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- Vulnerability repairing for Linux images
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- Solution to Tomcat Start Failure on Ubuntu14.04
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- No Charges When Shut Down for Pay-as-You-Go Instances
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- Unblocking Port 25
- Tags
- Monitoring and Alarms
- Sample Console Configuration
- Best Practice
- Best Practices
- Choosing the CVM Model
- Setting up a Website
- Building an Environment
- Building a Website
- Building an Application
- Building a Visual GUI
- Data Backup
- Uploading Local Files to CVM
- Copying Local Files to CVMs
- Uploading Files from Windows to a Windows CVM via MSTSC
- Uploading Files from MacOS to Windows CVM Using MRD
- Uploading Files from Linux to Windows CVM using RDP
- Uploading files via WinSCP to a Linux CVM from Windows
- Uploading Files from Linux or MacOS to Linux CVM via SCP
- Uploading Files from Linux to a CVM Using FTP
- Uploading Files from Windows to a CVM Using FTP
- Other CVM Operations
- CVM Access to COS via a Private Network
- Best Practices for Boot Mode Legacy BIOS and UEFI
- Recovering Data on Linux CVMs
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- Network Performance Test
- High-throughput Network Performance Test
- Using USB/IP to Share USB Devices in Linux
- Using RemoteFx to Redirect USB Devices in Windows
- Using AVX-512 Instructions to Accelerate AI Applications on CVM
- Building Tencent SGX Confidential Computing Environment
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- Calling Cloud APIs via Python to Share Custom Images in Batches
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- Initializing Data Disks
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- Installing Software
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- System Activation
- System Updates
- System Shutdown
- Configuring High-performance Power Management
- Windows Recovery Mode
- Updating the Virtio ENI Driver
- Modifying SID
- Modifying VNC Resolution
- Ensuring Unique SIDs for CVMs Using Sysprep
- Use of the atop Monitoring Tools by Linux Instances
- Introduction to Linux Kernel Parameters
- Others
- Troubleshooting
- Instance-Related Failures
- CVM Login Failures
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- Windows Instance Login Failures
- An authentication error occurred when you tried to log in to a Windows instance remotely
- Failed to Reset the CVM Password or the CVM Password Is Invalid
- Connection to a Windows CVM through Remote Desktop was denied
- Requires network-level identity verification
- Problems occurred when you tried to log in to a Windows CVM remotely on Mac
- Failed to log in to a Windows CVM due to high CPU and memory usage
- Failed to connect to a remote computer through Remote Desktop
- Credentials Not Work
- Windows instance: no remote Desktop license server can provide license
- Remote Login Failure Due To Port Issues
- Linux Instance Login Failures
- Linux Instance Login Failures
- Unable to Log in to a Linux Instance via SSH Key
- Failing to log in to a Linux CVM due to high CPU and memory usage
- Remote Login Failure due to Port Issues
- VNC Login Error (Module is Unknown)
- VNC Login Error (Account Locked due to XXX Failed Logins)
- VNC Login Error (Login Failed with Correct Password)
- VNC or SSH Login Error (Permission Denied)
- Login Failure Due to /etc/fstab Configuration Errors
- sshd Configuration File Permissions
- Infinite Loop Call in /etc/profile
- Login Failure Due to Server Isolation
- Login Failure Due to High Bandwidth Occupation
- Remote Connect Failure Due to Security Group Settings
- Troubleshooting Linux Instance Issues via VNC and Rescue Mode
- Failed to shut down or restart a CVM
- Network Namespace Creation Failure
- Kernel and IO Issues
- Missing System bin or lib Soft Link
- Suspected Infection with Virus
- "no space left on device" Error During File Creation
- Linux CVM Memory Issues
- Network Related Failures
- Instance-Related Failures
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Region APIs
- Instance APIs
- DescribeInstances
- DescribeInstanceFamilyConfigs
- DescribeZoneInstanceConfigInfos
- DescribeInstanceTypeConfigs
- DescribeInstancesOperationLimit
- DescribeInstanceVncUrl
- InquiryPriceRunInstances
- InquiryPriceResetInstance
- InquiryPriceResetInstancesType
- InquiryPriceResizeInstanceDisks
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- StartInstances
- RebootInstances
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- ResetInstance
- TerminateInstances
- ResetInstancesType
- ResizeInstanceDisks
- ResetInstancesPassword
- ModifyInstancesAttribute
- ModifyInstancesProject
- InquirePricePurchaseReservedInstancesOffering
- DescribeReservedInstancesConfigInfos
- DescribeInstancesStatus
- PurchaseReservedInstancesOffering
- Cloud Hosting Cluster APIs
- Placement Group APIs
- Image APIs
- Key APIs
- Security Group APIs
- Network APIs
- Instance Launch Template APIs
- Data Types
- Error Codes
- FAQs
- Related Agreement
- Glossary
- Tutorial
- Release Notes and Announcements
- Public Image Release Notes
- Announcements
- Updating Some Image Pip Package Management Tools for CentOS 7
- CentOS 8 End of Maintenance
- Discontinuation of Support for SUSE Commercial Images
- Price Reduction in Selected Availability Zones
- OrcaTerm Proxy IP Addresses Updates
- Pay-as-you-go Price Adjustments for Standard S3 CVMs in the Silicon Valley Region
- Vulnerability repairing for Linux images
- Stopping supporting for Ubuntu 10.04 images
- Solution to Tomcat Start Failure on Ubuntu14.04
- Upgrading Virtio network card drive for Windows CVMs
- About Configuration of Security Group Port 53
- Windows Server 2003 System Images End of Support Announcement
- End of Support for Windows Server 2008 R2 Enterprise Edition SP1 64-bit System Images
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Operation Guide Overview
- Use Limits
- Convenience Features
- Instances
- Creating Instances
- Managing Instance Launch Template
- Batch Sequential Naming or Pattern String-Based Naming
- Logging In to Linux Instances
- Logging in to Windows instance
- Adjusting Configuration
- View Instance Details
- Renaming Instances
- Resetting Instance Password
- Managing Instance IPs
- Changing Instance Subnet
- Changing Security Group
- Conversion from Pay-As-You-Go to Monthly Subscription
- Searching for Instances
- Exporting Instance List
- Renewing Instances
- Starting Up Instances
- Shutting Down Instances
- Restarting Instances
- Reinstalling System
- Using Tencent Cloud Automation Tools to execute commands
- Terminating/Returning Instances
- Enabling Instance Termination Protection
- Instance Repossession or Recovering
- Spot Instances
- Querying the Repossession Status of a Spot Instance
- No Charges When Shut Down for Pay-as-You-Go Instances
- Managing Roles
- Enabling and Disabling Hyper-Threading
- Reserved Instances
- Images
- Migrating Servers
- Maintenance Tasks
- Cloud Disks
- Networking
- Security
- Security Groups
- Protection of Sensitive Operations
- Managing Login Password
- Managing SSH Keys
- Spread Placement Group
- Unblocking Port 25
- Tags
- Monitoring and Alarms
- Sample Console Configuration
- Best Practice
- Best Practices
- Choosing the CVM Model
- Setting up a Website
- Building an Environment
- Building a Website
- Building an Application
- Building a Visual GUI
- Data Backup
- Uploading Local Files to CVM
- Copying Local Files to CVMs
- Uploading Files from Windows to a Windows CVM via MSTSC
- Uploading Files from MacOS to Windows CVM Using MRD
- Uploading Files from Linux to Windows CVM using RDP
- Uploading files via WinSCP to a Linux CVM from Windows
- Uploading Files from Linux or MacOS to Linux CVM via SCP
- Uploading Files from Linux to a CVM Using FTP
- Uploading Files from Windows to a CVM Using FTP
- Other CVM Operations
- CVM Access to COS via a Private Network
- Best Practices for Boot Mode Legacy BIOS and UEFI
- Recovering Data on Linux CVMs
- Managing Disk Space on Windows CVMs
- Changing Kernel of a Linux Instance Manually
- Setting Up Windows-based AD Domain on a CVM
- Network Performance Test
- High-throughput Network Performance Test
- Using USB/IP to Share USB Devices in Linux
- Using RemoteFx to Redirect USB Devices in Windows
- Using AVX-512 Instructions to Accelerate AI Applications on CVM
- Building Tencent SGX Confidential Computing Environment
- Configuring Persistent Memory in M6p Instances
- Calling Cloud APIs via Python to Share Custom Images in Batches
- Operations Guide
- Initializing Data Disks
- Environment Configurations
- Installing Software
- User Data
- Work with Operating Systems
- System Activation
- System Updates
- System Shutdown
- Configuring High-performance Power Management
- Windows Recovery Mode
- Updating the Virtio ENI Driver
- Modifying SID
- Modifying VNC Resolution
- Ensuring Unique SIDs for CVMs Using Sysprep
- Use of the atop Monitoring Tools by Linux Instances
- Introduction to Linux Kernel Parameters
- Others
- Troubleshooting
- Instance-Related Failures
- CVM Login Failures
- Windows Instance Login Failures
- Windows Instance Login Failures
- An authentication error occurred when you tried to log in to a Windows instance remotely
- Failed to Reset the CVM Password or the CVM Password Is Invalid
- Connection to a Windows CVM through Remote Desktop was denied
- Requires network-level identity verification
- Problems occurred when you tried to log in to a Windows CVM remotely on Mac
- Failed to log in to a Windows CVM due to high CPU and memory usage
- Failed to connect to a remote computer through Remote Desktop
- Credentials Not Work
- Windows instance: no remote Desktop license server can provide license
- Remote Login Failure Due To Port Issues
- Linux Instance Login Failures
- Linux Instance Login Failures
- Unable to Log in to a Linux Instance via SSH Key
- Failing to log in to a Linux CVM due to high CPU and memory usage
- Remote Login Failure due to Port Issues
- VNC Login Error (Module is Unknown)
- VNC Login Error (Account Locked due to XXX Failed Logins)
- VNC Login Error (Login Failed with Correct Password)
- VNC or SSH Login Error (Permission Denied)
- Login Failure Due to /etc/fstab Configuration Errors
- sshd Configuration File Permissions
- Infinite Loop Call in /etc/profile
- Login Failure Due to Server Isolation
- Login Failure Due to High Bandwidth Occupation
- Remote Connect Failure Due to Security Group Settings
- Troubleshooting Linux Instance Issues via VNC and Rescue Mode
- Failed to shut down or restart a CVM
- Network Namespace Creation Failure
- Kernel and IO Issues
- Missing System bin or lib Soft Link
- Suspected Infection with Virus
- "no space left on device" Error During File Creation
- Linux CVM Memory Issues
- Network Related Failures
- Instance-Related Failures
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Region APIs
- Instance APIs
- DescribeInstances
- DescribeInstanceFamilyConfigs
- DescribeZoneInstanceConfigInfos
- DescribeInstanceTypeConfigs
- DescribeInstancesOperationLimit
- DescribeInstanceVncUrl
- InquiryPriceRunInstances
- InquiryPriceResetInstance
- InquiryPriceResetInstancesType
- InquiryPriceResizeInstanceDisks
- RunInstances
- StartInstances
- RebootInstances
- StopInstances
- ResetInstance
- TerminateInstances
- ResetInstancesType
- ResizeInstanceDisks
- ResetInstancesPassword
- ModifyInstancesAttribute
- ModifyInstancesProject
- InquirePricePurchaseReservedInstancesOffering
- DescribeReservedInstancesConfigInfos
- DescribeInstancesStatus
- PurchaseReservedInstancesOffering
- Cloud Hosting Cluster APIs
- Placement Group APIs
- Image APIs
- Key APIs
- Security Group APIs
- Network APIs
- Instance Launch Template APIs
- Data Types
- Error Codes
- FAQs
- Related Agreement
- Glossary
This article describes how to troubleshoot remote login failures caused by port problems.
Note:
The following uses a CVM instance running Windows Server 2012 as an example to describe the steps.
Tools
You can use the following tools to check if the login issues are related to ports and security group configurations:
If the problem is indeed a security group configuration problem, use Open all ports in the Security group (port) helper to open related ports and try to log in again. If you still cannot log in after opening the ports, refer to the following for troubleshooting.
Troubleshooting
Checking network connectivity
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.
1. Open the command line tool on your local computer.
Windows: Click Start -> Run and enter cmd. A Command Prompt window appears.
MacOS: Open a Terminal window.
2. Run the following command to test network connection.
ping + CVM_Instance_public_IP_address
For example,
ping 139.199.xxx.xxx.If you see results similar to what is shown in the following figure, your network connection to the CVM instance is normal. In this case, check the remote desktop configuration.
If Request Timeout appears, your network connection to the CVM instance is not working properly. In this case, refer to Instance IP Address Ping Failure for troubleshooting instructions.
3. Run the following command to check whether the remote port is open.
telnet CVM_instance_public_IP_address port_number
For example, 
telnet 139.199.xxx.xxx 3389, as shown in the following figure:
If you see a black screen with only the cursor, that indicates the port (3389) is open. For the next step, check whether remote desktop service is enabled on the instance.
If the connection fails, as shown in the following figure, that means a network exception occurred. Check the corresponding part of the network.
Checking remote desktop configuration
Logging in to the CVM instance using VNC
Note:
It is recommended that you use VNC to login only if the standard login methods fail.
1. Log in to the CVM Console.
2. Select the desired CVM and click Log In, as shown in the following figure:
3. The Log into Windows instance page appears. Select Alternative login methods (VNC) and click Log In Now to log in to the CVM instance.
4. The log in page appears. Select Send Ctrl-Alt-Del in the top left corner and click Ctrl-Alt-Delete to enter the system login interface, as shown in the following figure:
Checking if remote desktop is enabled on the CVM instance
1. Log in to the CVM instance. Right click This Computer from the Desktop and select Properties to open the System window.
2. In the System window, select Advanced System Configurations to open the System Properties window.
3. In the System Properties window, select the Remote tab. Check whether Allow remote connections to this computer under Remote Desktop is selected, as shown in the following figure:
If it is selected, remote connection is enabled. Next, you should check whether remote access ports are open.
If it is cleared, select Allow remote connections to this computer and try to connect to the instance again.
Checking whether remote access ports are open
1. Log in to the CVM instance. Click 
2. In the Windows PowerShell window, run the following command to check the status of remote desktop (by default, the remote desktop uses port 3389).
netstat -ant | findstr 3389
If you see results similar to what is shown in the following figure, the status is normal. You can try to restart remote desktop and connect to the instance again to check whether the connection is successful.
If no connection is shown, remote desktop is not functioning properly. You can check whether the remote desktop ports in registry are consistent.
Checking whether the remote desktop ports in registry are consistent
Caution:
This section describes how to check the values of TCP PortNumber and RDP Tcp PortNumber. They must be the same.
1. Log in to the CVM instance, click 
2. In the navigation pane on the left, expand the following directories: HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> Control -> Terminal Server -> Wds -> rdpwd -> Tds -> tcp.
3. Locate the PortNumber in tcp and record the port number (3389 by default), as shown in the following figure:
4. In the navigation pane on the left, expand the following directories: HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> Control -> Terminal Server -> WinStations -> RDP-Tcp.
5. Locate PortNumber in RDP-Tcp and check whether the PortNumber value in RDP-Tcp is the same as the one in tcp, as shown in the following figure:
If they are not the same, follow Step 6.
If they are the same, restart remote desktop.
6.
Double click PortNumber in RDP-Tcp.
7. In the dialog box that appears, modify Value Data to an unoccupied port number between 0 - 65535. Ensure TCP PortNumber and RDP Tcp PortNumber are the same, and click OK.
8. Restart the instance using the CVM Console, and try to remotely connect to the instance again to check whether the connection is successful.
Restarting remote desktop
1. Log in to the CVM instance. Click 
2. In the Services window, right-click Remote Desktop Services and select Restart to restart the remote desktop service, as shown in the following figure:
If All Else Fails
If you are still unable to remotely log in after performing the above-mentioned steps, submit a ticket for further assistance.
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