This document describes how to diagnose and troubleshoot remote login failures caused by port problems.
The following operations use a CVM instance with the CentOS 7.8 operating system as an example.
You can use the following tools to check whether the login issues are related to port or security group configuration:
If the problem is indeed caused by security group configurations, click Open all ports in Port Verification and try to log in again. If you still cannot log in after opening the ports, refer to the following for troubleshooting.
You can use the
Ping command to test network connectivity from your PC. You should run the test from computers in different network environments (such as different IP ranges or ISPs) to check whether it is a local network problem or a server problem.
cmd. A Command Prompt window appears.
You should first obtain the public IP address of the CVM instance. For example,
ping [CVM instance’s public IP address]
For example, run the
telnet [CVM instance’s public IP address] [Port number]
telnet 119.XX.XXX.67 22command to check whether the port 22 is open.
If you are unable to log in to a Linux instance via SSH key due to connection failures, it may be because the SSHD port is not being listened on or the SSHD service is not started. In this case, refer to Unable to Log into a Linux Instance via SSH for troubleshooting instructions.