A Network Error Occurs During Software Installation on CentOS

Symptoms

When software is installed on CentOS, an error message is displayed, indicating that the network is unreachable.

Cause Analysis

• The target host failed to download the software package from the official image repository due to network connection timeout.
• The possible causes of network connection timeout are as follows:
  1. The network between the target host and the YUM repository is disconnected.
  2. The firewall restricts outbound access.
  3. The security group has an outbound rule to restrict access.

Solution

1. Run the ping $domainName command to check the network connectivity. $domainName indicates the domain name of the YUM repository. If the network is normal, perform steps 2 and 3 to check the firewall and security group. If the network is abnormal, contact the network administrator.
2. Check the firewall configurations.
   • Run the iptables -nL command to check whether outbound access is restricted on port 80.
3. Check the outbound rules of the security group to which the target host belongs.
   • Contact the network administrator to modify the outbound rules of the security group.