1. NIC eth0 can be started by running the ifconfig eth0 up command.
2. If you run the (bash -x /sbin/ifdown eth0 ;echo ---------; bash -x /sbin/ifup eth0) >>/tmp/log.txt 2>&1 command again, the problem persists.
3. According to the log.txt in Step 2, the ifdown and ifup scripts read the configuration file ifcfg-eth0 of eth0 and set the state of eth0 based on the configuration file, as shown in Figure 2.
Figure 2 Resetting eth0 by using the fdown and ifup scripts
4. The operating system (OS) of the onsite server does not independently configure the configuration file ifcfg-eth0 of eth0. As a result, eth0 cannot be started by running the ifup command.
5. Check the messages log and find that "No configuration found for eth0" is displayed, as shown in Figure 3.
Figure 3 messages log