Issue/Introduction
This article describes how to troubleshoot unstable external service port connections after an EIP is attached to a VM instance. It applies to the initial diagnosis and resolution of similar issues in ZStack Cloud.
Environment
- Product: ZCF
- Component: Cloud
- Version: 3.x-5.5.30
Symptoms
After an EIP is attached to a VM instance, connections to external service ports are unstable and frequently fail.
Possible causes
The VM instance might contain zombie processes, causing high CPU load and limited processing capacity so that the ports cannot respond to client requests.
Resolution
- Run
ps aux | grep 'defunct'to check for zombie processes. - Run
kill -s SIGCHLD <PID>to send a SIGCHLD signal to the zombie process. - Check whether the system is under a virus attack. If an attack has occurred, you can take the following security-hardening measures to prevent similar issues:
- Enable iptables on the firewall or VM instance.
- Restrict IP addresses and ports, and do not expose unnecessary ports externally.
- Use middleware to check remote sign-ins.
- Use a strong password policy.