OpenBSD related tutorial/FAQ

How To Protect SSH With Fail2Ban on CentOS 8

last updated September 26, 2019 in CentOS, Linux, OpenBSD, Security

My ssh log file shows too many password failures. Random IP address trying to brute force my sshd server running on CentOS 8 server. How do I protect ssh with fail2ban on CentOS 8 Linux server? How do I install Fail2Ban on CentOS 8?

How to check disk space on Unix servers

last updated July 26, 2019 in AIX, Commands, FreeBSD, HP-UX Unix, OpenBSD, UNIX

I recently switched from a Windows server 2016 to a FreeBSD Unix server. I need to check disk space on Unix command line. How do I find out disk space utilization information using the Unix command-line option?

OpenBSD install MariaDB database server

last updated October 1, 2019 in MySQL, OpenBSD, UNIX

How do I install MariaDB database servers on OpenBSD Unix operating systems?

How To Set Up SSH Keys on RHEL 8

last updated November 30, 2018 in Cryptography, Linux, OpenBSD, RedHat and Friends

I am a new RHEL 8 server sysadmin. How do I configure SSH public key-based authentication for RHEL (Red Hat Enterprise Linux) 8 server?

Ubuntu 18.04 Setup SSH Public Key Authentication

last updated October 24, 2018 in OpenBSD, Ubuntu Linux

I am a new Ubuntu 18.04 LTS user and I would like to setup ssh public key authentication. How do I set up ssh keys based authentication on Ubuntu Linux 18.04 LTS server? How do I set up SSH keys on an Ubuntu Linux 18.04 LTS server? In Ubuntu 18.04 LTS, how do I set up public key authentication?

Ansible reboot Linux machine or server with playbooks

last updated October 6, 2018 in CentOS, Debian / Ubuntu, FreeBSD, Linux, OpenBSD, RedHat and Friends, Suse, UNIX

I need to reboot the VM or bare metal Linux machine/server using Ansible and wait for it to come back, but it does not work with playbook as descried here. How to reboot Linux server with Ansible? How do I reboot and wait for reboot to complete in Ansible playbook for multiple Linux servers?

Ubuntu Linux install OpenSSH server

last updated October 14, 2019 in OpenBSD, Ubuntu Linux

How do I install OpenSSH server on Ubuntu Linux?

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