Elastic Compute Service:FAQ

FAQ about ECS

Latest topics

• What do I do if an instance cannot be pinged by running the ping command?

• How do I configure DNS in a Linux instance?

• How do I migrate data from the system disk of a Linux instance?

• What do I do if a Linux instance cannot be pinged even when ping requests are not blocked by the instance?

• How do I view the actual error message when "500 - Internal Server Error" is displayed on the website built by using IIS?

FAQ about connections

• What do I do if I cannot connect to a Windows instance?

• What do I do if I cannot connect to a Linux instance by using SSH?

• How do I view and modify the default port for remote desktop connection to a Windows instance?

• How do I query the logs about remote logons to an instance?

• How do I limit the number of remote desktop sessions for each user on a Windows instance?

• What do I do if I cannot select Allow Remote Assistance connections to this computer in the Remote Assistance section for an instance that runs Windows Server 2008 or 2012?

• What is the number of allowed remote desktop connections in different modes for a Windows Server instance? What is a Remote Desktop Licensing server?

• What do I do if an error occurs when I connect to a Linux instance by running the SSH command?

• What do I do if the "The remote session was disconnected because there are no Remote Desktop client access licenses available for this computer" error message appears when I connect to a Windows instance?

• What do I do if a protocol error message appears when I connect to a Windows instance?

• What do I do if the "Your credentials did not work" error message appears when I connect to a Windows instance for which password protected sharing is enabled?

• What do I do if the "The connection was denied because the user account is not authorized for remote login" error message appears when I use Remote Desktop Connection to connect to an instance?

• What do I do if the "Host key verification failed" error message appears when I connect to an instance by using SSH?

• What do I do if the "Permission denied, please try again" error message appears when I connect to a Linux instance as the root user by using SSH?

• What do I do if the "Disconnected: No supported authentication methods available" error message appears when I connect to a Linux instance by using SSH?

• What do I do if the "ssh_exchange_identification: read: Connection reset by peer" error message appears when I connect to an instance by using SSH?

• What do I do if the "requirement "uid >= 1000" not met by user "root"" error message appears when I connect to a Linux instance by using SSH?

• What do I do if I cannot use SSH to connect to a Linux instance that has SELinux enabled?

• What do I do if the "main process exited, code=exited" error message appears when I enable the SSH service on a Linux instance?

• What do I do if the "error while loading shared libraries" error message appears when I enable the SSH service on a Linux instance?

FAQ about networks

• What do I do if a Linux instance cannot be pinged even when ping requests are not blocked by the instance?

• What do I do if an instance cannot be pinged by running the ping command?

• How do I configure DNS in a Linux instance?

• How do I test links when packet loss or connection failures occur after the ping command is run?

• What do I do if I cannot access a website deployed on an instance?

• How do I check whether TCP port 80 works as expected on an instance?

• What do I do if an instance can be pinged but a port on it cannot be pinged?

• How do I test the network performance of an instance?

• How do I use packet capture tools to capture packets for an instance when network exceptions occur on the instance?

• What do I do if domain names cannot be resolved normally within a Linux instance?

• What do I do if an ENI bound to an instance cannot be accessed?

• What do I do if packet loss rate and network latency are high when I access a website deployed on a Linux instance?

• What do I do if packet loss rate and network latency are high when I access a website deployed on a Windows instance?

• What do I do if intermittent packet loss occurs when I use the ping command to test the IP address of a Linux instance?

• What do I do if no data is found in the traffic monitoring section in the ECS console?

• What do I do if the IP address of an instance that runs a CentOS 7 or Windows operating system cannot be pinged?

• How do I run the netstat command on a Linux instance to view its port information?

• What do I do if the "General failure" error message appears when an external IP address cannot be pinged from a Windows instance?

FAQ about website building

• What do I do if I cannot access an FTP server deployed on a Windows instance from external networks?

• Manually build an FTP site on a CentOS 7 instance

• Manually build an FTP site on a Windows instance

• What do I do if I cannot connect to a MySQL server deployed on a Linux instance?

• How do I use FTP tools to upload files to a macOS instance?

• What do I do if the "You access is blocked because your IP address may pose a security threat to the website" error message appears when I attempt to access a website deployed on an instance?

• What do I do if the "534 Policy requires SSL" error message appears when I access an FTP site deployed on a Windows instance?

• What do I do if the "No input file specified" error message appears when I access a website deployed on an instance?

• How do I view the actual error message when "500 - Internal Server Error" is displayed on the website built by using IIS?

FAQ about disks, CPU, memory, and bandwidth

• How do I view and analyze the loads of a Windows instance?

• How do I query and perform case studies on the CPU loads of a Linux instance?

• How do I configure virtual memory in a Windows instance?

• What are inbound bandwidth and outbound bandwidth?

• How do I query and perform case studies on the network traffic loads of a Linux instance?

• How do I query the number of physical CPUs and the memory information of a Linux instance?

• How do I query and analyze the system loads of a Linux instance?

• What do I do if no disk space is available or the number of inodes exceeds the inode quota in a Linux instance?

• What memory analysis tools are available for Windows instances?

• How do I query and perform case studies on the I/O loads of a Linux instance?

• What do I do if I run the df and du commands to query the disk capacity but obtain different disk capacities or a negative value for the disk capacity?

• How do I enable the Kernel Memory Dump feature for a Windows instance?

• What do I do if the "mount: can't find /root/nas in /etc/fstab" error message appears when I mount Apsara File Storage NAS file systems to a Linux instance?

FAQ about images and snapshots

• Replace the operating system of an instance

• Create a custom image from a snapshot

• Create an ECS instance by using a custom image

• How do I fix the security vulnerabilities of instances created from Linux images of historical versions?

FAQ about security groups and security issues

• What do I do if the security group rules that I configure for instances do not take effect?

• What do I do if my instance is infected by Trojan viruses?

• How do I configure the firewall on my computer to connect to Windows instances?

• How do I block specific IP addresses or CIDR blocks from accessing a Linux instance?

• How do I configure security group rules after the SSH service is enabled in a Linux instance?

• How do I configure firewalls for instances that run CentOS 7?

• How do I check the connection to the TCP or UDP ports of a Linux instance?

• What are Windows security auditing logs? How do I configure log auditing policies for Windows instances?

• What do I do if an instance cannot be pinged after the default security group rules of the instance are deleted?

• What do I do if an instance is locked for initiating DDoS attacks?

• How do I enhance the security of Windows instances?

• What do I do if the code upload from the Subversion server on my computer to the Subversion server on an instance is blocked by Alibaba Cloud Security?

• What do I do if viruses cause the SSH service to fail to run and the "fatal: mm_request_send: write: Broken pipe" error message appears?

FAQ about operating systems

• What do I do if the "UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY." error message appears when an instance cannot be started?

• How do I troubleshoot the exceptions that occur when I connect to an instance?

• What do I do if a Linux instance cannot be started after the kernel of the instance is upgraded?

• What are the common kernel network parameters of Linux instances? How do I troubleshoot issues related to these parameters?

• How do I view the operational logs of a Windows instance by using Windows Event Viewer?

• How do I resolve Windows Update issues to install patches on instances?

• How do I use tools to have software repositories automatically updated in a Linux instance?

• How do I use KMS domain names to activate Windows instances in VPCs?

• What do I do if system startup exceptions occur due to the configuration errors of the /etc/fstab file on Linux instances?

• How do I configure the startup sequence of kernels in a Linux instance?

• How do I run the netstat command on a Linux instance to view its port information?

• What do I do if a Windows instance cannot be activated?

• How do I configure software repositories in a Linux instance? How do I troubleshoot issues related to the software repositories?

• How do I configure a CentOS instance to enter the single-user mode?

• How do I obtain the logon records of Linux instances?

• How do I change the SIDs of Windows instances to build a domain environment?

• What do I do if .NET Framework 3.5.1 or language packs cannot be installed on instances that run Windows Server 2012 R2, 2016, or 2019?

• What do I do if the "entered promiscuous mode" and "left promiscuous mode" error messages appear in the message log of a Linux instance?

FAQ about billing methods and configuration upgrade and downgrade

• Billing overview

• Pay-as-you-go

• Overview of instance configuration changes

FAQ about API operations and SDKs

• What do I do if an instance created by calling the CreateInstance operation does not have a public IP address?

• What do I do if I cannot install ECS SDKs in a Linux instance?

• How do I specify parameters of different data types in Alibaba Cloud CLI?

• What do I do if only some security group rules in a security group can be displayed when I call API operations or use ECS SDKs to query the details about the security group rules?

• What do I do if the "InvalidDataDiskCategory.NotSupported" error message appears when I call an API operation to create an instance?

• What do I do if the "The IP is already in use" error message appears after I call an API operation to associate a public IP address with an instance?

FAQ about cloud migration and data migration

• How do I back up data stored on an instance to my computer?

• How do I migrate data from the system disk of a Linux instance?