18.17. 笔记本配置
The task of configuring your RHEL 5.1 loaded laptop for use on a network environment, presents a number of potential challenges. Most WiFi and wired connections switch constantly during any given day, and Red Hat Virtualization assumes it has access to the same interface consistently. This results in the system performing ifup/ifdown calls to the network interface in use by Red Hat Virtualization. WiFi cards are not the ideal network connection method since Red Hat Virtualization uses the default network interface.
The idea here is to create a 'dummy' network interface for Red Hat Virtualization to use.
This technique allows you to use a hidden IP address space for your guests and Virtual Machines. To do this operation successfully, you must use static IP addresses as DHCP does not listen for IP addresses on the dummy network. You also must configure NAT/IP masquerading to enable network access for your guests and Virtual Machines. You should attach a static IP when you create the 'dummy' network interface.
在这个例子里，接口被称为 dummy0，IP 地址为 10.1.1.1。脚本被称作
ifcfg-dummy0 并位于 /etc/sysconfig/network-scripts/ 目录下。
DEVICE =dummy0 BOOTPROTO=none ONBOOT=yes USERCTL=no IPV6INIT=no PEERDNS=yes TYPE=Ethernet NETMASK=255.255.255.0 IPADDR=10.1.1.1 ARP=yes
你应该把
xenbr0 绑定至 dummy0 ，这样即使和物理网络断开，这也可以允许网络连接。
You will need to make additional modifications to the
xend-config.sxp file. You must locate the ( network-script 'network-bridge' bridge=xenbr0 ) section and add include this in the end of the line:
netdev=dummy0
You must also make some modifications to your guest's domU networking configuration to enable the default gateway to point to dummy0. You must edit the DomU 'network' file that resides in the
/etc/sysconfig/ directory to reflect the example below:
NETWORKING=yes HOSTNAME=localhost.localdomain GATEWAY=10.1.1.1 IPADDR=10.1.1.10 NETMASK=255.255.255.0
启用 domain0 里的 NAT 是个好主意，这样 domU 就可以访问公共网络。用这种方式，即使是无线用户也可以绕过红帽虚拟化系统的无线限制。如下例所示，要实现这种方法，你必须修改
/etc/rc3.d 目录里的 S99XenLaptopNAT 文件。
#!/bin/bash
#
# XenLaptopNAT Startup script for Xen on Laptops
#
# chkconfig: - 99 01
# description: Start NAT for Xen Laptops
#
# PATH=/usr/bin:/sbin:/bin:/usr/sbin
# export PATH
GATEWAYDEV=`ip route | grep default | awk {'print $5'}`
iptables -F
case "$1" in
start)
if test -z "$GATEWAYDEV"; then
echo "No gateway device found"
else
echo "Masquerading using $GATEWAYDEV"
/sbin/iptables -t nat -A POSTROUTING -o $GATEWAYDEV -j MASQUERADE
fi
echo "Enabling IP forwarding"
echo 1 > /proc/sys/net/ipv4/ip_forward
echo "IP forwarding set to `cat /proc/sys/net/ipv4/ip_forward`"
echo "done."
;;
*)
echo "Usage: $0 {start|restart|status}"
;;
esac
如果你想在引导时自动设置网络，你必须创建
/etc/rc3.d/S99XenLaptopNAT 的软链接。
在修改
modprobe.conf 文件时，你必须包括下面的行：
alias dummy0 dummy options dummy numdummies=1
