Active FTP vs. Passive FTP, a Definitive Explanation

GRC | Port Authority, for Internet Port 21 Unless another port is specified, FTP servers listen for clients to connect on their port 21. The use of non-default FTP server ports is more common than for other protocols due to the historic trouble with malicious hackers searching for FTP servers on port 21. FTP Connection Issue: How to Check If FTP Port 21 Is Not Jun 16, 2020 security - I own an FTP server, and need port 21 open, how FTP actually requires two ports, 21 is the main control port, and 20 is for data. FTP is a weird protocol, it was created really early in the Internet days, before firewalls and security was thought of. As such, as designed, it sucks for firewalling. The ftp server listens on port 21 for connections from a client. But data goes over another port.

Jul 21, 2020

The connection with the FTP server's port 20 is the second connection created during an FTP session, the first one being to the server's port FTP servers open their machine's port 21 and listen for incoming client connections. FTP clients connect to port 21 of remote FTP servers to … How to Set Up Port Forwarding - Lifewire Apr 10, 2020

Firewall blocking ports 21 and 80? - Server Fault

Instead of port forwarding port 21 which is used by Orbi, please port forwad one of the free ports like 8121 to port 21 on the target device, and then use your public IP and port 8121 to connect remotely to port 21 on the target device Firewall blocking ports 21 and 80? - Server Fault The server has ports 80 and 21 open. – Markaway Dec 19 '12 at 19:28 BTW, This type of information should be put in the original note as it is of significant import in helping you to solve your problem. How to Check Port 21 is Open Solutions | Experts Exchange