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.

I've never played with VMWare so I don't know much about how you configure it.

But what I can see is that you got a # before 445 = 192.168.100.129:445.
What happends if you remove it?

I would've used iptables to forward the port.
Maybe something like this:
iptables -t nat -A PREROUTING -i <ethX> -p tcp --destination-port 445 -j DNAT --to-destination 192.168.100.129
iptables -A FORWARD -i <ethX> -o <vmX> -p tcp --destination-port 445 -j ACCEPT

Change <ethX> to the the NIC you are using, ie: eth0.
Change <vmX> to the vmware bridge or tap you are using. I have no idea if this will work.

- Simon

Oops, the # in front of 445 isn't really there. I commented that line it out briefly during tests. It actually is like this:

[incomingtcp]
445 = 192.168.100.129:445

Try my other idea.