在服务器上用qemu制作虚拟机

# Debian 12
sudo apt install qemu-kvm
# Centos 8 & Centos stream 8
sudo yum install qemu-kvm

grep -E 'vmx|svm' /proc/cpuinfo

lsmod | grep kvm

modprobe kvm-intel

dmesg | less

# Centos stream 8
sudo yum install libvirt virt-install
# Ubuntu 20.04, deepin 20
sudo apt install virtinst
# Debian 11
sudo apt install virtinst libvirt-daemon-system
sudo virsh net-start default

virt-install --name=centos8 --memory=1024 --vcpus=4 --osinfo detect=on,require=off --location=/home/searchstar/Downloads/CentOS-8.4.2105-x86_64-dvd1.iso --disk path=centos.img,size=100 --graphics=none --console=pty,target_type=serial --extra-args="console=tty0 console=ttyS0"

qemu-img create -f qcow2 centos.img 256G

# vnc=:2 可以换成其他可用端口。
sudo qemu-system-x86_64 -m 4096 -enable-kvm centos.img -cdrom ~/Downloads/CentOS-8.2.2004-x86_64-minimal.iso -display vnc=:2

sudo /usr/libexec/qemu-kvm -m 4096 -enable-kvm centos.img -cdrom ~/Downloads/CentOS-8.2.2004-x86_64-minimal.iso

sudo apt install bridge-utils uml-utilities

ip addr

set -e
if [ ! $1 ]; then
    echo Usage: $0 net_dev
    exit
fi
shutdown -r 1

brctl addbr br0
brctl addif br0 $1
# 这个时候会断网
ifconfig br0 0.0.0.0 promisc up
ifconfig $1 0.0.0.0 promisc up
dhclient br0
#brctl show br0
#brctl showstp br0

tunctl -t tap0 -u root              # 创建一个tap0接口，只允许root用户访问
brctl addif br0 tap0                # 在虚拟网桥中增加一个tap0接口
ifconfig tap0 0.0.0.0 promisc up    # 打开tap0接口
#brctl showstp br0                   # 显示br0的各个接口

if ping -c 1 baidu.com; then
    shutdown -c
    echo Shutdown canceled.
else
    shutdown -r now
fi

sudo bash net.sh eno1

sudo qemu-system-x86_64 -m 4096 -enable-kvm centos.img -net nic -net tap,ifname=tap0,script=no,downscript=no

dhclient

#!/bin/sh
#
# Copyright IBM, Corp. 2010
#
# Authors:
#  Anthony Liguori <aliguori@us.ibm.com>
#
# This work is licensed under the terms of the GNU GPL, version 2.  See
# the COPYING file in the top-level directory.

# Set to the name of your bridge
BRIDGE=br0

# Network information
NETWORK=192.168.53.0
NETMASK=255.255.255.0
GATEWAY=192.168.53.1
DHCPRANGE=192.168.53.2,192.168.53.254

# Optionally parameters to enable PXE support
TFTPROOT=
BOOTP=

do_brctl() {
    brctl "$@"
}

do_ifconfig() {
    ifconfig "$@"
}

do_dd() {
    dd "$@"
}

do_iptables_restore() {
    iptables-restore "$@"
}

do_dnsmasq() {
    dnsmasq "$@"
}

check_bridge() {
    if do_brctl show | grep "^$1" > /dev/null 2> /dev/null; then
	return 1
    else
	return 0
    fi
}

create_bridge() {
    do_brctl addbr "$1"
    do_brctl stp "$1" off
    do_brctl setfd "$1" 0
    do_ifconfig "$1" "$GATEWAY" netmask "$NETMASK" up
}

enable_ip_forward() {
    echo 1 | do_dd of=/proc/sys/net/ipv4/ip_forward > /dev/null
}

add_filter_rules() {
do_iptables_restore <<EOF
# Generated by iptables-save v1.3.6 on Fri Aug 24 15:20:25 2007
*nat
:PREROUTING ACCEPT [61:9671]
:POSTROUTING ACCEPT [121:7499]
:OUTPUT ACCEPT [132:8691]
-A POSTROUTING -s $NETWORK/$NETMASK -j MASQUERADE
COMMIT
# Completed on Fri Aug 24 15:20:25 2007
# Generated by iptables-save v1.3.6 on Fri Aug 24 15:20:25 2007
*filter
:INPUT ACCEPT [1453:976046]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1605:194911]
-A INPUT -i $BRIDGE -p tcp -m tcp --dport 67 -j ACCEPT
-A INPUT -i $BRIDGE -p udp -m udp --dport 67 -j ACCEPT
-A INPUT -i $BRIDGE -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -i $BRIDGE -p udp -m udp --dport 53 -j ACCEPT
-A FORWARD -i $1 -o $1 -j ACCEPT
-A FORWARD -s $NETWORK/$NETMASK -i $BRIDGE -j ACCEPT
-A FORWARD -d $NETWORK/$NETMASK -o $BRIDGE -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o $BRIDGE -j REJECT --reject-with icmp-port-unreachable
-A FORWARD -i $BRIDGE -j REJECT --reject-with icmp-port-unreachable
COMMIT
# Completed on Fri Aug 24 15:20:25 2007
EOF
}

start_dnsmasq() {
    do_dnsmasq \
	--strict-order \
	--except-interface=lo \
	--interface=$BRIDGE \
	--listen-address=$GATEWAY \
	--bind-interfaces \
	--dhcp-range=$DHCPRANGE \
	--conf-file="" \
	--pid-file=/var/run/qemu-dnsmasq-$BRIDGE.pid \
	--dhcp-leasefile=/var/run/qemu-dnsmasq-$BRIDGE.leases \
	--dhcp-no-override \
	${TFTPROOT:+"--enable-tftp"} \
	${TFTPROOT:+"--tftp-root=$TFTPROOT"} \
	${BOOTP:+"--dhcp-boot=$BOOTP"}
}

setup_bridge_nat() {
    if check_bridge "$1" ; then
	create_bridge "$1"
	enable_ip_forward
	add_filter_rules "$1"
	start_dnsmasq "$1"
    fi
}

setup_bridge_vlan() {
    if check_bridge "$1" ; then
	create_bridge "$1"
	start_dnsmasq "$1"
    fi
}

setup_bridge_nat "$BRIDGE"

if test "$1" ; then
    do_ifconfig "$1" 0.0.0.0 up
    do_brctl addif "$BRIDGE" "$1"
fi

chmod +x ifup_nat.sh

sudo qemu-system-x86_64 -m 4096 -enable-kvm centos.img -net nic -net tap,script=ifup_nat.sh

/usr/libexec/qemu-kvm -cpu help

virt-clone --original 源虚拟机 --name 新虚拟机名字 --file 新虚拟机的磁盘文件路径