Linux Instance Login Failures

Last updated: 2020-02-25 11:32:45


This document describes possible causes of Linux instance login failures and troubleshooting methods, helping you detect, locate and resolve problems.

Possible Causes

The primary causes of Linux instance login failures include:

If your problem cannot be checked using the self-diagnose tool, we recommend you Log in to the CVM via VNC And troubleshoot step by step.


Logging in via VNC

If you cannot use the standard method (Webshell) or remote login software to log into a Linux instance, you can use Tencent Cloud VNC to login and locate the problem causes.

  1. Log in to the CVM Console .
  2. In the instance management page, select the instance to be logged in to and click Log In . This is shown in the following figure:
  3. In the Log into Linux instance Window that pops up, select Alternative login methods (VNC) , and click Log In Now .

During login, if you forget the password of this instance, you can reset it in the console. For more information, see Reset Instance Password .

  1. Enter the username and password in the dialog box that pops up to complete the login process.

Login failures due to SSH problems

Fault phenomenon : Log in to the Linux instance using SSH Indicates that the connection cannot be made or that the connection fails.
Processing steps : referenc Unable to log in to Linux instance through SSH Conduct a canvassing.

Login failures due to password problems

Problem : You forget the password, enter it incorrectly or password reset failed resulting in login failures.
Troubleshooting : Reset the password for this instance in the Tencent Cloud Console , and restart the instance.
Steps : For information about how to reset the password of an instance, see Reset Instance Password .

Bandwidth utilization too high

Problem : The self-diagnosis tool shows that bandwidth utilization is too high.
Steps :

  1. Log in to the instance via VNC Login .
  2. Refer to Unable to log in due to high bandwidth consumption To view the bandwidth usage of the instance and handle failures

Server workload too high

Problem : The self-diagnosis tool or Cloud Monitor shows that server CPU workload is too high, and the system is unable to perform remote connection 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 rate, causing CVM login failures or slow access.
Steps :

  1. Log in to the instance via VNC Login .
  2. Refer to Linux instance: unable to log in due to high CPU and memory occupancy To locate high-load processes in the job manager

Remote port configuration exception

Problems : The remote port cannot connect, remote access port is not the default port or has been modified, or port 22 is not open.
Diagnosis : Whether the public IP of the instance can be pinged, use the telnet Command to check whether the port is open.
Processing steps For specific operation, please refer to Port problem makes it impossible to log in remotely .

Improper security group rules

Problems : The self-diagnosis tool shows that the security group rule configuration is improper, leading to login failures.
Steps : Check by using the Port verification tool .

If the problem is caused by security group configurations, you can use the Open All Tools To open all ports.

If you need to customize security group rules, see Security Group Operations For reconfiguration.

Other Solutions

If you still cannot log into the Linux instance using above-mentioned troubleshooting methods, please save your self-diagnosis results and Submit Ticket .