Hi Srinivas Obili
Given your setup and the error you're encountering, the issue could be with the way FTP modes are being handled. FTP operates in two modes, active and passive, which determine how the connection between client and server is established, especially for transferring data such as directory listings.
Here is a brief description of the modes:
Active FTP: In active mode, the client opens a port and listens. The server must actively connect to the client to establish a data transfer connection.
Passive FTP: In passive mode, it is the server that opens a port and waits for a connection from the client. The client then initiates the data transfer connection to the server.
Now, in your case, passive mode is generally the preferred option for modern FTP services as it is more firewall friendly on the client side. As Azure by default uses NSG, ensuring that Passive mode is configured correctly is crucial as they often have ingress security rules in place.
Configure FTP Server for Passive Mode: On your FTP Server in IIS, you need to specify the range of ports that will be used for passive mode. This is usually a range of high ports (1024-65535) you can create your range of ports (for example, 5000-5100)
you need to ensure the Network Security Group attached to your Azure VM allows inbound traffic over the range of passive ports you've selected, as well as port 21 for the FTP control connection.
Reference:
Get in touch if you need more help with this issue.
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