Today we are checking the basic settings of the router. The door 21 It is universally used for FTP connections (File Transfer Protocol), so if we have problems to connect to our remote FTP account can be a good idea to check that your router or provider is not blocking connections on port 21. The reasons for not having access to your router settings may be different: public hotspot, connection in a hotel or another.
Everything we serve is a computer with Linux and a console.
We will use a simple telnet
$ telnet tuodominio.it 21
Dove “tuodominio.it” is the name of your domain.
If the connection is successful the command returns the greeting set on the server. It looks like the following:
220---------- Welcome to Pure-FTPd [privsep] [TLS] ---------- 220-You are user number 8 of 100 allowed. 220-Local time is now 19:55. Server port: 21. 220-This is a private system - No anonymous login 220-IPv6 connections are also welcome on this server. 220 You will be disconnected after 3 minutes of inactivity.
It is not necessary that the welcome message is exactly the same as above. If the command does not return anything means that the door is closed.
Rarely it happens to find it closed, saw the extensive use made of it today. It is to be investigated if the door is closed on the router, if it is disabled by the provider or if it is closed on the server. This aspect must be investigated from time to time.