在默认情况下，如果不指定任何网络模式的话，kvm会默默的为我们选择NAT模式，除了NAT之外还有Bridge及Vlan模式。
User Networking(NAT模式)
采用该模式，不需要对宿主机进行任何额外配置。正常情况下虚拟机可以直接访问宿主机的物理网络、宿主机无法访问虚拟机。
好处是简单、无需任何配置，如果宿主机可以上网则虚拟机也可以上网。
坏处是虚拟机与虚拟机之间网络不可达、ICMP协议无法正常工作(即ping功能不能正常返回值)、NAT采用的是转发机制，因此效率比较低。
# 宿主机: ip地址 [[email protected] qemuImages]$ ifconfig p3p1 p3p1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.102 netmask 255.255.255.0 broadcast 0.0.0.0 inet6 fe80::ba88:e3ff:fef3:af7c prefixlen 64 scopeid 0x20<link> ether b8:88:e3:f3:af:7c txqueuelen 1000 (Ethernet) RX packets 232953 bytes 210207598 (200.4 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 282248 bytes 40669709 (38.7 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 # 宿主机: 可以正常访问互联网 [[email protected] qemuImages]$ ping PING www.a.shifen.com (119.75.217.56) 56(84) bytes of data. 64 bytes from 119.75.217.56: icmp_seq=1 ttl=56 time=33.8 ms 64 bytes from 119.75.217.56: icmp_seq=2 ttl=56 time=31.8 ms # 宿主机: 启动虚拟机 [[email protected] qemuImages]$ sudo qemu-kvm -m 2048 -hda networkNode.img
虚拟机:
ping www.baidu.com 结论: ping不通互联网
ping 宿主机(192.168.1.102) 结论: ping不通宿主机及互联网
wget http://www.baidu.com 结论: 可以正常下载页面
最后通过一些高级特性可以实现宿主机访问虚拟机。
# 宿主机: 启动虚拟机时提供hostfwd参数 # 该参数允许宿主机通过60000端口连接到虚拟机的22端口, 其他方面无任何变化. [[email protected] qemuImages]$ sudo qemu-kvm -m 2048 -hda networkNode.img -net nic -net user,hostfwd=tcp:127.0.0.1:60000-:22 # 宿主机: 连接到虚拟机 结论: 可以正常连接到虚拟机 [[email protected] qemuImages]$ ssh [email protected] -p 60000 The authenticity of host ‘[localhost]:60000 ([127.0.0.1]:60000)‘ can‘t be established. RSA key fingerprint is 42:73:36:58:f3:75:12:35:8a:07:8d:4d:32:1a:59:3a. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added ‘[localhost]:60000‘ (RSA) to the list of known hosts. [email protected]‘s password: Last login: Sun Nov 30 23:53:27 2014 [[email protected] ~]# ifconfig ens3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.0.2.15 netmask 255.255.255.0 broadcast 0.0.0.0 inet6 fe80::5054:ff:fe12:3456 prefixlen 64 scopeid 0x20<link> ether 52:54:00:12:34:56 txqueuelen 1000 (Ethernet) RX packets 66 bytes 8768 (8.5 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 81 bytes 11168 (10.9 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 6 bytes 560 (560.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 6 bytes 560 (560.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
时间： 2024-10-11 21:32:56