CentOSv8

https://spalinux.com/2015/06/centos-7-basic-configure-firewall-by-firewall-cmd

https://spalinux.com/2015/06/centos-7-using-nmtui-to-modify-network-configuration

https://spalinux.com/2015/06/centos-7-use-chrony-to-sync-time-with-ntp-server

https://dev.to/onichandame/ulimit-on-centos-8-1-3md3 ulimit on CentOS 8.1 https://www.linuxtechi.com/set-ulimit-file-descriptors-limit-linux-servers/ In  /etc/security/limits.conf   * soft nofile 32767 * hard nofile 65535 [username] soft nofile 32767 [username] hard nofile 65535 /etc/systemd/user.conf DefaultLimitNOFILE=65535 1. `/etc/security/limits.conf` works for processes not under the control of systemd. Therefore, since (for example) my Gnome Terminal is running under systemd, `limits.conf` doesn't affect my Terminal's `ulimit`. 2. `/etc/systemd/user.conf` translates as roughly what controls the soft limits for your `ulimit`. 3. `/etc/systemd/system.conf` acts roughly as the hard limit. Problem On a fresh-installed Centos 8.1(kernel 4.18.0-147.8.1.el8_1) machine, the max number of opened file descriptors is set to H: 2048, S: 1024. By editing  /etc/security/limits.conf  the limits can be upped. But this only takes effect in non-gnome-terminals...