本文代码参考《LINUX设备驱动程序》第十七章 网络驱动程序
网络地址和虚拟主机地址为：
snullnet0 192.168.0.0
snullnet1 192.168.1.0
local0 192.168.0.1
remote0 192.168.0.2
local1 192.168.1.2
remote1 192.168.1.1
注：ldd自带网络驱动程序中的很多函数和数据结构在最新2.6.32内核上有所变动，导致编译不通过。
修改源码参考：http://blog.csdn.net/xiebiwei/article/details/6210887#quote
修改后的代码下载
测试功能
1) #make
2) #insmod snull.ko
3) #ls /sys/devices/virtual/net/
lo sn0 sn1
4) # ifconfig sn0 192.168.0.1
5) # ifconfig sn1 192.168.1.2
6) # ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
sn0 Link encap:Ethernet HWaddr 00:53:4E:55:4C:30
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::253:4eff:fe55:4c30/64 Scope:Link
UP BROADCAST RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:70 (70.0 b) TX bytes:210 (210.0 b)
sn1 Link encap:Ethernet HWaddr 00:53:4E:55:4C:31
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::253:4eff:fe55:4c31/64 Scope:Link
UP BROADCAST RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:3 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:210 (210.0 b) TX bytes:70 (70.0 b)
7) # ping -c 2 192.168.0.2
PING 192.168.0.2 (192.168.0.2) 56(84) bytes of data.
64 bytes from 192.168.0.2: icmp_seq=1 ttl=64 time=0.052 ms
64 bytes from 192.168.0.2: icmp_seq=2 ttl=64 time=0.022 ms
--- 192.168.0.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.022/0.037/0.052/0.015 ms
8) # ping -c 2 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.028 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.022 ms
--- 192.168.1.1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.022/0.025/0.028/0.003 ms