qemu nat网络跑gentoo

yum install bridge-utils iptables dnsmasq

lsmod|grep tun
modprobe tun

chmod 777 /etc/qemu-ifup

[root@host-10-6-6-4 gentoo]# cat /etc/qemu-ifup 
#!/bin/sh
#
# Copyright IBM, Corp. 2010  
#
# Authors:
#  Anthony Liguori <[e-mail]>
#
# 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
[root@host-10-6-6-4 gentoo]# 

qemu-system-i386 -hda gentoo.img -boot order=d -cdrom install-x86-minimal-20141125.iso -m 1024 -net nic,macaddr=00:16:3e:22:22:22 -net tap -localtime -vnc 10.6.6.4:1 &
#dnsmasq --strict-order --except-interface=lo --interface=br0 --listen-address=192.168.53.1 --bind-interfaces --dhcp-range=192.168.53.2,192.168.53.254 --conf-file= --pid-file=/var/run/qemu-dnsmasq-br0.pid --dhcp-leasefile=/var/run/qemu-dnsmasq-br0.leases --dhcp-no-override

参考
http://wiki.qemu.org/Documentation/Networking/NAT#Overview