PASV works around some but not all NAT breakage. There are things FTP can do outside a NAT that it can't do with a NAT around. (Workarounds can be concocted, bu

PASV works around some but not all NAT breakage. There are things FTP can do outside a NAT that it can't do with a NAT around. (Workarounds can be concocted, but NAT really did take away some of the natural abilities of FTP.)