Resetting Network Interface Rules

To properly configure network interfaces for cloned virtual machines, you'll need to clear and regenerate the udev persistent network rules:

# Clear existing network rules
# rm -f /etc/udev/rules.d/70-persistent-net.rules

# Reload network module
# rmmod e1000 && modprobe e1000

KVM Virtualization Installation

First verify you're processor supports hardware virtualization extensions:

# Check CPU virtualization support
# grep -E "(svm|vmx)" /proc/cpuinfo

# Install required packages
# yum install -y qemu-kvm qemu-img virt-install libvirt python3-libvirt virt-manager

# Verify KVM module is loaded
# lsmod | grep kvm

Component Overview:

• kvm: Kernel module providing virtualization infrastructure
• qemu: Emulation layer for hardware virtualization
• qemu-kvm: Userspace component managing KVM resources

Virtual Network Configuraton

Method 1: Command Line Configuration

# Define and start custom networks
# virsh net-edit isolated-network
# virsh net-autostart isolated-network
# virsh net-start isolated-network

# Configure additional networks
# virsh net-autostart dmz-network
# virsh net-start dmz-network
# virsh net-list --all

Method 2: Graphical Configuration

# Install GUI dependencies
# yum install -y xorg-x11-xauth xorg-x11-fonts dejavu-sans-fonts

# Copy network definitions
# cp /custom/networks/isolated*.xml /etc/libvirt/qemu/networks/

# Launch virtualization manager
# virt-manager

VM Template Preparation

# Deploy base template and configuration
# cp /templates/rhel-base.img /var/lib/libvirt/images/
# cp /templates/rhel-base.xml /var/lib/libvirt/images/

# Create cloning utility
# cp /scripts/deploy-vm /usr/local/bin/deploy-vm
# chmod +x /usr/local/bin/deploy-vm

Essential KVM Management Commands

# List all virtual machines
# virsh list --all

# Power management operations
# virsh start webserver01
# virsh shutdown webserver01
# virsh destroy webserver01    # Force power off
# virsh reboot webserver01

# Remove VM configuration
# virsh undefine webserver01
# rm -f /var/lib/libvirt/images/webserver01.img

# Console access
# virsh console webserver01

File Locations:

• Configuration: /etc/libvirt/qemu/[vmname].xml
• Disk images: /var/lib/libvirt/images/[vmname].img

Network Address Translation Setup

# Disable conflicting services
# setenforce 0
# systemctl stop firewalld
# systemctl disable firewalld
# systemctl stop NetworkManager
# systemctl disable NetworkManager

# Configure NAT rules
# iptables -F
# iptables -t nat -F
# iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -o eth0 -j SNAT --to-source 203.0.113.45

# Enable IP forwarding
# sysctl -w net.ipv4.ip_forward=1
# echo 'net.ipv4.ip_forward = 1' >> /etc/sysctl.conf

System Administration Tools

• tcpdump: Network packet analysis and troubleshooting
• strace: System call tracing for debugging processes
• tmux: Terminal multiplexer for persistent sessions
• taskset: CPU affinity management for process binding

Vim Batch Operations

Multi-line commenting:

1. Press Ctrl+v to enter visual block mode
2. Select target lines using arrow keys
3. Press Shift+i and type comment character
4. Press Esc to apply to all selected lines

Removing comments:

1. Press Ctrl+v and select comment columns
2. Press d to delete selected content

Additional Storage Configuration

Create and mount secondary storage for VM images:

# Partition new disk
# fdisk /dev/vdb
# n (new partition)
# p (primary)
# 1 (partition number)
# [accept defaults]
# w (write changes)

# Format and mount
# mkfs.xfs /dev/vdb1
# mount /dev/vdb1 /var/lib/libvirt/images

# Persist mount across reboots
# echo '/dev/vdb1 /var/lib/libvirt/images xfs defaults 0 0' >> /etc/fstab