Files are either uploaded or downloaded to the FTP server. The files are moved from a personal computer to the server when you upload files. The files are moved from the cloud to your personal computer when the files are downloaded. In order to transfer files through FTP, TCP/IP (Transmission Control Protocol/Internet Protocol), or the language used by the internet to execute commands, is used.
To adjust the default Linux port of the Proftpd operation, first, open the Proftpd main configuration file for editing with your favorite text editor by issuing the command below.
Step 1: First open Proftpd main configuration file for editing.
$ nano /etc/proftpd/proftpd.conf
Step 2: Find the following line port number.
Step 3: And change the FTP default port 21 to a custom port, for example, 210.
Step 4: Save and close the file. To take effect the changes, restart the proftpd service using the below command
$ systemctl restart proftpd
Step 5: Check the table of local network sockets with the netstat or ss command.
$ netstat -tlpn| grep nginx OR $ ss -tlpn| grep nginx
Now your FTP port should be changed.