Samba on a router; doesn't work for outer network.

[Rob]

Hi,

I have tried to configure Samba on a FreeBSD (5.3) router & NAT.

I want to have a single accessible directory with a password,
that can be accessed from the inner network (10.0.0.X) as well
as from the outer network (outer network = Windows PCs that use
the same external router as the FreeBSD PC).

It works for the inner network, but not for the outer network
(see below for network scheme). All Windows PCs are XP.

For testing this, I use an 'open' firewall. I should tighten the
firewall as soon as this is working.

The /usr/local/etc/smb.conf (configured with swat) is as follows:

#------------ smb.conf ----------------------------------
[global]
         workgroup = CISR
         netbios name = SURFACE
         server string = FreeBSD Samba Server
         passdb backend = tdbsam
         log file = /var/log/samba/log.%m
         max log size = 50
         dns proxy = No
         ldap ssl = no

[share]
         comment = Shared stuff
         path = /home/share
         invalid users = @wheel
         valid users = share
         read only = No
         force create mode = 0700
         force security mode = 0700
#---------------------------------------------------------


The network scheme is as follows:

                        |IP on outer network
                        |
                      |---------|
                      | FreeBSD |
  |------------|      | Router  |
  |   Switch   |      |---------|
  |------------|        |10.0.0.1
    |  |  |  |          |
    |  |  |  \----------/
    |  |  |
    |  |  10.0.0.2
    |  |
    |  10.0.0.3
    |
    10.0.0.4


What could be blocking Samba on the outer network?
What communication is essential for Samba to work on the outer network?
What tests can I do on the router to find out what's going wrong?

Thanks so much,
Rob.