当我们无法获取ip地址时可以使用dhcp来动态获取ip地址，安装dhcpcd5和dhcpcd-gtk
sudo apt-get install dhcpcd5
sudo apt-get install dhcpcd-gtk
使用ifconfig查看网卡名称，比如我本子上的有线网无法获取到ipv4，而我的有线网卡的名称为enp7s0，那么使用下面的命令即可获取到ipv4地址
dhcpcd enp7s0
dhcpcd-gtk是用来查看当前各网络设备的状态
irving@celtics:~/.ssh$ dhcpcd-gtk
** Message: Connecting ...
** Message: Connected to dhcpcd-dbus-0.6.0
** Message: Status changed to connected
** Message: Connected to dhcpcd-6.10.1
** Message: enp7s0: IPV4LL
** Message: wlp0s20f3: NOCARRIER
** Message: wlp0s20f3: Received scan results