Handling process of the problem that the virtual machine's intranet communication Ping fails

One 、 Problem description

During a business cutover , It is found that part of the virtual machine Intranet can ping through , part ping No access to the scene , Especially like partition or isolation in network virtualization , And a host appears ping Gateway and 127.0.0.1 The echo unknown host The situation of , But it's normal ping localhost, Nothing else ping, But the host is not disabled ping, And telnet The port of the new address of the same network segment , Communication is normal , Prove that network communication should be normal . See below for details .

Two 、 process analysis

1、 Check whether it is forbidden ping

cat /proc/sys/net/ipv4/icmp_echo_ignore_all //1 For prohibition ping

2、ping Local address test ：

ping gw // no , There is a problem with the gateway ,ip Address conflict or mac Address conflict
ping 127.0.0.1 // Show unknown host, Maybe the network card driver is not working properly , namely tcp/ip Agreement question , Or firewall problems

3、 see network service , Although the service is normal , But there is an error ： The problem of network inaccessibility

Report errors ：

SIOCADDRT: Network is unreachable
RTNETLINK answers: File exists

The above error is usually the default gateway problem , Cause inaccessibility .ping Take a look at the gateway , however ping The connection of does not mean that the next hop of the route can be made .

4、 View network card information ：

lspci|grep -i eth
// Confirm whether the network card is connected
mii-tool eh0 // Normal display link ok
// Check the network card work mos
ethtool eth0

5、 Configure temporary ip Address

ifconfig  eth0 172.16.18.2 netmask 255.255.255.0
# For network card sub interface , It can be executed as follows 
ifconfig  eth0:1 172.16.18.2 netmask 255.255.255.0

6、 After restarting the network card, multiple gateway addresses are always displayed , Including manual configuration of static network card , The last few checks were issued /etc/sysconfig/static-routes, The old gateway address is written in , That is, the priority of the configuration file is higher than the static network card configuration , Restart after modification network After service , The gateway address is normal .

7、 After testing, the virtual machine intranet ping Still not , Check the security team , increase icmp Normal after the admission rules .

8、 About involving ping The echo unknown host That virtual machine , It is also found that execution yum Report errors ：

/usr/lib64/python2.7/site-packages/rpm/_rpm.so: undefined symbol: rpmpkgVerifySigs

Reference resources ： attach 1、 attach 2 Handle , This has not been verified in this case , Please leave a message if you have verified , Feedback related effects .