HI I am trying to access a ftp server . I am able to connect to it with the user name and password. However when i connect to the server and do a dir i get the following error.

C:\Documents and Settings\Admin>ftp XXX.XXX.XXX.XXX Connected to XXX.XXX.XXX.XXX 220 Microsoft FTP Service User (XXX.XX.XXX.XXX:(none)): user-name 331 Password required for user-name Password: 230 User user-name logged in. ftp> dir 500 Invalid PORT Command. 150 Opening ASCII mode data connection for /bin/ls. I got a fire wall running and i have opened port 21, The entry in the iptables is as follows .

-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 21 -j ACCEPT

why am i getting the error ?? when i am able to ftp to other ftp site with out authentication ( like ftp://202.96.64.144/pub/ )

Thanks !!