Opening port 21, good or bad ?

I have an application that requires to open a port on my pc (my friend suggested to open port 21), I know how to open that port but I am just a bit worry about any security issues by doing this.
I was thinking to open another port, other than 21, such as 8800, any idea?

 

If you can change default listening port - do it.

 

Hello,

You want to open FTP Port then try to choose other port number for more security and close port 21.

 

is there any reason to not use port 21?

 

You will get much of invalid logon attempts.

But you can also allow ftp connections only from known ip addresses.

 

It just adds a small layer of security (through.. obscurity) - it's just recommended to change it to avoid a large portion of bots.

That being said I personally change the port and then using iptables filter traffic to it and only allow connections from ranges / IP's I trust.