[FW1] MS FTP behind NAT

[Glenn Mabbutt <gmabbutt@FW1-NOSPAMquartetservice.com>]

Title: MS FTP behind NAT

I'm having a rather irritating problem:  someone behind one of our FW-1 firewalls has to use Microsoft's command-line FTP (from win98, win2k, and winnt) as part of a batch script (I know it's junk, but the scripter won't use anything else).  I tried it behind a different FW-1, and it worked.  Here is the common configuration between the 2 firewalls:

- FW-1 4.1 on NT sp 6a
- hosts are being NATted, the test PC's are statically mapped to valid IP's (doing it without the static NAT gives a host of errors)

- ftp is enabled in the rulebase for outbound connections

Here's what's different between the 2 firewalls (firewall A functions properly, firewall B does not):

- firewall A is running FW-1 service pack 2, firewall B is running FW-1 service pack 3

- SYNDefender is set to "none" on firewall A and is set to "passive gateway" on firewall B

- under "logs and alerts" in Policy > Properties, "log established TCP connections" is checked on firewall A and is unchecked on firewall B.

Those are the only differences I can find.  What happens when I try to connect to an ftp server behind firewall B is that I can log in, but when I try to do a directory listing or cd to a directory I get an error saying "invalid port command" - no such error from behind firewall A.

Any suggestions??

thanks,
Glenn