samba hackers?

[Mike Egglestone]

Hi all...
Here's my setup...
A simple linux 2.2 box with samba installed...
2 nics...
one is a public IP from my isp....
the other is a private IP... (192.168.1.1)
I have a bunch of workstations that login on the private IP subnet...

I am wondering if anyone could login from the the public IP subnet....?
If so... can I block it?

I ask this because I noticed in my /var/log/smb
that all these usernames were trying to login to samba and were
all being rejected....(non -existant in passwd file) 
names I have no idea where they came from....
The log did not tell me the IP that they were coming from.....
Usually when I login from my 192.168.1.19 win98 box.. it logs nicely
and tells me the IP and stuff...and also when I typed my password wrong....

Any help is really appreciated....
One more note:
This would have nothing do to with Napster would it?
I access Napster from my windows box on my Private IP subnet...
and if someone downloads a mp3 from me... somehow.. napster
would be trying to login into samba?

thanks
Mike