The default installation of Fastream NETFile FTP/Web Server 7.4.6, which supports FXP, does not require that the IP address in a PORT command be the same as the IP of the logged in user, which allows remote attackers to conduct FTP Bounce attacks to bypass firewall rules or cause a denial of service.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-1648
http://www.vupen.com/english/advisories/2005/0556