421 Service not available , remote server has closed connection


FTP error code 4xx means that the connection hasn’t been attempted and the requested action hasn’t taken place. But, this condition is temporary, and the action may be requested again.

And, FTP error 421 service not available means that the connection to the remote server can’t be established.

Refer Config file changes needed in Module 3


Make sure your server is running by using the ps command. Confirm the port where your server is listening by using the netstat command. Make sure the client is connecting to that port.

Use as the local host IP address if using the internal ftp client and the IP address of the QBox Server as seen in the top right section of your workspace if you are using an external client (Desktop or mobile client)

Another thing is to make sure you are starting the vsftpd process as root by using the sudo command.

Also, make sure you are typing in the correct username (crio-user) and password (can be seen in the top right section of your workspace).

To test if you are typing the password correctly, try the su - crio-user command to get to a password prompt. Enter the password here and you should login to a bash shell without any errors. This will confirm that you are using the password correctly.

If the error comes in while listing the files or changing the directories, this can be because of incorrect file read permissions. Make sure you have given the right file permissions.

If you are in Module4, remember that some versions are faulty. If this error is not seen with vsftpd_v1 (which is the correct version), then the version you are trying out may be faulty. Check if this behaviour can be classified under any of the error detection milestones in Module4.