Security setting to prevent passive ftp?

[Jonathan August]

For my users that use passive ftp, when they connect to ncftpd on my  
server, the connection takes a long time and eventually for them as  
dialup users, it times out.  If I try to ftp to the machine behind my  
firewall and specify to use passive, as soon as I try anything that  
sends data (ls, put, get), the connection gets dropped.  I turned off  
SELinux, but this didn't help.  Any ideas?

Also, when I try to ftp out from this box, I get the following:

$ ftp zimbabwe
Connected to zimbabwe.internection.com.
220 ready.
502 Command 'AUTH' not implemented.
502 Command 'AUTH' not implemented.
KERBEROS_V4 rejected as an authentication type
Name (zimbabwe:jon):

It doesn't do that from any other machine except this one with FC4 on  
it.

Any ideas are appreciated.

Thanks,
    -Jon