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2023-08-23 00:02| 来源: 网络整理| 查看: 265

Linux-Centos 7 网络NAT连接模式不能上网问题排查首先启动centos系统后，检查ping www.baidu.com 无法解析，后转root用户 [normal4@localhost ~]$ ping www.baidu.com ping: www.baidu.com: 未知的名称或服务 [normal4@localhost ~]$ su - 密码：上一次登录：三 6月 17 09:16:40 CST 2020pts/0 上 [root@localhost ~]# whoami root [root@localhost ~]#

1、检查网卡信息！！！

[root@localhost ~]# ifconfig lo: flags=73 mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 2631 bytes 1059258 (1.0 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2631 bytes 1059258 (1.0 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 irbr0: flags=4099 mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:7d:79:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@localhost ~]# ifconfig -a ens33: flags=4098 mtu 1500 ether 00:0c:29:e4:67:a0 txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73 mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 8008 bytes 3303986 (3.1 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 8008 bytes 3303986 (3.1 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099 mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:7d:79:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0-nic: flags=4098 mtu 1500 ether 52:54:00:7d:79:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 root@localhost ~]#

2、发现有个网卡没有启动！！！ PS.后期发现可以直接跳到第4步执行命令，也可以解决问题（即不需要手动启动网卡）

**先启动网卡** [root@localhost ~]#ifconfig ens33 up **检查网卡启动是否成功** [root@localhost ~]#ifconfig ens33:flags=4163 mtu 1500 inet6 fe80::20c:29ff:fee4:67a0 prefixlen 64 scopeid 0x20 ether 00:0c:29:e4:67:a0 txqueuelen 1000 (Ethernet) RX packets 1 bytes 60 (60.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 7 bytes 586 (586.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo:flags=73 mtu65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid0x10 loop txqueuelen 1000 (Local Loopback) RX packets 12452 bytes 5263410 (5.0 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 12452 bytes 5263410 (5.0 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0:flags=4099 mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast192.168.122.255 ether 52:54:00:7d:79:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@localhost ~]#

3、网卡已经启动，但未分配到IP地址！！！

**重启network服务** t@localhost ~]# service network restart Restarting network (via systemctl): Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details. [失败] [root@localhost ~]#

4、服务启动失败，猜测可能是NetworkManager服务导致，需要关闭它！！！

[root@localhost ~]# systemctl stop NetworkManager **同时需要重启network服务** [root@localhost ~]# service network restart Restarting network (via systemctl): [ 确定 ] [root@localhost ~]#

5、再次检查网卡信息！！！

[root@localhost ~]# ifconfig ens33: flags=4163 mtu 1500 inet 192.168.208.130 netmask 255.255.255.0 broadcast 192.168.208.255 inet6 fe80::20c:29ff:fee4:67a0 prefixlen 64 scopeid 0x20 ether 00:0c:29:e4:67:a0 txqueuelen 1000 (Ethernet) RX packets 471 bytes 30148 (29.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 32 bytes 4889 (4.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73 mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 41368 bytes 17635554 (16.8 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 41368 bytes 17635554 (16.8 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099 mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:7d:79:7c txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@localhost ~]#

6、上面的命令我们已经看到IPv4的地址了，检测下是否能正常联网！！！

[root@localhost ~]# ping -c 3 www.baidu.com PING www.a.shifen.com (180.101.49.11) 56(84) bytes of data. 64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=1 ttl=128 time=18.3 ms 64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=2 ttl=128 time=17.7 ms 64 bytes from 180.101.49.11 (180.101.49.11): icmp_seq=3 ttl=128 time=20.5 ms --- www.a.shifen.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2004ms rtt min/avg/max/mdev = 17.726/18.854/20.511/1.207 ms [root@localhost ~]#

7、如果当你下次重启虚拟机的时候，还是发现网卡没启动，那么就永久关闭NetworkManager服务！！！

[root@localhost ~]# systemctl disable NetworkManager Removed symlink /etc/systemd/system/multi-user.target.wants/NetworkManager.service. Removed symlink /etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service. Removed symlink /etc/systemd/system/network-online.target.wants/NetworkManager-wait-online.service. [root@localhost ~]#

8、这样就可以解决问题了.

本篇文章大部分采用了以下博客的信息，现贴链学习链接: link

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