From: John Beckett 

It doesn't have anything to do with domains. The issue is file sharing.

Downlevel (pre-Windows 2000) computers in a TCP/IP network need NBT
(NetBIOS over TCP/IP) to access file shares. That involves TCP port 139.

W2000 and later computers can use NBT, but can also perform "direct
hosting" where TCP port 445 directly provides the SMB file sharing
(whereas port 139 can do a bunch of things).

If you disable NBT, only W2000 and later computers can access file shares.

John


"Geo."  wrote in message
news::
> "Rich Gauszka"  wrote in message
> news:40c92036$1{at}w3.nls.net...
>
> > http://ntsecurity.nu/papers/port445/
>
> Thanks, smb instead of netbios, that's the one I was thinking of, I was
missing
> the protocol change. Netbios is only needed with NT4 domain servers and in
that
> case it can't use 445, right?
>
> Geo. (I'm still running NT4 domains so I've not played with this much)
>
>

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