What Shoud I Do If the FTP Connectivity Test Fails and an Internal Server Error Is Reported?

Symptom

The root and FTPadmin users can log in to the ECS through FTP. Ports 21 and 20 of the security group are enabled. However, an internal server error is reported during the creation of an FTP link.

Solution

The background log shows that the error is a connection timeout, which may be caused by security group restrictions. Verify that the connectivity test is successful when the security group allows all traffic to pass through.

The firewall of the FTP server must allow the following communications so that the active FTP mode is available:

1. Any port greater than 1024 to port 21 of the FTP server (initial connection of the client).

2. Port 21 of the FTP server to a port greater than 1024 (control port for the server to respond to the client)

3. Port 20 of the FTP server to a port greater than 1024 (port for the communication between the initialized data link and the data port of the client)

4. Port greater than 1024 to port 20 of the FTP server (port through which the client sends ACK responses to the server)