虚拟机重启后无法联网ifconfig后只出现127.0.0.1

前言

我的虚拟机网络设置为NAT模式，在终端输入ifconfig只显示127.0.0.1，不能连上外网。

xxx@xxx:~$ ifconfig 
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 1000  (Local Loopback)
        RX packets 226  bytes 16851 (16.8 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 226  bytes 16851 (16.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
<

---

解决步骤：

1.先切换为root用户:sudo -i

xxx@xxx:~$ sudo -i
[sudo] password for book: 
root@xxx:~# 

2.输入:dhclient -v

xxx@xxx:~# dhclient -v
Internet Systems Consortium DHCP Client 4.3.5
Copyright 2004-2016 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/ens33/00:0c:29:fc:48:55
Sending on   LPF/ens33/00:0c:29:fc:48:55
Sending on   Socket/fallback
DHCPREQUEST of 192.168.110.131 on ens33 to 255.255.255.255 port 67 (xid=0x70ddedb7)
DHCPACK of 192.168.110.131 from 192.168.110.254
bound to 192.168.110.131 -- renewal in 759 seconds.

3.再次：ifconfig

xxx@xxx:~# ifconfig 
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.110.131  netmask 255.255.255.0  broadcast 192.168.110.255
        inet6 fe80::20c:29ff:fefc:4855  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:fc:48:55  txqueuelen 1000  (Ethernet)
        RX packets 34  bytes 2699 (2.6 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 62  bytes 8284 (8.2 KB)
        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 1000  (Local Loopback)
        RX packets 1772  bytes 127502 (127.5 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1772  bytes 127502 (127.5 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

再次ifconfig后可以看到多了一个IP地址

4.输入：exit 返回登陆者用户

root@xxx:~# exit
logout
xxx@xxx:~$ 

相关问题解答：

该方法在重启虚拟机后，依旧会存在以上问题。
我们可以将该命令加入到~/.bashrc中，保存后执行source ~/.bashrc使其立即生效。