FTP bounce inside proxy

["Stout, Bill" <StoutB () pios com>]

One day browsing the web, I came across an FTP site that said "You are now
behind a firewall" and went on to discuss FTP proxy settings for using that
site.  Now recognizing that most small companies/sites only have one
firewall, don't have a DMZ, I'll guess that their network looks like this:
Internet----FW----Inside (including FTP server).

Can an FTP bounce attack systems (or other ports on that FTP server) behind
a proxy?

Note: For legacy FTP bounce attack description, see:
ftp://ftp.cert.org/pub/tech_tips/FTP_PORT_attacks

Bill Stout