Linux网络故障排查

1. 排查硬件网卡故障
   ethtool ethN

~ ethtool enp0s31f6 
Settings for enp0s31f6:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supported pause frame use: No
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
	Speed: 100Mb/s
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: on (auto)
Cannot get wake-on-lan settings: Operation not permitted
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes

2. ip addr 查看网卡ip

~ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s31f6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether c8:5b:76:3b:c4:43 brd ff:ff:ff:ff:ff:ff
    inet 192.168.60.26/22 brd 192.168.63.255 scope global noprefixroute enp0s31f6
       valid_lft forever preferred_lft forever
    inet6 fe80::4cf0:1171:7df0:df88/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

3. 网关设置

 ~ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.60.1    0.0.0.0         UG    0      0        0 enp0s31f6
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
192.168.0.0     192.168.60.1    255.255.0.0     UG    0      0        0 enp0s31f6
192.168.56.0    0.0.0.0         255.255.255.0   U     0      0        0 vboxnet0
192.168.60.0    0.0.0.0         255.255.252.0   U     100    0        0 enp0s31f6

4. DNS状况(dig,nslookup)

~ nslookup baidu.com
Server:		192.168.0.186
Address:	192.168.0.186#53

Non-authoritative answer:
Name:	baidu.com
Address: 39.156.69.79
Name:	baidu.com
Address: 220.181.38.148

5. 网络排查

traceroute www.cnblogs.com
traceroute to www.cnblogs.com (118.31.180.41), 30 hops max, 60 byte packets
 1  192.168.60.1 (192.168.60.1)  5.486 ms  5.965 ms  6.591 ms
 2  * * *
 3  * * *
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29  * * *
30  * * *

6. 端口是否开放

# telnet 220.181.111.188 80
Trying 220.181.111.188...
Connected to 220.181.111.188.
Escape character is '^]'.

Linux系统排查4——网络篇