wu-ftp SERVER INFO:

wu-ftp is automatically installed by Linux and is also 
automatically launched when the systems boots, assuming you 
have installed the network module.  While it is not so clear
where they store the configuration files it is all installed 
and operational!

A few important facts:

Executable :  /usr/sbin/wu.ftpd 

Configuration files: /etc
                        ftpaccess
                        ftpconversions
                        ftpgroups
                        ftpusers

FTP directory : /home/ftp

Other subdirectories under the /home/ftp directory:
      bin
      etc
      incoming
      lib
      pub
      usr
      (and a welcome.msg file for your automatic greeting)
 

HOW DOES IT GET LAUNCHED?

This is very interesting!

Ftpd is launched by inetd but under a wrapper of tcpd.  One
of the developers has created a cool way to add security to ANY
(almost)  server launched under inetd using TCP/IP. Check out
the details in the README file in /usr/sbin/real-daemon-dir.
tcpd is the name of the wrapper, but it is not listed as a
service per se because clients don't access it directly, but
indirectly as it accesses some other service.

What port? 21 as usual for ftp