CentOS related tutorial/FAQ

Linux copy and clone USB stick including partitions command

last updated August 11, 2018 in CentOS, Debian / Ubuntu, Linux, RedHat and Friends, Suse

I need to copy and clone existing data from a USB stick. How do I clone a bootable USB key/pen drive on Linux? How do I clone a USB stick including partitions on Linux operating system?

KVM forward ports to guests VM with UFW on Linux

last updated July 30, 2018 in CentOS, Debian / Ubuntu, Iptables, Linux, Linux KVM

My Debian/Ubuntu/CentOS Linux server using KVM as a hypervisor. I would like to forward ports to guests VM with UFW iptables. How do I forward ports on a Linux server running libvirt/KVM to specified ports on VM’s, when using NAT?

Slow performance issues of OpenBSD or FreeBSD KVM guest on Linux

last updated July 22, 2018 in CentOS, Linux KVM, RedHat and Friends, Troubleshooting

I run a couple of OpenBSD and FreeBSD guest/virtual machines under KVM. My server has 32GB ram and 4C/8T Intel Xeon CPU. Everything was working fine until recent CentOS Linux 7 kernel update. After a fresh reboot of my CentOS 7 Linux box OpenBSD and FreeBSD machine become very slow and after 24 hours stop responding to the network request. How can I solve significant performance problems with BSD family of oses running on CentOS 7 KVM?

How to Set Up and Use LXD on CentOS Linux 7.x Server

last updated July 17, 2018 in CentOS, Linux, Linux Containers (LXC), Virtualization

I know how to setup LXD on a Debian or Ubuntu Linux. How do I install, configure and setup LXD on CentOS Linux 7.x?
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How to reset a KVM clone virtual Machines with virt-sysprep on Linux

last updated August 14, 2018 in CentOS, Debian / Ubuntu, Linux KVM, RedHat and Friends, Suse, Virtualization

I know how to clone a KVM VM. Once cloned I would like to reset cloned VM. How do I reset, unconfigure or customize a virtual machine so clones can be made? How can I reset a KVM clone virtual Machines with virt-sysprep command on a Linux server based hypervisor?

Linux list a KVM vm guest using virsh command

last updated July 19, 2018 in CentOS, Debian / Ubuntu, Linux KVM, RedHat and Friends, Suse

How do I list a KVM vm guest using virsh command on a Linux based hypervisor?

How to add comments to iptables rules on Linux

last updated May 30, 2018 in CentOS, Debian / Ubuntu, Iptables, Linux, RedHat and Friends, Suse

I am a new Linux sysadmin. How can I add comments to iptables rules on Linux using the iptables command?

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