This document describes the possible causes of Linux instance login failures and troubleshooting methods, helping you detect, locate, and resolve problems.
The primary causes of Linux instance login failures include:
If you cannot check your problem by using the self-diagnose tool, we recommend that you log in to the CVM through VNC and troubleshoot step by step.
If you cannot use the standard method (Webshell) or remote login software to log in to a Linux instance, you can use Tencent Cloud VNC to log in and locate the problem causes.
During login, if you forget the password of this instance, you can reset it in the console. For more information, see Resetting the Instance Password.
Problem: during login to a Linux instance by using SSH, a message indicating that the connection is unavailable or failed appears.
Steps: see Unable to Log In to a Linux Instance by Using SSH for troubleshooting.
Problem: unable to log in because you forget the password, enter it incorrectly, or fail to reset it.
Solution: reset the password of this instance in the Tencent Cloud console, and restart the instance.
Steps: for information on how to reset the password of an instance, see Resetting the Instance Password.
Problem: the self-diagnosis tool shows that bandwidth utilization is too high.
Problem: Cloud Monitor shows that load of the server CPU is high, and the system cannot be accessed remotely or access is slow.
Possible Causes: viruses, trojans, third-party anti-virus software, application exceptions, driver exceptions, and software backend automatic updates may lead to high CPU usage, causing CVM login failures or slow access.
Problem: the remote port is inaccessible, the remote access port is not the default port or has been modified, or port 22 is not open.
Diagnosis: check whether the public IP address of the instance can be pinged through. Run the
telnet command to check whether the port is open.
Steps: see Unable to Log In Remotely Due To Port Issues.
Problem: unable to log in due to incorrect security group rules.
Steps: troubleshoot by using the port verification tool for security groups.
If the problem is caused by the incorrect security group port configuration, you can use Open All Tools to open all ports.
If you need to define a custom rule for the security group, see Adding Rules to Security Groups for information on how to reconfigure security group rules.
If you still cannot log in to the Linux instance after trying the preceding troubleshooting methods, save your self-diagnosis results and submit a ticket.