Elastic Compute Service:Connect to a Linux instance by using an SSH key pair from a third-party client

Connect to a Linux instance

You can use one of the following methods to connect to the Linux instance by using an SSH key pair based on the operating system of your device.

Use an SSH key pair to connect to a Linux instance from a device that supports SSH commands (configure information by using commands)

The following section describes how to use commands to configure the required settings on a device that supports SSH commands (such as a Linux client or MobaXterm for Windows) and then how to use SSH commands to connect to the instance from the device.

1. Find the path of the .pem private key file on the on-premises device. Example: ~/.ssh/ecs.pem.

   The path and file name used are for reference only. You can modify the information in subsequent commands based on actual conditions.

2. Run the following command to modify the attribute of the private key file:

   chmod 400 [Path of the .pem private key file on your on-premises device]

   Example:

   chmod 400 ~/.ssh/ecs.pem

3. Run the following command to connect to the instance:

   ssh -i [Path of the .pem private key file on your on-premises device] username@[Public IP address]

   Example:

   ssh -i ~/.ssh/ecs.pem ecs-user@10.10.xx.xxx

Use an SSH key pair to connect to a Linux instance from a device that supports SSH commands (configure information by using the config file)

The following section describes how to use commands to configure the required settings on a device that supports SSH commands (such as a Linux client or MobaXterm for Windows) and then how to use SSH commands to connect to the instance from the device.

1. Find the path of the .pem private key file on the on-premises device. Example: ~/.ssh/ecs.pem.

   The path and file name used are for reference only. You can modify the information in subsequent commands based on actual conditions.

2. Run the following command to modify the attribute of the private key file:

   chmod 400 [Path of the .pem private key file on your on-premises device]

   Example:

   chmod 400 ~/.ssh/ecs.pem

3. Run the following commands to go to the .ssh directory in the home directory and create a config file:

   cd ~/.ssh
   vim config

4. In the config file, press the I key to enter the Insert mode and add the following configuration items:

   Sample code used to add configuration items for a single ECS instance:

   # Enter the alias of the ECS instance that you want to connect to over SSH. 
   Host ecs
   # Enter the public IP address of the instance. 
   HostName 121.196.**.**
   # Enter the port number. The default port number is 22. 
   Port 22
   # Enter the logon username. 
   User ecs-user
   # Enter the path of the .pem private key file on your on-premises device. 
   IdentityFile ~/.ssh/ecs.pem

   Sample code used to add configuration items for multiple ECS instances:

   # Enter the alias of the ECS instance that you want to connect to over SSH. 
   Host ecs1
   # Enter the public IP address of the instance. 
   HostName 121.196.**.**
   # Enter the port number. The default port number is 22. 
   Port 22
   # Enter the logon username. 
   User ecs-user
   # Enter the path of the .pem private key file on your on-premises device. 
   IdentityFile ~/.ssh/ecs.pem
   
   # Enter the alias of the ECS instance that you want to connect to over SSH. 
   Host ecs2
   # Enter the public IP address of the instance. 
   HostName 121.196.**.**
   # Enter the port number. The default port number is 22. 
   Port 22
   # Enter the logon username. 
   User ecs-user
   # Enter the path of the .pem private key file on your on-premises device. 
   IdentityFile ~/.ssh/ecs.pem

   After the configuration items are added, press the Esc key and enter :wq to save the config file.

5. Run the following command to restart the SSH service:

   Warning

   If the SSH service fails to be restarted, the SSH service may become unavailable and service interruptions may occur. We recommend that you restart the SSH service during off-peak hours.

   service sshd restart

6. Run the following command to connect to the instance:

   ssh [Alias of the instance]

   Example:

   ssh ecs

References

• If you want to log on to a Linux instance by using an SSH key pair as a user that you created on the instance, you must copy the ~/.ssh/authorized_keys file to the. ssh directory of the user. For more information, see Log on to a Linux instance as a user-created user by using an SSH key pair.

• The ECS console cannot be used to bind key pairs to Windows instances. If you want to use a key pair to log on to a Windows instance, you can enable the sshd service and configure a key pair inside the instance. For more information, see Connect to a Windows instance by using a password or key.

• If you want to log on to an instance by using the password-based authentication method after you bind a key pair to the instance, reset the password for the instance. After you reset the password for the instance, use the key pair or the new password to log on to the instance. For more information, see Reset the logon password of an instance.

• If you do not want to connect to a Linux instance by using an SSH key pair from an on-premises device, you can log on to the Linux instance by using Workbench from the ECS console. For more information, see Connect to a Linux instance by using a password or key.