Instance connection FAQ

Symptom

An FTP service on a Windows ECS instance is unreachable from the internet.

Cause

Possible causes include:

• Incorrect security group rules for FTP: 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 FTP firewall support.

Solution

Choose a solution based on the cause.

Solution 1: Add security group rules for FTP

After you set up an FTP site on an ECS instance that runs Windows, you must add an inbound rule to the security group of the instance to allow traffic on port 21 for the FTP server and on the port range 1024-65535 for passive mode. For more information, see Add a security group rule.

Solution 2: Configure FTP firewall support

If the firewall is enabled, you must configure IIS Manager to allow FTP traffic on TCP port 21 and the port range 1024-65535. Follow these steps:

1. Connect to the Windows instance.

   For more information, see Connect to a Windows instance by using a password or key.

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

3. Set the parameters and click Apply.

   Note

   Parameters:

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

   • Data Channel Port Range: Specify the port range for passive connections. The valid port range is 1024-65535. This topic uses 1024-65535 as an example.

4. Open the command line and run the following command to restart the FTP service. This applies the new configuration to all FTP sites.

   net stop ftpsvc&net start ftpsvc

5. (Optional) If the FTP server is locally accessible but unreachable from other machines after configuration, the firewall might be misconfigured. Follow these steps to correctly configure the firewall:

   1. Check the inbound rules in Server Manager to make sure that the FTP server is enabled.

   2. Add the Windows service host process.

      1. Navigate to Control Panel > Windows Firewall and click Allow an App or Feature Through Windows Firewall in the left-side navigation pane.

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

      3. Select the new Windows Service Host Process item, select the Private and Public checkboxes, and then click OK.

Symptom

When you connect to the FTP server on an ECS instance that runs Windows, the following error is reported:

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

Cause

Possible causes include:

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

• Incorrect FTP user permissions: For more information, see Solution 2: Add FTP user permissions.

Solution

Choose a solution based on the cause.

Solution 1: Change the FTP password

1. Connect to the Windows instance.

   For more information, see Connect to a Windows instance by using a password or key.

2. On the desktop, right-click Computer > Manage to open Server Manager.

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

Solution 2: Add FTP user permissions

1. Connect to the Windows instance.

   For more information, see Connect to a Windows instance by using a password or key.

2. Check whether the FTP user directory exists.

   1. If the directory does not exist, re-create it and add the required permissions. For more information, see Step 3: Set permissions for shared files.

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

Symptom

When connecting to an FTP server on a Windows ECS instance by IP address, a "530 valid hostname is expected" or "503 Login with USER first" error occurs if the FTP site, configured in IIS 7.5, is bound to a domain name.

Cause

This error occurs because the username format is incorrect when you log on to an FTP service that is bound to a domain name in IIS 7.5.

Solution

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

Symptom

A "550 Permission denied" error is reported when you upload a file to FileZilla Server by using FTP on an ECS instance that runs Windows.

Cause

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

Solution

1. Connect to the Windows instance.

   For more information, see Connect to a Windows instance by using a password or key.

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

3. Select the corresponding user and directory, select the Write checkbox, and then click OK to grant the permission.

Symptom

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

Cause

This issue usually occurs because the client is in a NAT network that is associated with more than one public IP address. As a result, the source IP addresses for the control and data connections are inconsistent, causing the error.

Solution

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

1. Connect to the Linux instance.

   For more information, see Connect to a Linux instance by using a password or key.

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

   vi /etc/vsftpd/vsftpd.conf

3. Press i to enter edit mode and add the following content to the configuration file:

   pasv_promiscuous=yes

4. Press Esc to exit edit mode, enter :wq, and then press Enter to save and exit.

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

   systemctl restart vsftpd

Symptom

Uploading a file to an ECS instance that runs Linux by using vsftp fails with a "553 Could not create file" error.

Cause

Possible causes include:

• The disk space of the Linux instance is full.

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

Solution

Follow these steps to check the instance's disk space and the FTP home directory permissions:

1. Connect to the Linux instance.

   For more information, see Connect to a Linux instance by using a password or key.

2. Run the following command to check whether the disk is full.

   df -h

   Note

   If a partition's disk space usage reaches 100%, it is full.

   A similar output is displayed. For example, the space usage of the /dev/xvda1 partition is 59%.

   Filesystem      Size  Used Avail Use% Mounted on
   /dev/xvda1       20G   11G  7.8G  59% /
   tmpfs           498M  1.6M  496M   1% /dev/shm

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 your actual FTP home directory name.

   ls -l /home/user

   If the permission string in the output does not include w, you do not have the write permission. For example:

   dr-xr-xr-x  4 xxx              xxx            4096 May 10 21:47 zhengbo

4. Run the following command to add the write permission:

   chmod +w /home/user

5. Run the following command to verify the permission. If the command output contains w, the write permission is added.

   ls -l /home/user