FTP Port 21: Client/Host Usage & Alternatives

[tmt1]

I'm reading a text that is saying that the standard port for ftp is 21.

Do both the client/host use port 21? And what is the port is already being used, does it go to a different port?

 

[I like Serena]

I'm reading a text that is saying that the standard port for ftp is 21.

Do both the client/host use port 21? And what is the port is already being used, does it go to a different port?

Hi tmt,

The server listens on port 21.
Locally the client gets assigned an arbitrary port number, usually in the 5000+ range.
When a connection is made, the server usually spawns off a new socket on a new port, also in the 5000+ range.
That way port 21 on the server remains reserved for listening to new connections.

You can see this when you run the command line utility [m]netstat[/m] with the appropriate parameters.

 

[Nono713]

List of standard ports of various protocols for reference: Service Name and Transport Protocol Port Number Registry (IANA = Internet Assigned Numbers Authority)