Networking :: Mounting VMWare Guest (WinXP) Outside Host

I am running VMware workstation on a Linux host and WinXP guest using NAT. I have shared a folder on WinXP, and I am able to mount it on the linux host with:
mount -t smbfs -o username=Administrator,password=mypasswd //192.168.100.129/Shared /mnt/tmp
This works fine. However, I want to mount the same folder from a different linux machine (not the host).

I added port forwarding in /etc/vmware/vmnet8/nat/nat.conf:
[incomingtcp]
#445 = 192.168.100.129:445

If I run:
mount -t smbfs -o username=Administrator,password=mypasswd //external_ip_number/Shared /mnt/tmp

I am getting:
mount error 112 = Host is down
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)

It doesn't work even if I try the above command from the linux host itself. It only works if I use the internal IP number. I suspect vmware is not forwarding port 445 but I am not sure how to verify it. I am not running smbd on the linux host, in case that make any difference. I didn't think that was required because the server is really on the WinXP and the linux is just a client.