Allowing SSL connections through Linux firewall

[Art Mason <amason () webinterlink net>]

Hello, this is my first post to the list.  Just been here a few days and have
already gleaned a wealth of information.  
Okay, here's the problem:

I've set up a Linux box for a client of mine running NAT/IP Masquerading
(ipchains) and SMTP (postfix). It allows the private network of 9 win32 boxes to
browse and do e-mail over a 56 Kbps dialup digital line.  All seems to be going
well, except for the fact that when accessing an online banking account which
initiates an SSL transaction, the connection just sits there and times out. 
However, the same machine can connect to the same ISP via modem, and complete
the entire SSL-authenticated session w/ the same remote host error-free and w/o
incident.  I'm figuring that since default policy for ipchains handling
external (Internet) traffic coming in is DENY, the remote host requesting
acknowledgement from the local machine which started the SSL authentication
sesson in the first place fails because IP masquerading isn't properly
forwarding the SSL traffic to the local machine making the request correctly. 
Are there a fixed set of ports made w/ SSL authentication, and if so will I be
able to plug these ports into the ipchains startup script w/ policies to
correctly forward these SSL sessions w/o violating the integrity of the
firewall?  Any help would be greatly be appreciated, and my appologies if I
posted to the wrong list.

Art Mason
Rio Datacom Technologies