This document describes how to locate and troubleshoot the problems that cause website access failure.
Possible Causes
Website access failure may be caused by network problems, firewall configurations or CVM overload.
Troubleshooting
Troubleshooting CVM problems
CVM shutdown, hardware failure, and high CPU/memory/bandwidth usage may all cause website access failure. Thus, we recommend that you check CVM running status and CPU/memory/bandwidth usage.
1. Log in to the CVM Console and verify whether the running status of the CVM instance is normal on the instance management page, as shown below:
If yes, please execute step 2. If no, please restart the CVM instance.
2. Click the ID/name of the instance to enter its deta
ils page. 3. Select the Monitoring tab to view the instance resource usage, as shown below:
If CPU/memory/bandwidth usage is normal, please execute step 4. 4. Execute the following command
to check whether the corresponding Web service port is being monitored normally. Note:
The following operations take port 80, which is commonly used in HTTP service, as an example.
For a Linux instance: execute the netstat -ntulp |grep 80
command, as shown below:
For a Windows instance: open the CMD command line tool to execute the netstat -ano|findstr :80
command, as shown below:
If the port is being monitored normally, please execute step 5. If the port is not being monitored normally, please check whether the Web service process is launched or correctly configured.
5. Check whether the corresponding We
b service port is opened in the firewall configuration. For a Linux instance: execute the iptables -vnL
command to check whether iptables opens port 80.
If port 80 is not open, please execute the iptables -I INPUT 5 -p tcp --dport 80 -j ACCEPT
command to open it.
For a Windows instance: click Start > Control Panel > Windows Firewall on the OS interface to check whether Windows firewall configuration is off.
- If yes, please troubleshoot network-related problems.
- If no, please turn off the Windows firewall configuration. Troubleshoot network-related problems
Network problems can also cause network access failure. You can execute the following command to check whether the network has packet loss or high latency.
ping the public IP of the server
If a result similar to the one below is returned, there is packet loss or high latency. Please use MTR for troubleshooting. For more information, please see CVM Network Latency and Packet Loss.
Troubleshoot security group problems
Security group is a virtual firewall that allows you to control the inbound and outbound traffic of the associated instance. You can specify protocols, ports and policies for security group rules. If you did not open the ports related to the Web processes, website access failure may occur.
1. Log in to the CVM Console and click the ID/name of the instance to enter its details page. 2. Click the Security Group tab to view the bound security groups and their outbound and inbound rules. Confirm that the ports related to the Web processes are open, as shown below:
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