I would like to add to this answer, because it took me quite a while to find all the pieces.

/etc/inetd.conf must have the ftpd and telnetd lines uncommentd *with no leading spaces*:

ftp     stream  tcp     nowait  root    /usr/sbin/tcpd  in.proftpd
ftp     stream  tcp     nowait  root    /usr/sbin/tcpd  in.ftpd -l -a
telnet  stream  tcp     nowait  root    /usr/sbin/tcpd  in.telnetd

Notice there is "proftpd" and "ftpd".  Make sure you get "ftpd".

kill the inetd with a HUP signal.  Find the pid:

$ps -ax | grep inetd
$kill -1 pid_from_above

If this doesn't fix the problem, you probably don't have in.ftpd (this was my problem).  Check:

$ls -l /usr/sbin/in.ftpd

If it isn't there, go and get it from a mirror.  It is the wu-ftpdxxxx.rpm file.

Install it using rpm, and then check to make sure it is there.  Restart inetd
as above.  This should fix the problem.  If it doesn't, you can check 
/etc/access.allow and /etc/access.deny for any hosts.  Default is for these
to be empty (which shouldn't deny any machines).

Mike McCallum
<mmccallum@uop.edu>