changeing the port of the ftp server

fbsd_user fbsd_user at
Thu Feb 23 04:37:06 PST 2006

You would edit /etc/services to change the standard port numbers FTP
Say change port 20 & 21 to 35520 & 35521.

You also must realize that your public internet users who want to
your FTP server must also change their FTP port numbers to the same
ones you used in /etc/services before that can gain access to your FTP

This method is one way to hide your FTP server from attack because you
would only tell your trusted remote users what the new port numbers
All public attackers would be using the standard port 20 & 21 to
attack you.

If you want your public remote users to access your FTP server without
having to know the new port number, then this is no solution for you.

Now I have not heard of any ISP blocking ports 20/21 before, so I am
thinking maybe your firewall is blocking those port number.

What test did you run to verify your ISP is blocking those ports?
Does your ISP usage agreement say those ports are blocked?

-----Original Message-----
From: owner-freebsd-questions at
[mailto:owner-freebsd-questions at]On Behalf Of ross
Sent: Wednesday, February 22, 2006 11:59 PM
To: freebsd-questions at
Subject: changeing the port of the ftp server

I can't for the life of me figure out how to change the port of my ftp
server. My (crummy) ISP blocks port 21 and I would like to change the
default port of the ftp server in order to give access to the outside

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