问题描述
最近几天发现实验室的服务器无法连接外网，ping不通，无法git clone代码等等。每天花一点时间尝试排查一下问题出在哪里，看看怎么解决。
过程
ifconfig看一下信息。可以看到：平时ssh连接的网卡是ens192，它的内网IP是172.17.172.192，运行状态好像没什么问题；ens160的内网IP是169.254.8.98，好像有问题，本地没办法ping通；$ ifconfig docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 172.18.0.1 netmask 255.255.0.0 broadcast 172.18.255.255 inet6 fe80::42:50ff:fe64:4e73 prefixlen 64 scopeid 0x20<link> ether 02:42:50:64:4e:73 txqueuelen 0 (Ethernet) RX packets 178670 bytes 144916517 (144.9 MB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 3362197 bytes 340061285 (340.0 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fc00:7934:ba68:1:453f:626d:245b:93e8 prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:fa5b:3156:d9d2:37e0 prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:4e07:d3e:9f21:eea4 prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:6137:f06e:9597:d985 prefixlen 64 scopeid 0x0<global> inet6 fe80::c8b7:129e:b125:6a28 prefixlen 64 scopeid 0x20<link> inet6 fc00:7934:ba68:1:242d:4fe9:2c0c:cd2f prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:808c:f4a7:b0eb:bf63 prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:6d60:5c0:d8e4:d9cb prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:a6b:d8f7:cf36:9130 prefixlen 64 scopeid 0x0<global> inet6 fc00:7934:ba68:1:f654:1fe0:9220:daa1 prefixlen 64 scopeid 0x0<global> ether 00:0c:29:80:36:ef txqueuelen 1000 (Ethernet) RX packets 20356000 bytes 7320601513 (7.3 GB) RX errors 0 dropped 693 overruns 0 frame 0 TX packets 25632830 bytes 3912930954 (3.9 GB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ens192: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 172.17.172.192 netmask 255.255.248.0 broadcast 172.17.175.255 inet6 2001:250:6803:206:8ec4:af17:22a0:204c prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:1b61:1818:9181:3833 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:8b33:c189:6e29:a038 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:2381:b202:cd4d:c781 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:81ad:159d:f8bb:6893 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:5a18:1bd3:8525:f532 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:744f:830a:46fd:2cc9 prefixlen 64 scopeid 0x0<global> inet6 2001:250:6803:206:cf03:ab8a:585:5810 prefixlen 64 scopeid 0x0<global> inet6 fe80::2f79:480e:1041:4000 prefixlen 64 scopeid 0x20<link> inet6 2001:250:6803:206:8a4a:e39e:ee42:d311 prefixlen 64 scopeid 0x0<global> ether 00:0c:29:80:36:f9 txqueuelen 1000 (Ethernet) RX packets 50603025 bytes 9110805500 (9.1 GB) RX errors 0 dropped 703 overruns 0 frame 0 TX packets 29180189 bytes 18701212188 (18.7 GB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ens160:avahi: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 169.254.8.98 netmask 255.255.0.0 broadcast 169.254.255.255 ether 00:0c:29:80:36:ef txqueuelen 1000 (Ethernet) 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 8260572 bytes 1759584719 (1.7 GB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 8260572 bytes 1759584719 (1.7 GB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 vethabaa764: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fe80::f013:f5ff:fe7b:9d43 prefixlen 64 scopeid 0x20<link> ether f2:13:f5:7b:9d:43 txqueuelen 0 (Ethernet) RX packets 178663 bytes 147417543 (147.4 MB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2162158 bytes 290116295 (290.1 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 zt44xh4rxy: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 2800 inet 192.168.192.124 netmask 255.255.255.0 broadcast 192.168.192.255 inet6 fe80::9465:3eff:fee1:a8cc prefixlen 64 scopeid 0x20<link> ether 96:65:3e:e1:a8:cc txqueuelen 1000 (Ethernet) RX packets 119243 bytes 13381700 (13.3 MB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2653 bytes 229946 (229.9 KB) TX errors 0 dropped 6632 overruns 0 carrier 0 collisions 0route看一下路由表。路由表好像有点问题，172.17.168.1是什么IP？$ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.17.168.1 0.0.0.0 UG 0 0 0 ens192 0.0.0.0 0.0.0.0 0.0.0.0 U 1002 0 0 ens160 0.0.0.0 172.17.168.1 0.0.0.0 UG 20101 0 0 ens192 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 ens160 172.17.168.0 0.0.0.0 255.255.248.0 U 101 0 0 ens192 172.18.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0 192.168.192.0 0.0.0.0 255.255.255.0 U 0 0 0 zt44xh4rxy先尝试把ens192的IP加到路由表里面。
$ sudo route add -net 0.0.0.0 netmask 0.0.0.0 gw 172.17.172.1 $ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.17.172.1 0.0.0.0 UG 0 0 0 ens192 0.0.0.0 172.17.168.1 0.0.0.0 UG 0 0 0 ens192 0.0.0.0 0.0.0.0 0.0.0.0 U 1002 0 0 ens160 0.0.0.0 172.17.168.1 0.0.0.0 UG 20101 0 0 ens192 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 ens160 172.17.168.0 0.0.0.0 255.255.248.0 U 101 0 0 ens192 172.18.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0 192.168.192.0 0.0.0.0 255.255.255.0 U 0 0 0 zt44xh4rxy $ ping www.baidu.com ping: www.baidu.com: Temporary failure in name resolution“Temporary failure in name resolution”，是不是DNS解析的问题？尝试修改DNS服务器配置。网上常见的教程就是修改
/etc/resolv.conf，但是打开这个文件发现第一行就写着 “Do not edit.”# This file is managed by man:systemd-resolved(8). Do not edit. # # This is a dynamic resolv.conf file for connecting local clients to the # internal DNS stub resolver of systemd-resolved. This file lists all # configured search domains. # # Run "resolvectl status" to see details about the uplink DNS servers # currently in use. # # Third party programs must not access this file directly, but only through the # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way, # replace this symlink by a static file or a different symlink. # # See man:systemd-resolved.service(8) for details about the supported modes of # operation for /etc/resolv.conf. nameserver 127.0.0.53 options edns0 trust-ad按照文件中的指示，
resolvectl status：...... Link 3 (ens192) Current Scopes: DNS DefaultRoute setting: yes LLMNR setting: yes MulticastDNS setting: no DNSOverTLS setting: no DNSSEC setting: no DNSSEC supported: no DNS Servers: 210.34.48.59 218.104.128.106 218.85.157.99 DNS Domain: ~. ......这3个DNS Server都ping不通啊。现在有点怀疑会不会真是没有网了。
