Elastic Compute Service:Instance connection FAQ

Symptom

The FTP service on a Windows ECS instance cannot be connected to or accessed from the Internet.

Cause

This issue may occur for the following reasons:

• FTP security group rules are not configured to allow access: For more information, see Solution 1: Add security group rules for FTP.

• The firewall blocks the FTP process: For more information, see Solution 2: Configure firewall support for FTP.

Solutions

Choose one of the following solutions based on your requirements.

Solution 1: Add security group rules for FTP

After you set up an FTP site on a Windows ECS instance, you must add an inbound rule to the security group of the instance. This rule must allow access to port 21 and the port range from 1024 to 65535, which the FTP server may use in passive mode. For more information, see Add a security group rule.

Solution 2: Configure firewall support for FTP

If the firewall is enabled, you must configure IIS Manager to allow FTP traffic on TCP port 21 and the port range from 1024 to 65535. To do so, perform the following steps:

1. Remotely connect to the Windows instance.

   For more information, see Log on to a Windows instance using a password or key.

2. Open IIS Manager and double-click FTP Firewall Support to open its configuration page.

3. Configure the parameters and click Apply.

   Note

   The parameters are described as follows:

   • External IP Address of Firewall: Enter the public IP address of the Windows ECS instance.

   • Data Channel Port Range: The range of ports for passive connections. The valid port range is 1025 to 65535. You can set a custom range based on your requirements. For example, you can enter 1024 to 65535.

4. Open the command line and run the following command to restart the FTP service. This ensures that the new configuration overwrites the existing configuration for each FTP site.

   net stop ftpsvc&net start ftpsvc

5. (Optional) If you can access the FTP server from the local machine but not from other machines after the FTP server is configured, the issue is caused by an incorrect firewall configuration. Perform the following steps to configure the firewall:

   1. First, check the inbound rules in Server Manager to ensure that the FTP server is enabled.

   2. Add the main process of the Windows service.

      1. Go to Control Panel > Windows Firewall. In the left navigation pane, click Allow an App or Feature Through Windows Firewall.

      2. In the new window, click Allow Another App.... In the Browse window, open C:\Windows\System32\svchost.exe to add the service host process.

      3. When a Windows Service Host Process item appears, select the Private and Public checkboxes, and then click OK.

Symptom

When you connect to the FTP server on a Windows ECS instance, the following error message is displayed.

Response: 331 Please specify the password.
Command: PASS ************
Response: 530 Login incorrect.
Error: Critical error: Could not connect to server

Cause

This issue may occur for the following reasons:

• The FTP password is incorrect: For more information, see Solution 1: Change the FTP password.

• The FTP user permissions are configured incorrectly: For more information, see Solution 2: Add FTP user permissions.

Solutions

Choose one of the following solutions based on your requirements.

Solution 1: Change the FTP password

1. Remotely connect to the Windows instance.

   For more information, see Log on to a Windows instance using a password or key.

2. You can open Server Manager by right-clicking Computer > Manage on the desktop.

3. In the left navigation pane, click Local Users and Groups > Users. Right-click the FTP account and select Set Password.

Solution 2: Add FTP user permissions

1. Remotely connect to the Windows instance.

   For more information, see Log on to a Windows instance using a password or key.

2. Check whether the directory for the FTP user exists.

   1. If the directory does not exist, see Step 3: Set permissions for shared files to recreate the directory for the FTP user and add the required permissions.

   2. If the file already exists, right-click the folder and select Properties > Security. Then, select the FTP account and grant the required permissions.

Symptom

After you attach a domain name to an FTP site on IIS 7.5, a "530 valid hostname is expected" or "503 Login with USER first" error occurs when you connect to the FTP server on the Windows ECS instance using an IP address or other methods.

Cause

This issue occurs because the logon format is incorrect after you attach a domain name to an FTP site that is configured in IIS 7.5.

Solution

If the domain name attached to the FTP site is www.example.com and the username is user, you must use the www.example.com|user format to log on.

Symptom

When you use FTP to upload a file to FileZilla Server on a Windows ECS instance, a "550 Permission denied" error is returned.

Cause

The FTP account in FileZilla Server does not have the write permission.

Solution

1. Remotely connect to the Windows instance.

   For more information, see Log on to a Windows instance using a password or key.

2. Start FileZilla Server. On the Users page, select Shared folders.

3. Select the user and directory, select the Write check box, and click OK to grant the permission.

Symptom

A "425 Security:Bad IP connection" error occurs when a user uploads a file to an FTP site on a Linux ECS instance.

Cause

This issue usually occurs because the client is in a Network Address Translation (NAT) network that is associated with more than one public IP address. This causes the source IP address to be inconsistent between the control connection and the data connection, which results in the error.

Solution

Perform the following steps to disable the IP security check in passive mode.

1. Remotely connect to the Linux instance.

   For more information, see Log on to a Linux instance using a password or key.

2. Run the following command to edit the FTP configuration file.

   vi /etc/vsftpd/vsftpd.conf

3. Press the i key to enter edit mode. Add the following content to the configuration file.

   pasv_promiscuous=yes

4. After you finish editing, press the Esc key to exit edit mode. Then, enter :wq and press the Enter key to save the changes and exit.

5. Run the following command to restart the FTP service.

   systemctl restart vsftpd

Symptom

File uploads to a Linux ECS instance using vsftp fail with the "553 Could not create file" error.

Cause

This issue may occur for the following reasons:

• The disk space of the Linux instance is full.

• The FTP home directory does not have the write permission.

Solution

Perform the following steps to check the disk space of the Linux instance and the permissions of the FTP home directory.

1. Remotely connect to the Linux instance.

   For more information, see Log on to a Linux instance using a password or key.

2. Run the following command to check if insufficient disk space on the Linux instance caused the file upload to fail.

   df -h

   Note

   A disk partition is considered full when its space usage is 100%.

   The system returns a message similar to the following example, in which the space usage of the /dev/xvda1 partition is 59%.

   

3. Run the following command to check whether the FTP home directory has the write permission.

   Note

   Before you run the following command, replace /home/user with the actual FTP home directory.

   ls -l /home/user

   If the permissions shown in the red box in the following figure do not include w, you do not have the write permission.

   

4. Run the following command to add the write permission and save the change.

   chmod +w /home/user

5. Run the following command. If the command output contains w, the write permission is granted.

   ls -l /home/user