatar
  • 1,593
4 votes

CentOS 8.2 LDAP client configuration

sssd does not support LDAP authentication over unencrypted connections. From sssd-ldap(5) man page: If you want to authenticate against an LDAP server either TLS/SSL or LDAPS is required. sssd does ...
Kevin S's user avatar
  • 61
4 votes
Accepted

On CentOS Certbot / Lets Encrypt uses snap to keep SSL certificates up to date. Is there another method that will keep certificates up to date?

certbot is available on EPEL. Follow these instructions to add the Extra Packages for Enterprise Linux (EPEL) to your system. After that certbot can be installed like any other package with yum ...
Henrik Pingel's user avatar
4 votes
Accepted

Configuring Squid to not log TCP connections (lots of "error:transaction-end-before-headers" showing up in logs)

According to Squid ACL documentation you can try to add the following ACL in your Squid config: acl hasRequest has request Then log those transactions that have request: access_log /var/log/squid/...
semenchikus's user avatar
3 votes
Accepted

Infected server (bitcoin mining malware)

It sounds to me that this process was already running (ie in memory) when you did your cleanup and you didn't kill it, so its still there. The 990 username means the user no longer exists. It ...
davidgo's user avatar
  • 6,332

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