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- Tutorial
- Release Notes and Announcements
- Release Notes
- Public Image Release Notes
- Announcements
- Temporary Solution for the Windows Blue Screen Issue Caused by CrowdStrike Security Software on July 19, 2024
- Announcement on Flexible Discounts for Spot Instances in Some Regions
- 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 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
- Practical Tutorial
- Best Practices
- Choosing the CVM Model
- Setting up a Website
- Building an Environment
- Building a Website
- Building an Application
- Sending Emails through Port 465
- 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
- Region APIs
- Instance APIs
- RunInstances
- DescribeInstances
- DescribeInstanceFamilyConfigs
- DescribeInstancesOperationLimit
- InquiryPriceRunInstances
- InquiryPriceResetInstance
- InquiryPriceResetInstancesType
- StartInstances
- RebootInstances
- StopInstances
- ResizeInstanceDisks
- ResetInstancesPassword
- ModifyInstancesAttribute
- EnterRescueMode
- ExitRescueMode
- InquirePricePurchaseReservedInstancesOffering
- InquiryPriceResizeInstanceDisks
- TerminateInstances
- ModifyInstancesProject
- ResetInstancesType
- DescribeInstancesStatus
- DescribeReservedInstancesConfigInfos
- DescribeZoneInstanceConfigInfos
- PurchaseReservedInstancesOffering
- ResetInstance
- DescribeInstanceTypeConfigs
- DescribeInstanceVncUrl
- Cloud Hosting Cluster APIs
- Image APIs
- Instance Launch Template APIs
- Making API Requests
- Placement Group APIs
- Key APIs
- Security Group APIs
- Network APIs
- Data Types
- Error Codes
- FAQs
- Related Agreement
- Glossary
Issue Description
During login to a Linux instance via SSH key, "ssh_exchange_identification: Connection closed by remote host" or "no hostkey alg" is displayed.
Common Causes
sshd configuration file permissions, such as the permissions of the
/var/empty/sshd or /etc/ssh/ssh_host_rsa_key configuration file, are modified, which may cause a failure in login via SSH key.Solution
Perform the steps based on the actual error message to modify the configuration file permissions:
If the error message is "ssh_exchange_identification: Connection closed by remote host", see Modifying permissions of
/var/empty/sshd file.If the error message is "no hostkey alg", see Modifying permissions of
/etc/ssh/ssh_host_rsa_key file.Troubleshooting Procedure
Modifying permissions of /var/empty/sshd file
2. Run the following command to view the error cause:
sshd -t
Information similar to the following is returned:
"/var/empty/sshd must be owned by root and not group or world-writable."
3. Run the following command to modify the permissions of the
/var/empty/sshd/ file:chmod 711 /var/empty/sshd/
Modifying permissions of /etc/ssh/ssh_host_rsa_key file
2. Run the following command to view the error cause:
sshd -t
The returned information contains the following field:
"/etc/ssh/ssh_host_rsa_key are too open"
3. Run the following command to modify the permissions of the
/etc/ssh/ssh_host_rsa_key file:chmod 600 /etc/ssh/ssh_host_rsa_key
Yes
No
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