1、运行命令ifconfig查看当前网卡列表，确定名称，如果不在列表内，可能是驱动没装好

% ifconfig

dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500

inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255

ether 00:a0:cc:da:da:da

media: Ethernet autoselect (100baseTX <full-duplex>)

status: active

dc1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500

inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255

ether 00:a0:cc:da:da:db

media: Ethernet 10baseT/UTP

status: no carrier

lp0: flags=8810<POINTOPOINT,SIMPLEX,MULTICAST> mtu 1500

lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384

inet 127.0.0.1 netmask 0xff000000

tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500

2、vi /etc/rc.conf 添加

ifconfig_dc0="DHCP"

dhcp_program="/sbin/dhclient"

dccp_flags=""

3、reboot后，应该就可以用了